Monitor Microservices

Use the CDAP Monitor Microservices to examine the CDAP system services used internally by CDAP. Additional details on monitoring can be found in the Logging and Monitoring.

All methods or endpoints described in this API have a base URL (typically http://<host>:11015 or https://<host>:10443) that precedes the resource identifier, as described in the Microservices Conventions. These methods return a status code, as listed in the Microservices Status Codes.

Listing all System Services and their Details

For the detailed information of all available CDAP system services, use:

GET /v3/system/services

The response body will contain a JSON-formatted list of the existing system services:

[
    {
        "name": "appfabric",
        "description": "Service for managing application lifecycle.",
        "status": "OK",
        "logs": "OK",
        "min": 1,
        "max": 1,
        "requested": 1,
        "provisioned": 1
    }
    ...
]

HTTP Responses

Status Codes	Description

Status Codes	Description
`200 OK`	The event successfully called the method, and the body contains the results

Checking the Status of all System Services

To check the status of all the CDAP system services, use:

GET /v3/system/services/status

HTTP Responses

Status Codes	Description

Status Codes	Description
`200 OK`	The event successfully called the method, and the body contains the results

Checking the Status of a System Service

To check the status of a specific CDAP system service, use:

The status of these CDAP system services can be checked:

Service	Service ID	Description of the service

Service	Service ID	Description of the service
`Metrics`	`metrics`	Service that handles metrics related HTTP requests
`Transaction`	`transaction`	Service that handles transactions
`App Fabric`	`appfabric`	Service that handles application fabric requests
`Log Saver`	`log.saver`	Service that aggregates all system and application logs
`Metrics Processor`	`metrics.processor`	Service that aggregates all system and application metrics
`Dataset Executor`	`dataset.executor`	Service that handles all data-related HTTP requests
`Explore Service`	`explore.service`	Service that handles all HTTP requests for ad-hoc data exploration

Note: The service status checks are more useful when CDAP is running in a distributed cluster mode.

HTTP Responses

Status Codes	Description

Status Codes	Description
`200 OK`	The service is up and running
`404 Not Found`	The service is either not running or not found

Example

HTTP Method	`GET /v3/system/services/metrics/status`
Description	Returns the status of the metrics service

Checking the Status of a System Upgrade

To check the status of a CDAP system upgrade, use:

Note: This returns useful information only for Distributed CDAP installation upgrades.

HTTP Responses

Status Codes	Description

Status Codes	Description
`200 OK`	The event successfully called the method, and the body contains the results

Example

The response body will contain a JSON-formatted list of upgraded components:

Container Information of a System Service

If you are trying to debug a CDAP system service, you can retrieve container info for a system service with:

where

Parameter	Description

Parameter	Description
`service-id`	Name (ID) of the system service

Note: This returns useful information only for Distributed CDAP installations.

Example

For example, to retrieve the list of CDAP Master services, issue an HTTP GET request to the URL:

The response body will contain a JSON-formatted list of CDAP Master services, with the first container listed being the active CDAP Master in an HA deployment:

Restarting System Service Instances

To restart all instances of a CDAP system service, you can issue an HTTP POST request to the URL:

You can restart a particular instance of a system service in CDAP, using its instance id, by issuing an HTTP POST request to the URL:

Parameter	Description

Parameter	Description
`service-id`	Name (ID) of the system service whose instances are to be restarted
`instance-id`	Specific instance of a service that needs to be restarted; `instance-id` runs from 0 to (the number of instances-per-service -1)

HTTP Responses

Status Codes	Description

Status Codes	Description
`403 Bad Request`	The service is unavailable because it was not enabled
`404 Service not found`	The service name is not valid
`500 Internal error`	Internal error encountered when processing the request
`503 Service Unavailable`	The service is unavailable. For example, it may not yet have been started

To retrieve details of the last restart attempt made for a particular service, issue an HTTP GET request to the URL:

The response body will contain a JSON-formatted status of the last restart attempt for that service:

Parameter	Description

Parameter	Description
`service-id`	Name (ID) of the system service for which details of last restart are to be retrieved

HTTP Responses

Status Codes	Description

Status Codes	Description
`404 Service not found`	The service name is not valid
`500 Internal error`	Internal error encountered when processing the request

Scaling System Services

In distributed CDAP installations, the number of instances for CDAP system services can be queried and changed by using these commands:

with the arguments as a JSON string in the body:

Parameter	Description

Parameter	Description
`service-id`	Name (ID) of the system service
`quantity`	Number of instances to be used

Note: In the CDAP Sandbox, trying to set the instances of system services will return a Status Code 400 Bad Request.

Examples

HTTP Method	`GET /v3/system/services/metrics/instances`
Description	Determine the number of instances being used for the metrics HTTP service
HTTP Method	`PUT /v3/system/services/metrics/instances` `instances` with the arguments as a JSON string in the body: `{ "instances" : 2 }`
Description	Sets the number of instances of the metrics HTTP service to 2