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Migrate
go_deps to struct layer API (#339)
* Migrate go_deps layer to struct layer API * Drop go_clean, which is no longer used * Drop infallible result and logging side effects
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,108 +1,89 @@ | ||
| use crate::{cmd, GoBuildpack, GoBuildpackError}; | ||
| use crate::{GoBuildpack, GoBuildpackError}; | ||
| use libcnb::build::BuildContext; | ||
| use libcnb::data::layer_content_metadata::LayerTypes; | ||
| use libcnb::layer::{ExistingLayerStrategy, Layer, LayerData, LayerResult, LayerResultBuilder}; | ||
| use libcnb::data::layer_name; | ||
| use libcnb::layer::{ | ||
| CachedLayerDefinition, EmptyLayerCause, InvalidMetadataAction, LayerState, RestoredLayerAction, | ||
| }; | ||
| use libcnb::layer_env::{LayerEnv, Scope}; | ||
| use libcnb::{Buildpack, Env}; | ||
| use libherokubuildpack::log::log_info; | ||
| use serde::{Deserialize, Serialize}; | ||
| use std::fs; | ||
| use std::path::Path; | ||
|
|
||
| const LAYER_VERSION: &str = "1"; | ||
| const MAX_CACHE_USAGE_COUNT: f32 = 100.0; | ||
| const CACHE_ENV: &str = "GOMODCACHE"; | ||
| const CACHE_DIR: &str = "cache"; | ||
|
|
||
| /// A layer that caches the go modules cache | ||
| pub(crate) struct DepsLayer { | ||
| pub(crate) go_env: Env, | ||
| } | ||
|
|
||
| #[derive(Deserialize, Serialize, Clone, PartialEq)] | ||
| pub(crate) struct DepsLayerMetadata { | ||
| // Using float here due to [an issue with lifecycle's handling of integers](https://github.com/buildpacks/lifecycle/issues/884) | ||
| cache_usage_count: f32, | ||
| layer_version: String, | ||
| } | ||
|
|
||
| #[derive(thiserror::Error, Debug)] | ||
| pub(crate) enum DepsLayerError { | ||
| #[error("Couldn't create Go modules cache layer: {0}")] | ||
| Create(std::io::Error), | ||
| #[error("Couldn't clean Go modules cache: {0}")] | ||
| Clean(#[from] cmd::Error), | ||
| } | ||
|
|
||
| impl Layer for DepsLayer { | ||
| type Buildpack = GoBuildpack; | ||
| type Metadata = DepsLayerMetadata; | ||
|
|
||
| fn types(&self) -> LayerTypes { | ||
| LayerTypes { | ||
| /// Create or restore the layer for the go modules cache (non-vendored dependencies) | ||
| pub(crate) fn handle_deps_layer( | ||
| context: &BuildContext<GoBuildpack>, | ||
| ) -> libcnb::Result<LayerEnv, GoBuildpackError> { | ||
| let layer_ref = context.cached_layer( | ||
| layer_name!("go_deps"), | ||
| CachedLayerDefinition { | ||
| build: true, | ||
| launch: false, | ||
| cache: true, | ||
| } | ||
| } | ||
| invalid_metadata_action: &|_| InvalidMetadataAction::DeleteLayer, | ||
| restored_layer_action: &|restored_metadata: &DepsLayerMetadata, _| { | ||
| if restored_metadata.cache_usage_count >= MAX_CACHE_USAGE_COUNT { | ||
| return ( | ||
| RestoredLayerAction::DeleteLayer, | ||
| restored_metadata.cache_usage_count, | ||
| ); | ||
| } | ||
| ( | ||
| RestoredLayerAction::KeepLayer, | ||
| restored_metadata.cache_usage_count, | ||
| ) | ||
| }, | ||
| }, | ||
| )?; | ||
|
|
||
| fn create( | ||
| &mut self, | ||
| _ctx: &BuildContext<Self::Buildpack>, | ||
| layer_path: &Path, | ||
| ) -> Result<LayerResult<Self::Metadata>, GoBuildpackError> { | ||
| log_info("Creating new Go modules cache"); | ||
| let cache_dir = layer_path.join(CACHE_DIR); | ||
| fs::create_dir(&cache_dir).map_err(DepsLayerError::Create)?; | ||
| LayerResultBuilder::new(DepsLayerMetadata { | ||
| cache_usage_count: 1.0, | ||
| layer_version: LAYER_VERSION.to_string(), | ||
| }) | ||
| .env(LayerEnv::new().chainable_insert( | ||
| Scope::Build, | ||
| libcnb::layer_env::ModificationBehavior::Override, | ||
| CACHE_ENV, | ||
| cache_dir, | ||
| )) | ||
| .build() | ||
| match layer_ref.state { | ||
| LayerState::Empty { | ||
| cause: EmptyLayerCause::NewlyCreated, | ||
| } => (), | ||
| LayerState::Empty { | ||
| cause: EmptyLayerCause::RestoredLayerAction { .. }, | ||
| } => log_info("Discarding expired Go modules cache"), | ||
| LayerState::Empty { .. } => log_info("Discarding invalid Go modules cache"), | ||
| LayerState::Restored { .. } => log_info("Reusing Go modules cache"), | ||
| } | ||
|
|
||
| fn update( | ||
| &mut self, | ||
| _ctx: &BuildContext<Self::Buildpack>, | ||
| layer: &LayerData<Self::Metadata>, | ||
| ) -> Result<LayerResult<Self::Metadata>, GoBuildpackError> { | ||
| LayerResultBuilder::new(DepsLayerMetadata { | ||
| cache_usage_count: layer.content_metadata.metadata.cache_usage_count + 1.0, | ||
| layer_version: LAYER_VERSION.to_string(), | ||
| }) | ||
| .env(LayerEnv::new().chainable_insert( | ||
| Scope::Build, | ||
| libcnb::layer_env::ModificationBehavior::Override, | ||
| CACHE_ENV, | ||
| layer.path.join(CACHE_DIR), | ||
| )) | ||
| .build() | ||
| let mut cache_usage_count = 1.0; | ||
| match layer_ref.state { | ||
| LayerState::Restored { | ||
| cause: previous_cache_usage_count, | ||
| } => cache_usage_count += previous_cache_usage_count, | ||
| LayerState::Empty { .. } => { | ||
| log_info("Creating new Go modules cache"); | ||
| let cache_dir = layer_ref.path().join(CACHE_DIR); | ||
| fs::create_dir(&cache_dir).map_err(DepsLayerError::Create)?; | ||
| layer_ref.write_env(LayerEnv::new().chainable_insert( | ||
| Scope::Build, | ||
| libcnb::layer_env::ModificationBehavior::Override, | ||
| CACHE_ENV, | ||
| cache_dir, | ||
| ))?; | ||
| } | ||
| } | ||
| layer_ref.write_metadata(DepsLayerMetadata { cache_usage_count })?; | ||
| layer_ref.read_env() | ||
| } | ||
|
|
||
| fn existing_layer_strategy( | ||
| &mut self, | ||
| _ctx: &BuildContext<Self::Buildpack>, | ||
| layer: &LayerData<Self::Metadata>, | ||
| ) -> Result<ExistingLayerStrategy, <Self::Buildpack as Buildpack>::Error> { | ||
| if layer.content_metadata.metadata.cache_usage_count >= MAX_CACHE_USAGE_COUNT | ||
| || layer.content_metadata.metadata.layer_version != LAYER_VERSION | ||
| { | ||
| log_info("Expired Go modules cache"); | ||
| // Go restricts write permissions in cache folders, which blocks libcnb | ||
| // from deleting the layer in a `Recreate` scenario. Go clean will | ||
| // delete the entire cache, including the restricted access files. | ||
| let mut go_env = self.go_env.clone(); | ||
| go_env.insert(CACHE_ENV, layer.path.join(CACHE_DIR)); | ||
| cmd::go_clean("-modcache", &go_env).map_err(DepsLayerError::Clean)?; | ||
| return Ok(ExistingLayerStrategy::Recreate); | ||
| } | ||
| log_info("Reusing Go modules cache"); | ||
| Ok(ExistingLayerStrategy::Update) | ||
| impl From<DepsLayerError> for libcnb::Error<GoBuildpackError> { | ||
| fn from(value: DepsLayerError) -> Self { | ||
| libcnb::Error::BuildpackError(GoBuildpackError::DepsLayer(value)) | ||
| } | ||
| } |
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