Initial implementation

.github/workflows/release.yml

@@ -0,0 +1,80 @@
+name: Release Buildpack
+
+on:
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+env:
+  BUILDPACK_DOCKER_REPO: docker.io/heroku/buildpack-python
+  CARGO_TERM_COLOR: always
+
+jobs:
+  # Releases the buildpack to Docker Hub and registers it with the CNB Buildpack Registry.
+  # This release process intentionally does not create a .cnb file release for now, since
+  # there are currently no use-cases that need it for Python.
+  release:
+    name: Release heroku/python
+    runs-on: ubuntu-latest
+    steps:
+      # Setup
+      - name: Checkout
+        uses: actions/checkout@v3
+      - name: Install musl-tools
+        run: sudo apt-get install musl-tools --no-install-recommends
+      - name: Update Rust toolchain
+        run: rustup update
+      - name: Install Rust linux-musl target
+        run: rustup target add x86_64-unknown-linux-musl
+      - name: Rust Cache
+        uses: Swatinem/rust-cache@v2.2.1
+      - name: Install libcnb-cargo
+        run: cargo install libcnb-cargo
+      - name: Install Pack CLI
+        uses: buildpacks/github-actions/setup-pack@v5.0.1
+      - name: Install yj and crane
+        uses: buildpacks/github-actions/setup-tools@v5.0.1
+      - name: Login to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          registry: docker.io
+          username: ${{ secrets.DOCKER_HUB_USER }}
+          password: ${{ secrets.DOCKER_HUB_TOKEN }}
+
+      # Build
+      - name: Compile the buildpack
+        run: cargo libcnb package --release
+
+      # Publish
+      - name: Read buildpack metadata
+        run: |
+          echo "buildpack_id=$(yj -t < buildpack.toml | jq -r .buildpack.id)" >> $GITHUB_ENV
+          echo "buildpack_version=$(yj -t < buildpack.toml | jq -r .buildpack.version)" >> $GITHUB_ENV
+      - name: Check version is unique on Docker Hub
+        run: |
+          if docker manifest inspect "${{ env.BUILDPACK_DOCKER_REPO }}:${{ env.buildpack_version }}" > /dev/null; then
+            echo "Duplicate version found on Docker Hub ${{ env.BUILDPACK_DOCKER_REPO }}:${{ env.buildpack_version }}"
+            exit 1
+          fi
+      - name: Publish the buildpack to Docker Hub
+        run: pack buildpack package --path target/buildpack/release/heroku_python --publish "${{ env.BUILDPACK_DOCKER_REPO }}:${{ env.buildpack_version }}"
+      - name: Calculate the buildpack image digest
+        run: echo "buildpack_digest=$(crane digest ${{ env.BUILDPACK_DOCKER_REPO }}:${{ env.buildpack_version }})" >> $GITHUB_ENV
+      - name: Register the new version with the CNB Buildpack Registry
+        uses: docker://ghcr.io/buildpacks/actions/registry/request-add-entry:5.0.1
+        with:
+          token: ${{ secrets.CNB_REGISTRY_RELEASE_BOT_GITHUB_TOKEN }}
+          id: ${{ env.buildpack_id }}
+          version: ${{ env.buildpack_version }}
+          address: ${{ env.BUILDPACK_DOCKER_REPO }}@${{ env.buildpack_digest }}
+      - name: Create GitHub release
+        uses: actions/create-release@v1
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          tag_name: v${{ env.buildpack_version }}
+          release_name: v${{ env.buildpack_version }}
+          body: |
+            See the [CHANGELOG](./CHANGELOG.md) for details.
+          draft: false

src/layers/python.rs

@@ -340,7 +340,7 @@ fn generate_layer_env(layer_path: &Path, python_version: &PythonVersion) -> Laye
         //
         // One option to solve all of the above, would be to delete the `.pyc` files from the image
         // at the end of the buildpack's build phase, however:
-        //   - This means they need to be regenerated at app start boot, slowing boot times.
+        //   - This means they need to be regenerated at app boot, slowing boot times.
         //     (For a simple Django project on a Perf-M, boot time increases from ~0.5s to ~1.5s.)
         //   - If any other later buildpack runs any of the Python files added by this buildpack, then
         //     the timestamp based `.pyc` files will be created again, re-introducing non-determinism.
@@ -425,11 +425,10 @@ impl From<PythonLayerError> for BuildpackError {
 
 #[cfg(test)]
 mod tests {
+    use super::*;
     use indoc::indoc;
     use libcnb::data::stack_id;
 
-    use super::*;
-
     #[test]
     fn cache_invalidation_reason_unchanged() {
         let metadata = PythonLayerMetadata {

src/packaging_tool_versions.rs

@@ -2,6 +2,8 @@ use serde::{Deserialize, Serialize};
 
 /// The versions of various packaging tools used during the build.
 /// These are always installed, and are independent of the chosen package manager.
+/// Strings are unused instead of a semver version, since these packages don't use
+/// semver, and we never introspect the version parts anyway.
 #[derive(Clone, Deserialize, PartialEq, Serialize)]
 pub(crate) struct PackagingToolVersions {
     pub pip_version: String,

src/python_version.rs

@@ -30,6 +30,7 @@ impl PythonVersion {
     }
 
     pub fn url(&self, stack_id: &StackId) -> String {
+        // TODO: (W-11474658) Switch to tracking versions/URLs via a manifest file.
         format!(
             "https://heroku-buildpack-python.s3.us-east-1.amazonaws.com/{}/runtimes/python-{}.{}.{}.tar.gz",
             stack_id, self.major, self.minor, self.patch
@@ -77,9 +78,8 @@ pub(crate) enum PythonVersionError {
 
 #[cfg(test)]
 mod tests {
-    use libcnb::data::stack_id;
-
     use super::*;
+    use libcnb::data::stack_id;
 
     #[test]
     fn python_version_url() {
@@ -98,7 +98,7 @@ mod tests {
         assert_eq!(
             determine_python_version(Path::new("tests/fixtures/runtime_txt_non_existent_version"))
                 .unwrap(),
-            PythonVersion::new(999, 999, 999)
+            PythonVersion::new(999, 888, 777)
         );
     }
 

src/runtime_txt.rs

@@ -200,7 +200,7 @@ mod tests {
         );
         assert_eq!(
             read_version(Path::new("tests/fixtures/runtime_txt_non_existent_version")).unwrap(),
-            Some(PythonVersion::new(999, 999, 999))
+            Some(PythonVersion::new(999, 888, 777))
         );
     }
 

tests/fixtures/runtime_txt_non_existent_version/runtime.txt

@@ -1 +1 @@
-python-999.999.999
+python-999.888.777

tests/integration/python_version.rs

@@ -1,5 +1,3 @@
-// runtime.txt parsing
-
 use crate::integration_tests::{
     builder, DEFAULT_PYTHON_VERSION, LATEST_PYTHON_3_10, LATEST_PYTHON_3_11, LATEST_PYTHON_3_7,
     LATEST_PYTHON_3_8, LATEST_PYTHON_3_9,
@@ -125,7 +123,7 @@ fn runtime_txt_invalid_version() {
 fn runtime_txt_non_existent_version() {
     rejects_non_existent_python_version(
         "tests/fixtures/runtime_txt_non_existent_version",
-        "999.999.999",
+        "999.888.777",
     );
 }