Create tox environment to build pdf documentation

This patch enables building .pdf documentation using new 'pdf-docs'
tox environment. The newly created tox environment creates latex
source codes using sphinx-build and then builds the pdf
documentation using make.

Change-Id: I44b0dde9cec10359dd41cbf9a2d9b034a831f106
Task: 35471

doc/requirements.txt

@@ -4,3 +4,4 @@
 openstackdocstheme>=2.2.1 # Apache-2.0
 reno>=3.1.0 # Apache-2.0
 sphinx>=2.0.0,!=2.1.0 # BSD
+sphinxcontrib-svg2pdfconverter>=0.1.0 # BSD

doc/source/conf.py

@@ -23,7 +23,8 @@ sys.path.insert(0, os.path.abspath('../..'))
 extensions = [
     'sphinx.ext.autodoc',
     #'sphinx.ext.intersphinx',
-    'openstackdocstheme'
+    'openstackdocstheme',
+    'sphinxcontrib.rsvgconverter'
 ]
 
 # openstackdocstheme options
@@ -78,3 +79,16 @@ latex_documents = [
 
 # Example configuration for intersphinx: refer to the Python standard library.
 #intersphinx_mapping = {'http://docs.python.org/': None}
+
+# -- Options for LaTeX output -------------------------------------------------
+
+# Grouping the document tree into LaTeX files. List of tuples
+# (source start file, target name, title, author, documentclass
+# [howto/manual]).
+latex_documents = [
+   ('index', 'doc-stackviz.tex', u'Stackviz',
+    u'OpenStack Foundation', 'manual'),
+]
+
+# Disable usage of xindy https://bugzilla.redhat.com/show_bug.cgi?id=1643664
+latex_use_xindy = False

tox.ini

@@ -41,6 +41,14 @@ commands =
   sphinx-build -W -b html doc/source doc/build/html
 whitelist_externals = rm
 
+[testenv:pdf-docs]
+deps = {[testenv:docs]deps}
+whitelist_externals =
+    make
+commands =
+    sphinx-build -W -b latex doc/source doc/build/pdf
+    make -C doc/build/pdf
+
 [testenv:debug]
 commands = oslo_debug_helper {posargs}