Ceilometer doesn't read data from Secondary MongoDB nodes

[Ilya Tyaptin]

Currently, if we use MongoDB Ceilometer backend we can deploy MongoDB with ReplicaSet configuration
that provides a HA reliable data storaging.
In same time we use default MongoClient connection that reads only from the Primary node by default.
So if Primary node falls Ceilometer can't read any data from MongoDB during the voting (>1m in the worst case).

We can avoid it if we add readpreference=primaryPreferred to the connection url in ceilometer config file.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/8.0
Review: https://review.openstack.org/269110

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/267527
Committed: https://git.openstack.org/cgit/openstack/fuel-library/commit/?id=0ae748f09c707261530d001afdcea6c5a421f5c7
Submitter: Jenkins
Branch: master

commit 0ae748f09c707261530d001afdcea6c5a421f5c7
Author: iberezovskiy <email address hidden>
Date: Thu Jan 14 15:48:54 2016 +0300

    Configure read preference as primaryPreferred for ceilometer

    Set readpreference to primaryPreferred for ceilometer
    database conntection string to MongoDB.

    Change-Id: I35cd696e2c71ce3acd45fc3fde834ffd84737260
    Closes-bug: #1533749

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/269110
Committed: https://git.openstack.org/cgit/openstack/fuel-library/commit/?id=000418d00a7f15e35333035f4671a04a20b3c1e5
Submitter: Jenkins
Branch: stable/8.0

commit 000418d00a7f15e35333035f4671a04a20b3c1e5
Author: iberezovskiy <email address hidden>
Date: Thu Jan 14 15:48:54 2016 +0300

    Configure read preference as primaryPreferred for ceilometer

    Set readpreference to primaryPreferred for ceilometer
    database conntection string to MongoDB.

    Change-Id: I35cd696e2c71ce3acd45fc3fde834ffd84737260
    Closes-bug: #1533749
    (cherry picked from commit 0ae748f09c707261530d001afdcea6c5a421f5c7)

[Andrey Lavrentyev (alavrentyev)]

Verified on ISO #567

[root@nailgun build]# cat /etc/fuel/version.yaml
VERSION:
  feature_groups:
    - mirantis
  production: "docker"
  release: "8.0"
  api: "1.0"
  build_number: "567"
  build_id: "567"
  fuel-nailgun_sha: "558ca91a854cf29e395940c232911ffb851899c1"
  python-fuelclient_sha: "4f234669cfe88a9406f4e438b1e1f74f1ef484a5"
  fuel-agent_sha: "658be72c4b42d3e1436b86ac4567ab914bfb451b"
  fuel-nailgun-agent_sha: "b2bb466fd5bd92da614cdbd819d6999c510ebfb1"
  astute_sha: "b81577a5b7857c4be8748492bae1dec2fa89b446"
  fuel-library_sha: "33634ec27be77ecfb0b56b7e07497ad86d1fdcd3"
  fuel-ostf_sha: "3bc76a63a9e7d195ff34eadc29552f4235fa6c52"
  fuel-mirror_sha: "fb45b80d7bee5899d931f926e5c9512e2b442749"
  fuelmenu_sha: "78ffc73065a9674b707c081d128cb7eea611474f"
  shotgun_sha: "63645dea384a37dde5c01d4f8905566978e5d906"
  network-checker_sha: "a43cf96cd9532f10794dce736350bf5bed350e9d"
  fuel-upgrade_sha: "616a7490ec7199f69759e97e42f9b97dfc87e85b"
  fuelmain_sha: "d605bcbabf315382d56d0ce8143458be67c53434"

[Artem Minasyan (aminasyan)]

Verified on ISO: http://paste.openstack.org/show/495537/