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Kubernetes Diff

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The Kubernetes Diff step runs kubectl diff against your compiled manifests to show what would change if you applied them. Use this step anywhere in a Kubernetes stage to preview changes before they are applied.

Unlike the Kubernetes Dry Run step, which calls kubectl apply --dry-run, the Diff step calls kubectl diff and surfaces the delta between the current cluster state and the desired manifest state.

Add the Kubernetes Diff step​

To add the step:

  1. In your pipeline, go to the Kubernetes stage.
  2. Select + Add Step in the execution section.
  3. Search for Kubernetes Diff and select it.
  4. Configure the step parameters described below.
  5. Select Apply Changes.

Before you begin​

Before you configure the step, make sure you have the following in place:

  • A Kubernetes service: Go to Kubernetes services to set up service manifests and artifact source.
  • A Kubernetes infrastructure: Go to Kubernetes infrastructure to connect a cluster and namespace.
  • A Harness delegate in target cluster: The delegate runs deployment steps in the cluster.
  • Runtime configuration: Every Kubernetes stage requires a runtime block specifying connector and namespace. Go to Kubernetes runtime configuration to understand required fields.

Configure the step​

The following parameters are available on the Kubernetes Diff step.

ParameterDescriptionRequired
NameDisplay name for the step in the pipeline.Required
Manifest PathOne or more relative paths to the manifest files to diff, derived from the service configuration.Optional
Kubeconfig PathPath to the kubeconfig file, derived from the infrastructure configuration. Default: ${{infra.kube_config_path}}.Optional
NamespaceTarget namespace on the cluster. Default: default.Optional
Release NameName for this release. Default: ${{infra.releaseName}}.Optional
Command FlagsAdditional flags passed to the kubectl diff command.Optional
TimeoutMaximum time the step can run before it is marked as failed. Default: 5m.Optional
Log LevelVerbosity of step logs. Default: info.Optional
OpenShift ModeWhen enabled, Harness uses the oc client instead of kubectl. Default: false.Optional

The Kubernetes Diff step does not require a file path. It automatically uses the manifests configured in your service definition.

Add command flags​

To add a command flag:

  1. In the step configuration, select + Add next to Command Flags.
  2. Enter the flag value.

Common flags include --server-side to run the diff using server-side apply semantics.

YAML example​

- name: Kubernetes Diff
  id: k8sDiffStep
  template:
    uses: k8sDiffStep

Read the step output​

The step output shows the parameters used and the full diff output from kubectl diff, with added lines prefixed by + and removed lines prefixed by -.

The step also exposes two output variables you can reference in downstream steps.

Output variableDescription
manifestDiffThe full diff output as a string. Reference it in downstream steps with <+steps.[Step_Id].output.outputVariables.manifestDiff>.
exitValueThe exit code from kubectl diff. 0 means no differences. 1 means differences exist. Greater than 1 indicates an error.

Use exitValue in a conditional execution expression on a downstream step to branch your pipeline based on whether differences exist.

Secret values in diff output

Harness actively sanitizes Secret resource values from the diff output. Both data: and stringData: field values are replaced before logging, including values embedded in last-applied-configuration annotations.

OpenShift support​

When OpenShift Mode is enabled, Harness uses the oc client instead of kubectl. You can also leave this as false and Harness auto-detects OpenShift resources and switches clients automatically.

The Diff step is available only for Kubernetes stages. It is not available for Native Helm deployment stages. If your service uses Helm charts with the Kubernetes deployment type, the Diff step renders the Helm chart first and then diffs the rendered manifests.

Advanced settings​

The following advanced settings are available on the Kubernetes Diff step.

  • Timeout duration: Maximum time the step is allowed to run before being terminated.
  • On failure: Define what happens if the step fails, such as retry, mark as success, or abort.
  • Strategy: Configure a looping strategy to run this step over a list of values.
  • Conditional execution: Run this step only when a specified condition is true.

Next steps​

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