Kubernetes/Istio

Architecture Istio ~v1.7+

Namespace: <app namespace>
  | app1  |                | app2  |  # main container
  | proxy |  <---------->  | proxy |  # Data Plane (all Envoy sidecar proxies)
  |  pod  |                |  pod  |

Namespace: istio-system
| |citadel|        |mixer|       |pilot| |
| |  pod  |        | pod |       | pod | | 
|      C o n t r o l  P l a n e  A P I   |
 ----------------------------------------

Note: All proxies are collectively named Data Plane and everything else that Istio deployed is called Control Plane

Note: Proxy term meaning is when someone has authority to represent someone. In software proxy components are invisible to clients. proxies

Security Architecture

Pod networking changed v1.10 matching default Kubernetes behaviour

Ports

service/istiod:
15010 - grpc-xds
15012 - https-dns
15014 - http-monitoring
443   - https-webhook, container port 15017

Istio components

• Istio-telemetry
• Istio-pilot
• Istio-tracing

Istio components

Envoy L7 proxy	Pilot	Citadel	Mixer[deprecate]	Galley
Dynamic service discovery Load balancing TLS termination Health checks Staged rollouts Fault injection	Converts Istio configuration into a format that Envoy can understand. Aware about pods health, what pods are available and sends to the proxy pods that are alive with any other configuration updates. Propagates the configuration to the Proxies Service discovery Intelligent routing Resiliency	Manages certificates, allows to enable TLS/SSL across entire cluster. User authentication Credential management Certificate management Traffic encryption Pods istio-citadel-* It's certificate store.	handles Access control Usage policies, rate limiting Telemetry data (data scraping) It has a lot of modules/plugins. Pods: istio-policy-* istio-telemetry-*	Interface for underlying Istio API gateway(aka server). It reads in k8s yaml and transforms it into internal structure Istio understand.

Istio UI components:

• grafana:3000 - dashboards
• kiali:31000 - visualisation, tells what services are part of istio, how are they connected and performing
• jaeger:31001 - tracing

Noticeable changes

• In Istio 1.6, completed transition and fully moved functionality into Istiod. This has allow to remove the separate deployments for Citadel, the sidecar injector, and Galley.

Istio on minikube

# Minimum requirements are 8G and 4 CPUs
K8SVERSION=v1.18.9
PROFILE=minikube-$K8SVERSION-istio
minikube profile $PROFILE # set default profile

minikube start --kubernetes-version=$K8SVERSION
minikube start --memory=8192 --cpus=4 --kubernetes-version=$K8SVERSION --driver minikube
minikube start --memory=8192 --cpus=4 --kubernetes-version=$K8SVERSION --driver kvm

minikube tunnel
minikube addons enable istio # [1] error

Troubleshooting

[1] - no matches for kind "IstioOperator"

💣  enable failed: run callbacks: running callbacks: [sudo KUBECONFIG=/var/lib/minikube/kubeconfig /var/lib/minikube/binaries/v1.17.6/kubectl apply -f /etc/kubernetes/addons/istio-default-profile.yaml: Process exited with status 1
stdout:
namespace/istio-system unchanged

stderr:
error: unable to recognize "/etc/kubernetes/addons/istio-default-profile.yaml": no matches for kind "IstioOperator" in version "install.istio.io/v1alpha1"

Install bookinfo example app.

Install

istioctl cli

The curl ISTIO_VERSION=1.10.0 sh - just downloads istio files into its own directory. It does not install anything

# Option_1 - the official approach
curl -L https://istio.io/downloadIstio | ISTIO_VERSION=1.10.0 sh -
cd istio-1.10.0/  # istio package directory
export PATH=$PWD/bin:$PATH

# Option_2
export ISTIO_VERSION=1.10.0
curl -L https://istio.io/downloadIstio | sh -
export PATH=$PWD/istio-$ISTIO_VERSION/bin:$PATH
export ISTIO_INSTALL_DIR=$PWD/istio-$ISTIO_VERSION

# Check version
istioctl version --remote
client version: 1.9.1
control plane version: 1.9.1
data plane version: 1.9.1 (7 proxies)

# Pre-flight check
istioctl x precheck

# Verify the install
istioctl verify-install
...
CustomResourceDefinition: templates.config.istio.io.default checked successfully
CustomResourceDefinition: istiooperators.install.istio.io.default checked successfully
Checked 25 custom resource definitions
Checked 1 Istio Deployments
Istio is installed successfully

# Verify mesh coverage and the config status 
istioctl proxy-status
NAME                                                  CDS        LDS        EDS        RDS        ISTIOD                      VERSION
details-v1-5974b67c8-xbp8l.default                    SYNCED     SYNCED     SYNCED     SYNCED     istiod-5c6b7b5b8f-9npdz     1.9.1
istio-ingressgateway-5689f7c67-gvrh8.istio-system     SYNCED     SYNCED     SYNCED     SYNCED     istiod-5c6b7b5b8f-9npdz     1.9.1
...

# Analyse the mesh configuration
istioctl analyze --all-namespaces

control plane

• Install with Istioctl - recommended
• Istio Operator Install
• Install with Helm

Istio maintainers with increasing complexity of the project that goes against the user friendliness still support helm manifest based configuration although there is fair movement towards the operator pattern. See below for differences, v1.6 and v1.7 still support both methods.

There are a few operational modes to configure control plane:

• istio operator
  • install - istioctl install with --set or -f istio-overlay.yaml will be overlayed on top of a chosen profile
  • reconfigure - istioctl manifest apply -f istio-install.yaml --dry-run
  • istio operator init installs the operator pod istio-operator. Then using kubectl apply -f istio-overlay.yaml will trigger the operator to sync the changes. Also manually changing istio-system/istiooperators.install.istio.io/installed-state object will trigger an the operator event to sync the config and reconfigure teh control-plane.
• [deprecated] istioctl manifest install with --set or -f <manifests.yaml>

Install

# Tested with 1.7.3 [depreciating method via helm charts], --set values are prefixed with 'values.'
istioctl manifest install --skip-confirmation --set profile=default \
  --set values.kiali.enabled=true      \
  --set values.prometheus.enabled=true \
  --dry-run

# Tested with 1.8.2 [istio.operator via 'istioctl' cli]
istioctl x precheck
istioctl install --skip-confirmation --set profile=default --dry-run # via operator
istioctl upgrade --skip-confirmation --set profile=default --dry-run # via operator

Using istio.operator via manifest yaml

Basic	+Kiali,Prometheus	+ServiceEntry, mesh traffic only	+egress
<syntaxhighlightjs lang=yaml> istioctl manifest install -f <(cat <<EOF apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: default EOF ) </syntaxhighlightjs>	<syntaxhighlightjs lang=yaml> istioctl manifest install -f <(cat <<EOF apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: default values: kiali: enabled: true prometheus: enabled: true EOF ) </syntaxhighlightjs>	<syntaxhighlightjs lang=yaml> istioctl manifest install -f <(cat <<EOF apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: default values: kiali: enabled: true # Kiali uses Prometheus to populate its dashboards prometheus: enabled: true meshConfig: # debugging accessLogFile: /dev/stdout outboundTrafficPolicy: mode: REGISTRY_ONLY EOF ) </syntaxhighlightjs>	<syntaxhighlightjs lang=yaml> istioctl manifest install -f <(cat <<EOF apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: default components: egressGateways: - enabled: true name: istio-egressgateway values: kiali: enabled: true prometheus: enabled: true meshConfig: accessLogFile: /dev/stdout outboundTrafficPolicy: mode: REGISTRY_ONLY EOF ) </syntaxhighlightjs>

Uninstall

Uninstall v1.6.8, it's safe to ignore RBAC not existing resources.

istioctl manifest generate --set profile=default | kubectl delete --ignore-not-found=true -f -
kubectl delete namespace istio-system

Uninstall v1.7.x - view logs

# Removes istio-system resources and istio-operator
istioctl x uninstall --purge # cmd:experimental, aliases: experimental, x, exp
✔ Uninstall complete

Install - day 2 operation

This should be a preferred method for day 2 operations - canary upgrade where CP gets installed with revisions and Ingress-Gateway components are installed separately.

Pre checks

istioctl experimental precheck
istioctl analyze -A

# Optional labels
kubectl label namespace default istio-injection=enabled
kubectl label namespace default istio-injection=disabled

Install control-plane

Note: For installing v1.9.x you should first install without revisions eg.REVISION="" this is because revisions upgrade expects to have default revision set.

Note: Due to a bug in the creation of the ValidatingWebhookConfiguration during install, initial installations of Istio must not specify a revision. A workaround is to run command below, where <REVISION> is the name of the revision that should handle validation. This command creates an istiod service pointed to the target revision.

kubectl get service -n istio-system -o json istiod-<REVISION> | jq '.metadata.name = "istiod" | del(.spec.clusterIP) | del(.spec.clusterIPs)' | kubectl apply -f -

REVISION="" # don't use revisions
REVISION='--revision 1-10-0'

istioctl install -y -n istio-system $REVISION -f <(cat <<EOF
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
metadata:
  name: control-plane
  #namespace: istio-system # it's default
spec:
  profile: minimal # installs only control-plane
  hub: gcr.io/istio-release
  components:
    pilot:
      k8s:
        hpaSpec:
          minReplicas: 2
        env:
        - name: PILOT_FILTER_GATEWAY_CLUSTER_CONFIG # Reduce Gateway Config to services that have routing rules defined
          value: "true"
  meshConfig:
    defaultConfig:
      proxyMetadata:
        # https://preliminary.istio.io/latest/blog/2020/dns-proxy/
        # curl localhost:8080/debug/nsdz?proxyID=<POD-NAME>
        # dig @localhost -p 15053 postgres-stolon-proxy.sample.svc
        ISTIO_META_DNS_CAPTURE: "true"
    enablePrometheusMerge: true
    #discoverySelector: # new in v1.10, choose which namespaces Istiod should watch for configurations of services,endpoints,deployments
    #- matchLabels:
    #    istio-discovery: enabled # <- example label
    #    #env: prod
    #    #region: us-east-1
    #- matchExpressions:
    #  - key: app
    #    operator: In
    #    values:
    #    - cassandrs
    #    - spark
EOF
) --dry-run

Verify if there any clients are connected to Istio v1.10.0

kubectl create deployment sleep --image=curlimages/curl -- /bin/sleep 3650d
kubectl exec -it deploy/sleep -- curl istiod-1-10-0.istio-system:15014/debug/connections | jq .
{
  "totalClients": 0,
  "clients": null
}
# Show all discovered endpoints
kubectl exec -it deploy/sleep -- curl istiod-1-10-0.istio-system:15014/debug/endpointz | jq . # ~1800+ lines for empty Minikube

Sidecar proxy automatic injection by telling a namespace which revision (aka control plane) to select/use.

kubectl label namespace default istio.io/rev=1-10-0 istio-injection-

Note: The istio-injection label must be removed because it takes precedence over the istio.io/rev label for backward compatibility.

Upgrade with Canary tag revision for isolated testing

# Tag the new control-plane version with 'canary' tag
istioctl experimental revision tag set canary --revision 1-10-0
Revision tag "canary" created, referencing control plane revision "1-10-0". To enable injection using this
revision tag, use 'kubectl label namespace <NAMESPACE> istio.io/rev=canary'

# Show tagged revision
istioctl experimental revision list 
REVISION TAG    ISTIO-OPERATOR-CR                                 PROFILE REQD-COMPONENTS
1-10-0   canary istio-system/installed-state-control-plane-1-10-0 minimal base
                                                                          istiod

# Update a namespace label to use the newly tagged control-plane for the injected sidecars to use it/connect to it
kubectl label namespace default istio.io/rev=canary --overwrite

# Restart deployments for new proxy to be injected, test the application and if all is good delete the "app canary deployment" and continue with full rollout of all deployments.

Install ingress-gateway

We install the ingress-gateway components separated in a separated namespace istio-ingrss. This is to allow to upgrade CP and IGW components independent. We achieve this using 'minimal' profile that includes only control CP components. Then for IGW install we use 'empty' profile that adds only the ingress-gateway. More about included components in each of profiles

# Create ingress own namespace
kubectl create ns istio-ingress

# Install revision
REVISION='--revision 1-10-0'
istioctl install -y -n istio-ingress $REVISION -f <(cat <<EOF
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
metadata:
  name: istio-ingressgateway
spec:
  profile: empty # uses the 'empty' profile and enables the istio-ingressgateway component
  hub: gcr.io/istio-release
  components:
    ingressGateways:
    - name: istio-ingressgateway
      namespace: istio-ingress # if not set defaults to 'istio-system'
      enabled: true
      k8s:
        hpaSpec:
          minReplicas: 2
        service:
          type: LoadBalancer
        overlays:
        - apiVersion: apps/v1
          kind: Deployment
          name: istio-ingressgateway
          patches:
          - path: spec.template.spec.containers[name:istio-proxy].lifecycle
            value:
              preStop:
                exec:
                  command: ["sh", "-c", "sleep 5"]
EOF
) --dry-run

# Verify
# | Note that 'revision' relates to control-plane thus ingressgateway 'installed-state-istio-ingressgateway-1-10-0' installation
# | does hot have revision set

## Show IstioOperator installations
kubectl -n istio-system get istiooperators.install.istio.io 
NAME                                          REVISION   STATUS   AGE
installed-state-control-plane-1-10-0          1-10-0              165m
installed-state-istio-ingressgateway-1-10-0   1-10-0              8m47s

## Show revisions
istioctl experimental revision list 
REVISION TAG    ISTIO-OPERATOR-CR                                        PROFILE REQD-COMPONENTS
1-10-0   canary istio-system/installed-state-control-plane-1-10-0        minimal base
                                                                                 istiod
                istio-system/installed-state-istio-ingressgateway-1-10-0 empty   ingress:istio-ingressgateway

## Test
GATEWAY_IP=$(kubectl get svc -n istio-system istio-ingressgateway -o jsonpath="{.status.loadBalancer.ingress[0].ip}")
# With Gateway and VirtualService we can route traffic to a destination service via IngressGateway
curl -H "Host: example.com" http://$GATEWAY_IP

Note: As the next step IngressGateway can be integrated with Cert Manager

Reduce Gateway Config

# Show what services IngressGateway has discovered, the list has even those that no routing is defined
istioctl pc clusters deploy/istio-ingressgateway -n istio-system

# Set PILOT_FILTER_GATEWAY_CLUSTER_CONFIG environment variable in the istiod deployment
#  kind: IstioOperator
#  spec:
#    components:
#      pilot:
#        k8s:
#          env:                                                                            
#          - name: PILOT_FILTER_GATEWAY_CLUSTER_CONFIG                                                  
#            value: "true"

(Optional) Access logging for gateway only using EnvoyFilter

• Istio docs explain to enable Envoy's Access Logs for the entire service mesh

kubectl apply -f <(cat <<EOF
apiVersion: networking.istio.io/v1alpha3
kind: EnvoyFilter
metadata:
  name: ingressgateway-access-logging
  namespace: istio-system
spec:
  workloadSelector:
    labels:
      istio: ingressgateway
  configPatches:
  - applyTo: NETWORK_FILTER
    match:
      context: GATEWAY
      listener:
        filterChain:
          filter:
            name: "envoy.filters.network.http_connection_manager"
    patch:
      operation: MERGE
      value:
        typed_config:
          "@type": "type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager"
          access_log:
          - name: envoy.access_loggers.file
            typed_config:
              "@type": "type.googleapis.com/envoy.extensions.access_loggers.file.v3.FileAccessLog"
              path: /dev/stdout
              format: "[%START_TIME%] \"%REQ(:METHOD)% %REQ(X-ENVOY-ORIGINAL-PATH?:PATH)% %PROTOCOL%\" %RESPONSE_CODE% %RESPONSE_FLAGS% \"%UPSTREAM_TRANSPORT_FAILURE_REASON%\" %BYTES_RECEIVED% %BYTES_SENT% %DURATION% %RESP(X-ENVOY-UPSTREAM-SERVICE-TIME)% \"%REQ(X-FORWARDED-FOR)%\" \"%REQ(USER-AGENT)%\" \"%REQ(X-REQUEST-ID)%\" \"%REQ(:AUTHORITY)%\" \"%UPSTREAM_HOST%\" %UPSTREAM_CLUSTER% %UPSTREAM_LOCAL_ADDRESS% %DOWNSTREAM_LOCAL_ADDRESS% %DOWNSTREAM_REMOTE_ADDRESS% %REQUESTED_SERVER_NAME% %ROUTE_NAME%\n"
EOF
) --dry-run=server

Check status

kubectl get -n istio-system istiooperators.install.istio.io 
NAME                                         REVISION   STATUS   AGE
installed-state-control-plane                                    3m57s
installed-state-control-plane-1-9-1          1-9-1               2m34s
installed-state-istio-ingressgateway-1-9-1   1-9-1               111s

Uninstall

# This command uninstalls all revisions in default namespace of 'istio-system'
istioctl x uninstall --purge # uninstall all
istioctl x uninstall -f <(cat <<EOF
...
EOF
)

Install book info application

# Namespaces
kubectl create ns bookstore-1
kubectl create ns bookstore-2
kubectl label namespace bookstore-1 istio-injection=enabled
kubectl label namespace bookstore-2 istio.io/rev=1-9-1 istio-injection-

kubectl get ns --show-labels 
NAME              STATUS   AGE    LABELS
bookstore-1       Active   155m   istio-injection=enabled
bookstore-2       Active   155m   istio.io/rev=1-9-1

# Deploy application
kubectl apply -f samples/bookinfo/platform/kube/bookinfo.yaml -n bookstore-1
kubectl apply -f samples/bookinfo/platform/kube/bookinfo.yaml -n bookstore-2

istioctl proxy-status --revision 1-9-1 # show only proxies of revision '1-9-1'
istioctl proxy-status                  # show all proxies

You can see proxies connected only to revision '1-9-1' and at the bottom all proxies

Get info

Profiles are istiooperators.install.istio.io CRD manifests located in istio-1.7.3/manifests/profiles

# List profiles
istioctl profile list
ls istio-1.7.3/manifests/profiles
default.yaml  demo.yaml  empty.yaml  minimal.yaml  preview.yaml  remote.yaml

# profile configuration
istioctl profile dump demo
istioctl profile dump --config-path components.pilot demo

# Differences in the profiles
istioctl profile diff default demo

Available dashboards commands

istioctl dashboard <dashboard>
Available Commands:
  controlz    Open ControlZ web UI
  envoy       Open Envoy admin web UI
  grafana     Open Grafana web UI
  jaeger      Open Jaeger web UI
  kiali       Open Kiali web UI
  prometheus  Open Prometheus web UI
  zipkin      Open Zipkin web UI

List all Istio CRDs

k get crd -A | grep istio | cut -f1 -d" "
adapters.config.istio.io
attributemanifests.config.istio.io
authorizationpolicies.security.istio.io
destinationrules.networking.istio.io
envoyfilters.networking.istio.io
gateways.networking.istio.io
handlers.config.istio.io
httpapispecbindings.config.istio.io
httpapispecs.config.istio.io
instances.config.istio.io
istiooperators.install.istio.io
peerauthentications.security.istio.io
quotaspecbindings.config.istio.io
quotaspecs.config.istio.io
requestauthentications.security.istio.io
rules.config.istio.io
serviceentries.networking.istio.io
sidecars.networking.istio.io
templates.config.istio.io
virtualservices.networking.istio.io
workloadentries.networking.istio.io

IstioOperator

Output logs of istio-operator Kubernetes/Istio-logs-default-install when installing default istio+kiali=prometheus.

Initialize istio.operator

Note: This is being unfolded, check out here the second paragraph.

istioctl operator init # dump, remove, --force
Using operator Deployment image: docker.io/istio/operator:1.7.3
✔ Istio operator installed                                                                                                                                     
✔ Installation complete

# The operator deployment gets installed in a new namespace 'istio-operator'
kubectl get deployment -n istio-operator  -owide
NAME             READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS       IMAGES                           SELECTOR
istio-operator   1/1     1            1           7m14s   istio-operator   docker.io/istio/operator:1.7.3   name=istio-operator

kubectl get all -n istio-operator 
NAME                                 READY   STATUS    RESTARTS   AGE
pod/istio-operator-9dc6b7fd7-xf2m5   1/1     Running   0          5m42s
NAME                     TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)    AGE
service/istio-operator   ClusterIP   10.119.252.73   <none>        8383/TCP   5m43s
NAME                             READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/istio-operator   1/1     1            1           5m43s
NAME                                       DESIRED   CURRENT   READY   AGE
replicaset.apps/istio-operator-9dc6b7fd7   1         1         1       5m42s

Istio operator (v1.7.3), this is not super clear to me

find . -iname *operator*
./samples/operator
./samples/addons/extras/prometheus-operator.yaml
./manifests/charts/istio-operator # it's a chart to deploy operator
./manifests/charts/istio-operator/crds/crd-operator.yaml
./manifests/charts/base/crds/crd-operator.yaml
./manifests/charts/istio-telemetry/prometheusOperator
./manifests/deploy/crds/istio_v1alpha1_istiooperator_crd.yaml
./manifests/deploy/crds/istio_v1alpha1_istiooperator_cr.yaml
./manifests/deploy/operator.yaml # this [1]
./manifests/examples/customresource/istio_v1alpha1_istiooperator_cr.yaml

• [1] manifests/deploy/operator.yaml

<syntaxhighlightjs lang=yaml> --- apiVersion: apps/v1 kind: Deployment metadata:

 namespace: istio-operator
 name: istio-operator

spec:

 replicas: 1
 selector:
   matchLabels:
     name: istio-operator

... </syntaxhighlightjs>

This API get always installed

k -n istio-system get istiooperators.install.istio.io # kind: IstioOperator

CRDs aka new kind: objects - demystified

• Istio terminology
  • Use workload over service that can be misinterpreted by some
• Envoy terminiology Host, Downstream, Upstream, Listener, Cluster, Mesh, Runtime configuration
  • Cluster: A cluster is a group of logically similar upstream hosts that Envoy connects to, eg. group of pods reviews service v1, v2 and v3.
  • Cluster Discovery Service (CDS)
  • Listener discovery service (LDS)
  • Endpoint discovery service (EDS); cluster members are called endpoint.
  • Route Discovery Service (RDS)

• VirtualServices and DestinationRules are key resources for configuring Istio’s traffic routing functionality.
  • VirtualServices - is used to configure how requests are routed to a service within an Istio service mesh, define how traffic is routed to a given destination
  • DestinationRules define policies that apply to traffic intended for a service after routing has occurred. A DestinationRules is applied after VirtualServices routing rules are evaluated, so they apply to the traffic’s real destination.
    • subsets - defines a set of pods with common matching label eg. version: v1

• gateways,gw - taps on to ingressgateway; describe which controller to use eg. plugs into real network received by service/istio-ingressgateway that has label istio=ingressgateway
• virtualservices,vs - it bounds to a gateway(s), and describes how requests are routed to a service within the mesh
• destinationrules,dr - applied after vs routing rules to real traffic destination, defines available versions called subsets, they name (using subsets) different revisions available and contain a logic (selector) of what corresponds to each revision.
• serviceentries,se - holds a list of all endpoints services that they belong to, adds an entry into Istio’s internal service registry, then the Envoy proxies can send traffic to the specified host as if it was a service in the mesh. Allows traffic to be managed for services running outside of the mesh,can set redirect, forward, retry, timeout and fault injection policies fro external destinations. Two purposes:
  • used as external service
  • allows multi-cluster services

• adapters
• attributemanifests
• authorizationpolicies - defines policies of what service can access what workloads
• envoyfilters
• handlers
• httpapispecbindings
• httpapispecs
• instances
• istiooperators
• peerauthentications - defines what authenticated traffic within the cluster is allowed to access what workloads; used for service-to-service authentication to verify the client making the connection
• quotaspecbindings
• quotaspecs
• requestauthentications - it's for humans outside of the cluster to validate their identity and decide to allow enter the cluster
• rules
• sidecars
• templates
• workloadentries

Customize istio installation

Configure ingress-gateways

• Deploying multiple Istio Ingress Gateways
• Creating an Internal Load Balancer in AWS EKS using Istio
• how-to-set-aws-alb-instead-of-elb-in-istio
• Istio: external AWS Application LoadBalancer and Istio Ingress Gateway published on 2021-04-22

Gateways are a special type of component, since multiple ingress and egress gateways can be defined. In the IstioOperator API, gateways are defined as a list type. The default profile installs one ingress gateway, called istio-ingressgateway.

Ingress Gateway

describes a load balancer operating at the edge of the mesh that receives incoming HTTP/TCP connections.

Egress Gateway

An egress gateway configures a dedicated exit node for the traffic leaving the mesh, limiting which services can or should access external networks, or to enable secure control of egress traffic to add security to the mesh.

Show default values of the ingressgateway

istioctl profile dump --config-path components.ingressGateways
istioctl profile dump --config-path values.gateways.istio-ingressgateway

Install istio with ingressgateway servioce as internal AWS loadbalancer:

istioctl install \
   --set profile=default \
   --set components.ingressGateways[0].enabled="true" \
   --set components.ingressGateways[0].k8s.serviceAnnotations."service\.beta\.kubernetes\.io/aws-load-balancer-internal"=\"true\"
✔ Istio core installed                                                                                                                                         
✔ Istiod installed                                                                                                                                             
✔ Ingress gateways installed                                                                                                                                   
✔ Installation complete

# --set gateways.istio-ingressgateway.serviceAnnotations."service\.beta\.kubernetes\.io/aws-load-balancer-internal"="0\.0\.0\.0/0"

Configure using IstioOperator

istioctl manifest install -f <(cat <<EOF
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  profile: default
  components:
    ingressGateways:
    - enabled: true # default is true for default profile
      name: istio-ingressgateway # required key
    egressGateways:
    - enabled: true
      name: istio-egressgateway # required key
EOF
) --dry-run

Ingress Gateways - controller - get details

# manually inject the sidecar
kubectl -n bin apply -f <(istioctl kube-inject -f httpbin.yaml)

export INGRESS_HOST=$(       kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.status.loadBalancer.ingress[0].ip}')
# AWS, uses 'hostname'
export INGRESS_HOST=$(       kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.status.loadBalancer.ingress[0].hostname}')

export INGRESS_PORT=$(       kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="http2")].port}')
export SECURE_INGRESS_PORT=$(kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="https")].port}')

# Optional
export TCP_INGRESS_PORT=$(   kubectl -n istio-system get service istio-ingressgateway -o jsonpath='{.spec.ports[?(@.name=="tcp")].port}')

# Verify
env | grep INGRESS

Ingressgateway Kubernetes service

The istio istio-ingressgateway works as any other ingress controller, it has service type: LoadBalancer, that creates an endpoint with 4 ports, these in turn make external-loadbalancer to listen on these ports:

Port  Name        Protocol
8443  https       TCP
15443 tls         TCP
15021 status-port TCP
8080  http2       TCP

so, any incoming traffic via the ext-lb will end up being processed by istio-egressgateway-54884d6c57-mqgbg pod according to it's configuration that in reality is Envoy config built by pilot using using Istio CRDs.

Describe the service and the endpoint

vagrant@vagrant:~$ k -n istio-system describe svc istio-ingressgateway 
Name:                     istio-ingressgateway
Namespace:                istio-system
Labels:                   app=istio-ingressgateway
...
Selector:                 app=istio-ingressgateway,istio=ingressgateway
Type:                     LoadBalancer
IP:                       10.119.253.21
LoadBalancer Ingress:     34.76.42.198
Port:                     status-port  15021/TCP
TargetPort:               15021/TCP
NodePort:                 status-port  32231/TCP
Endpoints:                10.116.19.12:15021
Port:                     http2  80/TCP
TargetPort:               8080/TCP
NodePort:                 http2  31604/TCP
Endpoints:                10.116.19.12:8080
Port:                     https  443/TCP
TargetPort:               8443/TCP
NodePort:                 https  30747/TCP
Endpoints:                10.116.19.12:8443
Port:                     tls  15443/TCP
TargetPort:               15443/TCP
NodePort:                 tls  31901/TCP
Endpoints:                10.116.19.12:15443

vagrant@vagrant:~$ k -n istio-system describe ep istio-ingressgateway 
Name:         istio-ingressgateway
Namespace:    istio-system
Labels:       app=istio-ingressgateway
...
Annotations:  <none>
Subsets:
  Addresses:          10.116.19.12 # -> target: istio-ingressgateway-86f88b6f6-7mzf7
  NotReadyAddresses:  <none>
  Ports:
    Name         Port   Protocol
    ----         ----   --------
    https        8443   TCP
    tls          15443  TCP
    status-port  15021  TCP
    http2        8080   TCP

General traffic flow

Note: This overview applies to each workload including Ingress-gateways

The arrows in the diagram show the flow of a request through the configuration, and the five key elements are the ‘listener,’ ‘filter chains,’ ‘routes,’ ‘clusters,’ and ‘endpoints’. The route is part of the filter chain, which is part of the listener.

• listener - 'binds' to a port and listens for inbound requests. Any request that comes in via another port would not be seen or handled by Envoy. In Envoy terms, it manages downstream requests
• filter chain - after being accepted by 'the listener', describes how the request should be handled once it’s entered Envoy
• route - extension of the filter chain, takes the HTTP request information and directs it to the correct service
• cluster - address IP:port that are the backend for a service. A cluster is a group of logically similar upstream hosts that Envoy connects to. Envoy discovers the members of a cluster via CDS(Cluster Discovery Service).
• endpoints - network nodes that implement a logical service. They are grouped into clusters. Endpoints in a cluster are upstream of an Envoy proxy.

Ingress-gateway - routes verification

INGRESS_GATEWAY_LABEL=ingressgateway # ingressgateway-internal|external
INGRESS_GATEWAY_POD=$(kubectl -n istio-system get pod  -l istio=$INGRESS_GATEWAY_LABEL -o jsonpath='{.items[0].metadata.name}')

# Get listeners, other options: bootstrap,cluster,endpoint,listener,log,route,secret
istioctl proxy-config listeners -n istio-system $INGRESS_GATEWAY_POD
ADDRESS PORT  MATCH DESTINATION
0.0.0.0 8080  ALL   Route: http.80
0.0.0.0 15021 ALL   Inline Route: /healthz/ready*
0.0.0.0 15090 ALL   Inline Route: /stats/prometheus*

# Show routes, and virtual-services
istioctl proxy-config routes -n istio-system $INGRESS_GATEWAY_POD
NOTE: This output only contains routes loaded via RDS.
NAME        DOMAINS                                                         MATCH                  VIRTUAL SERVICE
http.80     alertmanager.staging.net                     /*                     alertmanager.monitoring
http.80     grafana.staging.net                          /*                     grafana.monitoring
http.80     prometheus.staging.net                       /*                     prometheus.monitoring
            *                                                               /healthz/ready*        
            *                                                               /stats/prometheus*

Object examples

Gateway, virtualservice

# istio-1.7.3/samples/bookinfo/networking/bookinfo-gateway.yaml
---
# Entry point gateway
apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: bookinfo-gateway
spec:
  selector:
    istio: ingressgateway # use istio default controller
  servers:
  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "*"
---
# Routes traffic to destination, could use subset for Traffic Shifting
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: bookinfo
spec:
  hosts:
  - "*"
  gateways:
  - bookinfo-gateway
  http:
  - match:
    - uri:
        exact: /productpage
    - uri:
        prefix: /static
    - uri:
        exact: /login
    - uri:
        exact: /logout
    - uri:
        prefix: /api/v1/products
    route:
    - destination:
        host: productpage
        port:
          number: 9080
       #subset: v1 # [1] if defined in DestinationRule for the host ('productpage'), it will route to any pods
                   # matching a label(s) defined in the subset

# samples/bookinfo/networking/destination-rule-all.yaml
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: productpage
spec:
  host: productpage
  subsets:   # pod selectors matching labels
  - name: v1 # [1] subset name for the host 'productpage'
    labels:
      version: v1
---
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: reviews
spec:
  host: reviews
  subsets:
  - name: v1
    labels:
      version: v1
  - name: v2
    labels:
      version: v2
  - name: v3
    labels:
      version: v3
---
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: ratings
spec:
  host: ratings
  subsets:
  - name: v1
    labels:
      version: v1
  - name: v2
    labels:
      version: v2
  - name: v2-mysql
    labels:
      version: v2-mysql
  - name: v2-mysql-vm
    labels:
      version: v2-mysql-vm
---
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
  name: details
spec:
  host: details
  subsets:
  - name: v1
    labels:
      version: v1
  - name: v2
    labels:
      version: v2
---
# Split traffic between reviews:v1 and reviews:v3
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: reviews
spec:
  hosts:
    - reviews
  http:
  - route:
    - destination:
        host: reviews
        subset: v1
      weight: 50
    - destination:
        host: reviews
        subset: v3
      weight: 50

ServiceEntry

It intercepts any traffic from pods in the mesh (pods having envoy proxy installed) that matches the spec.hosts then applies meshConfig.outboundTrafficPolicy policy ALLOW_ANY or REGISTRY_ONLY plus additional features like retry, timeout etc. if configured.

It depends on installation option meshConfig.outboundTrafficPolicy.mode that configures Envoy's handling of unknown services, that is, services that are not defined in Istio’s internal service registry:

• ALLOW_ANY by default, so may not be defined in the configMap/istio, tells Envoy to let calls to unknown services pass through, this also means that Istio's capabilities cannot be applied to these endpoints
• REGISTRY_ONLY tells Envoy to block any connections to endpoints without a registry entry

kubectl get configmap istio -n istio-system -o yaml | grep mode -m1 -B1

Set REGISTRY_ONLY policy

istioctl manifest install -f <(cat <<EOF
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
spec:
  profile: default
  values:
    meshConfig:
      accessLogFile: /dev/stdout
      outboundTrafficPolicy:
        mode: REGISTRY_ONLY
EOF
)

Example MESH_EXTERNAL service entry adds the ext-svc external dependency to Istio’s service registry. Required when REGISTRY_ONLY policy is set.

apiVersion: networking.istio.io/v1alpha3
kind: ServiceEntry
metadata:
  name: google
spec:
  hosts:
  - www.google.com # FQDN of external resource or wildcard prefix
  ports:
  - number: 443
    name: https
    protocol: HTTPS
  location: MESH_EXTERNAL # treat the service as external part of the mesh
  resolution: DNS         # | MESH_INTERNAL - Treat remote cluster services as part of the service mesh
                          # | as all clusters in the service mesh share the same root of trust.

peerauthentications and requestauthentications

peerauthentications

defines what authenticated traffic within the cluster is allowed to access what workloads; used for service-to-service authentication to verify the client making the connection. mutualTLS is used for transport authentication, Authentication policies apply to requests that a service receives.

apiVersion: "security.istio.io/v1beta1"
kind: "PeerAuthentication"
metadata:
  name: "example-peer-policy"
  namespace: "foo"
spec:
  selector:
    matchLabels:
      app: reviews
  mtls:
    mode: STRICT # PERMISSIVE, DISABLE

requestauthentications

it's for humans outside of the cluster to validate their identity and decide to allow enter the cluster, used for end-user authentication to verify credentials attached to the request.

apiVersion: "security.istio.io/v1beta1"
kind: "RequestAuthentication"
metadata:
  name: "jwt-example"
  namespace: istio-system
spec:
  selector:
    matchLabels:
      istio: ingressgateway # requires end-user JWT for ingress gateway
  jwtRules:
  - issuer: "testing@secure.istio.io"
  jwksUri: "https://raw.githubusercontent.com/istio/istio/release-1.5/..
  # ^ it's authentication token not authorization is being evaluated in this policy

authorizationpolicies

These can be compare to Kubernetes NetworkPolicies but much more powerful as being aware of L7 and not only packet level traffic.

authorizationpolicies

defines policies of what service can access what workloads; authorisation features provides mesh-level, namespace-level, and workload-level access control on workloads in an Istio Mesh.

There is no need to explicitly enable Istio’s authorisation feature, only the AuthorizationPolicy needs applying on workloads to enforce access control.

If no AuthorizationPolicy applies to a workload, no access control will be enforced, In other words, all requests will be allowed. If any AuthorizationPolicy applies to a workload, access to that workload is denied by default, unless explicitly allowed by a rule declared in the policy.

# allow-all policy full access to all workloads in the default namespace
apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: allow-all
  namespace: default
spec:
  rules:
  - {}
---
# deny-all policy to all workloads in admin namespace
apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: deny-all
  namespace: admin
spec:
  {}

Policies can distinguish in between authenticated and not authenticated users/services by specifying rules. There are reach configuration options so you may want to see docs.

code

spec:

 rules:
 - from:
   - source:
       principals: ["cluster.local/ns/default/sa/sleep"]
   - source:
       namespaces: ["dev"]

</syntaxhighlight>

Addons and integrations

Note: In v1.7.x the installation of telemetry addons by istioctl is deprecated, these are being managed now using addons integrations.

Kiali visualisations

• Visualizing Your Mesh

Note: Example needs redoing. Istio v1.6.8 requires kiali secret, v1.7.x by default no authentication is enabled

! values.kiali.enabled is deprecated; use the samples/addons/ deployments instead
! values.prometheus.enabled is deprecated; use the samples/addons/ deployments instead
! addonComponents.kiali.enabled is deprecated; use the samples/addons/ deployments instead
! addonComponents.prometheus.enabled is deprecated; use the samples/addons/ deployments instead

You install kiali manually from scratch or pass arg to istioctl

# Create user name and password
KIALI_USERNAME=admin
KIALI_PASSPHRASE=admin
kubectl apply -f <(cat <<EOF
apiVersion: v1
kind: Secret
metadata:
  name: kiali
  namespace: istio-system
  labels:
    app: kiali
stringData:
  username: $KIALI_USERNAME
  passphrase: $KIALI_PASSPHRASE
EOF
)

Install - Option 1

cd istio-1.#.#/samples/addons
kubectl apply -f kiali.yaml

Deprecated installation options

Option 2 - istioctl - deprecated in v1.8

istioctl manifest install \
  --set values.kiali.enabled=true \
  --set values.prometheus.enabled=true

Option 3 - IstioOperator manifest, this is desired configuration defaults are set is not specified, then installed what is set, any resources not default and not specified will be pruned. Deprecated in v1.8.

IstioOperator manifest to install Kiali

Basic

No auth

<syntaxhighlightjs lang=bash> istioctl manifest install -f <(cat <<EOF apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: default values: kiali: enabled: true prometheus: enabled: true EOF ) </syntaxhighlightjs>

<syntaxhighlightjs lang=bash> istioctl manifest install -f <(cat <<EOF apiVersion: install.istio.io/v1alpha1 kind: IstioOperator spec: profile: default meshConfig: # For debugging accessLogFile: /dev/stdout addonComponents: # Kiali uses Prometheus to populate its dashboards prometheus: enabled: true kiali: enabled: true namespace: kiali k8s: podAnnotations: sidecar.istio.io/inject: "true" values: kiali: prometheusAddr: http://prometheus.istio-system:9090 dashboard: auth: strategy: anonymous EOF ) </syntaxhighlightjs>

Verify installation and access the console

kubectl wait --for=condition=Available deployment/kiali -n istio-system --timeout=300s

# Access the dashboard
istioctl dashboard kiali

Add custom headers

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: httpbin
spec:
  hosts:
  - "*"
  gateways:
  - httpbin-gateway
  http:
  - match:
    - uri:
        prefix: /headers
    route:
    - destination:
        port:
          number: 8000
        host: httpbin
      headers:
        response:            # add to response
          add:
           "key1": "abc"
        request:             # add to request
           add:
             "key2": "def"

Handling Istio Sidecars in Kubernetes Jobs

A Job/CronJob is not considered complete until all containers have stopped running, and Istio Sidecars run indefinitely.

Option 1: Disabling Istio Sidecar injection

spec:
  template:
    metadata:
      annotations:
        sidecar.istio.io/inject: 'false'

Option 2: Use `pkill` to stop the Istio Process

Add pkill -f /usr/local/bin/pilot-agent inside Dockerfile command and shareProcessNamespace: true to the Pod spec (not the Job spec).

Istio 1.3 and Core k8s Support (unverified)

<job shell script aka command:>
curl -X POST http://127.0.0.0/quitquitquit

Debugging

• Debugging Envoy and Istiod

Analize

istioctl analyze --all-namespaces
istioctl analyze samples/bookinfo/networking/*.yaml
istioctl analyze --use-kube=false samples/bookinfo/networking/*.yaml

# Enable live analyzer, it will add to the status field eg.<code>status.validationMessages.type.code: IST0101</code>
istioctl install --set values.global.istiod.enableAnalysis=true

Debug a singular pod or a deployment pods

apiVersion: v1
kind: Namespace
metadata:
  name: redis
  labels:
    istio.io/rev: asm-173-6
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: debug-pod
  namespace: redis
  labels:
    app: debug-pod
spec:
  replicas: 1
  selector:
    matchLabels:
      app: debug-pod
  template:
    metadata:
      labels:
        app: debug-pod
      annotations:
        sidecar.istio.io/logLevel: debug # <- enable debug mode
    spec:
      containers:
        - image: samos123/docker-toolbox
          name: debug-pod

Istiocli debug commands

istioctl experimental describe pod <pod-name>[.<namespace>]

istioctl proxy-status
# | SYNCED means that Envoy has acknowledged the last configuration Istiod has sent to it.
# | NOT SENT means that Istiod hasn’t sent anything to Envoy. This usually is because Istiod has nothing to send.
# | STALE means that Istiod has sent an update to Envoy but has not received an acknowledgement. This usually indicates a networking issue between Envoy and Istiod or a bug with Istio itself.

# Retrieve information about cluster configuration for the Envoy instance in a specific pod:
istioctl proxy-config cluster <pod-name> [flags]

# To retrieve information about bootstrap configuration for the Envoy instance in a specific pod:
istioctl proxy-config bootstrap <pod-name> [flags]

# To retrieve information about listener configuration for the Envoy instance in a specific pod:
istioctl proxy-config listener <pod-name> [flags]

# To retrieve information about route configuration for the Envoy instance in a specific pod:
istioctl proxy-config route <pod-name> [flags]

# To retrieve information about endpoint configuration for the Envoy instance in a specific pod:
istioctl proxy-config endpoints <pod-name> [flags]
istioctl proxy-config endpoints productpage-v1-6c886ff494-7vxhs --cluster "outbound|9080||reviews.default.svc.cluster.local"

Istio helm starter

Project by Salesforce to scaffold a helm chart with Istio that uses helm-starter plugin.

# Install `helm-starter` helm plugin
helm plugin install https://github.com/salesforce/helm-starter.git

# Fetch starter templates: mesh-service, ingress-service, mesh-egress, auth-policy
helm starter fetch https://github.com/salesforce/helm-starter-istio.git

# Create a helm chart from the starter
helm create NAME --starter helm-starter-istio/[starter-name]
for starter in mesh-service ingress-service mesh-egress auth-policy; do helm create authservice-$starter --starter helm-starter-istio/$starter; done

Important labels

Deployment <syntaxhighlightjs lang="yaml"> apiVersion: apps/v1 kind: Deployment spec:

 selector:
   matchLabels:
     app: Template:.Values.service # <- Istio label
     version: Template:.Values.version     # <- Istio label
 template:
   metadata:
     labels:
       # Kubernetes recommended labels
       app.kubernetes.io/name: Template:.Values.service
       app.kubernetes.io/part-of: Template:.Values.system
       app.kubernetes.io/version: Template:.Values.version
       # Isio required labels
       app: Template:.Values.service # <- Istio label
       version: Template:.Values.version     # <- Istio label

     annotations:
       checksum/config: Template:Include (print $.Template.BasePath "/configmap.yaml") .

   spec:
     containers:

           - name: Template:.name
             containerPort: Template:.targetPort
             protocol: TCP # <-- TCP|HTTP or any other that is accepted

Template:- end </syntaxhighlightjs>

Service <syntaxhighlightjs lang="yaml"> apiVersion: v1 kind: Service spec:

 ports:

   - name: Template:.name # <- tcp-<name>, http-<name>, grcp-<name>
     port: Template:.port
     targetPort: Template:.targetPort
     protocol: TCP # <- TCP|HTTP or any other that is accepted

Template:- end </syntaxhighlightjs>

Envoy

• Upstream connections are the service Envoy is initiating the connection to.
• Downstream connections are the client that is initiating a request through Envoy.

Terminology in my own words:

Listeners

Declaration of ports to open on the proxy and listen for incoming connections

Clusters

Backend service to which we can route traffic. Also a group of logically similar upstream hosts that Envoy connects to

Envoy Discovery (XDS)

Envoy is driven by a set of APIs that configure certain aspects of the proxy. We saw earlier how we specified clusters, listeners, and routes. We can also configure those over Envoy's xDS APIs:

• Listener discovery service (LDS)
• Route discovery service (RDS)
• Cluster discovery service (CDS)
• Service discovery service (SDS/EDS)
• Aggregated discovery service (ADS)

Now we don't have to specify listeners ahead of time. We can open them up or close them at runtime. Below example of Envoy config for dynamic Listeners configuration, set/received from api_config_source. <syntaxhighlightjs lang="yaml"> dynamic_resources:

   lds_config:   
   api_config_source:
       api_type: GRPC
       grpc_services:
       - envoy_grpc:
           cluster_name: xds_cluster

</syntaxhighlightjs> Configuring Envoy through this API is exactly what Istio's control plane does. With Istio we specify configurations in a more user-friendly format and Istio translates that configuration into something Envoy can understand and delivers this configuration through Envoy's xDS API.

Service-to-service communication

This is zoom in on inbound connection from the sleep to http pod.

.

Troubleshooting

# Interrogate envoy stats endpoint 
kubectl exec -it deploy/sleep -- curl http://envoy:15000/stats| grep retry

Troubleshooting istio

Check istiod endpoint, get registry

# Get all services in the Istio registry, workloads are also included even if they are not officially part of the mesh
kubectl exec -n istio-system -it deploy/istiod-1-8-4 -- pilot-discovery request GET /debug/registryz
kubectl exec -n istio-system -it deploy/istiod-1-8-4 -- pilot-discovery version # [discovery,help,request,version]

Verify an app/pod iptables modified by istio-proxy. This rules are in the Network kernel namespace hold by the pod.

# List iptables rules - this should fail
kubectl -n default exec -it deploy/httpbin -c istio-proxy -- sudo iptables -L -t nat
sudo: effective uid is not 0, is /usr/bin/sudo on a file system with the 'nosuid' option set or an NFS file system without root privileges?

# Grant the proxy sidecar privileges escalation
kubectl edit deploy/httpbin -n default
      containers:
      - name: istio-proxy 
        image: docker.io/istio/proxyv2:1.8.4
        securityContext:
          allowPrivilegeEscalation: true # by default it's false
          privileged: true               # by default it's false

# Show iptables - 15006(incoming) and 15001(outgoing) traffic interception
kubectl -n default exec -it deploy/httpbin -c istio-proxy -- sudo iptables -L -t nat | grep -e ISTIO_IN_REDIRECT -e 15006 -e ISTIO_REDIRECT -e 15001
ISTIO_IN_REDIRECT  tcp  --  anywhere             anywhere            
Chain ISTIO_IN_REDIRECT (3 references)
REDIRECT   tcp  --  anywhere             anywhere             redir ports 15006
ISTIO_IN_REDIRECT  all  --  anywhere            !localhost            owner UID match istio-proxy
ISTIO_IN_REDIRECT  all  --  anywhere            !localhost            owner GID match istio-proxy
ISTIO_REDIRECT  all  --  anywhere             anywhere            
Chain ISTIO_REDIRECT (1 references)
REDIRECT   tcp  --  anywhere             anywhere             redir ports 15001

We can see here iptables is used to redirect incoming and outgoing traffic to Istio's data plane proxy. Incoming traffic goes to port 15006 of the Istio proxy while outgoing traffic will go through 15001. If we check the Envoy listeners for those ports, we can see exactly how the traffic gets handled.

IngressGateway

Query the gateway configuration to get all routes

istioctl proxy-config routes deploy/istio-ingressgateway.istio-system
NOTE: This output only contains routes loaded via RDS.
NAME        DOMAINS              MATCH                  VIRTUAL SERVICE
http.80     example.com          /*                     web-api-gw-vs.default
            *                    /stats/prometheus*     
            *                    /healthz/ready* 

# Show details of a single route
istioctl proxy-config routes deploy/istio-ingressgateway.istio-system --name http.80 -o json

Resources

• gitops-istio Istio on a Kubernetes cluster and automating A/B testing and canary releases with GitOps pipelines example

Training Istio v1.5

• What is Istio Service Mesh?
• Istio Hands on Demo Part 1
• Istio Hands on Demo Part 2 - Enabling Sidecar Injection
• Istio Hands on Demo Part 3 - Visualizing the System with Kiali
• Istio Hands on Demo Part 4 - Finding Performance Problems
• istio-fleetman Github source materials
• Istio Architecture Part 1 - Proxies
• Istio Architecture Part 2 - The Data Plane and Envoy
• Istio Architecture Part 3 - The Control Plane
• Istio Architecture Part 4 - Going Deeper into Envoy
• istio-cheatsheet by Tetratate A+++

Istio v1.7

• VM <-> K8s mesh demo at 30 min

Semi-related

• Knative on Kind (KonK)

Related technology

• Introduction to HTTP/2 http/2 is used by Envoy internally