Initial commit

.dockerignore

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+bin/*

.github/workflows/ci.yaml

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+name: Continuous Integration
+
+on: [push]
+
+jobs:
+    ci:
+        name: CI
+        runs-on: ubuntu-latest
+        env:
+            DOCKER_BUILDKIT: "1"
+        steps:
+          - name: Checkout code
+            uses: actions/checkout@v2
+          - name: Run linter
+            run: make lint
+          - name: Run unit tests
+            run: make unit-test
+          - name: Build Linux binary
+            run: make PLATFORM=linux/amd64
+          - name: Build Windows binary
+            run: make PLATFORM=windows/amd64

.gitignore

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+bin/

Dockerfile

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+# syntax = docker/dockerfile:1-experimental
+
+FROM --platform=${BUILDPLATFORM} golang:1.14.3-alpine AS base
+WORKDIR /src
+ENV CGO_ENABLED=0
+COPY go.* .
+RUN go mod download
+
+FROM base AS build
+ARG TARGETOS
+ARG TARGETARCH
+RUN --mount=target=. \
+    --mount=type=cache,target=/root/.cache/go-build \
+    GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build -o /out/example .
+
+FROM base AS unit-test
+RUN --mount=target=. \
+    --mount=type=cache,target=/root/.cache/go-build \
+    go test -v .
+
+FROM golangci/golangci-lint:v1.27-alpine AS lint-base
+
+FROM base AS lint
+RUN --mount=target=. \
+    --mount=from=lint-base,src=/usr/bin/golangci-lint,target=/usr/bin/golangci-lint \
+    --mount=type=cache,target=/root/.cache/go-build \
+    --mount=type=cache,target=/root/.cache/golangci-lint \
+    golangci-lint run --timeout 10m0s ./...
+
+FROM scratch AS bin-unix
+COPY --from=build /out/example /
+
+FROM bin-unix AS bin-linux
+FROM bin-unix AS bin-darwin
+
+FROM scratch AS bin-windows
+COPY --from=build /out/example /example.exe
+
+FROM bin-${TARGETOS} as bin
+

LICENSE

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+This is free and unencumbered software released into the public domain.
+
+Anyone is free to copy, modify, publish, use, compile, sell, or
+distribute this software, either in source code form or as a compiled
+binary, for any purpose, commercial or non-commercial, and by any
+means.
+
+In jurisdictions that recognize copyright laws, the author or authors
+of this software dedicate any and all copyright interest in the
+software to the public domain. We make this dedication for the benefit
+of the public at large and to the detriment of our heirs and
+successors. We intend this dedication to be an overt act of
+relinquishment in perpetuity of all present and future rights to this
+software under copyright law.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+For more information, please refer to <https://unlicense.org>

Makefile

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+all: bin/example
+test: lint unit-test
+
+PLATFORM=local
+
+.PHONY: bin/example
+bin/example:
+	@docker build . --target bin \
+	--output bin/ \
+	--platform ${PLATFORM}
+
+.PHONY: unit-test
+unit-test:
+	@docker build . --target unit-test
+
+.PHONY: lint
+lint:
+	@docker build . --target lint

README.md

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+![Continuous Integration](https://github.com/chris-crone/containerized-go-dev/workflows/Continuous%20Integration/badge.svg)
+
+Example Containerized Go Development Environment
+------------------------------------------------
+
+This repository contains an example Go project with a containerized development
+environment. The example project is a simple CLI tool that echos back its
+inputs.
+
+## Why should I containerize my development environment?
+
+There are several advantages to containerizing your development environment:
+* You make explicit the tools and versions of tools required to develop your
+  project
+* Your builds will be more deterministic and reproducible
+
+These will both make it easier for people to collaborate on your project, as
+everyone will have the same environment, and make it easier to debug things like
+CI failures.
+
+## Prerequisites
+
+The only requirements to build and use this project are Docker and `make`. The
+latter can easily be substituted with your scripting tool of choice.
+
+You will also need to enable the BuildKit builder in the Docker CLI. This can be
+done by setting `DOCKER_BUILDKIT=1` in your environment.
+
+### macOS
+
+* Install [Docker Desktop](https://www.docker.com/products/docker-desktop)
+* Ensure that you have `make` (included with Xcode)
+* Run `export DOCKER_BUILDKIT=1` in your terminal or add to your shell
+  initialization scripts
+
+### Windows
+
+* Install [Docker Desktop](https://www.docker.com/products/docker-desktop)
+* Ensure that you have `make`
+* If using PowerShell, run `$env:DOCKER_BUILDKIT=1`
+* If using command prompt, run `set DOCKER_BUILDKIT=1`
+
+### Linux
+
+* Install [Docker](https://docs.docker.com/engine/install/)
+* Ensure that you have `make`
+* Run `export DOCKER_BUILDKIT=1` in your terminal or add to your shell
+  initialization scripts
+
+## Getting started
+
+Building the project will output a static binary in the bin/ folder. The
+default platform is for macOS but this can be changed using the `PLATFORM` variable:
+```console
+$ make                        # build for your host OS
+$ make PLATFORM=darwin/amd64  # build for macOS
+$ make PLATFORM=windows/amd64 # build for Windows x86_64
+$ make PLATFORM=linux/amd64   # build for Linux x86_64
+$ make PLATFORM=linux/arm     # build for Linux ARM
+```
+
+You can then run the binary, which is a simple echo binary, as follows:
+```console
+$ ./bin/example hello world!
+hello world!
+```
+
+To run the unit tests run:
+```console
+$ make unit-test
+```
+
+To run the linter:
+```console
+$ make lint
+```
+
+There's then a helpful `test` alias for running both the linter and the unit
+tests:
+```console
+$ make test
+```
+
+## Structure of project
+
+### Dockerfile
+
+The [Dockerfile](./Dockerfile) codifies all the tools needed for the project
+and the commands that need to be run for building and testing it.
+
+### Makefile
+
+The [Makefile](./Makefile) is purely used to script the required `docker build`
+commands as these can get quite long. You can replace this file with a scripting
+language of your choice.
+
+### CI
+
+The CI is configured in the [ci.yaml file](./github/workflows/ci.yaml). By
+containerizing the toolchain, the CI relies on the toolchain we defined in the
+Dockerfile and doesn't require any custom setup.
+
+## Read more
+
+* [Docker build reference documentation](https://docs.docker.com/engine/reference/commandline/build/)
+* [Experimental Dockerfile syntax](https://github.com/moby/buildkit/blob/master/frontend/dockerfile/docs/experimental.md)

go.mod

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+module github.com/chris-crone/containerized-go
+
+go 1.14
+
+require (
+	github.com/pkg/errors v0.9.1
+	github.com/stretchr/testify v1.5.1
+)

go.sum

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+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.5.1 h1:nOGnQDM7FYENwehXlg/kFVnos3rEvtKTjRvOWSzb6H4=
+github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

main.go

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+package main
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+func echo(args []string) error {
+	if len(args) < 2 {
+		return errors.New("no message to echo")
+	}
+	_, err := fmt.Println(strings.Join(args[1:], " "))
+	return err
+}
+
+func main() {
+	if err := echo(os.Args); err != nil {
+		fmt.Fprintf(os.Stderr, "%+v\n", err)
+		os.Exit(1)
+	}
+}

main_test.go

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+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestEcho(t *testing.T) {
+	// Test happy path
+	err := echo([]string{"bin-name", "hello", "world!"})
+	require.NoError(t, err)
+}
+
+func TestEchoErrorNoArgs(t *testing.T) {
+	// Test empty arguments
+	err := echo([]string{})
+	require.Error(t, err)
+}