Automatically check for new Flutter versions (#297)

.github/workflows/check_flutter_versions.yml

@@ -0,0 +1,34 @@
+name: "Check Flutter versions"
+on:
+  schedule:
+    # Every 2 hours
+    - cron: "0 */2 * * *"
+  workflow_dispatch:
+
+jobs:
+  check_versions:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      # Install yq and jq
+      - name: Install yq and jq
+        run: |
+          mkdir -p ~/bin
+          wget https://github.com/mikefarah/yq/releases/latest/download/yq_linux_amd64 -O ~/bin/yq
+          chmod +x ~/bin/yq
+          echo "$HOME/bin" >> $GITHUB_PATH
+
+          sudo apt-get install -y jq curl
+
+      - name: Check for new Flutter versions 
+        run: sh scripts/update_flutter_versions.sh
+
+      # Create a Pull Request if there are any changes.
+      # This is automatically checked internally
+      - name: Create Pull Request
+        uses: peter-evans/create-pull-request@v5
+        with:
+          commit-message: "chore: Update Flutter version"
+          title: "chore: Update Flutter version"
+          branch: "chore/update-flutter-version"

scripts/update_flutter_versions.sh

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+#!/bin/bash
+set -e
+
+# This script fetches the latest version of a the stable and beta flutter channels
+# and edits the .cirrus.yml file with those versions
+
+releases_json=$(curl -s https://storage.googleapis.com/flutter_infra_release/releases/releases_linux.json)
+
+# This function edits the .cirrus.yml file with the given flutter version for the given docker tag
+edit_cirrus_file_for_tag() {
+    cirrus_file=".cirrus.yml"
+    docker_tag=$1
+    version=$2
+
+    # env for yq
+    docker_tag=$docker_tag version=$version \
+        yq -i '(.docker_builder.env.matrix[] | select(.DOCKER_TAG == env(docker_tag)) | .FLUTTER_VERSION) = env(version)' $cirrus_file
+}
+
+# This function fetches the latest version of a particular channel (stable, beta) for Flutter
+get_latest_version_in_channel() {
+    channel=$1
+    # This contains the hash of the latest version in the channel
+    channel_hash=$(echo "$releases_json" | jq -r '.current_release.'"$channel")
+    # Look for the version corresponding to the hash in the list of releases
+    version=$(echo "$releases_json" | jq -r --arg HASH "$channel_hash" \
+        '.releases[] | select(.hash == $HASH).version')
+
+    # check not empty
+    if [ -z "$version" ]; then
+        echo "Error fetching latest version in channel $channel"
+        exit 1
+    fi
+
+    echo "$version"
+}
+
+stable_version=$(get_latest_version_in_channel "stable")
+beta_version=$(get_latest_version_in_channel "beta")
+
+echo "Latest beta version: $beta_version"
+echo "Latest stable version: $stable_version"
+
+edit_cirrus_file_for_tag "stable" "$stable_version"
+edit_cirrus_file_for_tag "latest" "$stable_version"
+edit_cirrus_file_for_tag "beta" "$beta_version"
+
+exit 0