[SOLVED] rendered manifests contain a resource that already exists

Why we get "rendered manifests contain a resource that already exists"?

The other day I received this error while working on my application which is deployed via helm charts

Error: INSTALLATION FAILED: rendered manifests contain a resource that already exists. Unable to continue with install: Secret "cmn-secret" in namespace "default" exists and cannot be imported into the current release: invalid ownership metadata; annotation validation error: key "meta.helm.sh/release-name" must equal "dummy": current value is "another"

The error message "Error: INSTALLATION FAILED: rendered manifests contain a resource that already exists" indicates that the installation or upgrade process of a Helm chart has encountered a resource conflict. This error occurs when Helm attempts to deploy a resource (such as a Kubernetes object) that already exists in the target environment.

Helm is a package manager for Kubernetes that simplifies the deployment and management of applications and services. It uses charts, which are packaged collections of YAML files that define Kubernetes resources, to install, upgrade, and uninstall applications on a Kubernetes cluster.

During the installation or upgrade process, Helm renders the templates in the chart, which includes substituting values from the user-supplied configuration. The rendered templates are then applied to the Kubernetes cluster to create or update the desired resources.

The error occurs when Helm encounters a resource, such as a deployment, service, or secret, that already exists in the target environment. This conflict can happen due to various reasons, including:

1. Redeploying a Helm chart without deleting existing resources: If a resource with the same name already exists in the cluster and Helm attempts to create it again, the installation process fails because Kubernetes does not allow multiple resources with the same name in the same namespace.
2. Concurrent deployments: If multiple users or processes are deploying Helm charts simultaneously, conflicts can arise when they attempt to create resources with the same names. This can occur when different teams or individuals deploy charts that include resources with the same names.
3. Manual creation of resources: If someone manually creates a resource with the same name as a resource defined in a Helm chart, conflicts will occur when Helm tries to create the same resource during installation.
4. Same resource created as part of multiple charts: When multiple Helm charts are used within the same Kubernetes namespace, there might be instances where different charts define the same resource (e.g., a secret, a service, or a deployment) with identical names.

Resolving Error

Here are the four methods to resolve the "Error: INSTALLATION FAILED: rendered manifests contain a resource that already exists" error:

Manually deleting conflicting resources before deploying the Helm chart:

• This method involves manually identifying and deleting the conflicting resources from the Kubernetes cluster before deploying the Helm chart.
• By deleting the conflicting resources, you ensure that Helm can create the resources without any conflicts during installation.

You can use kubectl delete <resource-type>  <resource-name> to clear the resource and then attempt the installation again

Using conditional checks in Helm chart templates to skip the deployment of existing resources:

• This method involves adding conditional logic to the Helm chart templates to check if the resource already exists before attempting to create it.
• You can use the lookup function or other conditionals to check if the resource exists, and if it does, skip its deployment.
• This approach allows Helm to gracefully handle existing resources and continue with the deployment without errors.

For example, here I have a secret "cmn-secret" which is required to be created with multiple charts (let's not get into the discussion of why)

So, when I deployed my first chart, the secret got created. Now when I try to deploy second chart, I get

Error: INSTALLATION FAILED: rendered manifests contain a resource that already exists. Unable to continue with install: Secret "cmn-secret" in namespace "default" exists and cannot be imported into the current release: invalid ownership metadata; annotation validation error: key "meta.helm.sh/release-name" must equal "dummy": current value is "another"

So I have used lookup function to check if the secret already exists then skip the deployment of the secret

{{- if not (lookup "v1" "Secret" "default" "cmn-secret") }}
apiVersion: v1
kind: Secret
metadata:
  name: cmn-secret
data:
  my-secret-key: {{ .Values.secret.value | b64enc | quote }}
{{- end }}

In this template, the lookup function is used to check if the Secret named "cmn-secret" already exists in the "default" namespace. If the Secret does not exist, the Secret definition is rendered and applied. However, if the Secret already exists, the deployment of the Secret is skipped.

Now, I am able to successfully deploy both the charts.

Summary

This article provides guidance on resolving the "Error: INSTALLATION FAILED: rendered manifests contain a resource that already exists" encountered during Helm chart installation. It explains the causes of the error, such as redeploying without deleting existing resources or creating the same resource in multiple charts. The article covers two methods to address the error: using conditional checks in Helm chart templates to skip the deployment of existing resources and manually deleting conflicting resources before deploying the Helm chart. Detailed explanations, step-by-step instructions, and best practices are provided to help users overcome the error and ensure successful Helm deployments.

Further Reading

Rendered manifests contain a resource that already exists. Could not get information about the resource: resource name may not be empty
Error: rendered manifests contain a resource that already exists but nothing shows up on helm list --all #7418