chore(ci): add action to test abnf syntax and examples in OM2.0 spec

Action item from OpenMetrics 2.0 WG.

Signed-off-by: György Krajcsovits <[email protected]>

Author: krajorama

.github/workflows/openmetrics.yml

@@ -0,0 +1,24 @@
+name: OpenMetrics
+
+on:
+  pull_request:
+    paths:
+      - 'docs/specs/om/open_metrics_spec_2_0.md'
+
+jobs:
+  check-abnf:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Python 3.10
+      uses: actions/setup-python@v3
+      with:
+        python-version: "3.12.3"
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install abnf
+    - name: Check ABNF for OpenMetrics 2.0
+      run: |
+        python3 scripts/check_openmetrics_spec.py docs/specs/om/open_metrics_spec_2_0.md

docs/specs/om/open_metrics_spec_2_0.md

@@ -1,4 +1,5 @@
 ---
+
 title: "OpenMetrics 2.0"
 nav_title: "2.0"
 sort_rank: 2

scripts/check_openmetrics_spec.py

@@ -0,0 +1,49 @@
+#!/bin/env python3
+
+from abnf import Rule
+import sys
+
+class FromStringRule(Rule):
+    pass
+
+# Start node for the OpenMetrics spec.
+start_node = 'exposition'
+
+def get_spec(filename):
+    with open(filename, 'r') as file:
+        lines = file.readlines()
+    spec = []
+    collecting = False
+    for line in lines:
+        if collecting:
+            if line.startswith('```'):
+                collecting = False
+            else:
+                spec.append(line.strip())
+            continue
+        if line.startswith('```abnf'):
+            if len(spec) > 0:
+                raise ValueError("Multiple ABNF blocks found in the file.")
+            collecting = True
+
+    if len(spec) == 0:
+        raise ValueError("No or empty ABNF block found in the file. Wanted ```abnf ... ```.")
+    return spec
+
+# Main
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        print("Usage: python3 check_openmetrics_spec.py <filename.md>")
+        sys.exit(1)
+
+    filename = sys.argv[1]
+    if not filename.endswith('.md'):
+        print(f"Error: {filename} is not a Markdown file.")
+        sys.exit(1)
+    spec = get_spec(filename)
+    try:
+        rule = FromStringRule.load_grammar(grammar='\n'.join(spec), strict=True)
+    except Exception as e:
+        print(f"Error parsing ABNF: {e}")
+        sys.exit(1)
+    print("ABNF parsed successfully.")