Managing Secrets using Kustomize

Creating Secret objects using kustomization.yaml file.

kubectl supports using the Kustomize object management tool to manage Secrets and ConfigMaps. You create a resource generator using Kustomize, which generates a Secret that you can apply to the API server using kubectl.

Before you begin

You need to have a Kubernetes cluster, and the kubectl command-line tool must be configured to communicate with your cluster. It is recommended to run this tutorial on a cluster with at least two nodes that are not acting as control plane hosts. If you do not already have a cluster, you can create one by using minikube or you can use one of these Kubernetes playgrounds:

Create a Secret

You can generate a Secret by defining a secretGenerator in a kustomization.yaml file that references other existing files, .env files, or literal values. For example, the following instructions create a Kustomization file for the username admin and the password 1f2d1e2e67df.

Note: The stringData field for a Secret does not work well with server-side apply.

Create the Kustomization file

  2. secretGenerator:
  3. - name: database-creds
  4.   literals:
  5.   - username=admin
  6.   - password=1f2d1e2e67df

  1. Store the credentials in files. The filenames are the keys of the secret:

    1. echo -n 'admin' > ./username.txt
    2. echo -n '1f2d1e2e67df' > ./password.txt

    The -n flag ensures that there’s no newline character at the end of your files.

  2. Create the kustomization.yaml file:

    1. secretGenerator:
    2. - name: database-creds
    3.   files:
    4.   - username.txt
    5.   - password.txt

You can also define the secretGenerator in the kustomization.yaml file by providing .env files. For example, the following kustomization.yaml file pulls in data from an .env.secret file:

  1. secretGenerator:
  2. - name: db-user-pass
  3.   envs:
  4.   - .env.secret

In all cases, you don’t need to base64 encode the values. The name of the YAML file must be kustomization.yaml or kustomization.yml.

Apply the kustomization file

To create the Secret, apply the directory that contains the kustomization file:

  1. kubectl apply -k <directory-path>

The output is similar to:

  1. secret/database-creds-5hdh7hhgfk created

When a Secret is generated, the Secret name is created by hashing the Secret data and appending the hash value to the name. This ensures that a new Secret is generated each time the data is modified.

To verify that the Secret was created and to decode the Secret data,

  1. kubectl get -k <directory-path> -o jsonpath='{.data}'

The output is similar to:

  1. { "password": "UyFCXCpkJHpEc2I9", "username": "YWRtaW4=" }
  1. echo 'UyFCXCpkJHpEc2I9' | base64 --decode

The output is similar to:

  1. S!B\*d$zDsb=

For more information, refer to Managing Secrets using kubectl and Declarative Management of Kubernetes Objects Using Kustomize.

Edit a Secret

  1. In your kustomization.yaml file, modify the data, such as the password.

  2. Apply the directory that contains the kustomization file:

    1. kubectl apply -k <directory-path>

    The output is similar to:

    1. secret/db-user-pass-6f24b56cc8 created

The edited Secret is created as a new Secret object, instead of updating the existing Secret object. You might need to update references to the Secret in your Pods.

Clean up

To delete a Secret, use kubectl:

  1. kubectl delete secret db-user-pass

What’s next