How to use conditional in .ebextensions config (AWS Elastic Beanstalk)

Question

I wish I could use conditional for .ebextensions configuration, but I don't know how to use it, my current case are :

One of .ebextensions configuration content are create a folder, actually the folder that must be created it's only once, because if I'm deploying app for second times or more I've got error, and the error said "the folder already exist".

So I need to give conditional, if the folder already exist it's not necessary to run again the command for create a folder.

If anyone has any insight or direction on how this can be achieved, I would greatly appreciate it. Thank you!

Answer 1

The .ebextensions config files allow conditional command execution by using the test: directive on a command. Then the command only runs if the test is true (returns 0).

Example .ebextensions/create_dir.config file:

commands:
  01_create_dir:
    test: test ! -d "${DIR}"
    command: mkdir "${DIR}"

Another example (actually tested on EB) to conditionally run a script if a directory is not there:

commands:
  01_intall_foo:
    test: test ! -d /home/ec2-user/foo
    command: "/home/ec2-user/install-foo.sh"
    cwd: "/home/ec2-user/"

The sparse documentation from AWS is here:

http://docs.aws.amazon.com/elasticbeanstalk/latest/dg/customize-containers-ec2.html#customize-containers-format-commands

PS. If you just need to conditionally create the directory, you can do it without conditionals, using the -p option for mkdir to conditionally create the directory like so:

commands:
  01_create_dir:
    command: mkdir -p "${DIR}"

Answer 2

I think that the only way to do it is with shell conditions:

commands:
  make-directory:
    command: |
      if [ ! -f "${DIR}" ]; then
        mkdir "${DIR}"
      fi

See bigger example in jcabi-beanstalk-maven-plugin.