---
title: Performing advanced reference configuration customization
---

# Performing advanced reference configuration customization {#advanced-ref-config-customization}

For scenarios where you want to allow temporary deviations from the reference design, you can apply more advanced customizations.

> [!WARNING]
> These customizations override the default matching process that the `cluster-compare` plugin uses during a comparison. Use caution when applying these advanced customizations as it can lead to unintended consequences, such as excluding consequential information from a cluster comparison.

Some advanced tasks to dynamically customize your reference configuration include the following:

- **Manual matching**: Configure a user configuration file to manually match a custom resource from the cluster to a template in the reference configuration.
- **Patching the reference**: Patch a reference to configure a reference configuration by using a patch option with the `cluster-compare` command.

## Configuring manual matching between CRs and templates {#cluster-compare-manual-match_advanced-ref-config-customization}

In some cases, the `cluster-compare` plugin’s default matching might not work as expected. You can manually define how a custom resource (CR) maps to a template by using a user configuration file.

By default, the plugin maps a CR to a template based on the `apiversion`, `kind`, `name`, and `namespace` fields. However, multiple templates might match a single CR. For example, this can occur in the following scenarios:

- Multiple templates exist with the same `apiversion`, `kind`, `name`, and `namespace` fields.
- Templates match any CR with a specific `apiversion` and `kind`, regardless of its `namespace` or `name`.

When a CR matches multiple templates, the plugin uses a tie-breaking mechanism that selects the template with the fewest differences. To explicitly control which template the plugin chooses, you can create a user configuration YAML file that defines manual matching rules. You can pass this configuration file to the `cluster-compare` command to enforce the required template selection.

**Procedure**

1. Create a user configuration file to define the manual matching criteria:

   ```yaml {title="Example user-config.yaml file"}
   correlationSettings:
      manualCorrelation:
         correlationPairs:
           ptp.openshift.io/v1_PtpConfig_openshift-ptp_grandmaster: optional/ptp-config/PtpOperatorConfig.yaml
           ptp.openshift.io/v1_PtpOperatorConfig_openshift-ptp_default: optional/ptp-config/PtpOperatorConfig.yaml
   ```

   where:

   `correlationSettings`
   :   The `correlationSettings` section contains the manual correlation settings.

   `manualCorrelation`
   :   The `manualCorrelation` section specifies that manual correlation is enabled.

   `correlationPairs`
   :   The `correlationPairs` section lists the CR and template pairs to manually match.

   `ptp.openshift.io/v1_PtpConfig_openshift-ptp_grandmaster: optional/ptp-config/PtpOperatorConfig.yaml`
   :   Specifies the CR and template pair to match. The CR specification uses the following format: `<apiversion>_<kind>_<namespace>_<name>`. For cluster-scoped CRs that do not have a namespace, use the following format: `<apiversion>_<kind>_<name>`. The path to the template must be relative to the `metadata.yaml` file.
2. Reference the user configuration file in a `cluster-compare` command by running the following command:

   ```terminal
   $ oc cluster-compare -r <path_to_reference_config>/metadata.yaml -c <path_to_user_config>/user-config.yaml
   ```

   where:

   `-c <path_to_user_config>/user-config.yaml`
   :   Specify the `user-config.yaml` file by using the `-c` option.

## Patching a reference configuration {#cluster-compare-patching_advanced-ref-config-customization}

In certain scenarios, you might need to patch the reference configuration to handle expected deviations in a cluster configuration. The plugin applies the patch during the comparison process, modifying the specified resource fields as defined in the patch file.

For example, you might need to temporarily patch a template because a cluster uses a deprecated field that is out-of-date with the latest reference configuration. Patched files are reported in the comparison output summary.

You can create a patch file in two ways:

- Use the `cluster-compare` plugin to generate a patch YAML file.
- Create your own patch file.

### Using the cluster-compare plugin to generate a patch {#_using_the_cluster-compare_plugin_to_generate_a_patch}

You can use the `cluster-compare` plugin to generate a patch for specific template files. The plugin adjusts the template to ensure it matches with the cluster custom resource (CR). Any previously valid differences in the patched template are not reported. The plugin highlights the patched files in the output.

**Procedure**

1. Generate patches for templates by running the following command:

   ```terminal
   $ oc cluster-compare -r <path_to_reference_config>/metadata.yaml -o 'generate-patches' --override-reason "A valid reason for the override" --generate-override-for "<template1_path>" --generate-override-for "<template2_path>" > <path_to_patches_file>
   ```

   - `-r` specifies the path to the metadata.yaml file of the reference configuration.
   - `-o` specifies the output format. To generate a patch output, you must use the `generate-patches` value.
   - `--override-reason` describes the reason for the patch.
   - `--generate-override-for` specifies a path to the template that requires a patch.

     > [!NOTE]
     > You must use a file path for the target template that is relative to the `metadata.yaml` file. For example, if the file path for the `metadata.yaml` file is `./compare/metadata.yaml`, a relative file path for the template might be `optional/my-template.yaml`.
   - `<path_to_patches_file>` specifies the filename and path for your patch.
2. Optional: Review the patch file before applying to the reference configuration:

   ```yaml {title="Example patch-config file"}
   - apiVersion: storage.k8s.io/v1
     kind: StorageClass
     name: crc-csi-hostpath-provisioner
     patch: '{"provisioner":"kubevirt.io.hostpath-provisioner"}'
     reason: A valid reason for the override
     templatePath: optional/local-storage-operator/StorageClass.yaml
     type: mergepatch
   ```

   where:

   `patch`
   :   The plugin patches the fields in the template to match the CR.

   `templatePath`
   :   The path to the template.

   `type: mergepatch`
   :   The `mergepath` option merges the JSON into the target template. Unspecified fields remain unchanged.
3. Apply the patch to the reference configuration by running the following command:

   ```terminal
   $ oc cluster-compare -r <referenceConfigurationDirectory> -p <path_to_patches_file>
   ```

   - `-r` specifies the path to the metadata.yaml file of the reference configuration.
   - `-p` specifies the path to the patch file.

The following is example output:

```terminal
...

Cluster CR: storage.k8s.io/v1_StorageClass_crc-csi-hostpath-provisioner
Reference File: optional/local-storage-operator/StorageClass.yaml
Description: Component description
Diff Output: None
Patched with patch
Patch Reasons:
- A valid reason for the override

...

No CRs are unmatched to reference CRs
Metadata Hash: bb2165004c496b32e0c8509428fb99c653c3cf4fba41196ea6821bd05c3083ab
Cluster CRs with patches applied: 1
```

### Creating a patch file manually {#_creating_a_patch_file_manually}

You can write a patch file to handle expected deviations in a cluster configuration.

> [!NOTE]
> Patches have three possible values for the `type` field:
>
> - `mergepatch` - Merges the JSON into the target template. Unspecified fields remain unchanged.
> - `rfc6902` - Merges the JSON in the target template using `add`, `remove`, `replace`, `move`, and `copy` operations. Each operation targets a specific path.
> - `go-template` - Defines a Golang template. The plugin renders the template using the cluster custom resource (CR) as input and generates either a `mergepatch` or `rfc6902` patch for the target template.
>
> The following example shows the same patch using all three different formats.

**Procedure**

1. Create a patch file to match your use case. Use the following structure as an example:

   ```yaml {title="Example patch-config"}
   - apiVersion: v1
     kind: Namespace
     name: openshift-storage
     reason: known deviation
     templatePath: namespace.yaml
     type: mergepatch
     patch: '{"metadata":{"annotations":{"openshift.io/sa.scc.mcs":"s0:c29,c14","openshift.io/sa.scc.supplemental-groups":"1000840000/10000","openshift.io/sa.scc.uid-range":"1000840000/10000","reclaimspace.csiaddons.openshift.io/schedule":"@weekly","workload.openshift.io/allowed":null},"labels":{"kubernetes.io/metadata.name":"openshift-storage","olm.operatorgroup.uid/ffcf3f2d-3e37-4772-97bc-983cdfce128b":"","openshift.io/cluster-monitoring":"false","pod-security.kubernetes.io/audit":"privileged","pod-security.kubernetes.io/audit-version":"v1.24","pod-security.kubernetes.io/warn":"privileged","pod-security.kubernetes.io/warn-version":"v1.24","security.openshift.io/scc.podSecurityLabelSync":"true"}},"spec":{"finalizers":["kubernetes"]}}'
   - name: openshift-storage
     apiVersion: v1
     kind: Namespace
     templatePath: namespace.yaml
     type: rfc6902
     reason: known deviation
     patch: '[
       {"op": "add", "path": "/metadata/annotations/openshift.io~1sa.scc.mcs", "value": "s0:c29,c14"},
       {"op": "add", "path": "/metadata/annotations/openshift.io~1sa.scc.supplemental-groups", "value": "1000840000/10000"},
       {"op": "add", "path": "/metadata/annotations/openshift.io~1sa.scc.uid-range", "value": "1000840000/10000"},
       {"op": "add", "path": "/metadata/annotations/reclaimspace.csiaddons.openshift.io~1schedule", "value": "@weekly"},
       {"op": "remove", "path": "/metadata/annotations/workload.openshift.io~1allowed"},
       {"op": "add", "path": "/metadata/labels/kubernetes.io~1metadata.name", "value": "openshift-storage"},
       {"op": "add", "path": "/metadata/labels/olm.operatorgroup.uid~1ffcf3f2d-3e37-4772-97bc-983cdfce128b", "value": ""},
       {"op": "add", "path": "/metadata/labels/openshift.io~1cluster-monitoring", "value": "false"},
       {"op": "add", "path": "/metadata/labels/pod-security.kubernetes.io~1audit", "value": "privileged"},
       {"op": "add", "path": "/metadata/labels/pod-security.kubernetes.io~1audit-version", "value": "v1.24"},
       {"op": "add", "path": "/metadata/labels/pod-security.kubernetes.io~1warn", "value": "privileged"},
       {"op": "add", "path": "/metadata/labels/pod-security.kubernetes.io~1warn-version", "value": "v1.24"},
       {"op": "add", "path": "/metadata/labels/security.openshift.io~1scc.podSecurityLabelSync", "value": "true"},
       {"op": "add", "path": "/spec", "value": {"finalizers": ["kubernetes"]}}
       ]'
   - apiVersion: v1
     kind: Namespace
     name: openshift-storage
     reason: "known deviation"
     templatePath: namespace.yaml
     type: go-template
     patch: |
       {
           "type": "rfc6902",
           "patch": '[
               {"op": "add", "path": "/metadata/annotations/openshift.io~1sa.scc.mcs", "value": "s0:c29,c14"},
               {"op": "add", "path": "/metadata/annotations/openshift.io~1sa.scc.supplemental-groups", "value": "1000840000/10000"},
               {"op": "add", "path": "/metadata/annotations/openshift.io~1sa.scc.uid-range", "value": "1000840000/10000"},
               {"op": "add", "path": "/metadata/annotations/reclaimspace.csiaddons.openshift.io~1schedule", "value": "@weekly"},
               {"op": "remove", "path": "/metadata/annotations/workload.openshift.io~1allowed"},
               {"op": "add", "path": "/metadata/labels/kubernetes.io~1metadata.name", "value": "openshift-storage"},
               {"op": "add", "path": "/metadata/labels/olm.operatorgroup.uid~1ffcf3f2d-3e37-4772-97bc-983cdfce128b", "value": ""},
               {"op": "add", "path": "/metadata/labels/openshift.io~1cluster-monitoring", "value": "false"},
               {"op": "add", "path": "/metadata/labels/pod-security.kubernetes.io~1audit", "value": "privileged"},
               {"op": "add", "path": "/metadata/labels/pod-security.kubernetes.io~1audit-version", "value": "v1.24"},
               {"op": "add", "path": "/metadata/labels/pod-security.kubernetes.io~1warn", "value": "privileged"},
               {"op": "add", "path": "/metadata/labels/pod-security.kubernetes.io~1warn-version", "value": "v1.24"},
               {"op": "add", "path": "/metadata/labels/security.openshift.io~1scc.podSecurityLabelSync", "value": "true"},
               {"op": "add", "path": "/spec", "value": {"finalizers": {{ .spec.finalizers | toJson }} }}
           ]'
       }
   ```

   The patches use the `kind`, `apiVersion`, `name`, and `namespace` fields to match the patch with the correct cluster CR.
2. Apply the patch to the reference configuration by running the following command:

   ```terminal
   $ oc cluster-compare -r <referenceConfigurationDirectory> -p <path_to_patches_file>
   ```

   - `-r` specifies the path to the metadata.yaml file of the reference configuration.
   - `p` specifies the path to the patch file.

The following is example output:

```terminal
...

Cluster CR: storage.k8s.io/v1_StorageClass_crc-csi-hostpath-provisioner
Reference File: namespace.yaml
Description: Component description
Diff Output: None
Patched with patch
Patch Reasons:
- known deviation
- known deviation
- known deviation

...

No CRs are unmatched to reference CRs
Metadata Hash: bb2165004c496b32e0c8509428fb99c653c3cf4fba41196ea6821bd05c3083ab
Cluster CRs with patches applied: 1
```