Description of problem:
filestore to bluestore playbook fails due to undesired filter match.

when selecting OSDs to be purged, the list of OSDs returned contains OSDs for other than the target host, these osds are still up and running and so the purge block fails.

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        - name: set_fact osd_ids
          set_fact:
            osd_ids: "{{ osd_ids | default([]) + [item] }}"
          with_items:
            - "{{ ((osd_tree.stdout | default('{}') | from_json).nodes | selectattr('name', 'match', inventory_hostname) | map(attribute='children') | list) }}"

        - name: purge osd(s) from the cluster
          ceph_osd:
            ids: "{{ item }}"
            cluster: "{{ cluster }}"
            state: purge
          environment:
            CEPH_CONTAINER_IMAGE: "{{ ceph_docker_registry + '/' + ceph_docker_image + ':' + ceph_docker_image_tag if containerized_deployment | bool else None }}"
            CEPH_CONTAINER_BINARY: "{{ container_binary }}"
          run_once: true
          delegate_to: "{{ groups[mon_group_name][0] }}"
          with_items: "{{ osd_ids }}"
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The problem is in set_fact_osd_ids inside the with_items loop.  
This snip: selectattr('name', 'match', inventory_hostname)

returns matches for inventory hostnames other than the current target.  
Specifically when limiting the playbook to run on host "computehci-1", the match statement above will return OSDs from:
computehci-1
computehci-10
computehci-11

(and so on if the cluster is large enough)

The desired behavior is to only return the list of OSDs on the target host "computehci-1".

We don't want a match filter here, we want an equalto filter.  I changed the filter as follows:
selectattr('name', 'equalto', inventory_hostname)

and now the playbook runs as expected.


How reproducible:
This will occur whenever hostnames are similar as described above.