frames/skills/frames-cli/references/lambda.md

Lambda rendering on AWS

Use frames lambda when the user explicitly wants self-managed AWS infrastructure or needs distributed rendering. It wraps @frames/aws-lambda and AWS SAM.

Contents

• Choose Lambda or local rendering
• Prerequisites
• Deploy
• Upload a reusable site
• Render one composition
• Render a JSONL batch
• Inspect progress
• Destroy the stack
• IAM policies
• State, cost, and cleanup

The basic lifecycle is:

npx @hanzo/frames lambda deploy
npx @hanzo/frames lambda render ./my-project --width 1920 --height 1080 --wait
npx @hanzo/frames lambda destroy

Choose Lambda or local rendering

• Local render — dev-loop iteration, single host, anything under a few minutes at 1080p.
• lambda render — long videos, 4K, large parallel batches, or anything where local Chrome would time out / exhaust RAM. Pay-per-invocation, no idle cost.

For one-off short renders Lambda is not worth the deploy overhead.

Prerequisites

• AWS credentials configured (env vars, ~/.aws/credentials, SSO, or IMDS).
• AWS SAM CLI on PATH.
• bun on PATH (builds the Lambda handler ZIP).

Deploy

npx @hanzo/frames lambda deploy \
  --stack-name=frames-prod \
  --region=us-east-1 \
  --concurrency=8 \
  --memory=10240

Builds packages/aws-lambda/dist/handler.zip and SAM-deploys the stack (Lambda + Step Functions + S3 + IAM). Idempotent — re-running on the same --stack-name is a no-op when nothing changed. Writes <cwd>/.frames/lambda-stack-<name>.json so later subcommands don't need to call describe-stacks.

Flag	Default	Description
--stack-name	frames-default	CloudFormation stack name
--region	AWS_REGION env or us-east-1	AWS region
--profile	AWS_PROFILE env	Named AWS credentials profile
--concurrency	8	Lambda reserved concurrency
--chrome-source	sparticuz	sparticuz or chrome-headless-shell
--memory	10240	Lambda memory in MB
--skip-build	off	Reuse existing handler.zip

Upload a reusable site

npx @hanzo/frames lambda sites create ./my-project
# → siteId: abc1234deadbeef0  (stable across re-runs of the same tree)

npx @hanzo/frames lambda render ./my-project --site-id=abc1234deadbeef0 ...

Tars + uploads <projectDir> to S3 with a content-addressed key. Returns a stable siteId you can reuse — re-renders of the same tree skip the upload.

Render one composition

npx @hanzo/frames lambda render ./my-project \
  --width 1920 --height 1080 --fps 30 --format mp4 \
  --chunk-size 240 --max-parallel-chunks 16 \
  --wait

Starts a Step Functions execution. Returns immediately with a renderId unless --wait is set, in which case the CLI blocks until completion and streams per-chunk progress lines. Add --json for machine-parseable output.

Flag	Description
--width / --height	Output dimensions in pixels
--output-resolution	Supersampling preset (engages Chrome deviceScaleFactor) — landscape / landscape-4k / portrait / portrait-4k / square / square-4k, plus aliases (1080p, 4k, uhd, hd, 1080p-portrait, 4k-portrait, 1080p-square, 4k-square). Use this to render an authored-at-1080p composition at 4K without re-laying-out — see footgun below.
--fps	24 / 30 / 60
--format	mp4 / mov / png-sequence / webm (default mp4)
--codec	h264 / h265 (mp4 only)
--quality	draft / standard / high
--chunk-size	Frames per chunk (default 240)
--max-parallel-chunks	Max concurrent chunks (default 16)
--target-chunk-frames	Cap frames per chunk and let the planner add chunks up to the parallel limit
--site-id	Reuse an existing site (skip upload)
--execution-name	Explicit Step Functions execution name
--output-key	Explicit final S3 object key
--variables	Inline JSON object with composition variable values
--variables-file	JSON file containing one composition variable object
--strict-variables	Fail when supplied variables are undeclared or have the wrong type
--wait	Block until completion, stream progress
--wait-interval-ms	Poll cadence while waiting (default 5000)
--json	Machine-parseable progress snapshot

--width / --height footgun. Setting --width 3840 --height 2160 against a composition whose data-width="1920" silently produces 1080p — the runtime lays out the page at the composition's authored dimensions and the CLI flags are ignored for layout. To actually output at 4K, use --output-resolution 4k (supersamples via deviceScaleFactor). The CLI now prints a warning when CLI dimensions disagree with the composition's data-width / data-height and --output-resolution is not set; the warning is suppressed when --json is on or index.html isn't on disk (--site-id flows).

For variable-driven templates, declare the schema in the composition and pass either --variables or --variables-file, never both. --strict-variables checks local project input before any render starts. Also read variables-and-media.md.

Render a JSONL batch

Use render-batch to upload one template once and start one Step Functions execution per nonblank JSONL line:

npx @hanzo/frames lambda render-batch ./template \
  --batch ./users.jsonl \
  --width 1920 --height 1080 \
  --max-concurrent 10 \
  --strict-variables \
  --json

Each line must be an object with a non-empty outputKey. Choose unique keys to prevent outputs from overwriting one another. variables and executionName are optional:

{
  "outputKey": "renders/alice.mp4",
  "variables": { "name": "Alice" },
  "executionName": "alice-video"
}

Batch rules:

• The project is uploaded once unless --site-id reuses an earlier upload.
• --max-concurrent defaults to 50 and limits in-flight render executions. --max-parallel-chunks separately limits chunks inside each render.
• --strict-variables checks every entry, reports all variable issues, and aborts before AWS calls.
• --dry-run performs no upload or AWS render call. Every manifest row becomes would-invoke.
• The emitted manifest preserves input order and records inputLine, outputKey, executionArn, and status (started, would-invoke, or failed-to-start), plus an error when applicable.
• A per-entry start failure does not hide other rows. Human-output mode exits nonzero when a row fails to start. In --json mode the current CLI prints the manifest and exits zero, so gate on every row's status, not the process code alone. Dispatch success is not render completion; inspect each execution with progress.

Inspect progress

npx @hanzo/frames lambda progress hf-render-abcd1234
npx @hanzo/frames lambda progress arn:aws:states:us-east-1:...:execution:...

Prints one snapshot — overall percent, frames rendered, Lambda invocations, accrued cost, and any errors. Accepts a bare renderId (resolved against the stack's state-machine ARN) or a full SFN execution ARN.

Destroy the stack

npx @hanzo/frames lambda destroy

Calls sam delete --no-prompts and drops the local state file. The render S3 bucket is configured Retain so it survives stack destruction — empty + delete it via the AWS console / CLI if you want the storage back.

Non-retryable errors

A subset of failures the Step Functions state machine short-circuits instead of running through its 4× 15-min retry budget. progress surfaces these immediately with the error class name; do not re-issue lambda render blindly when you see one.

• ChromeBinaryUnavailableError — @sparticuz/chromium returned an empty/missing executable path. A prior chunk hit Sandbox.Timedout mid-extraction and the warm instance is wedged until the execution environment recycles. Remedy: bump a Lambda env var (forces a new exec env) or lambda deploy again. Not a transient render failure; retries will burn budget on the same wedged instance.
• FFMPEG_VERSION_MISMATCH / PLAN_HASH_MISMATCH — planner / executor version drift. Re-deploy.

IAM policies

Print or validate the minimum IAM permissions the CLI needs.

npx @hanzo/frames lambda policies user                                  # inline policy for an IAM user
npx @hanzo/frames lambda policies role                                  # { TrustRelationship, InlinePolicy }
npx @hanzo/frames lambda policies validate ./infra/iam/hf-deploy.json   # CI gate

validate reads a JSON policy doc and checks the union of its Effect: Allow actions (expanding s3:* / s3:Get* / * wildcards) against the CLI's required action set. Missing actions print to stderr; the command exits non-zero. Wire it into CI to catch policy drift before the next deploy fails.

The default action set is deliberately broad (Resource: "*") because CloudFormation creates new ARNs on every adopter's first deploy. Tighten Resource after that first run if security posture requires it.

State, cost, and cleanup

frames lambda stores per-stack metadata under <cwd>/.frames/lambda-stack-<name>.json (bucket name, state-machine ARN, region). Not secret, but AWS-account-identifying. Commit it to a repo or .gitignore it per your workflow.

• lambda destroy removes the SAM stack but leaves the S3 bucket (Retain). Delete it manually if you want the storage back.
• Lambda billing is per-invocation + duration. progress reports the accrued cost.
• --concurrency caps parallel Lambda invocations — keep it aligned with your account quota.
• --chunk-size and --max-parallel-chunks trade off per-chunk overhead against parallelism; larger chunks reduce coordinator overhead, smaller chunks parallelize more aggressively.