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amazon-web-servicesenvironment-variablesamazon-elastic-beanstalkebextensions

Environment specific ebextensions Beanstalk commands


I have a spring-boot application for which I need to specify graphite server and port (to send metrics). For that to work, I have to install and configure statsd. I do that using the ebextensions file.

commands:
  01_nodejs_install:
    command: sudo yum -y install nodejs npm --enablerepo=epel
    ignoreErrors: true

  02_mkdir_statsd:
    command: mkdir /home/ec2-user/statsd
    ignoreErrors: true

  03_fetch_statsd:
    command: git clone https://github.com/etsy/statsd.git /home/ec2-user/statsd
    ignoreErrors: true

  04_change_example_config:
    command: "cat exampleConfig.js | sed 's/2003/<graphite-port>/g' | sed 's/graphite.example.com/<my-graphite-server>/g' > config.js"
    cwd: /home/ec2-user/statsd

  05_run_statsd:
    command: setsid node stats.js config.js >/dev/null 2>&1 < /dev/null &
    cwd: /home/ec2-user/statsd

The problem with this configuration is that I can specify only 1 graphite server here for all environments.

So I decided to move commands 04 and 05 into container_commands. I am thinking of defining an environment variable called ENV_NAME using the beanstalk console/UI, and set it to dev, qa, or prod according to the environment. Then I can use test option of container_commands to run 04 and 05 commands only for specific environment based on this ENV_NAME.

So my problem is - how can I use AWS console to define environment variable? I tried using Beanstalk console to define my variable as explained in the documentation here but it did not work. I also found (see the answer with 5 upvotes) that this method sets only JVM properties and not ENV variables.

I cannot define environment variable using ebextensions because then I'll have the same problem - can't define different env vars for different envs :)

So I need help with either:

  • Set the ENV_NAME environment variable using beanstalk UI.

Or

  • Suggest a way to use ENV_NAME system property in container_commands to condition whether or not to run the command based on the value of ENV_NAME.

And in case you know a simpler/better way to specify different Graphite servers for different environments, please feel free to pitch in.


Solution

  • The way I resolved this was to define ENV_NAME as dev and prod in dev and prod environments respectively and use the following ebextensions configuration.

    commands:
      01_nodejs_install:
        command: sudo yum -y install nodejs npm --enablerepo=epel
        ignoreErrors: true
    
      02_mkdir_statsd:
        command: mkdir /home/ec2-user/statsd
        ignoreErrors: true
    
      03_fetch_statsd:
        command: git clone https://github.com/etsy/statsd.git /home/ec2-user/statsd
        ignoreErrors: true
    
    container_commands:
      04a_container_change_example_config:
        command: "cat exampleConfig.js | sed 's/2003/<graphite-dev-port>/g' | sed 's/graphite.example.com/<graphite-dev-host>/g' > config.js"
        cwd: /home/ec2-user/statsd
        test: '[ "${ENV_NAME}" == "dev" ]'
    
      04b_container_change_example_config:
        command: "cat exampleConfig.js | sed 's/2003/<graphite-prod-port>/g' | sed 's/graphite.example.com/<graphite-prod-host>/g' > config.js"
        cwd: /home/ec2-user/statsd
        test: '[ "${ENV_NAME}" == "prod" ]'
    
      05_run_statsd:
        command: setsid node stats.js config.js >/dev/null 2>&1 < /dev/null &
        cwd: /home/ec2-user/statsd
    

    Using test I can condition the execution of the container command on the ENV_NAME property which I have already defined in the beanstalk environment.