py3: switch to json based data from principle charms

[James Page]

In order to ensure that consistent data is presented from its principle charm when running under py3, we need to use a better serialization format that provided by AST for the passing of pacemaker configuration.

JSON provides the ability to consistently sort keys; in order to support upgrades we need to try to parse 'json_' prefixed data key versions first, and then fallback to ast parsed current key sets if not detected.

Principle charms can then switch safely to the new serialization format.

[James Page (james-page)]

https://review.openstack.org/#/c/531204/

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/531204
Committed: https://git.openstack.org/cgit/openstack/charm-hacluster/commit/?id=22d30c2294cffdb5c21361a1c6d102f916b0d205
Submitter: Zuul
Branch: master

commit 22d30c2294cffdb5c21361a1c6d102f916b0d205
Author: James Page <email address hidden>
Date: Thu Jan 4 18:01:28 2018 +0000

    Support use of json for relation data

    In order to provide consistent presentation of relation data
    in Python 3 based charms, support passing of data using JSON
    format which ensures that data on relations won't continually
    change due to non-deterministic dictionary iteration in py3.

    Change-Id: I364a60ca7b91327fe88ee729cf49ff8ab3f5e2b6
    Closes-Bug: 1741304

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/531207
Committed: https://git.openstack.org/cgit/openstack/charm-neutron-api/commit/?id=852d1f2f3ae4fefd19f0b2e4c02aaf5539cb7f99
Submitter: Zuul
Branch: master

commit 852d1f2f3ae4fefd19f0b2e4c02aaf5539cb7f99
Author: James Page <email address hidden>
Date: Thu Jan 4 18:12:14 2018 +0000

    Pass data to hacluster charm using JSON

    Encode dicts passed to hacluster charm using JSON serialization,
    supporting consistent data presentation under Python 3 where
    dict key iteration is non-deterministic.

    This is supported by prefixing json based data items with 'json_'
    and encoding with keys sorted.

    The charm will also clear any unprefixed based data items for
    upgrades.

    Change-Id: I21c6acff4a4a22cbcc5e6ea4e78394ce076e79d9
    Closes-Bug: 1741304
    Depends-On: I364a60ca7b91327fe88ee729cf49ff8ab3f5e2b6

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/17.11
Review: https://review.openstack.org/545521

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/545521
Committed: https://git.openstack.org/cgit/openstack/charm-hacluster/commit/?id=ff1625985915189f59a68f6c2d654d5953844a3b
Submitter: Zuul
Branch: stable/17.11

commit ff1625985915189f59a68f6c2d654d5953844a3b
Author: James Page <email address hidden>
Date: Thu Jan 4 18:01:28 2018 +0000

    Support use of json for relation data

    In order to provide consistent presentation of relation data
    in Python 3 based charms, support passing of data using JSON
    format which ensures that data on relations won't continually
    change due to non-deterministic dictionary iteration in py3.

    Change-Id: I364a60ca7b91327fe88ee729cf49ff8ab3f5e2b6
    Closes-Bug: 1741304
    (cherry picked from commit 22d30c2294cffdb5c21361a1c6d102f916b0d205)