wrangler containers build --build-arg

[alexminza]

Describe the solution

wrangler containers build does not support --build-arg, which prevents passing build-time variables to the Dockerfile (e.g., pinning a package version via ARG).

Current behavior

wrangler containers build --push --tag "myapp:v1" --build-arg "VERSION=1.2.3" ./
✘ [ERROR] Unknown arguments: build-arg, buildArg

The command only supports --tag, --push, --path-to-docker, and global flags.

Expected behavior

wrangler containers build --push --tag "myapp:v1" --build-arg "VERSION=1.2.3" ./

Passes --build-arg to the underlying docker build. It should be repeatable (matching docker build behavior):

wrangler containers build --push --tag "myapp:v1" \
  --build-arg "VERSION=1.2.3" \
  --build-arg "NODE_ENV=production" \
  ./

Workaround

Split into two commands:

1. docker build (supports --build-arg)
2. wrangler containers push

docker build --platform linux/amd64 --build-arg "VERSION=1.2.3" -t "myapp:v1" ./
wrangler containers push "myapp:v1"

This works but defeats the purpose of wrangler containers build as a single-command build+push workflow.

Use case

Dockerfiles commonly use ARG for version pinning, feature flags, or build-time configuration:

ARG VERSION=latest
RUN npm install -g mypackage@${VERSION}

Without --build-arg, the only alternatives are:

1. the two-command workaround above
2. writing a temporary Dockerfile with the value hardcoded
3. always using the ARG default

Suggested scope

Since wrangler containers build delegates to docker build internally, forwarding --build-arg (and potentially other common Docker build flags like --target, --no-cache, --secret) should be straightforward. At minimum, --build-arg is the most commonly needed.

wrangler version: 4.76.0