Ansible playbook shell output

问题:

I would like to quickly monitor some hosts using commands like ps,dstat etc using ansible-playbook. The ansible command itself perfectly does what I want, for instance I'd use:

ansible -m shell -a "ps -eo pcpu,user,args | sort -r -k1 | head -n5"

and it nicely prints all std output for every host like this:

localhost | success | rc=0 >>
0.0 root     /sbin/init
0.0 root     [kthreadd]
0.0 root     [ksoftirqd/0]
0.0 root     [migration/0]

otherhost | success | rc=0 >>
0.0 root     /sbin/init
0.0 root     [kthreadd]
0.0 root     [ksoftirqd/0]
0.0 root     [migration/0] 

However this requires me to keep a bunch of shell scripts around for every task which is not very 'ansible' so I put this in a playbook:

---
-
  hosts: all
  gather_facts: no
  tasks:
    - shell: ps -eo pcpu,user,args | sort -r -k1 | head -n5

and run it with -vv, but the output baiscally shows the dictionary content and newlines are not printed as such so this results in an unreadable mess like this:

changed: [localhost] => {"changed": true, "cmd": "ps -eo pcpu,user,args | sort -r -k1 
head -n5 ", "delta": "0:00:00.015337", "end": "2013-12-13 10:57:25.680708", "rc": 0,
"start": "2013-12-13 10:57:25.665371", "stderr": "", "stdout": "47.3 xxx    Xvnc4 :24
-desktop xxx:24 (xxx) -auth /home/xxx/.Xauthority -geometry 1920x1200\n
.... 

I also tried adding register: var and the a 'debug' task to show {{ var.stdout }} but the result is of course the same.

Is there a way to get nicely formatted output from a command's stdout/stderr when run via a playbook? I can think of a number of possible ways (format output using sed? redirect output to file on the host then get that file back and echo it to the screen?), but with my limited knowledge of the shell/ansible it would take me a day to just try it out.

回答1:

The debug module could really use some love, but at the moment the best you can do is use this:

- hosts: all
  gather_facts: no
  tasks:
    - shell: ps -eo pcpu,user,args | sort -r -k1 | head -n5
      register: ps

    - debug: var=ps.stdout_lines

It gives an output like this:

ok: [host1] => {
    "ps.stdout_lines": [
        "%CPU USER     COMMAND",
        " 1.0 root     /usr/bin/python",
        " 0.6 root     sshd: root@notty ",
        " 0.2 root     java",
        " 0.0 root     sort -r -k1"
    ]
}
ok: [host2] => {
    "ps.stdout_lines": [
        "%CPU USER     COMMAND",
        " 4.0 root     /usr/bin/python",
        " 0.6 root     sshd: root@notty ",
        " 0.1 root     java",
        " 0.0 root     sort -r -k1"
    ]
}

回答2:

This is a start may be :

- hosts: all
  gather_facts: no
  tasks:
    - shell: ps -eo pcpu,user,args | sort -r -k1 | head -n5
      register: ps

    - local_action: command echo item
      with_items: ps.stdout_lines

NOTE: Docs regarding ps.stdout_lines are covered here: ('Register Variables' chapter).

回答3:

Expanding on what leucos said in his answer, you can also print information with Ansible's humble debug module:

- hosts: all
  gather_facts: no
  tasks:
    - shell: ps -eo pcpu,user,args | sort -r -k1 | head -n5
      register: ps

    # Print the shell task's stdout.
    - debug: msg={{ ps.stdout }}

    # Print all contents of the shell task's output.
    - debug: var=ps

回答4:

If you need a specific exit status, Ansible provides a way to do that via callback plugins.

Example. It's a very good option if you need a 100% accurate exit status.

If not, you can always use the Debug Module, which is the standard for this cases of use.

Cheers

回答5:

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 ansible-playbook task like yours

---
-
  hosts: example
  gather_facts: no
  tasks:
    - shell: ps -eo pcpu,user,args | sort -r -k1 | head -n5

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

example | SUCCESS | rc=0 >>
%CPU USER     COMMAND
 0.2 root     sshd: root@pts/3
 0.1 root     /usr/sbin/CROND -n
 0.0 root     [xfs-reclaim/vda]
 0.0 root     [xfs_mru_cache]

I'm using ansible-playbook 2.2.1.0

回答6:

ANSIBLE_STDOUT_CALLBACK=debug ansible-playbook /tmp/foo.yml -vvv

Tasks with STDOUT will then have a section:

STDOUT:

What ever was in STDOUT

回答7:

Perhaps not relevant if you're looking to do this ONLY using ansible. But it's much easier for me to have a function in my .bash_profile and then run _check_machine host1 host2

function _check_machine() {
    echo 'hostname,num_physical_procs,cores_per_procs,memory,Gen,RH Release,bios_hp_power_profile,bios_intel_qpi_link_power_management,bios_hp_power_regulator,bios_idle_power_state,bios_memory_speed,'
    hostlist=$1
    for h in `echo $hostlist | sed 's/ /\n/g'`;
    do
        echo $h | grep -qE '[a-zA-Z]'
        [ $? -ne 0 ] && h=plabb$h
        echo -n $h,
        ssh root@$h 'grep "^physical id" /proc/cpuinfo | sort -u | wc -l; grep "^cpu cores" /proc/cpuinfo |sort -u | awk "{print \$4}"; awk "{print \$2/1024/1024; exit 0}" /proc/meminfo; /usr/sbin/dmidecode | grep "Product Name"; cat /etc/redhat-release; /etc/facter/bios_facts.sh;' | sed 's/Red at Enterprise Linux Server release //g; s/.*=//g; s/\tProduct Name: ProLiant BL460c //g; s/-//g' | sed 's/Red Hat Enterprise Linux Server release //g; s/.*=//g; s/\tProduct Name: ProLiant BL460c //g; s/-//g' | tr "\n" ","
         echo ''
    done
}

E.g.

$ _machine_info '10 20 1036'
hostname,num_physical_procs,cores_per_procs,memory,Gen,RH Release,bios_hp_power_profile,bios_intel_qpi_link_power_management,bios_hp_power_regulator,bios_idle_power_state,bios_memory_speed,
plabb10,2,4,47.1629,G6,5.11 (Tikanga),Maximum_Performance,Disabled,HP_Static_High_Performance_Mode,No_CStates,1333MHz_Maximum,
plabb20,2,4,47.1229,G6,6.6 (Santiago),Maximum_Performance,Disabled,HP_Static_High_Performance_Mode,No_CStates,1333MHz_Maximum,
plabb1036,2,12,189.12,Gen8,6.6 (Santiago),Custom,Disabled,HP_Static_High_Performance_Mode,No_CStates,1333MHz_Maximum,
$ 

Needless to say function won't work for you as it is. You need to update it appropriately.