Event Monitoring

Session Lifecycle Events

URI: /events/session
Method: GET

Provides a continuous message-by-message JSON object stream of session lifecycles. It uses HTML5 Server-Sent Events (SSE). Browser-based clients may use the EventSource API for convenience.

Added in version v4.20190615: First properly implemented in this version, deprecating prior unimplemented interfaces.

Changed in version v5.20191215: The URI is changed from /stream/session/_/events to /events/session.

Parameters

Parameter	Type	Description
`sessionId`	`slug`	The session ID to monitor the lifecycle events. If set `"*"`, the API will stream events from all sessions visible to the client depending on the client’s role and permissions.
`ownerAccessKey`	`str`	(optional) The access key of the owner of the specified session, since different access keys (users) may share a same session ID for different session instances. You can specify this only when the client is either a domain admin or a superadmin.
`group`	`str`	The group name to filter the lifecycle events. If set `"*"`, the API will stream events from all sessions visible to the client depending on the client’s role and permissions.

Responses

The response is a continuous stream of UTF-8 text lines following the text/event-stream format. Each event is composed of the event type and data, where the data part is encoded as JSON.

Possible event names (more events may be added in the future):

Event Name	Description
`session_preparing`	The session is just scheduled from the job queue and got an agent resource allocation.
`session_pulling`	The session begins pulling the session image (usually from a Docker registry) to the scheduled agent.
`session_creating`	The session is being created as containers (or other entities in different agent backends).
`session_started`	The session becomes ready to execute codes.
`session_terminated`	The session has terminated.

When using the EventSource API, you should add event listeners as follows:

const sse = new EventSource('/events/session', {
  withCredentials: true,
});
sse.addEventListener('session_started', (e) => {
  console.log('session_started', JSON.parse(e.data));
});

Note

The EventSource API must be used with the session-based authentication mode (when the endpoint is a console-server) which uses the browser cookies. Otherwise, you need to manually implement the event stream parser using the standard fetch API running against the manager server.

The event data contains a JSON string like this (more fields may be added in the future):

Field Name	Description
`sessionId`	The source session ID.
`ownerAccessKey`	The access key who owns the session.
`reason`	A short string that describes why the event happened. This may be `null` or an empty string.
`result`	Only present for `session-terminated` events. Only meaningful for batch-type sessions. Either one of: `"UNDEFINED"`, `"SUCCESS"`, `"FAILURE"`

{
  "sessionId": "mysession-01",
  "ownerAccessKey": "MYACCESSKEY",
  "reason": "self-terminated",
  "result": "SUCCESS"
}

Background Task Progress Events

URI: /events/background-task
Method: GET for server-side events

Added in version v5.20191215.

Parameters

Parameter	Type	Description
`taskId`	`UUID`	The background task ID to monitor the progress and completion.

Responses

The response is a continuous stream of UTF-8 text lines following text/event-stream format. Each event is composed of the event type and data, where the data part is encoded as JSON. Possible event names (more events may be added in the future):

Event Name	Description
`task_updated`	Updates for the progress. This can be generated many times during the background task execution.
`task_done`	The background task is successfully completed.
`tak_failed`	The background task has failed. Check the `message` field and/or query the error logs API for error details.
`task_cancelled`	The background task is cancelled in the middle. Usually this means that the server is being shutdown for maintenance.
`server_close`	This event indicates explicit server-initiated close of the event monitoring connection, which is raised just after the background task is either done/failed/cancelled. The client should not reconnect because there is nothing more to monitor about the given task.

The event data (per-line JSON objects) include the following fields:

Field Name	Type	Description
`task_id`	`str`	The background task ID.
`current_progress`	`int`	The current progress value. Only meaningful for `task_update` events. If `total_progress` is zero, this value should be ignored.
`total_progress`	`int`	The total progress count. Only meaningful for `task_update` events. The scale may be an arbitrary positive integer. If the total count is not defined, this may be zero.
`message`	`str`	An optional human-readable message indicating what the task is doing. It may be `null`. For example, it may contain the name of agent or scaling group being worked on for image preload/unload APIs.

Check out the session lifecycle events API for example client-side Javascript implementations to handle text/event-stream responses.

If you make the request for the tasks already finished, it may return either “404 Not Found” (the result is expired or the task ID is invalid) or a single event which is one of task_done, task_fail, or task_cancel followed by immediate response disconnection. Currently, the results for finished tasks may be archived up to one day (24 hours).