Add npm virtual repositories (#152)

npm clients need one registry for internal and public packages, but npm virtuals have no merger, so a local npm repo and npmjs cannot be served together.

- merge packuments across members: union versions (member order wins), first-defined dist-tags minus ones naming missing versions
- serve full and abbreviated (`install-v1`) packuments, scoped names included, via the shared virtual merge cache
- point tarballs at `<virtual>/<member>/<path>` and 302 them to the owning member
- reject an invalid Host with 400; serve virtual and local packuments `no-store` with `Vary: Host, X-Forwarded-Proto, Accept`
- return 502 when a member errors; skip members without the package
- add `docs/npm/virtual.md` and a stock `node:22` e2e-docker case

Reviewed-on: #152
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

e2e-docker/README.md

@@ -31,7 +31,8 @@ already-running stack.
   `node:22` client: `npm publish` unscoped + scoped, `npm install` + `require()`,
   second version, republish rejected).
 - **Virtual repositories** — pypi simple-index merge and helm `index.yaml` merge
-  across two members.
+  across two members; npm packument merge over two locals via a stock `node:22`
+  client (merged versions, install through the member redirect).
 - **Mirrorlist** — an rpm remote with a `mirrorlist` of extra upstream mirrors
   (pool = `base_url` + `mirrorlist`): round-robin distribution across both mirrors
   (constant-body `mockupstreama` / `mockupstreamb`), failover past a dead primary,

e2e-docker/npm_virtual_test.go

@@ -0,0 +1,68 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestVirtualNPMInstall publishes to two local npm repos and drives a stock
+// npm client through a virtual over both: merged versions and dist-tags, and
+// an install whose tarballs resolve via the virtual's member redirect.
+func TestVirtualNPMInstall(t *testing.T) {
+	network := os.Getenv("COMPOSE_NETWORK")
+	internal := os.Getenv("ARTIFACTAPI_INTERNAL")
+	if network == "" || internal == "" {
+		t.Skip("COMPOSE_NETWORK/ARTIFACTAPI_INTERNAL not set; run via scripts/docker-e2e.sh")
+	}
+	if _, err := exec.LookPath("docker"); err != nil {
+		t.Skip("docker not available on the test host")
+	}
+
+	id := time.Now().UnixNano()
+	a, b, virt := fmt.Sprintf("e2e-npm-a-%d", id), fmt.Sprintf("e2e-npm-b-%d", id), fmt.Sprintf("e2e-npm-v-%d", id)
+	for _, name := range []string{a, b} {
+		createRepo(t, fmt.Sprintf(`{"name":%q,"package_type":"npm","repo_type":"local"}`, name))
+		defer deleteRepo(t, name)
+	}
+	createVirtual(t, fmt.Sprintf(`{"name":%q,"package_type":"npm","members":[%q,%q]}`, virt, a, b))
+	defer deleteVirtual(t, virt)
+
+	base := strings.TrimRight(internal, "/")
+	script := `set -euo pipefail
+pub() { d="/w/src/$2-$3-$1"; mkdir -p "$d"; cd "$d"
+  printf '{"name":"%s","version":"%s","main":"index.js"}' "$2" "$3" > package.json
+  echo "module.exports = '$1:$2@$3';" > index.js
+  printf 'registry=%s\n%s:_authToken=unused\n' "$BASE/api/v1/local/$1/" "${BASE#http:}/api/v1/local/$1/" > .npmrc
+  npm publish; }
+pub "$A" @e2e/virt 1.0.0
+pub "$B" @e2e/virt 1.0.0
+pub "$B" @e2e/virt 1.1.0
+mkdir -p /w/app && cd /w/app && npm init -y >/dev/null
+echo "registry=$BASE/api/v1/virtual/$V/" > .npmrc
+echo "VERSIONS $(npm view @e2e/virt versions --json | tr -d ' \n')"
+npm install --no-audit --cache /tmp/fresh-cache @e2e/virt@1.0.0
+node -e "console.log('REQ', require('@e2e/virt'))"
+echo "RESOLVED $(node -p "require('./package-lock.json').packages['node_modules/@e2e/virt'].resolved")"`
+
+	out, err := exec.Command("docker", "run", "--rm", "--network", network,
+		"-e", "BASE="+base, "-e", "A="+a, "-e", "B="+b, "-e", "V="+virt,
+		"node:22", "bash", "-c", script).CombinedOutput()
+	if err != nil {
+		t.Fatalf("npm client run failed: %v\n%s", err, out)
+	}
+	for _, want := range []string{
+		`VERSIONS ["1.0.0","1.1.0"]`,
+		"REQ " + a + ":@e2e/virt@1.0.0",
+		"RESOLVED " + base + "/api/v1/virtual/" + virt + "/" + a + "/@e2e/virt/-/virt-1.0.0.tgz",
+	} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q in npm output:\n%s", want, out)
+		}
+	}
+}