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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.

v4.20190615

First properly implemented in this version, deprecating prior unimplemented interfaces.

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

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 <session-lifecycle-events> 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).