components: add pip repo for Python distributions

README.md

@@ -219,6 +219,16 @@ example, the rpmdb is a component repo (one can imagine similar component repos
 for other distros). There is also an xattr-based component repo (see the section
 "Customizing the layers" below). Multiple component repos can be active at once.
 
+The following component repos are supported:
+
+- `rpm`: files owned by RPM packages, grouped by source RPM.
+- `alpm`: files owned by pacman packages, grouped by package base.
+- `pip`: Python distributions installed by pip, uv, or any other installer
+  following [PEP 376][pep376].
+- `xattr`: files explicitly assigned via the `user.component` xattr.
+- `bigfiles`: large files not claimed by any other repo, each as their own
+  component.
+
 ### Customizing the layers
 
 It is possible to create custom components by setting the `user.component` xattr
@@ -416,6 +426,7 @@ well.
 
 [add-determinism]: https://github.com/keszybz/add-determinism
 [bootable container images]: https://containers.github.io/bootable/
+[pep376]: https://packaging.python.org/en/latest/specifications/recording-installed-packages/
 [buildah-annotations-bug]: https://github.com/containers/buildah/issues/6652
 [buildah-rfe]: https://github.com/containers/buildah/issues/6621
 [build-chunked-oci]: https://coreos.github.io/rpm-ostree/build-chunked-oci/

src/components/mod.rs

@@ -1,5 +1,6 @@
 mod alpm;
 mod bigfiles;
+mod pip;
 mod rpm;
 mod xattr;
 
@@ -24,6 +25,11 @@ pub const STABILITY_PERIOD_DAYS: f64 = 7.0;
 /// Maximum lookback period in days for changelog analysis.
 pub const STABILITY_LOOKBACK_DAYS: u64 = 365;
 
+/// Convert a stability interval in days to a probability using the Poisson model.
+pub fn interval_to_stability(interval_days: u64) -> f64 {
+    (-STABILITY_PERIOD_DAYS / interval_days as f64).exp()
+}
+
 /// Loaded component repos along with the default mtime to use.
 pub struct ComponentsRepos {
     repos: Vec<Box<dyn ComponentsRepo>>,
@@ -145,12 +151,19 @@ impl ComponentsRepos {
             repos.push(Box::new(repo));
         }
 
+        if let Some(repo) = pip::PipRepo::load(rootfs, files, default_mtime_clamp)
+            .context("loading pip dist-info")?
+        {
+            tracing::info!(repo = "pip", "loaded repo");
+            repos.push(Box::new(repo));
+        }
+
         if let Some(repo) = bigfiles::BigfilesRepo::load(files, default_mtime_clamp) {
             tracing::info!(repo = "bigfiles", "loaded repo");
             repos.push(Box::new(repo));
         }
 
-        // Other backends (e.g. deb, apk, pip, etc.) would go here...
+        // Other backends (e.g. deb, apk, etc.) would go here...
 
         Ok(Self {
             repos,