ci: add Dependabot and trim caches and artifacts

.github/actions/build-macos-x86_64/action.yml

@@ -51,12 +51,17 @@ runs:
         key: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-${{ hashFiles('webrtc-java-media/pom.xml') }}
         restore-keys: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-
 
+    # One cache per OS: the dependencies do not differ between the platforms of
+    # an OS. The project's own artifacts, which mvn deploy installs, change with
+    # every build and stay out of it.
     - name: Set up Maven cache
       uses: actions/cache@v6
       with:
-        path: ~/.m2/repository
-        key: maven-${{ inputs.platform-name }}-${{ hashFiles('**/pom.xml') }}
-        restore-keys: maven-${{ inputs.platform-name }}-
+        path: |
+          ~/.m2/repository
+          !~/.m2/repository/dev/onvoid/webrtc
+        key: maven-${{ runner.os }}-${{ hashFiles('**/pom.xml') }}
+        restore-keys: maven-${{ runner.os }}-
 
     # The runner is Apple Silicon. The build runs natively and cross compiles
     # for Intel; only the tests need an Intel JVM, to load what was built, and

.github/actions/build/action.yml

@@ -51,12 +51,17 @@ runs:
         key: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-${{ hashFiles('webrtc-java-media/pom.xml') }}
         restore-keys: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-
 
+    # One cache per OS: the dependencies do not differ between the platforms of
+    # an OS. The project's own artifacts, which mvn deploy installs, change with
+    # every build and stay out of it.
     - name: Set up Maven cache
       uses: actions/cache@v6
       with:
-        path: ~/.m2/repository
-        key: maven-${{ inputs.platform-name }}-${{ hashFiles('**/pom.xml') }}
-        restore-keys: maven-${{ inputs.platform-name }}-
+        path: |
+          ~/.m2/repository
+          !~/.m2/repository/dev/onvoid/webrtc
+        key: maven-${{ runner.os }}-${{ hashFiles('**/pom.xml') }}
+        restore-keys: maven-${{ runner.os }}-
 
     - name: Set up JDK ${{ inputs.java-version }}
       uses: actions/setup-java@v5

.github/actions/release-macos-x86_64/action.yml

@@ -43,12 +43,17 @@ runs:
         key: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-${{ hashFiles('webrtc-java-media/pom.xml') }}
         restore-keys: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-
 
+    # One cache per OS: the dependencies do not differ between the platforms of
+    # an OS. The project's own artifacts, which mvn deploy installs, change with
+    # every build and stay out of it.
     - name: Set up Maven cache
       uses: actions/cache@v6
       with:
-        path: ~/.m2/repository
-        key: maven-${{ inputs.platform-name }}-${{ hashFiles('**/pom.xml') }}
-        restore-keys: maven-${{ inputs.platform-name }}-
+        path: |
+          ~/.m2/repository
+          !~/.m2/repository/dev/onvoid/webrtc
+        key: maven-${{ runner.os }}-${{ hashFiles('**/pom.xml') }}
+        restore-keys: maven-${{ runner.os }}-
 
     # The runner is Apple Silicon. The build runs natively and cross compiles
     # for Intel; only the tests need an Intel JVM, to load what was built, and

.github/actions/release/action.yml

@@ -42,12 +42,17 @@ runs:
         key: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-${{ hashFiles('webrtc-java-media/pom.xml') }}
         restore-keys: ffmpeg-${{ env.FFMPEG_VERSION }}-${{ inputs.platform-name }}-${{ hashFiles('webrtc-java-media/src/main/cpp/dependencies/ffmpeg/CMakeLists.txt') }}-
 
+    # One cache per OS: the dependencies do not differ between the platforms of
+    # an OS. The project's own artifacts, which mvn deploy installs, change with
+    # every build and stay out of it.
     - name: Set up Maven cache
       uses: actions/cache@v6
       with:
-        path: ~/.m2/repository
-        key: maven-${{ inputs.platform-name }}-${{ hashFiles('**/pom.xml') }}
-        restore-keys: maven-${{ inputs.platform-name }}-
+        path: |
+          ~/.m2/repository
+          !~/.m2/repository/dev/onvoid/webrtc
+        key: maven-${{ runner.os }}-${{ hashFiles('**/pom.xml') }}
+        restore-keys: maven-${{ runner.os }}-
 
     - name: Set up JDK ${{ inputs.java-version }}
       uses: actions/setup-java@v5

.github/actions/test-natives/action.yml

@@ -67,7 +67,9 @@ runs:
     - name: Ensure Maven
       run: |
         if ! command -v mvn >/dev/null 2>&1; then
-          curl -sSLo maven.zip https://archive.apache.org/dist/maven/maven-3/3.9.9/binaries/apache-maven-3.9.9-bin.zip
+          url=https://archive.apache.org/dist/maven/maven-3/3.9.9/binaries/apache-maven-3.9.9-bin.zip
+          curl -sSfLo maven.zip "$url"
+          echo "$(curl -sSfL "$url.sha512" | cut -d' ' -f1)  maven.zip" | sha512sum -c -
           unzip -q maven.zip -d "$RUNNER_TEMP/maven"
           echo "$RUNNER_TEMP/maven/apache-maven-3.9.9/bin" >> "$GITHUB_PATH"
         fi

.github/dependabot.yml

@@ -0,0 +1,34 @@
+version: 2
+
+# Weekly version updates, one grouped PR per ecosystem. Security updates are
+# enabled separately in the repository settings and are not affected by this.
+#
+# The FFmpeg submodule and the WebRTC branch are left out on purpose: each bump
+# needs manual follow-up (FFmpeg's library file names and configure options,
+# the Chromium Clang pin in prepare-linux), so they are updated by hand.
+updates:
+  - package-ecosystem: github-actions
+    # Also covers the composite actions under .github/actions.
+    directories:
+      - "/"
+      - "/.github/actions/*"
+    schedule:
+      interval: weekly
+    groups:
+      github-actions:
+        patterns: ["*"]
+    commit-message:
+      prefix: ci
+
+  - package-ecosystem: maven
+    directory: "/"
+    schedule:
+      interval: weekly
+    groups:
+      maven-plugins:
+        patterns: ["org.apache.maven.plugins:*", "*-maven-plugin"]
+      maven-dependencies:
+        patterns: ["*"]
+    commit-message:
+      prefix: build
+      include: scope

.github/workflows/build.yml

@@ -81,6 +81,8 @@ jobs:
             webrtc-jni/target/webrtc-java-*.jar
             webrtc-java-media/target/webrtc-java-media-*.jar
           if-no-files-found: error
+          # Only test-natives of this same run reads them.
+          retention-days: 1
 
   build-linux:
     strategy:
@@ -124,6 +126,8 @@ jobs:
             webrtc-jni/target/webrtc-java-*.jar
             webrtc-java-media/target/webrtc-java-media-*.jar
           if-no-files-found: error
+          # Only test-natives of this same run reads them.
+          retention-days: 1
 
   build-macos:
     strategy: