ArgoCD Application

Overview

This topic covers how to mix in an ArgoCD Application to all components. We'll use the Artifacts field of ComponentConfig defined by the author schema.

The Code

Generating the structure

Use holos to generate a minimal platform directory structure. Start by creating a blank directory to hold the platform configuration.

mkdir holos-argocd-application && cd holos-argocd-application

holos init platform v1alpha5

Creating a component

Create a directory for the podinfo component. Create an empty file and then add the following CUE configuration to it.

Podinfo Helm Chart

mkdir -p components/podinfo
touch components/podinfo/podinfo.cue

cat <<EOF >components/podinfo/podinfo.cue

package holos

holos: Component.BuildPlan

Component: #Helm & {
	Name: "podinfo"
	Chart: {
		version: "6.6.2"
		repository: {
			name: "podinfo"
			url:  "https://stefanprodan.github.io/podinfo"
		}
	}
}

EOF

Integrate the podinfo component into the platform.

Register Podinfo

cat <<EOF >platform/podinfo.cue

package holos

Platform: Components: podinfo: {
	name: "podinfo"
	path: "components/podinfo"
}

EOF

Adding ArgoCD Application

Configure Holos to render an Application by defining an Artifact for it in every BuildPlan holos produces. We're unifying our custom configuration with the existing #ComponentConfig defined in schema.cue.

cat <<EOF >argocd-application.cue

package holos

import (
	"path"
	app "argoproj.io/application/v1alpha1"
)

#ComponentConfig: {
	Name:          _
	OutputBaseDir: _

	let ArtifactPath = path.Join([OutputBaseDir, "gitops", "\(Name).application.gen.yaml"], path.Unix)
	let ResourcesPath = path.Join(["deploy", OutputBaseDir, "components", Name], path.Unix)

	Artifacts: "\(Name)-application": {
		artifact: ArtifactPath
		generators: [{
			kind:   "Resources"
			output: artifact
			resources: Application: (Name): app.#Application & {
				metadata: name:      Name
				metadata: namespace: "argocd"
				spec: {
					destination: server: "https://kubernetes.default.svc"
					project: "default"
					source: {
						path:           ResourcesPath
						repoURL:        "https://example.com/example.git"
						targetRevision: "main"
					}
				}
			}
		}]
	}
}

EOF

Inspecting the BuildPlan

Our customized #ComponentConfig results in the following BuildPlan.

note

The second artifact around line 40 contains the configured Application resource.

Command

holos cue export --expression holos --out=yaml ./components/podinfo

Output

kind: BuildPlan
apiVersion: v1alpha5
metadata:
  name: podinfo
spec:
  artifacts:
    - artifact: components/podinfo/podinfo.gen.yaml
      generators:
        - kind: Helm
          output: helm.gen.yaml
          helm:
            chart:
              name: podinfo
              version: 6.6.2
              release: podinfo
              repository:
                name: podinfo
                url: https://stefanprodan.github.io/podinfo
            values: {}
            enableHooks: false
        - kind: Resources
          output: resources.gen.yaml
          resources: {}
      transformers:
        - kind: Kustomize
          inputs:
            - helm.gen.yaml
            - resources.gen.yaml
          output: components/podinfo/podinfo.gen.yaml
          kustomize:
            kustomization:
              labels:
                - includeSelectors: false
                  pairs: {}
              resources:
                - helm.gen.yaml
                - resources.gen.yaml
              kind: Kustomization
              apiVersion: kustomize.config.k8s.io/v1beta1
    - artifact: gitops/podinfo.application.gen.yaml
      generators:
        - kind: Resources
          output: gitops/podinfo.application.gen.yaml
          resources:
            Application:
              podinfo:
                apiVersion: argoproj.io/v1alpha1
                kind: Application
                metadata:
                  name: podinfo
                  namespace: argocd
                spec:
                  destination:
                    server: https://kubernetes.default.svc
                  project: default
                  source:
                    path: deploy/components/podinfo
                    repoURL: https://example.com/example.git
                    targetRevision: main
source:
  component:
    name: podinfo
    path: no-path
    parameters: {}

Rendering manifests

Command

holos render platform ./platform

Output

cached podinfo 6.6.2
rendered podinfo in 1.938665041s
rendered platform in 1.938759417s

Reviewing the Application

The Artifact we added to #ComponentConfig will produce an ArgoCD Application resource for every component in the platform. The output in this example is located at:

deploy/gitops/podinfo.application.gen.yaml

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
    name: podinfo
    namespace: argocd
spec:
    destination:
        server: https://kubernetes.default.svc
    project: default
    source:
        path: deploy/components/podinfo
        repoURL: https://example.com/example.git
        targetRevision: main