fix: preserve Content-Length on blob and manifest GET/HEAD

src/router.ts

@@ -27,6 +27,11 @@ function formatNextLink(url: URL): string {
   return `<${url.toString()}>; rel="next"`;
 }
 
+// Stops the runtime's automatic gzip, which switches the response to chunked transfer-encoding and
+// drops the Content-Length the distribution spec requires on blob/manifest GET and HEAD. Bodies are
+// served verbatim. Spread into each such response's headers.
+const identityEncoding = { "Content-Encoding": "identity" } as const;
+
 const v2Router = Router({ base: "/v2/" });
 
 v2Router.get("/", async (_req, _env: Env) => {
@@ -148,6 +153,7 @@ v2Router.head("/:name+/manifests/:reference", async (req, env: Env) => {
         "Content-Length": res.size.toString(),
         "Content-Type": res.contentType,
         "Docker-Content-Digest": res.digest,
+        ...identityEncoding,
       },
     });
   }
@@ -207,6 +213,7 @@ v2Router.head("/:name+/manifests/:reference", async (req, env: Env) => {
       "Content-Length": checkManifestResponse.size.toString(),
       "Content-Type": checkManifestResponse.contentType,
       "Docker-Content-Digest": checkManifestResponse.digest,
+      ...identityEncoding,
     },
   });
 });
@@ -220,6 +227,7 @@ v2Router.get("/:name+/manifests/:reference", async (req, env: Env, context: Exec
         "Content-Length": res.size.toString(),
         "Content-Type": res.contentType,
         "Docker-Content-Digest": res.digest,
+        ...identityEncoding,
       },
     });
   }
@@ -270,6 +278,7 @@ v2Router.get("/:name+/manifests/:reference", async (req, env: Env, context: Exec
       "Content-Length": getManifestResponse.size.toString(),
       "Content-Type": getManifestResponse.contentType,
       "Docker-Content-Digest": getManifestResponse.digest,
+      ...identityEncoding,
     },
   });
 });
@@ -366,6 +375,7 @@ v2Router.get("/:name+/blobs/:digest", async (req, env: Env, context: ExecutionCo
       headers: {
         "Docker-Content-Digest": res.digest,
         "Content-Length": `${res.size}`,
+        ...identityEncoding,
       },
     });
   }
@@ -404,6 +414,7 @@ v2Router.get("/:name+/blobs/:digest", async (req, env: Env, context: ExecutionCo
     headers: {
       "Docker-Content-Digest": layerResponse.digest,
       "Content-Length": `${layerResponse.size}`,
+      ...identityEncoding,
     },
   });
 });
@@ -625,6 +636,7 @@ v2Router.head("/:name+/blobs/:tag", async (req, env: Env) => {
     headers: {
       "Content-Length": layerExistsResponse.size.toString(),
       "Docker-Content-Digest": layerExistsResponse.digest,
+      ...identityEncoding,
     },
   });
 });

test/index.test.ts

@@ -344,6 +344,7 @@ describe("v2 manifests", () => {
       "content-length": "2",
       "content-type": "application/gzip",
       "docker-content-digest": sha256,
+      "content-encoding": "identity",
     });
     await bindings.REGISTRY.delete(`${name}/manifests/${reference}`);
   });
@@ -2380,3 +2381,50 @@ test("docker.io", () => {
     }
   }
 });
+
+describe("blob and manifest GET/HEAD response headers", () => {
+  // These responses must carry a literal Content-Length (and the manifest its Content-Type), and
+  // set Content-Encoding: identity so the runtime does not switch to chunked transfer-encoding and
+  // drop Content-Length — the regression these tests guard.
+  test("blob GET and HEAD return Content-Length, Content-Encoding identity, and the exact bytes", async () => {
+    const name = "headers/blob";
+    const data = "blob-bytes-for-content-length";
+    const sha256 = await getSHA256(data);
+    const post = await fetch(createRequest("POST", `/v2/${name}/blobs/uploads/`, null, {}));
+    const patch = await fetch(
+      createRequest("PATCH", post.headers.get("location")!, limit(new Blob([data]).stream(), data.length), {}),
+    );
+    await fetch(createRequest("PUT", patch.headers.get("location")! + "&digest=" + sha256, null, {}));
+
+    const get = await fetch(createRequest("GET", `/v2/${name}/blobs/${sha256}`, null));
+    expect(get.status).toBe(200);
+    expect(get.headers.get("Content-Length")).toEqual(`${data.length}`);
+    expect(get.headers.get("Content-Encoding")).toEqual("identity");
+    expect(await get.text()).toEqual(data);
+
+    const head = await fetch(createRequest("HEAD", `/v2/${name}/blobs/${sha256}`, null));
+    expect(head.status).toBe(200);
+    expect(head.headers.get("Content-Length")).toEqual(`${data.length}`);
+    expect(head.headers.get("Content-Encoding")).toEqual("identity");
+  });
+
+  test("manifest GET and HEAD return Content-Length, Content-Type and Content-Encoding identity", async () => {
+    const name = "headers/manifest";
+    const manifest = await generateManifest(name);
+    const { sha256 } = await createManifest(name, manifest, "v1");
+    const size = new Blob([JSON.stringify(manifest)]).size;
+
+    // Manifests are stored (uploadManifest) with this content type; GET/HEAD must echo it exactly.
+    const get = await fetch(createRequest("GET", `/v2/${name}/manifests/v1`, null));
+    expect(get.status).toBe(200);
+    expect(get.headers.get("Content-Length")).toEqual(`${size}`);
+    expect(get.headers.get("Content-Type")).toEqual("application/gzip");
+    expect(get.headers.get("Content-Encoding")).toEqual("identity");
+
+    const head = await fetch(createRequest("HEAD", `/v2/${name}/manifests/${sha256}`, null));
+    expect(head.status).toBe(200);
+    expect(head.headers.get("Content-Length")).toEqual(`${size}`);
+    expect(head.headers.get("Content-Type")).toEqual("application/gzip");
+    expect(head.headers.get("Content-Encoding")).toEqual("identity");
+  });
+});