Json parsing in Ansible

Question

I have to parse the output of the following command:

mongo <dbname> --eval "db.isMaster()" 

which gives output as follows:

 {     "hosts" : [         "xxx:<port>",         "xxx:<port>",         "xxx:<port>"     ],     "setName" : "xxx",     "setVersion" : xxx,     "ismaster" : true,     "secondary" : false,     "primary" : "xxx",     "me" : "xxx",     "electionId" : ObjectId("xxxx"),     "maxBsonObjectSize" : xxx,     "maxMessageSizeBytes" : xxxx,     "maxWriteBatchSize" : xxx,     "localTime" : ISODate("xxx"),     "maxWireVersion" : 4,     "minWireVersion" : 0,     "ok" : 1 } 

I need to parse the above output to check the value of "ismaster" is true. Please let me know how i can do this in ansible.

At the moment i am simply checking that the text "ismaster" : true is shown in the output using the following code:

  tasks:      - name: Check if the mongo node is primary        shell: mongo <dbname> --eval "db.isMaster()"        register: output_text       - name: Run command on master        shell: <command to execute>        when: "'\"ismaster\\\" : true,' in output_text.stdout" 

However it would be nice to use Ansible's json processing to check the same. Please advise.

Answer 1

There are quite a bit of helpful filters in Ansible.

Try: when: (output_text.stdout | from_json).ismaster