Module apt with state=build-dep reports change even when there is none

[kayhayen]

ISSUE TYPE

• Bug Report

COMPONENT NAME

apt

ANSIBLE VERSION

ansible 2.5.0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/home/hayen/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python2.7/dist-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 2.7.13 (default, Nov 24 2017, 17:33:09) [GCC 6.3.0 20170516]

CONFIGURATION

ANSIBLE_PIPELINING(/etc/ansible/ansible.cfg) = True
DEFAULT_GATHERING(/etc/ansible/ansible.cfg) = smart
DEFAULT_REMOTE_USER(/etc/ansible/ansible.cfg) = root

OS / ENVIRONMENT

Debian Stretch for both master and controlled node. The master is running amd64 arch and controlled node armhf.

SUMMARY

When using state=build-dep there is a change each time the task is run. When using -d I am getting this kind of output:

TASK [buildbot-tools : Install Python2.7 build dependencies] *****************************
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
changed: [donatix.home] => (item=[u'python2.7'])

TASK [buildbot-tools : Install Python3.5 build dependencies] *****************************
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
changed: [donatix.home] => (item=[u'python3.5'])

STEPS TO REPRODUCE

  - name: Install Python2.7 build dependencies
    action: apt pkg={{item}} state=build-dep
    with_items:
         - python2.7

  - name: Install Python3.5 build dependencies
    action: apt pkg={{item}} state=build-dep
    with_items:
         - python3.5

EXPECTED RESULTS

I was expecting build-dep to report "changed" only once. However it seems that the status output from build-dep of apt is seen as indicating a change even when there is one.

ACTUAL RESULTS

With verbose, I am getting more output:

Using module file /usr/local/lib/python2.7/dist-packages/ansible/modules/packaging/os/apt.py
<donatix.home> ESTABLISH SSH CONNECTION FOR USER: root
<donatix.home> SSH: EXEC ssh -vvv -C -o ControlMaster=auto -o ControlPersist=60s -o KbdInteractiveAuthentication=no -o PreferredAuthentications=gssapi-with-mic,gssapi-keyex,hostbased,publickey -o PasswordAuthentication=no -o User=root -o ConnectTimeout=10 -o ControlPath=/data/home/hayen/.ansible/cp/1fa446c277 donatix.home '/bin/sh -c '"'"'/usr/bin/python && sleep 0'"'"''
<donatix.home> (0, '\n{"stdout": "Reading package lists...\\nReading package lists...\\nBuilding dependency tree...\\nReading state information...\\n0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.\\n", "cache_updated": false, "changed": true, "stderr": "", "invocation": {"module_args": {"dpkg_options": "force-confdef,force-confold", "upgrade": null, "force": false, "force_apt_get": false, "install_recommends": null, "package": ["python2.7"], "autoclean": false, "name": ["python2.7"], "purge": false, "allow_unauthenticated": false, "state": "build-dep", "autoremove": false, "update_cache": null, "default_release": null, "only_upgrade": false, "deb": null, "cache_valid_time": 0}}, "diff": {}, "cache_update_time": 1524113826}\n', 'OpenSSH_7.4p1 Debian-10+deb9u3, OpenSSL 1.0.2l  25 May 2017\r\ndebug1: Reading configuration data /home/hayen/.ssh/config\r\ndebug1: /home/hayen/.ssh/config line 1: Applying options for *\r\ndebug1: Reading configuration data /etc/ssh/ssh_config\r\ndebug1: /etc/ssh/ssh_config line 19: Applying options for *\r\ndebug1: auto-mux: Trying existing master\r\ndebug2: fd 3 setting O_NONBLOCK\r\ndebug2: mux_client_hello_exchange: master version 4\r\ndebug3: mux_client_forwards: request forwardings: 0 local, 0 remote\r\ndebug3: mux_client_request_session: entering\r\ndebug3: mux_client_request_alive: entering\r\ndebug3: mux_client_request_alive: done pid = 10027\r\ndebug3: mux_client_request_session: session request sent\r\ndebug1: mux_client_request_session: master session id: 2\r\ndebug3: mux_client_read_packet: read header failed: Broken pipe\r\ndebug2: Received exit status from master 0\r\n')
changed: [donatix.home] => (item=[u'python2.7']) => {
    "cache_update_time": 1524113826, 
    "cache_updated": false, 
    "changed": true, 
    "diff": {}, 
    "invocation": {
        "module_args": {
            "allow_unauthenticated": false, 
            "autoclean": false, 
            "autoremove": false, 
            "cache_valid_time": 0, 
            "deb": null, 
            "default_release": null, 
            "dpkg_options": "force-confdef,force-confold", 
            "force": false, 
            "force_apt_get": false, 
            "install_recommends": null, 
            "name": [
                "python2.7"
            ], 
            "only_upgrade": false, 
            "package": [
                "python2.7"
            ], 
            "purge": false, 
            "state": "build-dep", 
            "update_cache": null, 
            "upgrade": null
        }
    }, 
    "item": [
        "python2.7"
    ], 
    "stderr": "", 
    "stderr_lines": [], 
    "stdout": "Reading package lists...\nReading package lists...\nBuilding dependency tree...\nReading state information...\n0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.\n", 
    "stdout_lines": [
        "Reading package lists...", 
        "Reading package lists...", 
        "Building dependency tree...", 
        "Reading state information...", 
        "0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded."
    ]
}

[ansibot]

Files identified in the description:

• lib/ansible/modules/packaging/os/apt.py

If these files are inaccurate, please update the component name section of the description or use the !component bot command.

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[ansibot]

cc @mgwilliams
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[kayhayen]

This code from "parse_diff" of apt.py ought to match:

diff_end = next(i for i, item in enumerate(diff) if re.match('[0-9]+ (packages )?upgraded', item))

My diff output is:

0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

I have to assume that code is not run for some reason for build-dep, but it is not obvious (to me) what would cause this.