parsear manifests de docker y limpiar lógica de parseo

rootfs/init/src/main.rs

@@ -8,7 +8,8 @@ use std::{env, io, os::unix, path::Path, process};
 #[serde(rename_all = "PascalCase")]
 struct Config {
     env: Vec<String>,
-    cmd: Vec<String>,
+    cmd: Option<Vec<String>>,
+    entrypoint: Option<Vec<String>>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
@@ -39,8 +40,20 @@ fn main() -> Result<(), io::Error> {
     unix::fs::chroot(src_path)?;
     env::set_current_dir("/")?;
 
-    let mut child = process::Command::new(&config.config.cmd[0])
-        .args(&config.config.cmd[1..])
+    // https://github.com/opencontainers/image-spec/blob/b5ec432b1c946c09e1568b18ef70b654a93739f6/conversion.md#verbatim-fields
+    let args = match (config.config.cmd, config.config.entrypoint) {
+        (None, Some(args)) => args,
+        (Some(args), None) => args,
+        (None, None) => panic!("Invalid config"),
+        (Some(cmd), Some(entrypoint)) => {
+            let mut args = entrypoint.clone();
+            args.append(&mut cmd.clone());
+            args
+        }
+    };
+
+    let mut child = process::Command::new(&args[0])
+        .args(&args[1..])
         .env_clear()
         .envs(config.config.env.iter().map(|s| s.split_once('=').unwrap()))
         .spawn()?;

server/container-baby.ts

@@ -1,8 +1,9 @@
 import { execFile as _execFile } from "node:child_process";
-import { access, mkdir, writeFile } from "node:fs/promises";
+import { access, mkdir, open, writeFile } from "node:fs/promises";
 import { join } from "node:path";
 import { tar2squashfs } from "./tar2squashfs.js";
 import { subtle } from "node:crypto";
+import { Writable } from "node:stream";
 
 type RegistryName = string;
 type RegistrySecret = string;
@@ -27,7 +28,7 @@ export function parseImageRef(ref: string): { image: string; tag: string } {
 
 export async function downloadImage(image: string, tag: string) {
   await mkdir(tmpDir, { recursive: true });
-  const manifest = await getContainerManifest(image, tag);
+  const manifest = await getManifest(image, tag);
 
   // sanity check
   if (
@@ -79,6 +80,14 @@ async function saveSquashfs(
         await access(output);
         // ya está cacheado
       } catch {
+        if (process.env.DEBUG_WRITE_BLOBS)
+          await Promise.all(
+            manifest.layers.map(async (layer) => {
+              const res = await getBlob(image, layer.digest);
+              const file = await open(layer.digest, "w");
+              await res.body!.pipeTo(Writable.toWeb(file.createWriteStream()));
+            })
+          );
         const layerStreams = manifest.layers.map(async (layer) => {
           const res = await getBlob(image, layer.digest);
           return res.body!;
@@ -131,6 +140,19 @@ async function call(registryName: string, path: string, init: RequestInit) {
   return res;
 }
 
+// https://github.com/opencontainers/image-spec/blob/v1.0.1/image-index.md
+type ManifestIndex = {
+  schemaVersion: 2;
+  mediaType: "application/vnd.oci.image.index.v1+json";
+  manifests: ManifestPointer[];
+};
+type DockerManifestV2 = {
+  schemaVersion: 2;
+  mediaType: "application/vnd.docker.distribution.manifest.v2+json";
+  config: Descriptor;
+  layers: DockerManifestV2Layer[];
+};
+
 type ManifestPointer = {
   mediaType: "application/vnd.oci.image.manifest.v1+json";
   digest: string;
@@ -141,13 +163,9 @@ type ManifestPointer = {
   };
   annotations?: { [k: string]: string };
 };
-
-// https://github.com/opencontainers/image-spec/blob/v1.0.1/image-index.md
-type ManifestIndex = {
-  mediaType: "application/vnd.oci.image.index.v1+json";
-  schemaVersion: 2;
-  manifests: ManifestPointer[];
-};
+type DockerManifestV2Layer = {
+  mediaType: "application/vnd.docker.image.rootfs.diff.tar.gzip";
+} & Descriptor;
 
 function getImageParts(image: string): [string, string] {
   const parts = image.split("/");
@@ -156,35 +174,43 @@ function getImageParts(image: string): [string, string] {
   return [registryName, imgPath];
 }
 
-async function getContainerManifest(image: string, tag: string) {
-  const index = await getManifestIndex(image, tag);
-  // badly behaved registries will return whatever they want
-  if (
-    (index.mediaType as string) === "application/vnd.oci.image.manifest.v1+json"
-  ) {
-    return index as unknown as Manifest;
-  }
-  const arch = "amd64";
-  const ptr = chooseManifest(index, arch);
-  if (!ptr)
-    throw new Error(`Image ${image}:${tag} doesn't exist for arch ${arch}`);
-  const manifest = await getManifest(image, ptr);
-  return manifest;
-}
-
-async function getManifestIndex(
-  image: string,
-  tag: string
-): Promise<ManifestIndex> {
+async function getManifest(image: string, tag: string): Promise<Manifest> {
   const [registryName, imgPath] = getImageParts(image);
-
   const res = await call(registryName, `/${imgPath}/manifests/${tag}`, {
     headers: {
       Accept: "application/vnd.oci.image.index.v1+json",
     },
   });
-  const json = await res.json();
-  return json as ManifestIndex;
+  const json = (await res.json()) as object;
+  if (!("mediaType" in json)) throw new Error(`Received invalid manifest`);
+
+  if (
+    json.mediaType === "application/vnd.docker.distribution.manifest.v2+json"
+  ) {
+    const manifest = json as DockerManifestV2;
+    return {
+      mediaType: "application/vnd.oci.image.manifest.v1+json",
+      config: {
+        ...manifest.config,
+        mediaType: "application/vnd.oci.image.config.v1+json",
+      },
+      layers: manifest.layers.map((l) => ({
+        ...l,
+        mediaType: "application/vnd.oci.image.layer.v1.tar+gzip",
+      })),
+    };
+  } else if (json.mediaType === "application/vnd.oci.image.manifest.v1+json") {
+    return json as Manifest;
+  } else if (json.mediaType === "application/vnd.oci.image.index.v1+json") {
+    const index = json as ManifestIndex;
+    // XXX: hardcoded amd64
+    const arch = "amd64";
+    const manifestPtr = chooseManifest(index, arch);
+    if (!manifestPtr) throw new Error(`No manifest for arch ${arch}`);
+
+    const manifest = await jsonBlob<Manifest>(image, manifestPtr.digest);
+    return manifest;
+  } else throw new Error(`Received invalid manifest`);
 }
 
 function chooseManifest(list: ManifestIndex, arch: string) {
@@ -240,7 +266,3 @@ type Manifest = {
       | "application/vnd.oci.image.layer.nondistributable.v1.tar+gzip";
   } & Descriptor)[];
 };
-
-async function getManifest(image: string, ptr: ManifestPointer) {
-  return await jsonBlob<Manifest>(image, ptr.digest);
-}