Add an Alpine APK repository client for v2 indexes

README.md

@@ -1,6 +1,6 @@
 # registries
 
-Go library for fetching package metadata from registry APIs. Supports 27 ecosystems with a unified interface. Also provides sub-packages for HTTP client usage (`client/`) and streaming artifact downloads (`fetch/`).
+Go library for fetching package metadata from registry APIs. Supports 28 ecosystems with a unified interface. Also provides sub-packages for HTTP client usage (`client/`) and streaming artifact downloads (`fetch/`).
 
 ## Installation
 
@@ -134,6 +134,7 @@ packages = registries.BulkFetchPackagesWithConcurrency(ctx, purls, nil, 5)
 | Maven | `pkg:maven/org.apache.commons/commons-lang3@3.12.0` |
 | RubyGems | `pkg:gem/rails@7.1.0` |
 | Terraform | `pkg:terraform/hashicorp/consul/aws@0.11.0` |
+| Alpine | `pkg:apk/alpine/curl@8.22.0-r0?arch=x86_64&repository_url=https://dl-cdn.alpinelinux.org/alpine/v3.23/main/x86_64` |
 
 ## Direct Registry Usage
 
@@ -193,6 +194,9 @@ import _ "github.com/git-pkgs/registries/all"
 | Deno | `deno` | https://apiland.deno.dev |
 | Terraform | `terraform` | https://registry.terraform.io |
 | Swift | `swift` | URL required |
+| Alpine | `apk` | URL required |
+
+The Alpine URL is one repository architecture directory, such as `https://dl-cdn.alpinelinux.org/alpine/v3.23/main/x86_64`, or the `APKINDEX.tar.gz` inside it. The client doesn't pick a release, component or architecture from a mirror root. It reads v2 `APKINDEX.tar.gz` indexes. When a directory serves a v3 `Packages.adb`, the client returns an error rather than reading the v2 index.
 
 ### Swift registries
 

all/all.go

@@ -9,10 +9,11 @@
 //
 //	// Now all ecosystems are available
 //	ecosystems := registries.SupportedEcosystems()
-//	// ["brew", "cargo", "clojars", "cocoapods", "composer", "conda", "cpan", "cran", "deno", "dub", "elm", "gem", "golang", "hackage", "haxelib", "helm", "hex", "julia", "luarocks", "maven", "nimble", "npm", "nuget", "pub", "pypi", "swift", "terraform"]
+//	// ["apk", "brew", "cargo", "clojars", "cocoapods", "composer", "conda", "cpan", "cran", "deno", "dub", "elm", "gem", "golang", "hackage", "haxelib", "helm", "hex", "julia", "luarocks", "maven", "nimble", "npm", "nuget", "pub", "pypi", "swift", "terraform"]
 package all
 
 import (
+	_ "github.com/git-pkgs/registries/internal/apk"
 	_ "github.com/git-pkgs/registries/internal/cargo"
 	_ "github.com/git-pkgs/registries/internal/clojars"
 	_ "github.com/git-pkgs/registries/internal/cocoapods"

fetch/apk_resolver_test.go

@@ -0,0 +1,29 @@
+package fetch
+
+import (
+	"context"
+	"testing"
+
+	"github.com/git-pkgs/registries"
+	_ "github.com/git-pkgs/registries/internal/apk"
+)
+
+func TestResolveAPK(t *testing.T) {
+	reg, err := registries.New("apk", "https://dl-cdn.alpinelinux.org/alpine/v3.23/main/x86_64", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	r := NewResolver()
+	r.RegisterRegistry(reg)
+
+	info, err := r.Resolve(context.Background(), "apk", "alpine/curl", "8.22.0-r0")
+	if err != nil {
+		t.Fatalf("Resolve failed: %v", err)
+	}
+	if want := "https://dl-cdn.alpinelinux.org/alpine/v3.23/main/x86_64/curl-8.22.0-r0.apk"; info.URL != want {
+		t.Errorf("URL = %q, want %q", info.URL, want)
+	}
+	if info.Filename != "curl-8.22.0-r0.apk" {
+		t.Errorf("Filename = %q", info.Filename)
+	}
+}