Remove duplication via Go chaining/structs/WithOptions()

[alexellis]

Description

There are opportunities to remove duplication between each app through the use of method chaining / fluent APIs and the use of structs or WithOptions().

Chaining:

app := arkade.App{}

app.SetArch("x86_64")
.SetRepo("https://x.com/etc")
.SetNamespace("default")
.SetKubeconfig(kubeconfigPath)

err, helpMessage:= app.Install()

Structs could reduce custom variables and flags parsing:

type App struct {
  ChartRepo string
  ChartName string
}

WithOptions:

containerd has a non-fluent API that is not chained, but passed in via a series of extra args:

chart.Install(arkade.WithArch("x86_64"), arkade.WithOverride("basic-auth", "true"))

At some later point, a manifest file, or a series of manifests could populate this information from an external source, to remove hard-coded paths/variables/flags from the codebase.

[Waterdrips]

I think this is a great idea, we could get it into one app we know well (like inlets-operator or openfaas) and work out the kinks?

What about something to "automate" getting kubeconfig, cluster/client ARCH and such things too?

[alexellis]

That approach sounds ideal, incremental and experimental, then we could include more after that.

[LucasRoesler]

Who is responsible for validating the value that is passed in? I don't think this approach would allow the SetFoo method to validate the value and return an error because the signature would have to be

func (a *App) SetFoo(value string) (a *App, err error) {}

but for chaining to work, it needs to be

func (a *App) SetFoo(value string) a *App {}

I guess we could add a separate

func (a *App) Validate() error {}

or this is returned from the Install method?

[aidun]

I introduced the app type and some cleanups in #24 maybe you can take some parts of it.

[aidun]

Hi all, I provided a implementation proposol for the App type in #46 and a like to make a draft pr with a sample app for helm 3. It would be no problem, because I already did it in #24 and can recycle some parts. What do you think @Waterdrips @alexellis

[aidun]

@alexellis I was working on this issue before as you can see. I saw also the changes made for the Loki app, they are targeting in the same direction. The details from #129 are additions to it.

[aidun]

@Waterdrips I added a solution for pre and post tasks to draft pr, to show how it could work.

[aidun]

@Waterdrips @alexellis should I work on it more in my sparetime or is it a task with low priority?

[Waterdrips]

I like the implementation - it would be potentially more valuable to start porting some of the apps over to the existing new style.

Probably pick some of the simpler apps (without pre and post steps).

[aidun]

I saw no specific issue for that. If it is okay, I will raise issues to migrate some apps. I can do some of the PRs to, but not all.

Can we label the issues as good first issue?

[Waterdrips]

sure - if you mention this issue in the ones you open I can go and add the label.