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A template project to create a minimal Docker image for a Go application

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Project Template: Create a Docker image for a Go application

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A template project to create a Docker image for a Go application. The example application exposes an HTTP endpoint.

Features:

Requirements

Docker must be installed on your local machine. That's it. You do not need to have Go installed.

Usage and Demo

Step 1: Create the Docker image according to Dockerfile. This step builds, tests, and packages the Go application. The resulting image is 5MB in size.

# ***Creating an image may take a few minutes!***
$ docker build --build-arg PROJECT_VERSION=1.0.0-alpha -t miguno/golang-docker-build-tutorial:latest .

# You can also build with the new BuildKit.
# https://docs.docker.com/build/
$ docker buildx build --build-arg PROJECT_VERSION=1.0.0-alpha -t miguno/golang-docker-build-tutorial:latest .

Optionally, you can check the size of the generated Docker image:

$ docker images miguno/golang-docker-build-tutorial
REPOSITORY                            TAG       IMAGE ID       CREATED          SIZE
miguno/golang-docker-build-tutorial   latest    2de05b854c1b   11 minutes ago   4.78MB

Step 2: Start a container for the Docker image.

$ docker run -p 8123:8123 miguno/golang-docker-build-tutorial:latest

Step 3: Open another terminal and access the example API endpoint of the running container.

$ curl http://localhost:8123/status
{"status": "idle"}

Usage with just

If you have just installed, you can run the commands above more conveniently:

$ just
Available recipes:
    audit                   # detect known vulnerabilities (requires https://github.com/sonatype-nexus-community/nancy)
    build                   # build executable for local OS
    coverage                # show test coverage
    default                 # print available targets
    deps                    # show dependencies
    docker-image-create     # create a docker image (requires Docker)
    docker-image-run        # run the docker image (requires Docker)
    docker-image-size       # size of the docker image (requires Docker)
    evaluate                # evaluate and print all just variables
    explain lint-identifier # explain lint identifier (e.g., "SA1006")
    format                  # format source code
    lint                    # run linters (requires https://github.com/dominikh/go-tools)
    outdated                # detect outdated modules (requires https://github.com/psampaz/go-mod-outdated)
    release                 # build release executables for all supported platforms
    run                     # run executable for local OS
    send-request-to-app     # send request to the app's HTTP endpoint (requires running container)
    system-info             # print system information such as OS and architecture
    test *FLAGS             # run tests with colorized output (requires https://github.com/kyoh86/richgo)
    test-vanilla *FLAGS     # run tests (vanilla), used for CI workflow
    tidy                    # add missing module requirements for imported packages, removes requirements that aren't used anymore
    vulnerabilities         # detect known vulnerabilities (requires https://pkg.go.dev/golang.org/x/vuln/cmd/govulncheck)

Example:

$ just docker-image-create
$ just docker-image-run

Notes

You can run the Go application locally if you have Go installed. See justfile for additional commands and options.

# Build
$ go build -trimpath -ldflags="-w -s" -v -o app cmd/golang-docker-build-tutorial/main.go

# Test
$ go test -cover -v ./...

# Run
$ ./app

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