Merge pull request #1805 from TomChv/doc/add-go-use-case

Docs: Add dagger golang use case

docs/use-cases/1216-go-on-docker-hub.md

@@ -0,0 +1,117 @@
+---
+slug: /1216/ci-cd-for-go-project
+displayed_sidebar: europa
+---
+
+# Go on Docker Hub
+
+Dagger stand as a powerful CI/CD tool that works on any environment.
+
+For instance, you can use [go package](https://github.com/dagger/dagger/tree/main/pkg/universe.dagger.io/go)
+to control the whole CI/CD process, from test to push into a remote registry.
+
+:::tip
+Following examples can be used as a template for any standalone go project.
+:::
+
+## Retrieve Go project
+
+First important step is to make go project accessible in dagger plan.
+
+You can indeed choose which files to include in the filesystem.  
+Since it's a Golang project, filesystem should contain module and every go
+source files:
+
+```cue file=../tests/use-cases/ci-cd-for-go-project/retrieve-go-project/dagger.cue
+```
+
+:::tip
+To make it more accessible in actions, you can set a private field that will
+act as an alias.
+:::
+
+## Build a Go base image
+
+[Dagger go universe](https://github.com/dagger/dagger/tree/main/pkg/universe.dagger.io/go)
+provide a [base image](https://github.com/dagger/dagger/blob/main/pkg/universe.dagger.io/go/image.cue)
+to build your pipeline but your project may use `CGO` or any external dependencies.
+
+You can customize that base image to install required dependencies:
+
+```cue file=../tests/use-cases/ci-cd-for-go-project/base.cue.fragment
+```
+
+## Run unit test
+
+Before deliver your application, you certainly want to run unit test.
+
+By using previous steps, you can use the [test](https://github.com/dagger/dagger/blob/main/pkg/universe.dagger.io/go/test.cue)
+definition to run your unit test:
+
+```cue file=../tests/use-cases/ci-cd-for-go-project/test.cue.fragment
+```
+
+<!-- FIXME(TomChv): we should write a bunch of documentation about TDD with dagger -->
+:::tip
+You can also use dagger to write integration tests
+:::
+
+## Build Go binary
+
+To put your go project on docker hub, you first need to compile a binary.
+
+Go universe expose a [build](https://github.com/dagger/dagger/blob/main/pkg/universe.dagger.io/go/build.cue)
+definition so you can build a binary:
+
+```cue file=../tests/use-cases/ci-cd-for-go-project/build.cue.fragment
+```
+
+:::tip
+You can control the binary platform with `os` and `arch` field.
+:::
+
+## Prepare docker image
+
+To make it usable by other user, you must put your binary in an image and set an entrypoint.
+
+For optimisation purpose, you can use alpine as base image to contain your binary:
+
+```cue file=../tests/use-cases/ci-cd-for-go-project/image.cue.fragment
+```
+
+## Push to Docker Hub
+
+To push an image to docker hub, you will need to forward credential to allow
+dagger push.
+
+To not hard code your docker password in the plan, you can retrieve it as an
+environment value:
+
+```cue
+dagger.#Plan & {
+    client: {
+        // ...
+
+        env: DOCKER_PASSWORD: dagger.#Secret
+    }
+}
+```
+
+You can now push your image:
+
+```cue file=../tests/use-cases/ci-cd-for-go-project/push.cue.fragment
+```
+
+## Complete CI/CD
+
+After merging all examples, you will have a complete CI/CD to deliver a go
+binary on Docker Hub.
+
+```cue file=../tests/use-cases/ci-cd-for-go-project/complete-ci-cd/dagger.cue
+```
+
+You can then use `dagger do` to select which action you want to run.
+
+## Push multi-platform
+
+Coming soon...