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Golang Actions

Shuttle supports multiple types of actions. Actions are the things command you do on the command line via. shuttle which does stuff.

That is shuttle run build, shuttle run test etc.

These actions can be defined in multiple ways, and in multiple formats. As the examples show they can be docker, shell or golang.

As defined in either the shuttle.yaml or plan.yaml when building a plan.

A script section can be defined.

scripts:
  build:
	  actions:
		  - shell: echo "build...

That of course is a shell action, it can also call a file via: - shell: $scripts/build.sh

However, we can also use golang. To use golang you need a few prerequisites:

  • golang 1.19+
  • or docker

To create an action in your plan, you don't need either the plan.yaml or the shuttle.yaml script sections. You just create a folder: mkdir -p actions && cd actions

The actions folder is the place our golang code actions will live. Each regular golang file in this folder will be treated as an action, this doesn't include tests or folders. As such if you need files that aren't actions, create a folder and put the code in there.

go mod init actions
go get github.com/lunarway/shuttle

Create a golang submodule, and add shuttle to it.

echo <--GOEOF
package main

import (
	"context",
	_ "github.com/lunarway/shuttle" // default the base shuttle so that it doesn't disappear from go.mod
)

func Build(ctx context.Context) error {
	println("build")

	return nil
}
GOEOF > build.go

This will create a file and a function with the same name. Note, the file name and the function name have to match. golang file names support snake_case, and golang func names support PascalCase. As such they have to match. Otherwise the build will fail.

  1. file: "build_production.go" -> func BuildProduction
  2. file: "build.go" -> func Build

Lower case functions are ignored, only 1 public function is allowed pr actions file.

  1. func handleBuild -> ignored
  2. func Build -> allowed
  3. func build, func Build -> allowed
  4. func Build, func TestBuild -> error (only 1 public function pr file is allowed)

Now you can run the command via. shuttle.

shuttle run build
stdout: build

Why

Why would you want such a feature?

  • First of all software engineering. Using golang over bash, enables a few things.
  • It is easier to build solid tools in golang than bash. Golang code can be shared and distributed.
  • You can include packages, snippets and whatnot in golang.
  • Golang can more easily be tested and benchmarked.
  • Binaries can be saved and reused to improve performance and startup time.
  • A more thorough user experience can be designed.
  • No longer bound to what is installed on a client machine, you don't need curl, wget, uname, grep, yq, jq etc. installed

Configuration

SHUTTLE_GOLANG_ACTIONS

This variable controls whether or not to enable or disable the golang actions. This may be wanted in environments where golang or docker isn't available, or wanted.

The variable is default true, false will disable golang, and any other value will be considered true

SHUTTLE_GOLANG_ACTIONS_IMAGE

This variable controls an override for proving different image for building the golang actions. The image is automatically kept up-to-date, but it may be needed to set this in the place of use, such that a race condition doesn't occur.

SHUTTLE_GOLANG_ACTIONS_DAGGER_FALLBACK

default: false, meaning we don't use dagger as a fallback true is enabled, and will use a dagger pipeline to build the actions if go isn't installed anything is false and will be disabled