Kafka Connect REST Interface

Posted 2021-12-10 lenmom

Since Kafka Connect is intended to be run as a service, it also supports a REST API for managing connectors. By default this service runs on port 8083. When executed in distributed mode, the REST API will be the primary interface to the cluster. You can make requests to any cluster member; the REST API automatically forwards requests if required.

Although you can use the standalone mode just by submitting a connector on the command line, it also runs the REST interface. This is useful for getting status information, adding and removing connectors without stopping the process, and more.

Currently the top level resources are connector and connector-plugins. The sub-resources for connector lists configuration settings and tasks and the sub-resource for connector-plugins provides configuration validation and recommendation.

Note that if you try to modify, update or delete a resource under connector which may require the request to be forwarded to the leader, Connect will return status code 409 while the worker group rebalance is in process as the leader may change during rebalance.

Content Types

Currently the REST API only supports application/json as both the request and response entity content type. Your requests should specify the expected content type of the response via the HTTP Accept header:

Accept: application/json

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and should specify the content type of the request entity (if one is included) via the Content-Type header:

Content-Type: application/json

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Statuses & Errors

The REST API will return standards-compliant HTTP statuses. Clients should check the HTTP status, especially before attempting to parse and use response entities. Currently the API does not use redirects (statuses in the 300 range), but the use of these codes is reserved for future use so clients should handle them.

When possible, all endpoints will use a standard error message format for all errors (status codes in the 400 or 500 range). For example, a request entity that omits a required field may generate the following response:

HTTP/1.1 422 Unprocessable Entity
Content-Type: application/json

{
    "error_code": 422,
    "message": "config may not be empty"
}

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Connectors

GET /connectors

Get a list of active connectors

Response JSON Object:
	connectors (array) -- List of connector names

Example request:

GET /connectors HTTP/1.1
Host: connect.example.com
Accept: application/json

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Example response:

HTTP/1.1 200 OK
Content-Type: application/json

["my-jdbc-source", "my-hdfs-sink"]

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POST /connectors

Create a new connector, returning the current connector info if successful. Return 409 (Conflict) if rebalance is in process.

Request JSON Object:
	name (string) -- Name of the connector to create config (map) -- Configuration parameters for the connector. All values should be strings.
Response JSON Object:
	name (string) -- Name of the created connector config (map) -- Configuration parameters for the connector. tasks (array) -- List of active tasks generated by the connector tasks[i].connector (string) -- The name of the connector the task belongs to tasks[i].task (int) -- Task ID within the connector.

Example request:

POST /connectors HTTP/1.1
Host: connect.example.com
Content-Type: application/json
Accept: application/json

{
    "name": "hdfs-sink-connector",
    "config": {
        "connector.class": "io.confluent.connect.hdfs.HdfsSinkConnector",
        "tasks.max": "10",
        "topics": "test-topic",
        "hdfs.url": "hdfs://fakehost:9000",
        "hadoop.conf.dir": "/opt/hadoop/conf",
        "hadoop.home": "/opt/hadoop",
        "flush.size": "100",
        "rotate.interval.ms": "1000"
    }
}

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Example response:

HTTP/1.1 201 Created
Content-Type: application/json

{
    "name": "hdfs-sink-connector",
    "config": {
        "connector.class": "io.confluent.connect.hdfs.HdfsSinkConnector",
        "tasks.max": "10",
        "topics": "test-topic",
        "hdfs.url": "hdfs://fakehost:9000",
        "hadoop.conf.dir": "/opt/hadoop/conf",
        "hadoop.home": "/opt/hadoop",
        "flush.size": "100",
        "rotate.interval.ms": "1000"
    },
    "tasks": [
        { "connector": "hdfs-sink-connector", "task": 1 },
        { "connector": "hdfs-sink-connector", "task": 2 },
        { "connector": "hdfs-sink-connector", "task": 3 }
    ]
}

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GET /connectors/(string:name)

Get information about the connector.

Response JSON Object:
	name (string) -- Name of the created connector config (map) -- Configuration parameters for the connector. tasks (array) -- List of active tasks generated by the connector tasks[i].connector (string) -- The name of the connector the task belongs to tasks[i].task (int) -- Task ID within the connector.

Example request:

GET /connectors/hdfs-sink-connector HTTP/1.1
Host: connect.example.com
Accept: application/json

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Example response:

HTTP/1.1 200 OK
Content-Type: application/json

{
    "name": "hdfs-sink-connector",
    "config": {
        "connector.class": "io.confluent.connect.hdfs.HdfsSinkConnector",
        "tasks.max": "10",
        "topics": "test-topic",
        "hdfs.url": "hdfs://fakehost:9000",
        "hadoop.conf.dir": "/opt/hadoop/conf",
        "hadoop.home": "/opt/hadoop",
        "flush.size": "100",
        "rotate.interval.ms": "1000"
    },
    "tasks": [
        { "connector": "hdfs-sink-connector", "task": 1 },
        { "connector": "hdfs-sink-connector", "task": 2 },
        { "connector": "hdfs-sink-connector", "task": 3 }
    ]
}

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GET /connectors/(string:name)/config

Get the configuration for the connector.

Response JSON Object:
	config (map) -- Configuration parameters for the connector.

Example request:

GET /connectors/hdfs-sink-connector/config HTTP/1.1
Host: connect.example.com
Accept: application/json

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Example response:

HTTP/1.1 200 OK
Content-Type: application/json

{
    "connector.class": "io.confluent.connect.hdfs.HdfsSinkConnector",
    "tasks.max": "10",
    "topics": "test-topic",
    "hdfs.url": "hdfs://fakehost:9000",
    "hadoop.conf.dir": "/opt/hadoop/conf",
    "hadoop.home": "/opt/hadoop",
    "flush.size": "100",
    "rotate.interval.ms": "1000"
}

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PUT /connectors/(string:name)/config

Create a new connector using the given configuration, or update the configuration for an existing connector. Returns information about the connector after the change has been made. Return 409 (Conflict) if rebalance is in process.

Request JSON Object:
	config (map) -- Configuration parameters for the connector. All values should be strings.
Response JSON Object:
	name (string) -- Name of the created connector config (map) -- Configuration parameters for the connector. tasks (array) -- List of active tasks generated by the connector tasks[i].connector (string) -- The name of the connector the task belongs to tasks[i].task (int) -- Task ID within the connector.

Example request:

PUT /connectors/hdfs-sink-connector/config HTTP/1.1
Host: connect.example.com
Accept: application/json

{
    "connector.class": "io.confluent.connect.hdfs.HdfsSinkConnector",
    "tasks.max": "10",
    "topics": "test-topic",
    "hdfs.url": "hdfs://fakehost:9000",
    "hadoop.conf.dir": "/opt/hadoop/conf",
    "hadoop.home": "/opt/hadoop",
    "flush.size": "100",
    "rotate.interval.ms": "1000"
}

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Example response:

HTTP/1.1 201 Created
Content-Type: application/json

{
    "name": "hdfs-sink-connector",
    "config": {
        "connector.class": "io.confluent.connect.hdfs.HdfsSinkConnector",
        "tasks.max": "10",
        "topics": "test-topic",
        "hdfs.url": "hdfs://fakehost:9000",
        "hadoop.conf.dir": "/opt/hadoop/conf",
        "hadoop.home": "/opt/hadoop",
        "flush.size": "100",
        "rotate.interval.ms": "1000"
    },
    "tasks": [
        { "connector": "hdfs-sink-connector", "task": 1 },
        { "connector": "hdfs-sink-connector", "task": 2 },
        { "connector": "hdfs-sink-connector", "task": 3 }
    ]
}

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Note that in this example the return status indicates that the connector was Created. In the case of a configuration update the status would have been 200 OK.

GET /connectors/(string:name)/status

Get current status of the connector, including whether it is running, failed or paused, which worker it is assigned to, error information if it has failed, and the state of all its tasks.

Response JSON Object:
	name (string) -- The name of the connector. connector (map) -- The map containing connector status. tasks[i] (map) -- The map containing the task status.

Example request:

GET /connectors/hdfs-sink-connector/status HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 200 OK

{
    "name": "hdfs-sink-connector",
    "connector": {
        "state": "RUNNING",
        "worker_id": "fakehost:8083"
    },
    "tasks":
    [
        {
            "id": 0,
            "state": "RUNNING",
            "worker_id": "fakehost:8083"
        },
        {
            "id": 1,
            "state": "FAILED",
            "worker_id": "fakehost:8083",
            "trace": "org.apache.kafka.common.errors.RecordTooLargeException\n"
        }
    ]
}

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POST /connectors/(string:name)/restart

Restart the connector and its tasks. Return 409 (Conflict) if rebalance is in process.

Example request:

POST /connectors/hdfs-sink-connector/restart HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 200 OK

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PUT /connectors/(string:name)/pause

Pause the connector and its tasks, which stops message processing until the connector is resumed. This call asynchronous and the tasks will not transition to PAUSED state at the same time.

Example request:

PUT /connectors/hdfs-sink-connector/pause HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 202 Accepted

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PUT /connectors/(string:name)/resume

Resume a paused connector or do nothing if the connector is not paused. This call asynchronous and the tasks will not transition to RUNNINGstate at the same time.

Example request:

PUT /connectors/hdfs-sink-connector/resume HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 202 Accepted

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DELETE /connectors/(string:name)/

Delete a connector, halting all tasks and deleting its configuration. Return 409 (Conflict) if rebalance is in process.

Example request:

DELETE /connectors/hdfs-sink-connector HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 204 No Content

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Tasks

GET /connectors/(string:name)/tasks

Get a list of tasks currently running for the connector.

Response JSON Object:
	tasks (array) -- List of active task configs that have been created by the connector tasks[i].id (string) -- The ID of task tasks[i].id.connector (string) -- The name of the connector the task belongs to tasks[i].id.task (int) -- Task ID within the connector. tasks[i].config (map) -- Configuration parameters for the task

Example request:

GET /connectors/hdfs-sink-connector/tasks HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 200 OK

[
    {
        "task.class": "io.confluent.connect.hdfs.HdfsSinkTask",
        "topics": "test-topic",
        "hdfs.url": "hdfs://fakehost:9000",
        "hadoop.conf.dir": "/opt/hadoop/conf",
        "hadoop.home": "/opt/hadoop",
        "flush.size": "100",
        "rotate.interval.ms": "1000"
    },
    {
        "task.class": "io.confluent.connect.hdfs.HdfsSinkTask",
        "topics": "test-topic",
        "hdfs.url": "hdfs://fakehost:9000",
        "hadoop.conf.dir": "/opt/hadoop/conf",
        "hadoop.home": "/opt/hadoop",
        "flush.size": "100",
        "rotate.interval.ms": "1000"
    }
]

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GET /connectors/(string:name)/tasks/(int:taskid)/status

Get a task‘s status.

Example request:

GET /connectors/hdfs-sink-connector/tasks/1/status HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 200 OK

{"state":"RUNNING","id":1,"worker_id":"192.168.86.101:8083"}

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POST /connectors/(string:name)/tasks/(int:taskid)/restart

Restart an individual task.

Example request:

POST /connectors/hdfs-sink-connector/tasks/1/restart HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 200 OK

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Connector Plugins

GET /connector-plugins/

Return a list of connector plugins installed in the Kafka Connect cluster. Note that the API only checks for connectors on the worker that handles the request, which means it is possible to see inconsistent results, especially during a rolling upgrade if you add new connector jars.

Response JSON Object:
	class (string) -- The connector class name.

Example request:

GET /connector-plugins/ HTTP/1.1
Host: connect.example.com

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Example response:

HTTP/1.1 200 OK

[
    {
        "class": "io.confluent.connect.hdfs.HdfsSinkConnector"
    },
    {
        "class": "io.confluent.connect.jdbc.JdbcSourceConnector"
    }
]

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PUT /connector-plugins/(string:name)/config/validate

Validate the provided configuration values against the configuration definition. This API performs per config validation, returns suggested values and error messages during validation.

Request JSON Object:
	config (map) -- Configuration parameters for the connector. All values should be strings.
Response JSON Object:
	name (string) -- The class name of the connector plugin. error_count (int) -- The total number of errors encountered during configuration validation. groups (array) -- The list of groups used in configuration definitions. configs[i].definition (map) -- The definition for a config in the connector plugin, which includes the name, type, importance, etc. configs[i].value (map) -- The current value for a config, which includes the name, value, recommended values, etc.

Example request:

PUT /connector-plugins/FileStreamSinkConnector/config/validate/ HTTP/1.1
Host: connect.example.com
Accept: application/json

{
    "connector.class": "org.apache.kafka.connect.file.FileStreamSinkConnector",
    "tasks.max": "1",
    "topics": "test-topic"
}

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Example response:HTTP/1.1 200 O

{
    "name": "FileStreamSinkConnector",
    "error_count": 1,
    "groups": [
        "Common"
    ],
    "configs": [
        {
            "definition": {
                "name": "topics",
                "type": "LIST",
                "required": false,
                "default_value": "",
                "importance": "HIGH",
                "documentation": "",
                "group": "Common",
                "width": "LONG",
                "display_name": "Topics",
                "dependents": [],
                "order": 4
        },
            "value": {
                "name": "topics",
                "value": "test-topic",
                "recommended_values": [],
                "errors": [],
                "visible": true
            }
        },
        {
            "definition": {
                "name": "file",
                "type": "STRING",
                "required": true,
                "default_value": "",
                "importance": "HIGH",
                "documentation": "Destination filename.",
                "group": null,
                "width": "NONE",
                "display_name": "file",
                "dependents": [],
                "order": -1
            },
            "value": {
                "name": "file",
                "value": null,
                "recommended_values": [],
                "errors": [
                    "Missing required configuration \"file\" which has no default value."
                ],
                "visible": true
            }
        },
        {
            "definition": {
                "name": "name",
                "type": "STRING",
                "required": true,
                "default_value": "",
                "importance": "HIGH",
                "documentation": "Globally unique name to use for this connector.",
                "group": "Common",
                "width": "MEDIUM",
                "display_name": "Connector name",
                "dependents": [],
                "order": 1
            },
            "value": {
                "name": "name",
                "value": "test",
                "recommended_values": [],
                "errors": [],
                "visible": true
            }
        },
        {
            "definition": {
                "name": "tasks.max",
                "type": "INT",
                "required": false,
                "default_value": "1",
                "importance": "HIGH",
                "documentation": "Maximum number of tasks to use for this connector.",
                "group": "Common",
                "width": "SHORT",
                "display_name": "Tasks max",
                "dependents": [],
                "order": 3
        },
            "value": {
                "name": "tasks.max",
                "value": "1",
                "recommended_values": [],
                "errors": [],
                "visible": true
            }
        },
        {
            "definition": {
                "name": "connector.class",
                "type": "STRING",
                "required": true,
                "default_value": "",
                "importance": "HIGH",
                "documentation": "Name or alias of the class for this connector. Must be a subclass of org.apache.kafka.connect.connector.Connector. If the connector is org.apache.kafka.connect.file.FileStreamSinkConnector, you can either specify this full name,  or use \"FileStreamSink\" or \"FileStreamSinkConnector\" to make the configuration a bit shorter",
                "group": "Common",
                "width": "LONG",
                "display_name": "Connector class",
                "dependents": [],
                "order": 2
            },
            "value": {
                "name": "connector.class",
                "value": "org.apache.kafka.connect.file.FileStreamSinkConnector",
                "recommended_values": [],
                "errors": [],
                "visible": true
            }
        }
    ]
}


reference:
https://docs.confluent.io/current/connect/references/restapi.html