mistral/doc/source/api/v2.rst

V2 API

This API describes the ways of interacting with Mistral service via HTTP protocol using Representational State Transfer concept (ReST).

Basics

Media types

Currently this API relies on JSON to represent states of REST resources.

Error states

The common HTTP Response Status Codes (https://github.com/for-GET/know-your-http-well/blob/master/status-codes.md) are used.

Application root [/]

Application Root provides links to all possible API methods for Mistral. URLs for other resources described below are relative to Application Root.

API v2 root [/v2/]

All API v2 URLs are relative to API v2 root.

Workbooks

mistral.api.controllers.v2.resources.Workbook

name is immutable. tags is a list of values associated with a workbook that a user can use to group workbooks by some criteria (deployment workbooks, Big Data processing workbooks etc.). Note that name and tags get inferred from workbook definition when Mistral service receives a POST request. So they can't be changed in another way.

mistral.api.controllers.v2.resources.Workbooks

mistral.api.controllers.v2.workbook:WorkbooksController

Workflows

mistral.api.controllers.v2.resources.Workflow

name is immutable. tags is a list of values associated with a workflow that a user can use to group workflows by some criteria. Note that name and tags get inferred from workflow definition when Mistral service receives a POST request. So they can't be changed in another way.

mistral.api.controllers.v2.resources.Workflows

mistral.api.controllers.v2.workflow:WorkflowsController

Actions

mistral.api.controllers.v2.resources.Action

mistral.api.controllers.v2.resources.Actions

mistral.api.controllers.v2.action:ActionsController

Executions

mistral.api.controllers.v2.resources.Execution

mistral.api.controllers.v2.resources.Executions

mistral.api.controllers.v2.execution:ExecutionsController

Tasks

When a workflow starts Mistral creates an execution. It in turn consists of a set of tasks. So Task is an instance of a task described in a Workflow that belongs to a particular execution.

mistral.api.controllers.v2.resources.Task

mistral.api.controllers.v2.resources.Tasks

mistral.api.controllers.v2.task:TasksController

mistral.api.controllers.v2.task:ExecutionTasksController

Action Executions

When a Task starts Mistral creates a set of Action Executions. So Action Execution is an instance of an action call described in a Workflow Task that belongs to a particular execution.

mistral.api.controllers.v2.resources.ActionExecution

mistral.api.controllers.v2.resources.ActionExecutions

mistral.api.controllers.v2.action_execution:ActionExecutionsController

mistral.api.controllers.v2.action_execution:TasksActionExecutionController

Cron Triggers

Cron trigger is an object that allows to run Mistral workflows according to a time pattern (Unix crontab patterns format). Once a trigger is created it will run a specified workflow according to its properties: pattern, first_execution_time and remaining_executions.

mistral.api.controllers.v2.resources.CronTrigger

mistral.api.controllers.v2.resources.CronTriggers

mistral.api.controllers.v2.cron_trigger:CronTriggersController

Environments

Environment contains a set of variables which can be used in specific workflow. Using an Environment it is possible to create and map action default values -just provide '__actions' key in 'variables'. All these variables can be accessed using the Workflow Language with the <% $.__env %> expression.

Example of usage:

workflow:
  tasks:
    task1:
      action: std.echo output=<% $.__env.my_echo_output %>

Example of creating action defaults

...ENV...
"variables": {
  "__actions": {
    "std.echo": {
      "output": "my_output"
    }
  }
},
...ENV...

Note: using CLI, Environment can be created via JSON or YAML file.

mistral.api.controllers.v2.resources.Environment

mistral.api.controllers.v2.resources.Environments

mistral.api.controllers.v2.environment:EnvironmentController

Services

Through service management API, system administrator or operator can retrieve Mistral services information of the system, including service group and service identifier. The internal implementation of this feature make use of tooz library, which needs coordinator backend(the most commonly used at present is Zookeeper) installed, please refer to tooz official documentation for more detailed instruction.

There are three service groups according to Mistral architecture currently, namely api_group, engine_group and executor_group. The service identifier contains name of the host that the service is running on and the process identifier of the service on that host.

mistral.api.controllers.v2.resources.Service

mistral.api.controllers.v2.resources.Services

mistral.api.controllers.v2.service:ServicesController

Validation

Validation endpoints allow to check correctness of workbook, workflow and ad-hoc action Workflow Language without having to upload them into Mistral.

POST /v2/workbooks/validation

Validate workbook content (Workflow Language grammar and semantics).

POST /v2/workflows/validation

Validate workflow content (Workflow Language grammar and semantics).

POST /v2/actions/validation

Validate ad-hoc action content (Workflow Language grammar and semantics).

These endpoints expect workbook, workflow or ad-hoc action text (Workflow Language) correspondingly in a request body.