Rule files

A rule file is a JSON document with a rules list. Each rule is either a reaction (when an event matches, then send a command) or a veto (deny a command). Rules are checked when the file is loaded, so a mistake such as an invalid condition or an unknown command stops the server from using the file and reports which rule is wrong.

{
  "rules": [
    {
      "id": "pause-on-repeated-http-failure",
      "when": {
        "event": "NodeStatusChanged",
        "status": "FAILURE",
        "module": "HTTP_REQUEST",
        "count": 3,
        "withinSeconds": 60
      },
      "then": { "command": "PauseWorkflow" }
    },
    {
      "id": "stop-node-on-server-error",
      "when": { "event": "NodeStatusChanged", "status": "FAILURE", "if": "metadata['code'] == 500" },
      "then": { "command": "StopNode", "immediate": true, "reason": "server error" }
    },
    {
      "id": "no-kill",
      "deny": { "command": "StopWorkflow", "if": "mode == 'KILL'", "reason": "use DRAIN or CANCEL" }
    }
  ]
}

Rule fields

Field	Meaning
`id`	Names the rule in logs and errors
`when`	The events that trigger a reaction
`then`	The command to send when triggered
`deny`	A command to refuse. A rule has either `when` and `then`, or `deny`

`when`: which events

Every field you set must match. Omit a field to match any value.

Field	Meaning
`event`	`NodeStatusChanged`, `WorkflowStatusChanged`, `ControlOutcome` or `LogLine`
`status`	The status, for status events, for example `FAILURE`
`module`	The node’s plugin type, for node events, for example `HTTP_REQUEST`
`nodeId`	A specific node, for node and log events
`workflowId`	A specific workflow, for status events
`if`	A condition expression over the event’s fields
`count`	How many matching events trigger the rule. Default `1`
`withinSeconds`	The window in which `count` events must occur, counted per execution. Default `60`

Event fields available to `if`

Event	Fields
All events	`executionId`
`NodeStatusChanged`	`workflowId`, `nodeId`, `module`, `status`, `metadata` (a map, for example `metadata['code']`)
`WorkflowStatusChanged`	`workflowId`, `status`
`ControlOutcome`	`command`, `actor`, `applied`, `reason`
`LogLine`	`nodeId`, `line`

A condition that cannot be evaluated counts as not matching, so a faulty reaction never fires.

`then`: which command

Field	Meaning
`command`	`PauseWorkflow`, `ResumeWorkflow`, `StopWorkflow`, `PauseNode`, `ResumeNode` or `StopNode`. Node commands address the node that triggered the rule
`mode`	For `StopWorkflow`: `DRAIN` (default), `CANCEL` or `KILL`
`reason`	Recorded with a stop. Default `Stopped by rule`
`immediate`	For `StopNode`: interrupt instead of draining

The command is addressed to the execution that produced the event.

`deny`: which commands to refuse

A deny rule makes the rule engine act as a reviewer: matching commands are refused before they run.

Field	Meaning
`command`	The command name, with or without the `Command` suffix, for example `StopWorkflow`
`if`	A condition over the command’s fields. Omit it to always refuse
`reason`	Shown to the caller. Default `denied by rule <id>`

Command fields available to if: executionId, actor, nodeId, mode, reason and immediate. A deny condition that cannot be evaluated refuses the command, so a faulty rule never lets a forbidden command through.

Enabling a rule file

To use it as	Set
A supervisor	`yukta.supervisor.rules.file`
A control plane	`yukta.control-plane.rules.file`

Both read the same format.

Get started

Concepts

Building workflows

Plugin reference

Running and controlling

Interfaces

Operations

Reference

Rule fields

`when`: which events

Event fields available to `if`

`then`: which command

`deny`: which commands to refuse

Enabling a rule file

​Rule fields

​when: which events

​Event fields available to if

​then: which command

​deny: which commands to refuse

​Enabling a rule file

​Related

Rule fields

`when`: which events

Event fields available to `if`

`then`: which command

`deny`: which commands to refuse

Enabling a rule file

Related