Refactor Buildpack (#165)

Author: Malax

.github/workflows/ci.yml

@@ -10,27 +10,38 @@ permissions:
   contents: read
 
 jobs:
+  lint:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+      - name: Install Ruby and dependencies
+        uses: ruby/setup-ruby@v1
+        with:
+          bundler-cache: true
+          ruby-version: "3.4"
+      - name: Install shfmt
+        run: sudo apt-get install shfmt
+      - run: make lint-scripts
+      - run: make check-format
+      - run: make lint-ruby
+
   hatchet:
     name: "Hatchet (${{ matrix.stack }})"
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
+    needs: lint
     strategy:
       fail-fast: false
       matrix:
-        stack: [ "heroku-22", "heroku-24"]
+        stack: ["heroku-22", "heroku-24"]
     env:
       HATCHET_APP_LIMIT: 100
-      HATCHET_RUN_MULTI: 1
-      HATCHET_EXPENSIVE_MODE: 1
-      PARALLEL_SPLIT_TEST_PROCESSES: 6
+      PARALLEL_SPLIT_TEST_PROCESSES: 20
       HEROKU_API_KEY: ${{ secrets.HEROKU_API_KEY }}
       HEROKU_API_USER: ${{ secrets.HEROKU_API_USER }}
       HEROKU_DISABLE_AUTOUPDATE: 1
-      # TODO: Remove once Hatchet supports GitHub Actions natively:
-      # https://github.com/heroku/hatchet/pull/189
-      HATCHET_BUILDPACK_BRANCH: ${{ github.head_ref || github.ref_name }}
       HATCHET_BUILDPACK_BASE: https://github.com/heroku/heroku-buildpack-gradle
-      # Default stack for all Heroku apps created by Hatchet
-      DEFAULT_APP_STACK: ${{ matrix.stack }}
+      HATCHET_DEFAULT_STACK: ${{ matrix.stack }}
     steps:
       - uses: actions/checkout@v5
       - name: Install Ruby and dependencies
@@ -43,41 +54,14 @@ jobs:
       - name: Run Hatchet integration tests
         run: bundle exec parallel_split_test test/spec/
 
-  buildpack-testrunner:
-    runs-on: ubuntu-22.04
-    env:
-      SHUNIT_HOME: /tmp/shunit2-2.1.6
-      # Note the missing STACK environment variable here. This works since there is a default value in the buildpack
-      # source. I ported this as-is from the Travis config. Given we're trying to get rid of testrunner entirely,
-      # it will stay like this. If we, for some reason, decide to keep testrunner, we should look into a fixed STACK env var.
+  container-test:
+    runs-on: ubuntu-24.04
     steps:
-      - uses: actions/checkout@v5
-      - uses: actions/setup-java@v5
-        with:
-          distribution: zulu
-          java-version: 8
-      - name: Download and unpack shunit 2.1.6
-        run: curl -sSf --retry 3 --retry-connrefused --connect-timeout 5 https://storage.googleapis.com/google-code-archive-downloads/v2/code.google.com/shunit2/shunit2-2.1.6.tgz | tar xz -C /tmp/
-      - name: Clone heroku-buildpack-testrunner
-        run: git clone https://github.com/heroku/heroku-buildpack-testrunner.git /tmp/testrunner
-      - name:  Apply heroku-buildpack-testrunner patches to enforce bash shell
-        run:  |
-          cd /tmp/testrunner
-          git apply <<'EOF'
-          diff --git a/bin/run b/bin/run
-          index 0d5b790..a0ff25c 100755
-          --- a/bin/run
-          +++ b/bin/run
-          @@ -101,7 +101,7 @@ for bp in ${@}; do
-               suite_start_time="$(date +%s)"
-          
-               echo "  TEST SUITE: $(basename ${f})"
-          -    ${SHUNIT_HOME?"'SHUNIT_HOME' environment variable must be set"}/src/shunit2 ${f} | indent
-          +    /bin/bash ${SHUNIT_HOME?"'SHUNIT_HOME' environment variable must be set"}/src/shunit2 ${f} | indent
-               exit_code=$(max ${exit_code} ${PIPESTATUS[0]})
-          
-               suite_end_time="$(date +%s)"
-          
-          EOF
-      - name: Execute buildpack-testrunner
-        run: /tmp/testrunner/bin/run .
+      - name: Checkout
+        uses: actions/checkout@v5
+      # These test both the local development `make run` workflow and that `bin/report` completes successfully
+      # for both passing and failing builds (since `bin/report` can't easily be tested via Hatchet tests).
+      - name: Run buildpack using default app fixture
+        run: make run
+      #- name: Run buildpack using an app fixture that's expected to fail
+      #  run: make run FIXTURE=spec/fixtures/failing/

.gitignore

@@ -1,2 +1,7 @@
+.idea/
+*.swp
+target
+*.iml
 .DS_Store
-.idea
+.rspec_status
+test/spec/fixtures/repos/github

.rubocop.yml

@@ -0,0 +1,34 @@
+plugins:
+  - rubocop-rspec
+
+AllCops:
+  NewCops: enable
+
+Layout/TrailingWhitespace:
+  # Required since we use heredocs to assert against Hatchet output, and sometimes that output
+  # contains trailing newlines which we must match against. The alternative is to end the lines
+  # with the unsightly `#{' '}` workaround.
+  AllowInHeredoc: true
+
+Metrics/BlockLength:
+  Enabled: false
+
+RSpec/DescribeClass:
+  Enabled: false
+
+RSpec/ExampleLength:
+  Enabled: false
+
+RSpec/Focus:
+  # Disable auto-correct otherwise format-on-save will remove the annotation
+  # whilst developing locally.
+  AutoCorrect: false
+
+RSpec/MultipleExpectations:
+  Enabled: false
+
+Style/TrailingCommaInArrayLiteral:
+  EnforcedStyleForMultiline: consistent_comma
+
+Style/TrailingCommaInHashLiteral:
+  EnforcedStyleForMultiline: consistent_comma

CHANGELOG.md

@@ -1,7 +1,24 @@
 # Changelog
 
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
+
 ## [Unreleased]
 
+### Added
+
+- Gradle daemon lifecycle management for faster builds. ([#165](https://github.com/heroku/heroku-buildpack-gradle/pull/165))
+
+### Changed
+
+- Framework detection now uses Gradle dependency resolution instead of build file parsing for more reliable detection across all DSL syntax, version catalogs, and dependency sources. ([#165](https://github.com/heroku/heroku-buildpack-gradle/pull/165))
+- Improved error messages with detailed troubleshooting steps, documentation links, and local reproduction guidance. ([#165](https://github.com/heroku/heroku-buildpack-gradle/pull/165))
+
+### Removed
+
+- `GRADLE_TESTPACK_LEGACY_TASK` legacy feature - always exclude `check` task during builds instead of just `test` task. ([#165](https://github.com/heroku/heroku-buildpack-gradle/pull/165))
+- Gradle wrapper installation feature. Projects must include their own Gradle wrapper (`gradlew`). To add a wrapper, run `gradle wrapper` locally and commit the generated files. The buildpack's default wrapper provision was deprecated in 2014 (see [#17](https://github.com/heroku/heroku-buildpack-gradle/pull/17)). ([#165](https://github.com/heroku/heroku-buildpack-gradle/pull/165))
 
 ## [v43] - 2025-07-14
 

Gemfile

@@ -1,7 +1,15 @@
-source "https://rubygems.org"
+# frozen_string_literal: true
 
-gem 'heroku_hatchet'
-gem 'rspec-retry'
-gem 'rspec-expectations'
-gem 'parallel_split_test'
-gem 'java-properties'
+source 'https://rubygems.org'
+
+ruby '>= 3.2', '< 3.5'
+
+group :test, :development do
+  gem 'heroku_hatchet'
+  gem 'parallel_split_test'
+  gem 'rspec-core'
+  gem 'rspec-expectations'
+  gem 'rspec-retry'
+  gem 'rubocop', require: false
+  gem 'rubocop-rspec', require: false
+end

Gemfile.lock

@@ -1,10 +1,11 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    ast (2.4.3)
     base64 (0.3.0)
     diff-lcs (1.6.2)
     erubis (2.7.0)
-    excon (1.2.8)
+    excon (1.3.0)
       logger
     heroics (0.1.3)
       base64
@@ -19,41 +20,77 @@ GEM
       rrrretry (~> 1)
       thor (~> 1)
       threaded (~> 0)
-    java-properties (0.3.0)
+    json (2.13.2)
+    language_server-protocol (3.17.0.5)
+    lint_roller (1.1.0)
     logger (1.7.0)
     moneta (1.0.0)
     multi_json (1.17.0)
-    parallel (1.20.1)
+    parallel (1.27.0)
     parallel_split_test (0.10.0)
       parallel (>= 0.5.13)
       rspec-core (>= 3.9.0)
+    parser (3.3.9.0)
+      ast (~> 2.4.1)
+      racc
     platform-api (3.8.0)
       heroics (~> 0.1.1)
       moneta (~> 1.0.0)
       rate_throttle_client (~> 0.1.0)
+    prism (1.4.0)
+    racc (1.8.1)
+    rainbow (3.1.1)
     rate_throttle_client (0.1.2)
+    regexp_parser (2.11.2)
     rrrretry (1.0.0)
-    rspec-core (3.13.0)
+    rspec-core (3.13.5)
       rspec-support (~> 3.13.0)
     rspec-expectations (3.13.5)
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.13.0)
     rspec-retry (0.6.2)
       rspec-core (> 3.3)
-    rspec-support (3.13.4)
+    rspec-support (3.13.5)
+    rubocop (1.80.2)
+      json (~> 2.3)
+      language_server-protocol (~> 3.17.0.2)
+      lint_roller (~> 1.1.0)
+      parallel (~> 1.10)
+      parser (>= 3.3.0.2)
+      rainbow (>= 2.2.2, < 4.0)
+      regexp_parser (>= 2.9.3, < 3.0)
+      rubocop-ast (>= 1.46.0, < 2.0)
+      ruby-progressbar (~> 1.7)
+      unicode-display_width (>= 2.4.0, < 4.0)
+    rubocop-ast (1.46.0)
+      parser (>= 3.3.7.2)
+      prism (~> 1.4)
+    rubocop-rspec (3.7.0)
+      lint_roller (~> 1.1)
+      rubocop (~> 1.72, >= 1.72.1)
+    ruby-progressbar (1.13.0)
     thor (1.4.0)
     threaded (0.0.4)
+    unicode-display_width (3.1.5)
+      unicode-emoji (~> 4.0, >= 4.0.4)
+    unicode-emoji (4.0.4)
     webrick (1.9.1)
 
 PLATFORMS
+  arm64-darwin-24
   ruby
 
 DEPENDENCIES
   heroku_hatchet
-  java-properties
   parallel_split_test
+  rspec-core
   rspec-expectations
   rspec-retry
+  rubocop
+  rubocop-rspec
+
+RUBY VERSION
+   ruby 3.4.5p51
 
 BUNDLED WITH
-   2.6.9
+   2.7.1

Makefile

@@ -0,0 +1,44 @@
+# These targets are not files
+.PHONY: lint lint-scripts check-format format run publish
+
+STACK ?= heroku-24
+FIXTURE ?= test/spec/fixtures/repos/simple-http-service-gradle-8-groovy
+
+# Converts a stack name of `heroku-NN` to its build Docker image tag of `heroku/heroku:NN-build`.
+STACK_IMAGE_TAG := heroku/$(subst -,:,$(STACK))-build
+
+lint: lint-scripts check-format lint-ruby
+
+lint-scripts:
+	@git ls-files -z --cached --others --exclude-standard 'bin/*' 'etc/*' 'lib/*' 'opt/*' | xargs -0 shellcheck --check-sourced --color=always
+
+lint-ruby:
+	@bundle exec rubocop
+
+check-format:
+	@shfmt -f . | grep -v "vendor/" | grep -v "test/spec/fixtures/" | xargs shfmt --diff
+
+format:
+	@shfmt -f . | grep -v "vendor/" | grep -v "test/spec/fixtures/" | xargs shfmt --write --list
+
+run:
+	@echo "Running buildpack using: STACK=$(STACK) FIXTURE=$(FIXTURE)"
+	@docker run --rm -v $(PWD):/src:ro --tmpfs /app --platform linux/amd64 -e "HOME=/app" -e "STACK=$(STACK)" "$(STACK_IMAGE_TAG)" \
+		bash -euo pipefail -c '\
+			mkdir /tmp/buildpack /tmp/build /tmp/cache /tmp/env; \
+			cp -r /src/{bin,lib} /tmp/buildpack; \
+			cp -rT /src/$(FIXTURE) /tmp/build; \
+			cd /tmp/buildpack; \
+			unset $$(printenv | cut -d '=' -f 1 | grep -vE "^(HOME|LANG|PATH|STACK)$$"); \
+			echo -e "\n~ Detect:" && ./bin/detect /tmp/build; \
+			echo -e "\n~ Compile:" && { ./bin/compile /tmp/build /tmp/cache /tmp/env || COMPILE_FAILED=1; }; \
+			echo -e "\n~ Report:" && ./bin/report /tmp/build /tmp/cache /tmp/env; \
+			[[ "$${COMPILE_FAILED:-}" == "1" ]] && exit 0; \
+			[[ -f /tmp/build/bin/compile ]] && { echo -e "\n~ Compile (Inline Buildpack):" && (source ./export && /tmp/build/bin/compile /tmp/build /tmp/cache /tmp/env); }; \
+			echo -e "\n~ Release:" && ./bin/release /tmp/build; \
+			echo -e "\nBuild successful!"; \
+		'
+	@echo
+
+publish:
+	@etc/publish.sh

README.md

@@ -10,7 +10,7 @@ It uses Gradle to build your application and OpenJDK to run it.
 1. Install the [Gradle Wrapper](http://www.gradle.org/docs/current/userguide/gradle_wrapper.html) into your project.
     - This allows control over the Gradle version and exact distribution to be used.
 2. Specify the Java version to be used as per [these instructions](https://devcenter.heroku.com/articles/java-support#specifying-a-java-version).
-3. If you are not using Spring Boot or Ratpack, then follow the instructions for [configuring your build](https://devcenter.heroku.com/articles/deploying-gradle-apps-on-heroku).
+3. If you are not using Spring Boot, then follow the instructions for [configuring your build](https://devcenter.heroku.com/articles/deploying-gradle-apps-on-heroku).
 
 You do not need to explicitly declare that your project should use this buildpack.
 The presence of a `gradlew` script in the root of your project will allow the fact that your app is built with Gradle to detected.