stdout looks empty, but 'when' thinks it isn't?

[Steve Kersley]

As an Ansible newcomer, I'm trying to write some scripts to standardize Cisco switch configuration.  Unfortunately since Cisco doesn't offer a way to clear existing configuration before setting (in this instance I'm wanting to erase and standardize syslog targets, which is mostly configured as one value, but on some switches may have never been set, or may have been pointed at one of three other hosts in addition to the normal), I decided the easiest way was to first fetch the current setting(s), then iterate through and erase them, then set the correct target.

This works fine, but it fails on a switch that has no current value set, so I used a 'when' clause to check if stdout from the collection task is empty.  However, this isn't working.  If I print via debug the value of stdout, it certainly looks empty so why isn't the when clause working?

Any help on what I'm doing wrong (or a better way to do it) appreciated?  For the moment I can kludge around it by setting a value before I delete all the values, so that I know it should always have something and not worry about it, but that's bad practice and I'd prefer to know what I'm doing wrong for next time!

- hosts: switches

  gather_facts: False

  vars:

    cli:

      host: "{{ inventory_hostname }}"

      username: user

      password: password

      auth_pass: password

      transport: cli

  tasks:

  - name: Collect logging configuration

    connection: local

    become: false

    register: syslog

    ios_command:

      provider: "{{ cli }}"

      authorize: yes

      commands:

        - show running-config | include logging host

  - debug: msg="empty"

    when: syslog.stdout == ""

  - debug: msg="not empty"

    when: syslog.stdout != ""

  - debug: var=syslog.stdout

  - name: Remove existing syslog config

    connection: local

    become: false

    when: syslog.stdout != ""

    ios_command:

      provider: "{{ cli }}"

      authorize: yes

      commands:

        - configure terminal

        - no {{ item }}

        - exit

    with_items: "{{ syslog.stdout_lines }}"

Output:

PLAY [switches] ****************************************************************

TASK [Collect logging configuration] *******************************************

ok: [switchname]

TASK [debug] *******************************************************************

skipping: [switchname]

TASK [debug] *******************************************************************

ok: [switchname] => {

    "msg": "not empty"

}

TASK [debug] *******************************************************************

ok: [switchname] => {

    "syslog.stdout": [

        ""

    ]

}

TASK [Remove existing syslog config] *******************************************

failed: [switchname] (item=) => {"commands": ["configure terminal", "no ", "exit"], "failed": true, "item": "", "msg": "matched error in response: no \r\n% Incomplete command.\r\n\r\nSwitchName(config)#"}

Thanks,

Steve.

[Kai Stian Olstad]

It's not empty, it does contain a list.
So if you do this I think it should work
when: syslog.stdout[0] != ""

--
Kai Stian Olstad

[Steve Kersley]

Aha - yes, had missed that in the output.  Have been trying to work out why it differed from the example use of 'when' to check for empty stdout in the documentation, but I now see in the module docs for ios_command, that since it takes a list of commands as input, it also returns a list of stdout values rather than a single value.  That makes sense and explains the difference.

Many thanks for pointing me the right way.

[Peter Sprygada]

Also, I noticed you are using ios_command to send configuration statements.  Please switch to using ios_config.  In 2.2, ios_command will no longer allow you to send configuration commands

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