[ci] Updated CI failure bot caller and docs #616

- Set write permissions only on "call-ci-failure-bot"
- Handled case in which PR author cannot be fetched

Related to #616

Author: stktyagi

.github/workflows/bot-ci-failure.yml

@@ -7,8 +7,8 @@ on:
       - completed
 
 permissions:
-  pull-requests: write
-  actions: write
+  pull-requests: read
+  actions: read
   contents: read
 
 concurrency:
@@ -34,8 +34,8 @@ jobs:
           emit_pr() {
             local pr_number="$1"
             local pr_author
-            pr_author=$(gh pr view "$pr_number" --repo "$REPO" --json author --jq '.author.login' 2>/dev/null || echo "")
-            if [ -z "$pr_author" ]; then
+            pr_author=$(gh pr view "$pr_number" --repo "$REPO" --json author --jq '.author.login // empty' 2>/dev/null || echo "")
+            if [ -z "$pr_author" ] || [ "$pr_author" = "null" ]; then
               echo "::warning::Could not fetch PR author for PR #$pr_number"
             fi 
             echo "number=$pr_number" >> "$GITHUB_OUTPUT"
@@ -68,6 +68,10 @@ jobs:
   call-ci-failure-bot:
     needs: find-pr
     if: ${{ needs.find-pr.outputs.pr_number != '' }}
+    permissions:
+      pull-requests: write
+      actions: write
+      contents: read
     uses: openwisp/openwisp-utils/.github/workflows/reusable-bot-ci-failure.yml@master
     with:
       pr_number: ${{ needs.find-pr.outputs.pr_number }}

docs/developer/reusable-github-utils.rst

@@ -383,8 +383,8 @@ job:
           - completed
 
     permissions:
-      pull-requests: write
-      actions: write
+      pull-requests: read
+      actions: read
       contents: read
 
     concurrency:
@@ -410,8 +410,8 @@ job:
               emit_pr() {
                 local pr_number="$1"
                 local pr_author
-                pr_author=$(gh pr view "$pr_number" --repo "$REPO" --json author --jq '.author.login' 2>/dev/null || echo "")
-                if [ -z "$pr_author" ]; then
+                pr_author=$(gh pr view "$pr_number" --repo "$REPO" --json author --jq '.author.login // empty' 2>/dev/null || echo "")
+                if [ -z "$pr_author" ] || [ "$pr_author" = "null" ]; then
                   echo "::warning::Could not fetch PR author for PR #$pr_number"
                 fi
                 echo "number=$pr_number" >> "$GITHUB_OUTPUT"
@@ -444,6 +444,10 @@ job:
       call-ci-failure-bot:
         needs: find-pr
         if: ${{ needs.find-pr.outputs.pr_number != '' }}
+        permissions:
+          pull-requests: write
+          actions: write
+          contents: read
         uses: openwisp/openwisp-utils/.github/workflows/reusable-bot-ci-failure.yml@master
         with:
           pr_number: ${{ needs.find-pr.outputs.pr_number }}