Derive render Java version from Minecraft

.gitea/workflows/build-readme.yml

@@ -18,19 +18,6 @@ jobs:
         with:
           python-version: "3.11"
 
-      - name: Set up Java
-        uses: actions/setup-java@v4
-        with:
-          distribution: temurin
-          java-version: "25"
-
-      - name: Set up Gradle
-        run: |
-          GRADLE_VERSION=8.10.2
-          curl -fsSL -o /tmp/gradle.zip "https://services.gradle.org/distributions/gradle-${GRADLE_VERSION}-bin.zip"
-          sudo unzip -q /tmp/gradle.zip -d /opt
-          echo "/opt/gradle-${GRADLE_VERSION}/bin" >> "$GITHUB_PATH"
-
       - name: Resolve latest Minecraft release
         run: |
           mkdir -p build
@@ -41,7 +28,24 @@ jobs:
         shell: bash
         run: |
           release=$(head -n 1 build/minecraft-version.txt)
+          snapshot=$(sed -n '2s/^snapshot=//p' build/minecraft-version.txt)
+          java_version=$(sed -n '3s/^java_version=//p' build/minecraft-version.txt)
           echo "release=$release" >> "$GITHUB_OUTPUT"
+          echo "snapshot=$snapshot" >> "$GITHUB_OUTPUT"
+          echo "java_version=$java_version" >> "$GITHUB_OUTPUT"
+
+      - name: Set up Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: ${{ steps.minecraft_version.outputs.java_version }}
+
+      - name: Set up Gradle
+        run: |
+          GRADLE_VERSION=8.10.2
+          curl -fsSL -o /tmp/gradle.zip "https://services.gradle.org/distributions/gradle-${GRADLE_VERSION}-bin.zip"
+          sudo unzip -q /tmp/gradle.zip -d /opt
+          echo "/opt/gradle-${GRADLE_VERSION}/bin" >> "$GITHUB_PATH"
 
       - name: Build readme
         run: python build/scripts/build_readme.py --pack-root resourcepack --output-dir build

build/scripts/resolve_latest_minecraft_release.py

@@ -15,8 +15,17 @@ def main() -> int:
     latest_release = manifest["latest"]["release"]
     latest_snapshot = manifest["latest"]["snapshot"]
 
+    latest_release_entry = next(version for version in manifest["versions"] if version["id"] == latest_release)
+    with urlopen(latest_release_entry["url"], timeout=30) as response:
+        version_metadata = json.load(response)
+
+    java_version = version_metadata.get("javaVersion", {}).get("majorVersion")
+    if not isinstance(java_version, int):
+        raise RuntimeError(f"Latest Minecraft release {latest_release} does not declare a javaVersion.majorVersion")
+
     print(latest_release)
     print(f"snapshot={latest_snapshot}")
+    print(f"java_version={java_version}")
     return 0