Jinja2 templates

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The example below show use of Jinja2 to generate Bash script that reads dynamic data from EC2 AWS Metadata. The solution helps setting up JVM params based on instance type as these come with different memory sizes.

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# Ansible group file: server-nodes
###################################################################################################

jvm_memory                     :
  - tier                       : 1
    list                       : " m1.small | m1.medium | m1.large | m1.xlarge | t1.micro "
    xms                        : 256m
    xmx                        : 1024m
    maxpermsize                : 512m
  - tier                       : 2
    list                       : " t2.medium | c3.large | c5.large "
    xms                        : 2048m
    xmx                        : 2048m
    maxpermsize                : 1024m
  - tier                       : 3
    list                       : " t2.large | t3.large | c5.xlarge "
    xms                        : 2048m
    xmx                        : 4096m
    maxpermsize                : 1024m
  - tier                       : 4
    list                       : " t2.xlarge | t3.xlarge | c5d.large | c4.2xlarge | c5.2xlarge "
    xms                        : 2048m
    xmx                        : 8192m
    maxpermsize                : 2048m

###################################################################################################

jvm_memory_proxy         : '{{ jvm_memory }}'
jvm_memory_lb            : '{{ jvm_memory }}'


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# Bash template: server_start.sh.j2
###################################################################################################
#!/bin/sh

INSTANCE_TYPE=`wget -q -O - http://169.254.169.254/latest/meta-data/instance-type`

case $INSTANCE_TYPE in
{% if inventory_hostname in groups['server-nodes'] | default([]) %}
{% for proxy in jvm_memory_proxy %}
{{proxy.list}} )
	XMS={{proxy.xms }}
	XMX={{proxy.xmx }}
      MAXPERMSIZE={{ proxy.maxpermsize }}
	;;
{% endfor %}
{% elif 'proxy-api-nodes' in group_names and inventory_hostname in groups['proxy-api-nodes'] | default([]) %}
{% for proxy in jvm_memory_proxy_api %}
{{proxy.list}} )
	XMS={{proxy.xms }}
	XMX={{proxy.xmx }}
      MAXPERMSIZE={{ proxy.maxpermsize }}
	;;
{% endfor %}
{% elif inventory_hostname in groups['proxy-wkr-nodes'] | default([]) %}
{% for proxy in jvm_memory_proxy_wkr %}
{{proxy.list}} )
  XMS={{proxy.xms }}
  XMX={{proxy.xmx }}
      MAXPERMSIZE={{ proxy.maxpermsize }}
  ;;
{% endfor %}    
{% endif %}
      * )
        XMS={{ jvm_memory_xms }}
        XMX={{ jvm_memory_xmx }} 
        MAXPERMSIZE={{ jvm_memory_maxpermsize }}
        ;;
esac

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