Use some better linting

Lints docs and yaml files in addition to Python.

This also fixes the encountered issues.

Change-Id: I111cc93939ae4cd2e878e7f863c1a45db51cdbbe

.yamllint

@@ -0,0 +1,8 @@
+---
+extends: default
+
+ignore: |
+  .tox/
+
+rules:
+  line-length: disable

.zuul.yaml

@@ -1,3 +1,4 @@
+---
 - project:
     templates:
       - check-requirements
@@ -6,3 +7,9 @@
       - release-notes-jobs-python3
       - periodic-stable-jobs
       - periodic-jobs-with-oslo-master
+    check:
+      jobs:
+        - openstack-tox-linters
+    gate:
+      jobs:
+        - openstack-tox-linters

HACKING.rst

@@ -4,7 +4,7 @@ masakari-monitors Style Commandments
 Read the OpenStack Style Commandments http://docs.openstack.org/developer/hacking/
 
 masakari-monitors Specific Commandments
-------------------------------
+---------------------------------------
 
 - [M301] Ensure that the _() function is explicitly imported to ensure proper translations.
 - [M302] Validate that log messages are not translated.

tox.ini

@@ -21,9 +21,42 @@ passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY OS_DEB
 [testenv:genconfig]
 commands = oslo-config-generator --config-file=etc/masakarimonitors/masakarimonitors-config-generator.conf
 
+[testenv:linters]
+skip_install = True
+deps =
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  {[testenv:pep8]deps}
+  {[testenv:doc8]deps}
+  {[testenv:yamllint]deps}
+commands =
+  {[testenv:pep8]commands}
+  {[testenv:doc8]commands}
+  {[testenv:yamllint]commands}
+
 [testenv:pep8]
+skip_install = True
+deps =
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  hacking
 commands = flake8 {posargs}
 
+[testenv:doc8]
+skip_install = True
+deps =
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  doc8
+commands =
+  doc8 README.rst CONTRIBUTING.rst HACKING.rst doc/source
+  doc8 releasenotes/source
+  doc8 -e '.yaml' releasenotes/notes
+
+[testenv:yamllint]
+skip_install = True
+deps =
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  yamllint
+commands = yamllint -s .
+
 [testenv:venv]
 commands = {posargs}
 
@@ -94,3 +127,8 @@ paths = ./masakarimonitors/hacking
 deps = bindep
 commands = bindep test
 usedevelop = False
+
+[doc8]
+# NOTE(yoctozepto): this is due to multiple violations - it is better to keep
+# it limited sanely rather than disable the D001 "Line too long" rule altogether
+max-line-length = 105