feat(cloudflare/container): build images from a prebuilt context directory by Butch78 · Pull Request #583 · alchemy-run/alchemy-effect

Butch78 · 2026-06-11T06:02:40Z

Build a Cloudflare Container straight from a self-contained Docker build context, skipping JS bundling entirely. Cloudflare Containers run any linux/amd64 image; only the resource assumed a JS entrypoint.

export class SqlCompute extends Cloudflare.Container<SqlCompute>()("sql-compute", {
  context: "./sql-container",      // dir with its own Dockerfile
  // dockerfile: "Dockerfile.prod" // path, or inline contents; defaults to "Dockerfile"
  instanceType: "standard-1",
}) {}

context (a build-context dir) replaces the JS-bundling pipeline when no main is set. main and context are mutually exclusive; main stays optional.
dockerfile accepts a path or inline contents (told apart by whether it resolves to a file), in both modes. Context mode passes docker build -f; dockerBuild gains a dockerfile option.
One resolveContextMode helper decides mode + Dockerfile location for both the hash and the build, so they can't drift.
The context image hash folds in each file's contents (streamed, never buffered whole) plus its unix mode, honoring .dockerignore and always skipping .git, so content changes trigger a rebuild and rollout.

Used to deploy a Rust (DataFusion) container attached to a Durable Object: builds, pushes to registry.cloudflare.com with the content-addressed tag, and serves via ctx.container.

The caller supplies a complete Docker build context (its own Dockerfile plus everything it COPYs) and the JS bundling pipeline is skipped: no main, no runtime shim, no appended ENTRYPOINT. The image hash folds in every file in the directory so content changes still trigger a rebuild and rollout. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

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Pull request overview

Note

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Adds support for deploying Cloudflare Containers from a fully self-contained, prebuilt Docker build context (skipping JS bundling and generated Dockerfile/entrypoint logic).

Changes:

Introduces prebuiltContext to allow building/pushing images directly from a caller-provided Docker context directory.
Adjusts validation so main is no longer required when prebuiltContext is provided.
Updates the build pipeline to branch between “prebuilt context” and “bundled JS context” modes.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 6 comments.

File	Description
packages/alchemy/src/Cloudflare/Container/ContainerApplication.ts	Implements `prebuiltContext` mode: hashes the directory contents for tagging and builds the provided context verbatim.
packages/alchemy/src/Cloudflare/Container/Container.ts	Makes `main` optional to support `prebuiltContext`-only containers and documents the new behavior.

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+  /**
+   * JS entrypoint. Required unless `prebuiltContext` supplies a complete
+   * non-JS Docker build context.
+   */
+  main?: string;


+          const entries = yield* fs.readDirectory(contextDir, {
+            recursive: true,
+          });
+          const fileHashes: Record<string, string> = {};
+          for (const entry of [...entries].sort()) {
+            const fullPath = `${contextDir}/${entry}`;
+            const info = yield* fs.stat(fullPath);
+            if (info.type === "File") {
+              fileHashes[entry] = yield* sha256(yield* fs.readFile(fullPath));
+            }
+          }


+          });
+          const fileHashes: Record<string, string> = {};
+          for (const entry of [...entries].sort()) {
+            const fullPath = `${contextDir}/${entry}`;


+            const info = yield* fs.stat(fullPath);
+            if (info.type === "File") {
+              fileHashes[entry] = yield* sha256(yield* fs.readFile(fullPath));
+            }


+        if (props.prebuiltContext) {
+          // Prebuilt-context mode: the caller supplies a complete Docker
+          // build context. Hash every regular file in it (sorted, so the
+          // digest is order-stable) in place of the bundle hash.


+          return { files: [], imageRef, imageHash };
+        }


sam-goodwin · 2026-06-11T06:26:53Z

+        if (props.prebuiltContext) {
+          // Prebuilt-context mode: build the caller's directory verbatim,
+          // with its own Dockerfile, no bundle files, no appended ENTRYPOINT.
+          yield* dockerBuild({
+            tag: imageRef,
+            context: props.prebuiltContext,
+            platform: "linux/amd64",
+          });


I don't think prebuiltContext is an intuitive name for this property. I do agree it should be possible to skip bundling.

Why not just call it context?: string and make main?: string optional. Skip JS bundling if main and dockerfile are not provided?

I also wonder if dockerfile should be a path (or maybe even allow it to be both a path or dockerfile contents because we can detect that with path.resolve?

Cloudflare.Container("container", { context: "./sql-container", // dockerfile: "Dockerfile.custom" // <- defaults to "Dockerfile" })

Good call, done in 9fbf01d:

Renamed prebuiltContext → context. JS bundling is skipped whenever there's no main (the two are now mutually exclusive).

dockerfile accepts a path or inline contents, resolved by whether it points at an existing file (path.resolve against the context, then cwd). In context mode it defaults to <context>/Dockerfile and is passed via docker build -f.

Cloudflare.Container("container", { context: "./sql-container", // dockerfile: "Dockerfile.custom" // path, or inline "FROM …" contents })

…dress review Respond to PR review (sam-goodwin + Copilot): - Rename `prebuiltContext` -> `context`; build context mode iff no `main` (the two are mutually exclusive). `main` stays optional. - `dockerfile` accepts a path OR inline contents, resolved by existence, in both modes. Context mode defaults to `<context>/Dockerfile` and passes `docker build -f`; `dockerBuild` gains a `dockerfile` option. - Single `resolveContextMode` helper decides mode + Dockerfile location for both the hash and build steps, so they can't drift. - Context hash: honor `.dockerignore` + always skip `.git`, fold in unix mode, and stream each file via `sha256File` (no whole-file buffering). - Cross-platform `path.join` instead of string concatenation. - Tests: streaming `sha256File`, and `docker build -f` custom Dockerfile. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Butch78 · 2026-06-11T07:39:30Z

Thanks @copilot — addressed in 9fbf01d (alongside the prebuiltContext → context rename @sam-goodwin asked for):

Path building / Windows — now uses path.join everywhere instead of string concatenation; directory-walk keys are normalized to POSIX.
Reads every file into memory — context files are now hashed with a streaming sha256File (chunks through node:crypto, never buffered whole). Added .dockerignore support plus an always-on .git skip so large/volatile dirs aren't walked.
File mode / symlinks — each file's unix mode is folded into the hash. fs.stat follows symlinks (effect exposes no lstat), so links are hashed by their dereferenced target; documented on the helper.
Duplicated branching — extracted a single resolveContextMode helper that decides the mode and resolves the Dockerfile location; both the hash step and the build step consume it, so they can't drift.
main optional weakens typing — kept main optional per the API direction in this thread (main/context mutually exclusive, validated at runtime) rather than a discriminated union, since the union would have to duplicate the full shared prop set across both members.

Added unit coverage for streaming sha256File and for the new docker build -f path.

sam-goodwin · 2026-06-11T07:41:24Z

+export const sha256File = Effect.fn(function* (filePath: string) {
+  const fs = yield* FileSystem.FileSystem;
+  const hash = createHash("sha256");
+  yield* fs
+    .stream(filePath)
+    .pipe(Stream.runForEach((chunk) => Effect.sync(() => hash.update(chunk))));
+  return hash.digest("hex");
+});


Do we already have a util for this in sha256.ts?

If not, add it to that file for re-usability.

Good idea — moved it to Util/sha256.ts as sha256File (streams via the FileSystem service through node:crypto, alongside sha256/sha256Object) in 607f4ed. Tests moved to test/Util/sha256.test.ts.

Per review: keep the streaming file hash with the other SHA-256 helpers for reuse instead of in Bundle/Docker.ts. Tests move to test/Util/sha256. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Butch78 · 2026-06-11T07:50:38Z

Thanks for the suggestions, @sam-goodwin — both are in: context + path-or-inline dockerfile, and the streaming hash now lives in Util/sha256.ts. Let me know if you'd like anything else tweaked.

Copilot AI review requested due to automatic review settings June 11, 2026 06:02

Copilot AI reviewed Jun 11, 2026

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sam-goodwin reviewed Jun 11, 2026

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Butch78 changed the title ~~feat(cloudflare/container): prebuiltContext for non-JS container images~~ feat(cloudflare/container): build images from a prebuilt context directory Jun 11, 2026

sam-goodwin mentioned this pull request Jun 11, 2026

feat(cloudflare/container): support image-only containers without a main entrypoint #579

Closed

sam-goodwin reviewed Jun 11, 2026

View reviewed changes

refactor(util): move streaming sha256File into Util/sha256.ts

607f4ed

Per review: keep the streaming file hash with the other SHA-256 helpers for reuse instead of in Bundle/Docker.ts. Tests move to test/Util/sha256. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

sam-goodwin self-assigned this Jun 11, 2026

Merge branch 'main' into feat/container-prebuilt-context

649a30c

john-royal self-assigned this Jun 16, 2026

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feat(cloudflare/container): build images from a prebuilt context directory#583

feat(cloudflare/container): build images from a prebuilt context directory#583
Butch78 wants to merge 4 commits into
alchemy-run:mainfrom
Butch78:feat/container-prebuilt-context

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