Hooks

Different projects have different needs and as the developer you might want to configure arrower run according to your application's situation.

Hooks are a way to customise and extend the behaviour of arrower run, by registering different functions at specific points in the livecycle of the command.

As an example let's look at the devops situation: Arrower is shipping with docker-compose as the default mechanism. But what if your project does not rely on docker-compose but on Minikube instead? Not a problem with hooks, you can just change this to your specific setup.

Similarly, you can do many other things with hooks as well, like changing the configuration values of the run command or customizing the frontend stack to your specific needs.

Hooks

The following hooks in the livecycle of the arrower run command can be registered and used extend the behaviour of the cli.

Hook	Description
OnConfigLoaded(c *RunConfig)	Arrower has loaded it's default configuration
OnStart	arrower run has started . It is watching for changes on the file system and rebuilds the app
OnChanged(file string)	A specific file has changed
OnShutdown	arrower run is shutting down

Conventions

The following conventions are important to understand, to be able to develop your own hooks.

• Hooks can customize the behaviour of arrower run in a flexible but still limited manner
• Each hook is a file saved in the .config folder of the project.
• All files matching the *.hook.go pattern are recognised as a hook
• The loading of the hooks only happens ones at the startup of the cli command
• Hooks are sorted by filename, so you can control the execution order
• All methods block
• Only imports from the standard library are possible
  • You might view this as a limitation, but the hooks are intended to be small scripts or even just calling out the OS via os.Exec and do not perform any elaborate calculations
• The package of the hooks should be main
• There is no configuration file for the arrower cli command, use the hooks to overwrite settings

Example Hook

This example shows the basics of how a hook looks like.

.config/001_my-config.hook.go

package main

import . "github.com/go-arrower/arrower/arrower/hooks"

func init() {
    Register(Hook{
        Name: "my hook name",
        OnConfigLoaded: func(c *RunConfig) {
            c.Port = 6060
        },
    })
}