Kustomize uses a file called kustomization.yaml that contains declarative specifications to what resources need to be imported from what manifest files and what changes need to be made. Once it has processed the resources, it emits them to the standard output, which can be stored in a file or directly used with kubectl to apply it to a particular cluster.
One of the excellent use cases of Kustomize is to manage Kubernetes resources for multiple environments. For Kustomize to work in that scenario, you would need a base directory that would contain all manifest files with all the common elements and an overlays directory that contains all the differences for a particular environment.
The following script detects your OS and downloads the appropriate kustomize binary to your current working directory:
curl -s "https://raw.githubusercontent.com/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh" | bash
Give the execution permission and move it to yout $PATH:
chmod +x kustomize
sudo mv kustomize /usr/local/bin/
Test the command:
kustomize version
This is basic case with a folder with simple yaml manifests.
Fisrt, generate the kustomization file:
kustomize create --autodetect --recursive
Kustomize has a subcommand to generate the result manifest with all listed on the kustomization.yaml file:
kustomize build .
After that, it is possible to apply it with kubectl:
kubectl apply -k .
Install basic manifests, a deployment and a service, into two different namespaces, simulating two environments, staging and production.
- Directory Structure
├── base
│ ├── deployment.yaml
│ ├── kustomization.yaml
│ └── service.yaml
└── overlays
├── production
│ ├── deployment.yaml
│ ├── kustomization.yaml
│ └── namespace.yaml
└── staging
├── deployment.yaml
├── kustomization.yaml
└── namespace.yaml
- The Base Configuration
To test the base manifests, run the kustomize build on the base directory. Kustomize emits a manifest yaml that is a combination of the two.
kustomize build base
- Deploy on Staging
To generate the result manifest to output, run the follow command:
kustomize build overlays/staging
To apply the manifests, run the follow command:
kubectl apply -k overlays/staging
- Deploy on Production
To generate the result manifest to output, run the follow command:
kustomize build overlays/production
To apply the manifests, run the follow command:
kubectl apply -k overlays/production