conf.py/set_versions/poky.yaml: Set version in conf.py from poky.yaml

Allow conf.py to read the versions it needs from poky.yaml and have
set_versions.py write this out. This means we don't have to change as
many files when making new releases.

(From yocto-docs rev: bfe74c67f327f0c6445cb4129ee0c32db022b95a)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

documentation/conf.py

@@ -15,9 +15,27 @@
 import os
 import sys
 import datetime
+try:
+    import yaml
+except ImportError:
+    sys.stderr.write("The Yocto Project Sphinx documentation requires PyYAML.\
+    \nPlease make sure to install pyyaml python package.\n")
+    sys.exit(1)
 
-current_version = "dev"
-bitbake_version = "" # Leave empty for development branch
+# current_version = "dev"
+# bitbake_version = "" # Leave empty for development branch
+# Obtain versions from poky.yaml instead
+with open("poky.yaml") as data:
+    buff = data.read()
+    subst_vars = yaml.safe_load(buff)
+    if "DOCCONF_VERSION" not in subst_vars:
+        sys.stderr.write("Please set DOCCONF_VERSION in poky.yaml")
+        sys.exit(1)
+    current_version = subst_vars["DOCCONF_VERSION"]
+    if "BITBAKE_SERIES" not in subst_vars:
+        sys.stderr.write("Please set BITBAKE_SERIES in poky.yaml")
+        sys.exit(1)
+    bitbake_version = subst_vars["BITBAKE_SERIES"]
 
 # String used in sidebar
 version = 'Version: ' + current_version