Github Comment Reporter: Use a html comment to mark the comment (#1356)

This replaces the old method, which looked for the "see error details" link, but that link was not always present in comments. The comment records the current workflow and jobid, so multiple mega-linters can comment on the same PR without colliding. Co-authored-by: Nicolas Vuillamy <[email protected]>
oxsecurity · Mar 27, 2022 · b1e9f2e · b1e9f2e
1 parent 7694809
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -11,6 +11,9 @@ Note: Can be used with `megalinter/megalinter@beta` in your GitHub Action mega-l
 - Linters
   - Disable rstfmt as it is neither stable or maintained
 
+- Fixes
+  - Github Comment Reporter: switch to using a hidden HTML comment to mark the comment, with the current workflow and jobid. This is more robust than the old method. ([[#1355](https://github.com/megalinter/megalinter/issues/1355))
+
 - Linter versions upgrades
   - [checkov](https://www.checkov.io/) from 2.0.975 to **2.0.977** on 2022-03-21
   - [bash-exec](https://tiswww.case.edu/php/chet/bash/bashtop.html) from 5.1.0 to **5.1.16** on 2022-03-22

diff --git a/megalinter/reporters/GithubCommentReporter.py b/megalinter/reporters/GithubCommentReporter.py
@@ -32,6 +32,19 @@ def manage_activation(self):
         ):  # Legacy - true by default
             self.is_active = True
 
+    @property
+    def comment_marker(self):
+        """Generate the comment marker
+
+        This marker is used to find the same comment again so it can be updated.
+
+        """
+        workflow = os.getenv("GITHUB_WORKFLOW", "")
+        jobid = os.getenv("GITHUB_JOB", "")
+        identifier = "".join(filter(None, (workflow, jobid)))
+        identifier_with_padding = identifier and f" {identifier}"
+        return f"<!-- megalinter: github-comment-reporter{identifier_with_padding} -->"
+
     def produce_report(self):
         # Post comment on GitHub pull request
         if config.get("GITHUB_TOKEN", "") != "":
@@ -47,7 +60,12 @@ def produce_report(self):
                 )
             else:
                 action_run_url = ""
-            p_r_msg = build_markdown_summary(self, action_run_url)
+
+            # add comment marker, with extra newlines in between.
+            marker = self.comment_marker
+            p_r_msg = "\n".join(
+                [build_markdown_summary(self, action_run_url), "", marker, ""]
+            )
 
             # Post comment on pull request if found
             github_auth = (
@@ -83,14 +101,12 @@ def produce_report(self):
                 if pr.is_merged():
                     continue
                 # Check if there is already a comment from MegaLinter
+                # start searching from the most recent comment, backwards.
                 existing_comment = None
-                existing_comments = pr.get_issue_comments()
-                for comment in existing_comments:
-                    if (
-                        "See errors details in [**artifact MegaLinter reports** on"
-                        in comment.body
-                    ):
+                for comment in pr.get_issue_comments().reversed:
+                    if marker in comment.body:
                         existing_comment = comment
+                        break
                 # Process comment
                 try:
                     # Edit if there is already a MegaLinter comment