How to use the command cmctl (with examples)

cmctl is a command-line tool for managing cert-manager resources inside your Kubernetes cluster. It allows you to check the status of certificates, create new certificate requests, and manage the signing process. This article will guide you through different use cases of the cmctl command, explaining each use case in detail along with example code and output.

Use case 1: Check if the cert-manager API is ready

Code:

cmctl check api

Motivation: This use case is useful to determine if the cert-manager API is ready to accept requests. It ensures that the cert-manager installation is functioning properly.

Explanation:

• check api is a subcommand of cmctl used to verify if the API is ready.

Example output:

API is ready

Use case 2: Check the status of a certificate

Code:

cmctl status certificate cert_name

Motivation: This use case allows you to quickly check the status of a specific certificate. It provides information about whether the certificate is ready, pending, or has encountered any errors.

Explanation:

• status certificate is a subcommand of cmctl used to retrieve the status of a certificate.
• cert_name is the name of the certificate you want to check the status for.

Example output:

Name: example-certificate
Namespace: default
Status: Ready

Use case 3: Create a new certificate request based on an existing certificate

Code:

cmctl create certificaterequest my-cr --from-certificate-file cert.yaml

Motivation: This use case allows you to create a new certificate request based on an existing certificate file. It is useful when you want to generate a new certificate using the same configuration as an existing one.

Explanation:

• create certificaterequest is a subcommand of cmctl used to create a new certificate request.
• my-cr is the name of the certificate request.
• --from-certificate-file cert.yaml specifies that the new request should be based on the certificate configuration provided in the cert.yaml file.

Example output:

Certificate request 'my-cr' created successfully

Use case 4: Create a new certificate request, fetch the signed certificate, and set a maximum wait time

Code:

cmctl create certificaterequest my-cr --from-certificate-file cert.yaml --fetch-certificate --timeout 20m

Motivation: This use case is helpful when you want to create a new certificate request, wait for the signed certificate to be available, and set a maximum wait time to avoid indefinite waiting.

Explanation:

• fetch-certificate is an argument used to automatically fetch the signed certificate.
• timeout 20m is an argument that sets the maximum wait time to 20 minutes.

Example output:

Certificate request 'my-cr' created successfully
Waiting for the signed certificate...
Signed certificate fetched successfully

Conclusion:

The cmctl command is a powerful tool for managing cert-manager resources in your Kubernetes cluster. It provides a range of functionalities, including checking the API readiness, retrieving certificate status, creating new certificate requests, and fetching signed certificates. The examples provided in this article demonstrate the versatility of the cmctl command and can be used as a starting point for managing certificates in your cluster effectively.