Migrate to Kustomize

Kustomize is a useful tool for customizing Kubernetes resources declaratively. With Kustomize you can specify patches or new resources that can be applied to a specific runtime environment.

To migrate from a default project to a Kustomize project you need to follow these steps:

1. Since Kustomize uses a folder structure that is different from the default project's one, you need to manually move resources in the git repository.

First of all, you need to move all of your environment folders (located at configuration/%envId%) to a new first-level directory called overlays. Then, move the variables/%envId%.env files into overlays/%envId%/variables.env.

Create the file configuration/kustomization.yaml with the following content:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization

And the overlays/%envId%/kustomization.yaml files with the following content:

apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - ../../configuration

For more information on how to fill the kustomization.yaml files, please refer to the official documentation.

In practice, you should change the structure from this one:

.
├── configuration
│   ├── %resourceName%.yaml
│   └── %envId%
|       └── %resourceName%.yaml
└── variables
    └── %envId%.env

To this one:

.
├── configuration
│   ├── kustomization.yaml
│   └── %resourceName%.yaml
└── overlays
    └── %envId%
        ├── kustomization.yaml
        ├── variables.env
        ├── %resourceName%.yaml        
        └── %patchName%.patch.yaml

2. Enable the feature from the CMS. Go to the projects page, search for the project and select it. Inside the project drawer go to the deploy section and add the following property: "projectStructure": "kustomize" to the deploy configuration JSON object.

3. Configure the deploy pipeline. Add in the deploy pipeline the command to generate the customized resources with mlp:

mlp hydrate "configuration" "overlays/${ENV_ID}"
mlp kustomize "overlays/${ENV_ID}" -o "${DESTINATION_FILE}"

This command will generate the customized resources for the provided ${ENV_ID} environment and store them into a single file at ${DESTINATION_FILE}. The generated file should then be provided as an argument to the mlp deploy command later in the pipeline.

Once you have migrated your project successfully, learn how to manage a Kustomize project here.