Docker build failures

COPY failed: file not found in build context

This usually happens when trying to build the binary again from source code in the Docker image build process.

The way GoReleaser works, the correct binary for the platform you’re building should be already available, so you don’t need to build it again and can still reuse the Dockerfile.

Another common misconception is trying to copy the binary as if the context is the repository root. It’s not. GoReleaser creates a temporary build context. The artifact paths depend on which Docker integration you use:

• Docker v2 puts binaries and packages in platform directories, such as linux/amd64/.
• Legacy Docker puts them at the context root.

Below you can find some don’ts as well as what you should do.

Don’t

Build the binary again.

FROM golang AS builder
WORKDIR /app
COPY cmd ./cmd
COPY go.mod ./
COPY *.go ./
RUN GOOS=linux GOARCH=amd64 go build -ldflags="-w -s" -o app .

FROM scratch
COPY --from=builder /app/app /app
ENTRYPOINT ["/app"]

Don’t

Copy from the dist directory.

FROM scratch
COPY /dist/app_linux_amd64/app /app
ENTRYPOINT ["/app"]

Do: Docker v2

Use Docker’s TARGETPLATFORM build argument to select the platform directory:

FROM scratch
ARG TARGETPLATFORM
COPY ${TARGETPLATFORM}/app /app
ENTRYPOINT ["/app"]

Docker supplies TARGETPLATFORM, for example linux/amd64.

Do: legacy Docker

With the legacy dockers configuration, copy the binary from the context root:

FROM scratch
COPY app /app
ENTRYPOINT ["/app"]

expected to find X artifacts for ids [id1 id2], found Y

The ids property in the Dockers configuration tells GoReleaser which build IDs to include. You need to remove IDs that don’t exist and/or don’t build for the architecture of the image being built. Leaving it empty is also fine if you don’t need any binaries.

use docker --context=default buildx to switch to context "default"

The default context is a built-in context in docker buildx, and it is created automatically. This context typically points to the local Docker environment and is used by default for building images. It has to be active for goreleaser to build images with buildx.

You can switch to the default context using docker context use default.

This change should be persistent.