Warn on EOL stacks (heroku-18, heroku-20)

.github/workflows/build.yml

@@ -218,66 +218,6 @@ jobs:
           cat apppack.toml
           test "$(python -c 'import tomllib; print(tomllib.load(open("apppack.toml", "rb"))["services"]["web"]["command"])')" = "bash -c 'gunicorn --access-logfile - --bind 0.0.0.0:\$PORT --forwarded-allow-ips '\"'\"'*'\"'\"' app:app'"
 
-  integration-heroku20:
-    runs-on: ubuntu-latest
-    needs: [test, build-image]
-    permissions:
-      id-token: write
-      contents: read
-      packages: read
-    steps:
-      - name: Login to GitHub Container Registry
-        uses: docker/login-action@v2
-        with:
-          registry: ghcr.io
-          username: ${{ github.actor }}
-          password: ${{ secrets.GITHUB_TOKEN }}
-      - name: Pull image
-        run: docker pull ${{ needs.build-image.outputs.image }}
-      - name: configure aws credentials
-        uses: aws-actions/configure-aws-credentials@v4
-        with:
-          role-to-assume: arn:aws:iam::891426818781:role/github-actions-integration-tests
-          aws-region: us-east-1
-      - name: Checkout sample repo
-        run: git clone --branch buildpacks-20 https://github.com/apppackio/apppack-demo-python.git
-      - name: Run integration tests
-        working-directory: ./apppack-demo-python
-        run: |
-          cat <<EOF > .envfile
-          APPNAME=gh-integration
-          CODEBUILD_BUILD_ID=demo-python:${{ github.run_id }}
-          CODEBUILD_SOURCE_VERSION=${{ github.sha }}
-          DOCKERHUB_USERNAME=${{ secrets.DOCKERHUB_USERNAME }}
-          DOCKERHUB_ACCESS_TOKEN=${{ secrets.DOCKERHUB_ACCESS_TOKEN }}
-          DOCKER_REPO=891426818781.dkr.ecr.us-east-1.amazonaws.com/github-integration-test
-          ARTIFACT_BUCKET=integration-test-buildartifacts
-          ALLOW_EOL_SHIMMED_BUILDER=1
-          AWS_REGION
-          AWS_ACCESS_KEY_ID
-          AWS_SECRET_ACCESS_KEY
-          AWS_SESSION_TOKEN
-          EOF
-
-          docker run \
-            --rm \
-            --privileged \
-            --env-file .envfile \
-            --volume /var/run/docker.sock:/var/run/docker.sock \
-            --volume "$(pwd):/app" \
-            --workdir /app \
-            ${{ needs.build-image.outputs.image }} \
-            /bin/sh -c "set -x; git config --global --add safe.directory /app && apppack-builder prebuild; apppack-builder build; apppack-builder postbuild"
-      - uses: actions/setup-python@v4
-        with:
-          python-version: "3.11"
-      - name: Verify apppack.toml
-        working-directory: ./apppack-demo-python
-        run: |
-          set -ex
-          cat apppack.toml
-          test "$(python -c 'import tomllib; print(tomllib.load(open("apppack.toml", "rb"))["services"]["web"]["command"])')" = 'gunicorn --access-logfile - --bind 0.0.0.0:$PORT --forwarded-allow-ips '"'"'*'"' app:app"
-
   integration-docker:
     runs-on: ubuntu-latest
     needs: [test, build-image]
@@ -346,7 +286,6 @@ jobs:
       - integration
       - integration-docker
       - integration-appjson
-      - integration-heroku20
       - integration-heroku24
     permissions:
       id-token: write

CHANGELOG.md

@@ -5,6 +5,12 @@ 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/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Changed
+
+* Removed support for EOL `heroku-20` builds 
+
 ## [2.5.0] - 2025-10-21
 
 ### Added

Dockerfile

@@ -1,13 +1,9 @@
 FROM golang:1.25-alpine AS builder
 RUN apk add --no-cache curl
-# Install current `pack` and v0.31.0, the last pack version that supports heroku/buildpacks:20 builder
 ENV PACK_VER=0.38.0
 RUN set -ex && \
-    mkdir -p /tmp/legacy-pack /tmp/current-pack && \
-    cd /tmp/legacy-pack && \
-    curl -sLO "https://github.com/buildpacks/pack/releases/download/v0.31.0/pack-v0.31.0-linux.tgz" && \
-    tar xvzf "pack-v0.31.0-linux.tgz" && \
-    cd /tmp/current-pack && \
+    mkdir -p /tmp/pack && \
+    cd /tmp/pack && \
     curl -sLO "https://github.com/buildpacks/pack/releases/download/v$PACK_VER/pack-v$PACK_VER-linux.tgz" && \
     tar xvzf "pack-v$PACK_VER-linux.tgz"
 
@@ -16,7 +12,6 @@ COPY ./builder .
 RUN go build -o /go/bin/apppack-builder main.go
 
 FROM docker:27-dind
-COPY --from=builder /tmp/legacy-pack/pack /usr/local/bin/pack-legacy
-COPY --from=builder /tmp/current-pack/pack /usr/local/bin/pack
+COPY --from=builder /tmp/pack/pack /usr/local/bin/pack
 RUN apk add --no-cache git
 COPY --from=builder /go/bin/apppack-builder /usr/local/bin/apppack-builder

builder/build/appjson.go

@@ -3,6 +3,7 @@ package build
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"os"
 
 	"github.com/rs/zerolog/log"
@@ -31,27 +32,6 @@ const DefaultStack = "heroku-22"
 
 // buildpacks included in builder
 var IncludedBuildpacks = map[string][]string{
-	"heroku-20": {
-		// $ pack builder inspect heroku/buildpacks:20 -o json | jq '.remote_info.buildpacks[].id'
-		"heroku/builder-eol-warning",
-		"heroku/go",
-		"heroku/gradle",
-		"heroku/java",
-		"heroku/jvm",
-		"heroku/maven",
-		"heroku/nodejs",
-		"heroku/nodejs-corepack",
-		"heroku/nodejs-engine",
-		"heroku/nodejs-npm-engine",
-		"heroku/nodejs-npm-install",
-		"heroku/nodejs-pnpm-install",
-		"heroku/nodejs-yarn",
-		"heroku/php",
-		"heroku/procfile",
-		"heroku/python",
-		"heroku/ruby",
-		"heroku/scala",
-	},
 	"heroku-22": {
 		// $ pack builder inspect heroku/builder:22 -o json | jq '.remote_info.buildpacks[].id'
 		"heroku/deb-packages",
@@ -101,6 +81,9 @@ func patchBuildpack(buildpack string, stack string) string {
 	return buildpack
 }
 
+// EOLStacks contains stacks that have reached end-of-life
+var EOLStacks = []string{"heroku-18", "heroku-20"}
+
 func (a *AppJSON) Unmarshal() error {
 	content, err := a.reader()
 	if err != nil {
@@ -115,6 +98,9 @@ func (a *AppJSON) Unmarshal() error {
 		log.Ctx(a.ctx).Error().Err(err).Msg("failed to parse app.json")
 		return err
 	}
+	if contains(EOLStacks, a.Stack) {
+		return fmt.Errorf("stack %q is end-of-life and no longer supported; upgrade to heroku-24", a.Stack)
+	}
 	return nil
 }
 
@@ -136,12 +122,6 @@ func ParseAppJson(ctx context.Context) (*AppJSON, error) {
 // the first item in the list is the builder, followed by the stack image
 // the stack image is only used for prefetching, so non-heroku stacks should still work
 func (a *AppJSON) GetBuilders() []string {
-	if a.Stack == "heroku-18" {
-		return []string{"heroku/buildpacks:18", "heroku/heroku:18-cnb"}
-	}
-	if a.Stack == "heroku-20" {
-		return []string{"heroku/buildpacks:20", "heroku/heroku:20-cnb"}
-	}
 	if a.Stack == "heroku-22" {
 		return []string{"heroku/builder:22", "heroku/heroku:22-cnb"}
 	}

builder/build/appjson_test.go

@@ -4,10 +4,10 @@ import (
 	"context"
 	"os"
 	"reflect"
+	"strings"
 	"testing"
 
 	"github.com/rs/zerolog"
-	"github.com/rs/zerolog/log"
 )
 
 func stringSliceEqual(a, b []string) bool {
@@ -24,21 +24,6 @@ func stringSliceEqual(a, b []string) bool {
 
 var testContext = zerolog.New(os.Stdout).With().Timestamp().Logger().WithContext(context.Background())
 
-func TestAppJsonBuildpackPatch(t *testing.T) {
-	a := AppJSON{
-		Buildpacks: []Buildpack{
-			{URL: "heroku/nodejs"},
-			{URL: "heroku/python"},
-		},
-		Stack: "heroku-20",
-		ctx:   log.With().Logger().WithContext(context.Background()),
-	}
-	expected := []string{"urn:cnb:builder:heroku/nodejs", "urn:cnb:builder:heroku/python"}
-	if !stringSliceEqual(a.GetBuildpacks(), expected) {
-		t.Errorf("expected %s, got %s", expected, a.GetBuildpacks())
-	}
-}
-
 func TestAppJsonMissing(t *testing.T) {
 	a := AppJSON{
 		reader: func() ([]byte, error) {
@@ -58,27 +43,49 @@ func TestAppJsonMissing(t *testing.T) {
 func TestAppJsonStack(t *testing.T) {
 	a := AppJSON{
 		reader: func() ([]byte, error) {
-			return []byte(`{"stack": "heroku-18"}`), nil
+			return []byte(`{"stack": "heroku-22"}`), nil
 		},
 		ctx: testContext,
 	}
 	err := a.Unmarshal()
 	if err != nil {
 		t.Errorf("expected no error, got %s", err)
 	}
-	if a.Stack != "heroku-18" {
+	if a.Stack != "heroku-22" {
 		t.Errorf("expected heroku-22, got %s", a.Stack)
 	}
 }
 
 func TestAppJsonBuilders(t *testing.T) {
-	a := AppJSON{
-		Stack: "heroku-22",
-		ctx:   testContext,
+	tests := []struct {
+		stack    string
+		expected []string
+	}{
+		{"heroku-22", []string{"heroku/builder:22", "heroku/heroku:22-cnb"}},
+		{"custom/builder:latest", []string{"custom/builder:latest"}},
+	}
+	for _, tt := range tests {
+		a := AppJSON{Stack: tt.stack, ctx: testContext}
+		if !stringSliceEqual(a.GetBuilders(), tt.expected) {
+			t.Errorf("stack %s: expected %s, got %s", tt.stack, tt.expected, a.GetBuilders())
+		}
 	}
-	expected := []string{"heroku/builder:22", "heroku/heroku:22-cnb"}
-	if !stringSliceEqual(a.GetBuilders(), expected) {
-		t.Errorf("expected %s, got %s", expected, a.GetBuilders())
+}
+
+func TestAppJsonEOLStackError(t *testing.T) {
+	for _, stack := range EOLStacks {
+		a := AppJSON{
+			reader: func() ([]byte, error) {
+				return []byte(`{"stack": "` + stack + `"}`), nil
+			},
+			ctx: testContext,
+		}
+		err := a.Unmarshal()
+		if err == nil {
+			t.Errorf("stack %s: expected error for EOL stack, got nil", stack)
+		} else if !strings.Contains(err.Error(), "end-of-life") {
+			t.Errorf("stack %s: expected end-of-life error, got: %s", stack, err)
+		}
 	}
 }
 

builder/build/build.go

@@ -144,13 +144,7 @@ func (b *Build) buildWithDocker(config *containers.BuildConfig) error {
 func (b *Build) buildWithPack(config *containers.BuildConfig) error {
 	b.Log().Debug().Msg("pack config registry-mirrors")
 	builder := b.BuildpackBuilders()[0]
-	packBinary := "pack"
-	if builder == "heroku/buildpacks:20" {
-		// use legacy pack for heroku/buildpacks:20
-		packBinary = "pack-legacy"
-		b.Log().Debug().Msg(fmt.Sprintf("using legacy pack version for %s", builder))
-	}
-	cmd := exec.Command(packBinary, "config", "registry-mirrors", "add", "index.docker.io", "--mirror", DockerHubMirror)
+	cmd := exec.Command("pack", "config", "registry-mirrors", "add", "index.docker.io", "--mirror", DockerHubMirror)
 	if err := cmd.Run(); err != nil {
 		return err
 	}
@@ -170,7 +164,7 @@ func (b *Build) buildWithPack(config *containers.BuildConfig) error {
 	}
 	packArgs = append(packArgs, config.Image)
 	b.Log().Debug().Str("builder", builder).Str("buildpacks", buildpacks).Msg("building image")
-	cmd = exec.Command(packBinary, packArgs...)
+	cmd = exec.Command("pack", packArgs...)
 	out := io.MultiWriter(os.Stdout, config.LogFile)
 	cmd.Stdout = out
 	cmd.Stderr = out