Show head commit sha in footer on preview builds (#2384)

csc-overrides/partials/footer.html

@@ -51,6 +51,11 @@
   <div class="md-footer-meta md-typeset">
     <div class="md-footer-meta__inner md-grid">
       {% include "partials/copyright.html" %}
+      {% if page and page.meta and page.meta["head_sha"] %}
+          <pre style="color: pink;
+                      font-size: small;"
+          >commit {{ page.meta["head_sha"] | string }}</pre>
+      {% endif %}
       {% if config.extra.social %}
         {% include "partials/social.html" %}
       {% endif %}

hooks/preview.py

@@ -0,0 +1,42 @@
+from pathlib import Path
+
+from git import Repo
+from mkdocs.plugins import get_plugin_logger
+
+
+class PreviewHook:
+    MKDOCS_HOOK_NAME = "preview-hook"
+    ENVIRONMENT_KEY = "environment"
+    PREVIEW_ENVIRONMENT = "preview"
+
+    def __init__(self):
+      self.environment = None
+      self.startup_command = None
+      self.logger = get_plugin_logger(self.MKDOCS_HOOK_NAME)
+      self.head_sha = Repo(Path.cwd()).head.commit.hexsha
+
+    @property
+    def is_preview_build(self):
+        return self.environment == self.PREVIEW_ENVIRONMENT and \
+               self.startup_command == "build"
+
+    def on_startup(self, command, dirty):
+      self.startup_command = command
+      return None
+
+    def on_config(self, config):
+        self.environment = config.extra[self.ENVIRONMENT_KEY]
+        if self.is_preview_build:
+            self.logger.info(f"preview build, commit {self.head_sha}")
+        return None
+
+    def on_page_markdown(self, markdown, page, config, files):
+      if self.is_preview_build:
+          page.meta["head_sha"] = self.head_sha
+      return None
+
+
+hook = PreviewHook()
+on_startup = hook.on_startup
+on_config = hook.on_config
+on_page_markdown = hook.on_page_markdown

mkdocs.yml

@@ -32,6 +32,7 @@ extra:
 
 hooks:
   - hooks/archives.py
+  - hooks/preview.py
 
 plugins:
   - tags: