How to see stdout of ansible commands?

Question

How do I see stdout for ansible-playbook commands? -v only shows ansible output, not the individual commands. It would be great if I could figure out how to do this immediately, so if something fails or hangs I can see why.

e.g.

- name: print to stdout
  action: command echo "hello"

would print

TASK: [print variable] ******************************************************** 

hello

Solution 1

I think you can register the result to a variable, then print with debug.

- name: print to stdout
  command: echo "hello"
  register: hello

- debug: msg="{{ hello.stdout }}"

- debug: msg="{{ hello.stderr }}"

Solution 2

Instead of stdout I would suggest using stdout_lines. For multiline output this is much nicer, e.g.

- hosts: all
  tasks:
    - name: Run ls.sh and output "ls /"
      script: ls.sh
      register: out

    - debug: var=out.stdout_lines

gives

TASK: [debug var=out.stdout_lines] ******************************************** 
ok: [local] => {
    "var": {
        "out.stdout_lines": [
            "total 61", 
            "lrwxrwxrwx   1 root root     7 Feb 15  2015 bin -> usr/bin", 
            "drwxr-xr-x   6 root root  1024 Aug 24 22:08 boot", 
            "drwxr-xr-x  22 root root  3580 Sep  8 18:41 dev",  
            [...] 
            "drwxr-xr-x   9 root root  4096 Aug 25 19:14 usr", 
            "drwxr-xr-x  13 root root  4096 Feb 25  2015 var"
        ]
    }
}

Regarding real time output for debugging purposes there is a closed bug report https://github.com/ansible/ansible/issues/3887#issuecomment-54672569 discussing the reasons why this is not possible and will not be implemented.

Solution 3

I found using the minimal stdout_callback with ansible-playbook gave similar output to using ad-hoc ansible.

In your ansible.cfg (Note that I'm on OS X so modify the callback_plugins path to suit your install)

stdout_callback     = minimal
callback_plugins    = /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/ansible/plugins/callback

So that a task such as this

---
- hosts: example
  tasks:
   - name: Say hi
     command: echo "hi ..."

Gives output like this, like an ad-hoc command would

example | SUCCESS | rc=0 >>
hi ...

I'm using ansible-playbook 2.2.1.0

Solution 4

If you really want to watch the output in realtime, there is a hacky way around it, at least for the ansible shell module.

In whatever shell script wraps your call to ansible, touch and tail a log file in a background job. Then redirect the ansible shell command's output to append to that log file. You need to make sure you kill the background tail job after ansible finishes, or it will be left dangling.

For example, in a bash script that calls ansible:

set -m
touch /tmp/debug.log && tail -f /tmp/debug.log &
ansible-playbook ... call playbook here
kill %1   # ensure the background tail job is stopped

Then in some ansible role:

- name: Run a script and print stdout/stderr
  shell: bash -c "/run/something.sh 2>&1 >> /tmp/debug.log"

Solution 5

I've found that just killing a stuck process on the remote via ssh gives back the stdout. I find thats shorter than writing workarounds that won't be used in the final playbook anyways:

kill -9 PID

View more solutions

Comments

[Capi Etheriel]

related: serverfault.com/questions/667252/…

[JonnyJD]

stackoverflow.com/questions/20563639/…

[geerlingguy]

Additionally, you can debug a variable directly with - debug: var=hello. Sometimes this is more helpful for multiline output or Ansible module output (rather than command/shell output).

[Matthias Braun]

I had trouble getting Java output using this. The fix is to redirect all of Java's output to stdout: shell: java -version 2>&1

[Michael B]

that's a lot better nothing, but you only get the stdout message after the command has successfully completed. I was having an issue where ansible would appear to hang. The reason was that I was using the wrong username for an rsync command, which spooled the interactive password request, which just hanged ansible. It was very difficult to debug - but if I could see stdout in realtime, I would have immediately realised what I'd done wrong. I would LOVE this functionality, if possible.

[vlad-ardelean]

while this works, it means ansible makes debugging really hard. Let's imagine the first task never terminates (perhaps it is foolishly waiting for user input)... the user would never know! Moreover, the register module, or whatever it is doesn't produce objects that have the stdout or stderr variable set.... so it's really bad that we don't just get the output by default :|

[ntc2]

+1 for linking the "real time output" bug.

[Chris F]

If I want to send out.stdout_lines (as body of Ansible mail task), how can I send it so it does NOT look like this when email is received? [u'total 61', u'lrwxrwxrwx 1 root root 7 Feb 15 2015 bin -> usr/bin', u'drwxr-xr-x 6 root root 1024 Aug 24 22:08 boot', u'.....'] I want it to look like this, as seen on terminal

[Daniel]

fatal: [127.0.0.1]: FAILED! => {"reason": "Syntax Error while loading YAML.\n did not find expected <document start>\n\nThe error appears to be in...syntax problem.\n\nThe offending line appears to be:\n\n\n- name: Run ls.sh and output \"ls /\"\n^ here\n"}

[Joshua K]

very interesting and creative. thanks for the insight. looks like i can apply the technique to other things so that's pretty neat.

[tfwright]

Make sure the command you're running has a timeout, or use the ansible async to force a timeout. Then you should be prompted something is wrong and see the previous output.

[Moataz Elmasry]

Honestly this is the only correct answer here...

[Kuberchaun]

@MoatazElmasry I had the same issue with puppet bolt. This worked like a charm.

[cjnash]

but what if the process is only appearing to hang because ansible doesn't output anything and is in fact chugging along?

[M. Rostami]

Make sure you use command instead of script on the new versions of Ansible.

[Kuberchaun]

Puppet bolt now has an experiential feature for live streaming! ospassist.puppet.com/hc/en-us/articles/…

[Kuberchaun]

Yeah what is stuck if your're flying blind in this case? Imagine a CI build process that normally takes 5 hours and while you thought it was running for 5 hours that run of it was actually just stuck. That's a lot of lost time.