request: add support/docs for running using Dagger.io

[senare]

Already have 'go-lang' style integration, would it be possible to create doc's / example for using it with dagger.io ?

REF daggerio i.e. pipeline independent builds ?

[stieglma]

Integrating with dagger is actually pretty easy, I think. I played around with it today and you can just wrap the kargo-render docker image and directly use it. The kargo-render go library is IMHO not the way to go here, as dagger wants to execute the stuff in a docker image anyway.

As of now there's no module on daggerverse, but you can easily create your own and use it like that. From what I played with, it looks something like this:

// A dagger module for kargo-rendered
package main

import (
	"context"
	"fmt"
)

type DaggerKargo struct{}

// Render plain (json/yaml) manifests for a given repo
// containing either helm or kustomize resources
func (m *DaggerKargo) RenderManifests(
		ctx context.Context,
		// the URL of a remote gitops repo
		repoUrl string,
		// a branch or a precise commit to render from;
		// if this is not provided, Kargo Render renders from the head of the default branch
		// +optional
		baseBranch string,
		// the environment-specific branch to render manifests into
		targetBranch string,
		// username for reading from and writing to the remote gitops repo
		repoUsername string,
		// password for reading from and writing to the remote gitops repo
		repoPassword *Secret,
		// a format for command output (json or yaml)
		// +default="yaml"
		outputFormat string,
		// the version of the kargo-renderer used internally
		// +default="v0.1.0-rc.35"
		kargoRendererVersion string,
) (string, error) {
	plainPassword, err := repoPassword.Plaintext(ctx)
	if err != nil {
		return "", err
	}
	return dag.Container().
		From(fmt.Sprintf("ghcr.io/akuity/kargo-render:%s", kargoRendererVersion)).
		// fix some issues with wrong home variable stuff when it comes to helm templating
		WithEnvVariable("XDG_CONFIG_HOME", "/tmp").
		WithEnvVariable("XDG_CACHE_HOME", "/tmp").
		WithEnvVariable("XDG_DATA_HOME", "/tmp").
		// execute the docker command
		WithExec([]string{
			"kargo-render",
			"render",
			"--repo", repoUrl,
			"--ref", baseBranch,
			"--target-branch", targetBranch,
			"--output", outputFormat,
			"--repo-username", repoUsername,
			"--repo-password", plainPassword,
		}).
		Stdout(ctx)
}