Automatic update of the extension list

Automatic update of the k6 extension list in the docs/sources/next/extensions/explore.md
file in case of changes based on the https://registry.k6.io/registry.json extension registry.

The change is pushed to the extension-registry-changed branch and a pull request is opened
(or updated) about the change.

Author: szkiba

.github/workflows/extension-registry-changed.yml

@@ -0,0 +1,48 @@
+# This workflow keeps the list of extensions up to date
+# in the docs/sources/next/extensions/explore.md file.
+#
+# The workflow is activated by a workflow dispatch event
+# of the "extension-registry-changed" type.
+# This event is triggered by the grafana/k6-extension-registry
+# repository when the extension registry changes.
+#
+# The list of extensions is generated based on https://registry.k6.io/registry.json.
+# If the generated list differs from the previous one,
+# it is pushed to the "extension-registry-changed" branch and
+# a pull request is created with the change (or updated if it already existed).
+#
+# It is not a problem if the registry changes several times before merging the pull request,
+# the pull request will be updated. The "extension-registry-changed" branch can be deleted
+# after merging the pull request, it will be created again if necessary.
+
+name: extension-registry-changed
+
+on:
+  workflow_dispatch:
+  repository_dispatch:
+    types: [extension-registry-changed]
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Generate Files
+        run: ${{ github.workspace }}/scripts/extension-registry-changed
+
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v6
+        with:
+          branch: extension-registry-changed
+          commit-message: |
+            Keep files generated from the k6 extension registry up to date
+          title: |
+            Update files generated from the k6 Extension Registry
+          body: |
+            The [k6 Extension Registry](https://registry.k6.io) has changed.
+            This pull request contains the files generated from the k6 Extension Registry.
+          add-paths: |
+            docs/sources/next/extensions/explore.md

scripts/extension-registry-changed

@@ -0,0 +1,45 @@
+#!/bin/bash
+
+# This script keeps the list of extensions up to date 
+# in the docs/sources/next/extensions/explore.md file.
+#
+# The script is run by the extension-registry.changed.yml
+# workflow when the extension registry changes.
+# 
+# The list of extensions is generated based on https://registry.k6.io/registry.json.
+#
+# In the docs/sources/next/extensions/explore.md file 
+# the content of the <div class="nav-cards"> HTML element
+# is replaced with the generated extension list.
+
+generate_extension_list_partial() {
+curl -sL https://registry.k6.io/registry.json | 
+ jq -r '
+ map(select(.module != "go.k6.io/k6") | { name:.repo.name, url: .repo.url, description: .description } ) |
+ sort_by(.name) | map(
+"    <a href=\"\(.url)\" target=\"_blank\" class=\"nav-cards__item nav-cards__item--guide\">
+        <h4>\(.name)</h4>
+        <p>\(.description)</p>
+    </a>"
+) | .[] 
+'
+}
+
+replace_extension_list_partial() {
+ed -s $1 <<EOF
+/<div class=.nav-cards.>/+,/<.div>/-d
+/<div class=.nav-cards.>/ r $2
+w
+q
+EOF
+}
+
+scriptdir=$(dirname $(readlink -f "$0"))
+docfile=$scriptdir/../docs/sources/next/extensions/explore.md
+
+tmpfile=/tmp/explore.$$
+
+generate_extension_list_partial > $tmpfile
+replace_extension_list_partial $docfile $tmpfile
+
+rm -f $tmpfile