JSON Object References

Paging Query Object

It describes how many items to fetch for object listing APIs. If index exceeds the number of pages calculated by the server, an empty list is returned.

Key Type Description
size int The number of items per page. If set zero or this object is entirely omitted, all items are returned and index is ignored.
index int The page number to show, zero-based.

Paging Info Object

It contains the paging information based on the paging query object in the request.

Key Type Description
pages int The number of total pages.
count int The number of all items.

KeyPair Item Object

Key Type Description
accessKey slug The access key part.
isActive bool Indicates if the keypair is active or not.
totalQueries int The number of queries done via this keypair. It may have a stale value.
created datetime The timestamp when the keypair was created.

KeyPair Properties Object

Key Type Description
isActive bool Indicates if the keypair is activated or not. If not activated, all authentication using the keypair returns 401 Unauthorized. When changed from true to false, existing running kernel sessions continue to run but any requests to create new kernel sessions are refused. (default: true)
concurrecy int The maximum number of concurrent kernel sessions allowed for this keypair. (default: 5)
ML.clusterSize int Sets the number of instances clustered together when launching new machine learning kernel sessions. (default: 1)
ML.instanceMemory int (MiB) Sets the memory limit of each instance in the cluster launched for new machine learning kernel sessions. (default: 8)

The enterprise edition offers the following additional properties:

Key Type Description
cost.automatic bool If set true, enables automatic cost optimization (BETA). With supported kernel types, it automatically suspends or resize the kernel sessions not to exceed the configured cost limit per day. (default: false)
cost.dailyLimit str The string representation of money amount as decimals. The currency is fixed to USD. (default: "50.00")

Batch Execution Query Object

Key Type Description
build str

The bash command to build the main program from the given uploaded files.

If this field is not present, an empty string or null, it skips the build step.

If this field is a constant string "*", it will use a default build script provided by the kernel. For example, the C kernel’s default Makefile adds all C source files under the working directory and copmiles them into ./main executable, with commonly used C/link flags: "-pthread -lm -lrt -ldl".

exec str

The bash command to execute the main program.

If this is not present, an empty string, or null, the server only performs the build step and options.buildLog is assumed to be true (the given value is ignored).


A client can distinguish whether the current output is from the build phase or the execution phase by whether it has received build-finished status or not.


All shell commands are by default executed under /home/work. The common environment is:


but individual kernels may have additional environment settings.


The shell does NOT have access to sudo or the root privilege. Though, some kernels may allow installation of language-specific packages in the user directory.

Also, your build script and the main program is executed inside Backend.AI Jail, meaning that some system calls are blocked by our policy. Since ptrace syscall is blocked, you cannot use native debuggers such as gdb.

This limitation, however, is subject to change in the future.


  "build": "gcc -Wall main.c -o main -lrt -lz",
  "exec": "./main"

Execution Result Object

Key Type Description
runId str The user-provided run identifier. If the user has NOT provided it, this will be set by the API server upon the first execute API call. In that case, the client should use it for the subsequent execute API calls during the same run.
status enum[str] One of "continued", "waiting-input", "finished", or "build-finished". See more details at Code Execution Model.
exitCode int | null

The exit code of the last process. This field has a valid value only when the status is "finished" or "build-finished". Otherwise it is set to null.

For batch-mode kernels and query-mode kernels without global context support, exitCode is the return code of the last executed child process in the kernel. In the execution step of a batch mode run, this is always 127 (a UNIX shell common practice for “command not found”) when the build step has failed.

For query-mode kernels with global context support, this value is always zero, regardless of whether the user code has caused an exception or not.

A negative value (which cannot happen with normal process termination) indicates a Backend.AI-side error.

    enum[str], *
Contains a list of console output items. Each item is a pair of the item type (enum[str]) and its value (*). See more details at Handling Console Output.
options object An object containing extra display options. If there is no options indicated by the kernel, this field is null. When result.status is "waiting-input", it has a boolean field is_password so that you could use different types of text boxes for user inputs.

Kernel Session Item Object

Key Type Description
id slug The kernel session ID.
type str The kernel type (typically the name of runtime or programming lanauge).
status enum[str] One of "preparing", "building”, "running", "restarting", "resizing", "success", "error", "terminating", "suspended".
statusInfo str An optional message related to the current status. (e.g., error information)
age int (msec) The time elapsed since the kernel has started.
execTime int (msec) The time taken for execution. Excludes the time taken for being suspended, restarting, and resizing.
numQueriesExecuted int The total number of queries executed after start-up.
memoryUsed int (MiB) The amount of memory currently used (sum of all resident-set size across instances). It may show a stale value.
cpuUtil int (%)

The current CPU utilization (sum of all used cores across instances, hence may exceed 100%). It may show a stale value.

Changed in version v3.20170615: This had been separated into multiple credit-based fields, but that was never implemented properly. We has changed it to represent more intuitive value.

config object Creation Config Object specified when created.

Creation Config Object

Key Type Description
environ object A dictionary object specifying additional environment variables. The values must be strings.
mounts list[str]

An optional list of the name of virtual folders that belongs to the current API key. These virtual folders are mounted under /home/work. For example, if the virtual folder name is abc, you can access it on /home/work/abc.

If the name contains a colon in the middle, the second part of the string indicates the alias location in the kernel’s file system which is relative to /home/work.

You may mount up to 5 folders for each kernel session.

clusterSize int The number of instances bundled for this session.
instanceMemory int (MiB) The maximum memory allowed per instance. The value is capped by the per-kernel image limit. Additional charges may apply on the public API service.
instanceCores int The number of CPU cores. The value is capped by the per-kernel image limit. Additional charges may apply on the public API service.
instanceGPUs float The fraction of GPU devices (1.0 means a whole device). The value is capped by the per-kernel image limit. Additional charges may apply on the public API service.

Virtual Folder Item Object

Key Type Description
name str The human readable name set when created.
id slug The unique ID of the folder. Use this when making API requests referring this folder.
linked bool Indicates if this folder is linked to an external service. (enterprise edition only)
usedSize int (MiB) The sum of the size of files in this folder.
numFiles int The number of files in this folder.
maxSize int (MiB) The maximum size of this folder.
created datetime The date and time when the folder is created.