This repository contains sources for the Go App Engine Flex build pipeline. This build pipeline utilizes Google Cloud Build to produce the application image. The go-1.x.yaml configuration files are used in the build pipeline. User can now specify a Go version in app.yaml via runtime: go1.x, where 1.x can be 1.8, 1.9, etc. The resulting application image uses gcr.io/distroless/base as the base image, which contains a minimal Linux, glibc-based system.

The builder image gcr.io/gcp-runtimes/go1-builder is tagged with supported Go major versions for builds to be able to target specific Go version to build against. Run the following gcloud command to list supported versions --

$ gcloud container images list-tags gcr.io/gcp-runtimes/go1-builder

Use only the Go major version tags e.g. 1.8, 1.9, instead of the unique version-datetime tags.

There are different ways to reuse the go1-builder image outside of AppEngine Flex. Here are a couple of examples.

Read up on how to use Docker's multi-stage builds.

Following is a trivial example of a Dockerfile with multi-stage build using the go1-builder image to bring in the Go SDK. The Go SDK is located under /usr/local/go of the builder image.

FROM gcr.io/gcp-runtimes/go1-builder:1.9 as builder

WORKDIR /go/src/app
COPY main.go .

RUN /usr/local/go/bin/go build -o app .

# Application image.
FROM gcr.io/distroless/base:latest

COPY --from=builder /go/src/app/app /usr/local/bin/app

CMD ["/usr/local/bin/app"]

Read up on Google Cloud Build.

You can use one of the go-1.x.yaml files for configuration file. The builder image's ENTRYPOINT is the go-build.sh script, which expects a certain layout of the uploaded directory. In particular, it expects --

• _gopath/src directory containing Go source files within package directory structure.
• _gopath/main-package-path file containing the import path of the main application to be built.
• top level directory can contain resource files that will be bundled into the application image's /app directory.

The build script will build the application as referenced in _gopath/main-package-path file and produce an application Dockerfile which the next step will run a docker build on.

You can customize your own cloudbuild.yaml file with your own Dockerfile.