Setting an environment variable in Ansible from a command output of bash command

Question

I would like to set output of a shell command as an environment variable in Ansible.

I did the following to achieve it:

- name: Copy content of config.json into variable
  shell:  /bin/bash -l -c "cat /storage/config.json"
  register: copy_config
  tags: something

- name: set config
  shell: "echo $TEMP_CONFIG"
  environment:
    TEMP_CONFIG: "{{copy_config}}"
  tags: something

But somehow after the ansible run, when I do run the following command:

echo ${TEMP_CONFIG}

in my terminal it gives an empty result.

Any help would be appreciated.

techraf · Accepted Answer · 2017-02-26 14:47:02Z

10

There are at least two problems:

You should pass copy_config.stdout as a variable

- name: set config
  shell: "echo $TEMP_CONFIG"
  environment:
    TEMP_CONFIG: "{{copy_config.stdout}}"
  tags: something

You need to register the results of the above task and then again print the stdout, so:

- name: set config
  shell: "echo $TEMP_CONFIG"
  environment:
    TEMP_CONFIG: "{{copy_config.stdout}}"
  tags: something
  register: shell_echo

- debug:
    var: shell_echo.stdout

You never will be able to pass the variable to a non-related process this way. So unless you registered the results in an rc-file (like ~/.bash_profile which is sourced on interactive login if you use Bash) no other shell process would be able to see the value of TEMP_CONFIG. This is how system works.

answered Feb 26, 2017 at 14:47

techraf

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2 Comments

Spaniard89 Over a year ago

thanks a lot for the prompt answer, I have question with respect to point 2 and 3, why do I need to register it and echo out the std.out? what's the purpose of it? I thought doing environment: TEMP_CONFIG: "{{copy_config.stdout}}" will add this into the .bash_profile file, why do I need to explicitly add it?

techraf Over a year ago

You need to reference stdout subkey, because that's where Ansible stores the stdout of the command. No, it won't add anything to .bash_profile, it just sets the environment for the command specified in the module.

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