Session Management

Here are the API calls to create and manage compute sessions.

Creating Session

URI: /session (/session/create also works for legacy)
Method: POST

Creates a new session or returns an existing session, depending on the parameters.

Parameters

Parameter	Type	Description
`image`	`str`	The kernel runtime type in the form of the Docker image name and tag. For legacy, the API also recognizes the `lang` field when `image` is not present. Changed in version v4.20190315.
`clientSessionToken`	`slug`	A client-provided session token, which must be unique among the currently non-terminated sessions owned by the requesting access key. Clients may reuse the token if the previous session with the same token has been terminated. It may contain ASCII alphabets, numbers, and hyphens in the middle. The length must be between 4 to 64 characters inclusively. It is useful for aliasing the session with a human-friendly name.
`enqueueOnly`	`bool`	(optional) If set true, the API returns immediately after queueing the session creation request to the scheduler. Otherwise, the manager will wait until the session gets started actually. (default: `false`) Added in version v4.20190615.
`maxWaitSeconds`	`int`	(optional) Set the maximum duration to wait until the session starts after queued, in seconds. If zero, the manager will wait indefinitely. (default: `0`) Added in version v4.20190615.
`reuseIfExists`	`bool`	(optional) If set true, the API returns without creating a new session if a session with the same ID and the same image already exists and not terminated. In this case `config` options are ignored. If set false but a session with the same ID and image exists, the manager returns an error: “session already exists”. (default: `true`) Added in version v4.20190615.
`group`	`str`	(optional) The name of a user group (aka “project”) to launch the session within. (default: `"default"`) Added in version v4.20190615.
`domain`	`str`	(optional) The name of a domain to launch the session within (default: `"default"`) Added in version v4.20190615.
`config`	`object`	(optional) A Creation Config Object to specify kernel configuration including resource requirements. If not given, the kernel is created with the minimum required resource slots defined by the target image.
`tag`	`str`	(optional) A per-session, user-provided tag for administrators to keep track of additional information of each session, such as which sessions are from which users.

Example:

{
  "image": "python:3.6-ubuntu18.04",
  "clientSessionToken": "mysession-01",
  "enqueueOnly": false,
  "maxWaitSeconds": 0,
  "reuseIfExists": true,
  "domain": "default",
  "group": "default",
  "config": {
    "clusterSize": 1,
    "environ": {
      "MYCONFIG": "XXX",
    },
    "mounts": ["mydata", "mypkgs"],
    "resources": {
      "cpu": "2",
      "mem": "4g",
      "cuda.devices": "1",
    }
  },
  "tag": "example-tag"
}

Response

HTTP Status Code	Description
200 OK	The session is already running and you are okay to reuse it.
201 Created	The session is successfully created.
401 Invalid API parameters	There are invalid or malformed values in the API parameters.
406 Not acceptable	The requested resource limits exceed the server’s own limits.

Fields	Type	Values
`sessId`	`slug`	The session ID used for later API calls, which is same to the value of `clientSessionToken`. This will be random-generated by the server if `clientSessionToken` is not provided.
`status`	`str`	The status of the created kernel. This is always `"PENDING"` if `enqueueOnly` is set true. In other cases, it may be either `"RUNNING"` (normal case), `"ERROR"`, or even `"TERMINATED"` depending on what happens during session startup. Added in version v4.20190615.
`servicePorts`	`list[object]`	The list of Service Port Object. This field becomes an empty list if `enqueueOnly` is set true, because the final service ports are determined when the session becomes ready after scheduling. Note In most cases the service ports are same to what specified in the image metadata, but the agent may add shared services for all sessions. Changed in version v4.20190615.
`created`	`bool`	True if the session is freshly created.

Example:

{
  "sessId": "mysession-01",
  "status": "RUNNING",
  "servicePorts": [
    {"name": "jupyter", "protocol": "http"},
    {"name": "tensorboard", "protocol": "http"}
  ],
  "created": true
}

Getting Session Information

URI: /session/:id
Method: GET

Retrieves information about a session. For performance reasons, the returned information may not be real-time; usually they are updated every a few seconds in the server-side.

Parameters

Parameter	Type	Description
`:id`	`slug`	The session ID.

Response

HTTP Status Code	Description
200 OK	The information is successfully returned.
404 Not Found	There is no such session.

Key	Type	Description
`lang`	`str`	The kernel’s programming language
`age`	`int` (msec)	The time elapsed since the kernel has started.
`memoryLimit`	`int` (KiB)	The memory limit of the kernel in KiB.
`numQueriesExecuted`	`int`	The number of times the kernel has been accessed.
`cpuCreditUsed`	`int` (msec)	The total time the kernel was running.

Destroying Session

URI: /session/:id
Method: DELETE

Terminates a session.

Parameters

Parameter	Type	Description
`:id`	`slug`	The session ID.

Response

HTTP Status Code	Description
204 No Content	The session is successfully destroyed.
404 Not Found	There is no such session.

Key	Type	Description
`stats`	`object`	The Container Stats Object of the kernel when deleted.

Restarting Session

URI: /session/:id
Method: PATCH

Restarts a session. The idle time of the session will be reset, but other properties such as the age and CPU credit will continue to accumulate. All global states such as global variables and modules imports are also reset.

Parameters

Parameter	Type	Description
`:id`	`slug`	The session ID.

Response

HTTP Status Code	Description
204 No Content	The session is successfully restarted.
404 Not Found	There is no such session.