kustomize

Create a kustomization file with resources and namespace

$ kustomize create --resources [deployment.yaml,service.yaml] --namespace [staging]

$ kustomize build . | kubectl apply [[-f|--filename]] -

$ kustomize edit set image [busybox=alpine:3.6]

$ kustomize create --autodetect

kustomize command [options] [path]

build
    Build complete YAML from kustomization in directory

create
    Create skeleton kustomization directory structure

edit
    Manipulate kustomization files (add/remove resources, set images, etc.)

fmt
    Reformat and validate kustomization.yaml

cfg
    Inspect/print kustomization configuration

version
    Print kustomize version

--enable-alpha-plugins
    Allow alpha (experimental) plugins

--enable-exec
    Enable exec plugins (insecure, for remote execution)

--load-restrictor
    Restrict loaded files (LoadRestrictionsNone|...|RootOnly)

-o, --output
    Output to file instead of stdout

--output-map
    Print field indexes for output objects

Kustomize is a standalone tool for customizing raw, template-free Kubernetes YAML configurations declaratively. Using a kustomization.yaml file, it applies overlays, strategic merge patches, JSON 6902 patches, image transformations, namespace changes, common labels/annotations, and generators for ConfigMaps and Secrets from literals or files. It supports bases, resources, and remote fetching via Git or HTTP. The core workflow involves placing YAML files in a directory, defining transformations in kustomization.yaml, and running kustomize build to generate final YAML. Unlike templating tools like Helm, it avoids scripts or logic, promoting GitOps and reproducibility across environments (dev/staging/prod). Integrated into kubectl since v1.14 as kubectl kustomize and kubectl apply -k. Ideal for managing variants of Kubernetes manifests without duplication.

Not installed by default; install via package managers or binaries. Alpha/exec plugins insecure. Relies on valid YAML input; errors can be verbose. Path-sensitive for relative refs.

Download from github.com/kubernetes-sigs/kustomize/releases or go install sigs.k8s.io/kustomize/kustomize/v5@latest.
Or via package: brew install kustomize (macOS), apt install kustomize.

Create kustomization.yaml:
{resources: [nginx.yaml], images: [{name: nginx, newName: mynginx/image}] }
Run: kustomize build . | kubectl apply -f -

Developed 2017-2018 by Kubernetes API Machinery SIG as KEP-593. Standalone release v2.0.3 (2019) by Michael Turek. Maintained by SIG-CLI. kubectl integration v1.14+. Current v5.x supports modern features like Helm chart inflation.

kubectl(1), helm(1), yq(1), jq(1)