Migrate inventory code

CHANGELOG.md

@@ -9,6 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `libherokubuildpack`:
+  - Added `inventory` module. ([#861](https://github.com/heroku/libcnb.rs/pull/861))
 
 ## [0.23.0] - 2024-08-28
 

libherokubuildpack/Cargo.toml

@@ -18,10 +18,13 @@ all-features = true
 workspace = true
 
 [features]
-default = ["command", "download", "digest", "error", "log", "tar", "toml", "fs", "write", "buildpack_output"]
+default = ["command", "download", "digest", "error", "inventory", "log", "inventory-semver", "inventory-sha2", "tar", "toml", "fs", "write", "buildpack_output"]
 download = ["dep:ureq", "dep:thiserror"]
 digest = ["dep:sha2"]
 error = ["log", "dep:libcnb"]
+inventory = ["dep:hex", "dep:serde", "dep:thiserror", "dep:toml"]
+inventory-semver = ["dep:semver"]
+inventory-sha2 = ["dep:sha2"]
 log = ["dep:termcolor"]
 tar = ["dep:tar", "dep:flate2"]
 toml = ["dep:toml"]
@@ -38,8 +41,11 @@ crossbeam-utils = { version = "0.8.20", optional = true }
 # https://github.com/rust-lang/libz-sys/issues/93
 # As such we have to use the next best alternate backend, which is `zlib`.
 flate2 = { version = "1.0.33", default-features = false, features = ["zlib"], optional = true }
+hex = { version = "0.4.3", optional = true }
 libcnb = { workspace = true, optional = true }
 pathdiff = { version = "0.2.1", optional = true }
+semver = { version = "1.0.21", features = ["serde"], optional = true }
+serde = { version = "1.0.209", features = ["derive"], optional = true }
 sha2 = { version = "0.10.8", optional = true }
 tar = { version = "0.4.41", default-features = false, optional = true }
 termcolor = { version = "1.4.1", optional = true }
@@ -50,4 +56,5 @@ ureq = { version = "2.10.1", default-features = false, features = ["tls"], optio
 [dev-dependencies]
 indoc = "2.0.5"
 libcnb-test = { workspace = true }
+serde_test = "1.0.177"
 tempfile = "3.12.0"

libherokubuildpack/src/inventory.rs

@@ -0,0 +1,284 @@
+//! # Inventory
+//!
+//! Many buildpacks need to provide artifacts from different URLs. A helpful pattern
+//! is to provide a list of artifacts in a TOML file, which can be parsed and used by
+//! the buildpack to download the correct artifact. For example, a Ruby buildpack
+//! might need to download pre-compiled Ruby binaries hosted on S3.
+//!
+//! This module can be used to produce and consume such an inventory file.
+//!
+//! ## Features
+//!
+//! - Version lookup and comparison: To implement the inventory, you'll need to define how
+//!   versions are compared. This allows the inventory code to find an appropriate artifact
+//!   based on whatever custom version logic you need. If you don't need custom logic, you can
+//!   use the included `inventory-semver` feature.
+//! - Architecture aware: Beyond version specifiers, buildpack authors may need to provide different
+//!   artifacts for different computer architectures such as ARM64 or AMD64. The inventory encodes
+//!   this information which is used to select the correct artifact.
+//! - Checksum validation: In addition to knowing the URL of an artifact, buildp authors
+//!   want to be confident that the artifact they download is the correct one. To accomplish this
+//!   the inventory contains a checksum of the download and can be used to validate the download
+//!   has not been modified or tampered with. To use sha256 or sha512 checksums out of the box,
+//!   enable the `inventory-sha2` feature
+//! - Extensible with metadata: The default inventory format covers a lot of common use cases,
+//!   but if you need more, you can extend it by adding custom metadata to each artifact.
+//!
+//! ## Example usage
+//!
+//! This example demonstrates:
+//! * Creating an artifact using the `inventory-sha2` and `inventory-semver` features.
+//! * Adding the artifact to an inventory.
+//! * Serializing and deserializing the inventory [to](Inventory#method.fmt) and [from](Inventory::from_str) TOML.
+//! * [Resolving an inventory artifact](Inventory::resolve) specifying relevant OS, architecture, and version requirements.
+//! * Using the resolved artifact's checksum value to verify "downloaded" data.
+//!
+//! ```rust
+//! use libherokubuildpack::inventory::{artifact::{Arch, Artifact, Os}, Inventory, checksum::Checksum};
+//! use semver::{Version, VersionReq};
+//! use sha2::{Sha256, Digest};
+//!
+//! // Create an artifact with a SHA256 checksum and `semver::Version`
+//! let new_artifact = Artifact {
+//!     version: Version::new(1, 0, 0),
+//!     os: Os::Linux,
+//!     arch: Arch::Arm64,
+//!     url: "https://example.com/foo.txt".to_string(),
+//!     checksum: "sha256:2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae"
+//!         .parse::<Checksum<Sha256>>()
+//!         .unwrap(),
+//!     metadata: None,
+//! };
+//!
+//! // Create an inventory and add the artifact
+//! let mut inventory = Inventory::<Version, Sha256, Option<()>>::new();
+//! inventory.push(new_artifact.clone());
+//!
+//! // Serialize the inventory to TOML
+//! let inventory_toml = inventory.to_string();
+//! assert_eq!(
+//!     r#"[[artifacts]]
+//! version = "1.0.0"
+//! os = "linux"
+//! arch = "arm64"
+//! url = "https://example.com/foo.txt"
+//! checksum = "sha256:2c26b46b68ffc68ff99b453c1d30413413422d706483bfa0f98a5e886266e7ae"
+//! "#,
+//!     inventory_toml
+//! );
+//!
+//! // Deserialize the inventory from TOML
+//! let parsed_inventory = inventory_toml
+//!     .parse::<Inventory<Version, Sha256, Option<()>>>()
+//!     .unwrap();
+//!
+//! // Resolve the artifact by OS, architecture, and version requirement
+//! let version_req = VersionReq::parse("=1.0.0").unwrap();
+//! let resolved_artifact = parsed_inventory.resolve(Os::Linux, Arch::Arm64, &version_req).unwrap();
+//!
+//! assert_eq!(&new_artifact, resolved_artifact);
+//!
+//! // Verify checksum of the resolved artifact
+//! let downloaded_data = "foo";  // Example downloaded file content
+//! let downloaded_checksum = Sha256::digest(downloaded_data).to_vec();
+//!
+//! assert_eq!(downloaded_checksum, resolved_artifact.checksum.value);
+//! println!(
+//!     "Successfully downloaded {} with checksum {}",
+//!     resolved_artifact.url,
+//!     hex::encode(&resolved_artifact.checksum.value)
+//! );
+//! ```
+pub mod artifact;
+pub mod checksum;
+pub mod version;
+
+#[cfg(feature = "inventory-semver")]
+mod semver;
+#[cfg(feature = "inventory-sha2")]
+mod sha2;
+mod unit;
+
+use crate::inventory::artifact::{Arch, Artifact, Os};
+use crate::inventory::checksum::Digest;
+use crate::inventory::version::ArtifactRequirement;
+use serde::de::DeserializeOwned;
+use serde::{Deserialize, Serialize};
+use std::cmp::Ordering;
+use std::fmt::Formatter;
+use std::str::FromStr;
+
+/// Represents an inventory of artifacts.
+///
+/// An inventory can be read directly from a TOML file on disk and used by a buildpack to resolve
+/// requirements for a specific artifact to download.
+///
+/// The inventory can be manipulated in-memory and then re-serialized to disk to facilitate both
+/// reading and writing inventory files.
+#[derive(Debug, Serialize, Deserialize)]
+pub struct Inventory<V, D, M> {
+    #[serde(bound = "V: Serialize + DeserializeOwned, D: Digest, M: Serialize + DeserializeOwned")]
+    pub artifacts: Vec<Artifact<V, D, M>>,
+}
+
+impl<V, D, M> Default for Inventory<V, D, M> {
+    fn default() -> Self {
+        Self { artifacts: vec![] }
+    }
+}
+
+impl<V, D, M> Inventory<V, D, M> {
+    /// Creates a new empty inventory
+    #[must_use]
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    /// Add a new artifact to the in-memory inventory
+    pub fn push(&mut self, artifact: Artifact<V, D, M>) {
+        self.artifacts.push(artifact);
+    }
+
+    /// Return a single artifact as the best match given the input constraints
+    ///
+    /// If multiple artifacts match the constraints, the one with the highest version is returned.
+    pub fn resolve<R>(&self, os: Os, arch: Arch, requirement: &R) -> Option<&Artifact<V, D, M>>
+    where
+        V: Ord,
+        R: ArtifactRequirement<V, M>,
+    {
+        self.artifacts
+            .iter()
+            .filter(|artifact| {
+                artifact.os == os
+                    && artifact.arch == arch
+                    && requirement.satisfies_version(&artifact.version)
+                    && requirement.satisfies_metadata(&artifact.metadata)
+            })
+            .max_by_key(|artifact| &artifact.version)
+    }
+
+    /// Resolve logic for Artifacts that implement `PartialOrd` rather than `Ord`
+    ///
+    /// Some version implementations are only partially ordered. One example could be f32 which is not totally ordered
+    /// because NaN is not comparable to any other number.
+    pub fn partial_resolve<R>(
+        &self,
+        os: Os,
+        arch: Arch,
+        requirement: &R,
+    ) -> Option<&Artifact<V, D, M>>
+    where
+        V: PartialOrd,
+        R: ArtifactRequirement<V, M>,
+    {
+        #[inline]
+        fn partial_max_by_key<I, F, A>(iterator: I, f: F) -> Option<I::Item>
+        where
+            I: Iterator,
+            F: Fn(&I::Item) -> A,
+            A: PartialOrd,
+        {
+            iterator.fold(None, |acc, item| match acc {
+                None => Some(item),
+                Some(acc) => match f(&item).partial_cmp(&f(&acc)) {
+                    Some(Ordering::Greater | Ordering::Equal) => Some(item),
+                    None | Some(Ordering::Less) => Some(acc),
+                },
+            })
+        }
+
+        partial_max_by_key(
+            self.artifacts.iter().filter(|artifact| {
+                artifact.os == os
+                    && artifact.arch == arch
+                    && requirement.satisfies_version(&artifact.version)
+                    && requirement.satisfies_metadata(&artifact.metadata)
+            }),
+            |artifact| &artifact.version,
+        )
+    }
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum ParseInventoryError {
+    #[error("TOML parsing error: {0}")]
+    TomlError(toml::de::Error),
+}
+
+impl<V, D, M> FromStr for Inventory<V, D, M>
+where
+    V: Serialize + DeserializeOwned,
+    D: Digest,
+    M: Serialize + DeserializeOwned,
+{
+    type Err = ParseInventoryError;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        toml::from_str(s).map_err(ParseInventoryError::TomlError)
+    }
+}
+
+impl<V, D, M> std::fmt::Display for Inventory<V, D, M>
+where
+    V: Serialize + DeserializeOwned,
+    D: Digest,
+    M: Serialize + DeserializeOwned,
+{
+    #![allow(clippy::unwrap_used)]
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&toml::to_string(self).unwrap())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::inventory::artifact::{Arch, Artifact, Os};
+    use crate::inventory::checksum::tests::BogusDigest;
+    use crate::inventory::Inventory;
+
+    #[test]
+    fn test_matching_artifact_resolution() {
+        let mut inventory = Inventory::new();
+        inventory.push(create_artifact("foo", Os::Linux, Arch::Arm64));
+
+        assert_eq!(
+            "foo",
+            &inventory
+                .resolve(Os::Linux, Arch::Arm64, &String::from("foo"))
+                .expect("should resolve matching artifact")
+                .version,
+        );
+    }
+
+    #[test]
+    fn test_dont_resolve_artifact_with_wrong_arch() {
+        let mut inventory = Inventory::new();
+        inventory.push(create_artifact("foo", Os::Linux, Arch::Arm64));
+
+        assert!(inventory
+            .resolve(Os::Linux, Arch::Amd64, &String::from("foo"))
+            .is_none());
+    }
+
+    #[test]
+    fn test_dont_resolve_artifact_with_wrong_version() {
+        let mut inventory = Inventory::new();
+        inventory.push(create_artifact("foo", Os::Linux, Arch::Arm64));
+
+        assert!(inventory
+            .resolve(Os::Linux, Arch::Arm64, &String::from("bar"))
+            .is_none());
+    }
+
+    fn create_artifact(version: &str, os: Os, arch: Arch) -> Artifact<String, BogusDigest, ()> {
+        Artifact {
+            version: String::from(version),
+            os,
+            arch,
+            url: "https://example.com".to_string(),
+            checksum: BogusDigest::checksum("cafebabe"),
+            metadata: (),
+        }
+    }
+}