This section provides examples of Merge Patch and Strategic Merge Patch method operations.

Operation Example

By way of example, Merge Patch and Strategic Merge Patch method operations are performed at the time of creating a ReplicationController resource object.

Sample request

{
    "apiVersion": "v1",
    "kind": "ReplicationController",
    "metadata": {
        "name": "frontend-controller"
    },
    "spec": {
        "replicas": 2,
        "selector": {
            "app": "nginx"
        },
        "template": {
            "metadata": {
                "labels": {
                    "app": "nginx"
                }
            },
            "spec": {
                "containers": [
                    {
                        "name": "redis",
                        "image": "redis:latest",
                        "ports": [
                            {
                                "containerPort": 80
                            }
                        ]
                    }
                ]
            }
        }
    }
}

Sample response

{
    "kind": "ReplicationController",
    "apiVersion": "v1",
    "metadata": {
        "name": "frontend-controller",
        "namespace": "default",
        "selfLink": "/api/v1/namespaces/default/replicationcontrollers/nginx-controller",
        "uid": "549b2234-5d46-11e6-aeb9-286ed488fafe",
        "resourceVersion": "4110",
        "generation": 1,
        "creationTimestamp": "2016-08-08T08:58:52Z",
        "labels": {
            "app": "nginx"
        }
    },
    "spec": {
        "replicas": 2,
        "selector": {
            "app": "nginx"
        },
        "template": {
            "metadata": {
                "creationTimestamp": null,
                "labels": {
                    "app": "nginx"
                }
            },
            "spec": {
                "containers": [
                    {
                        "name": "redis",
                        "image": "redis:latest",
                        "ports": [
                            {
                                "containerPort": 80,
                                "protocol": "TCP"
                            }
                        ],
                        "resources": {},
                        "terminationMessagePath": "/dev/termination-log",
                        "imagePullPolicy": "Always"
                    }
                ],
                "restartPolicy": "Always",
                "terminationGracePeriodSeconds": 30,
                "dnsPolicy": "ClusterFirst",
                "securityContext": {}
            }
        }
    },
    "status": {
        "replicas": 0
    }
}

If you use Merge Patch to add a container to the template field of a specified ReplicationController, the list of existing containers is then replaced by the newly added container.

Merge Patch request

{
    "spec": {
        "template": {
            "spec": {
                "containers": [
                    {
                        "name": "hello-world",
                        "image": "busybox:latest"
                    }
                ]
            }
        }
    }
}

Merge Patch response

{
    "kind": "ReplicationController",
    "apiVersion": "v1",
    "metadata": {
        "name": "frontend-controller",
        "namespace": "default",
        "selfLink": "/api/v1/namespaces/default/replicationcontrollers/nginx-controller",
        "uid": "549b2234-5d46-11e6-aeb9-286ed488fafe",
        "resourceVersion": "4159",
        "generation": 2,
        "creationTimestamp": "2016-08-08T08:58:52Z",
        "labels": {
            "app": "nginx"
        }
    },
    "spec": {
        "replicas": 2,
        "selector": {
            "app": "nginx"
        },
        "template": {
            "metadata": {
                "creationTimestamp": null,
                "labels": {
                    "app": "nginx"
                }
            },
            "spec": {
                "containers": [
                    {
                        "name": "hello-world",
                        "image": "busybox:latest",
                        "resources": {},
                        "terminationMessagePath": "/dev/termination-log",
                        "imagePullPolicy": "Always"
                    }
                ],
                "restartPolicy": "Always",
                "terminationGracePeriodSeconds": 30,
                "dnsPolicy": "ClusterFirst",
                "securityContext": {}
            }
        }
    },
    "status": {
        "replicas": 2,
        "fullyLabeledReplicas": 2,
        "observedGeneration": 1
    }
}

The containers are replaced by the newly added container.

If you use Strategic Merge Patch to add metadata to a resource object, the new metadata then determines which list should b merged and which should not.

Strategic Merge Patch request

{
    "spec": {
        "template": {
            "spec": {
                "containers": [
                    {
                        "name": "hello-world",
                        "image": "busybox:latest"
                    }
                ]
            }
        }
    }
}'

Strategic Merge Patch response

{
    "kind": "ReplicationController",
    "apiVersion": "v1",
    "metadata": {
        "name": "frontend-controller",
        "namespace": "default",
        "selfLink": "/api/v1/namespaces/default/replicationcontrollers/nginx-controller",
        "uid": "f2e048bb-5d46-11e6-aeb9-286ed488fafe",
        "resourceVersion": "4250",
        "generation": 2,
        "creationTimestamp": "2016-08-08T09:03:18Z",
        "labels": {
            "app": "nginx"
        }
    },
    "spec": {
        "replicas": 2,
        "selector": {
            "app": "nginx"
        },
        "template": {
            "metadata": {
                "creationTimestamp": null,
                "labels": {
                    "app": "nginx"
                }
            },
            "spec": {
                "containers": [
                    {
                        "name": "redis",
                        "image": "redis:latest",
                        "ports": [
                            {
                                "containerPort": 80,
                                "protocol": "TCP"
                            }
                        ],
                        "resources": {},
                        "terminationMessagePath": "/dev/termination-log",
                        "imagePullPolicy": "Always"
                    },
                    {
                        "name": "hello-world",
                        "image": "busybox:latest",
                        "resources": {},
                        "terminationMessagePath": "/dev/termination-log",
                        "imagePullPolicy": "Always"
                    }
                ],
                "restartPolicy": "Always",
                "terminationGracePeriodSeconds": 30,
                "dnsPolicy": "ClusterFirst",
                "securityContext": {}
            }
        }
    },
    "status": {
        "replicas": 2,
        "fullyLabeledReplicas": 2,
        "observedGeneration": 1
    }
}

The containers merge with the new content according to the value of the name field.

Patch Request Method Operation Example

Operation Example