Red Hat Summit6.7. Timeouts
OpenShift Serverless Logic defines several timeouts configurations that you can use to configure maximum times for the workflow execution in different scenarios. You can configure how long a workflow can wait for an event to arrive when it is in a given state or the maximum execution time for the workflow.
Regardless of where it is defined, a timeout must be configured as an amount of time or duration, which starts when the referred workflow element becomes active. Timeouts use the ISO 8601 data and time standard to specify a duration of time and follow the format PnDTnHnMn.nS, with days considered to be exactly 24 hours. For example, PT15M configures 15 minutes, and P2DT3H4M defines 2 days, 3 hours, and 4 minutes.
Month-based timeouts like P2M, or period of two months, are not valid since the month duration might vary. In that case, use PT60D instead.
6.7.1. Workflow timeout
To configure the maximum amount of time that a workflow can be running before being canceled, you can use the workflow timeouts. Once canceled, the workflow is considered to be finished, and is not accessible through a GET request anymore. Therefore, it behaves as if the interrupt was true by default.
Workflow timeouts are defined with the top-level timeouts property. It can have two types, string and object. The string type defines an URI that points to a JSON or YAML file containing the workflow timeout definitions. The object type, is used to define the timeout definitions inline.
For example, to cancel the workflow after an hour of execution, use the following configuration:
Example of workflow timeout
{
"id": "workflow_timeouts",
"version": "1.0",
"name": "Workflow Timeouts",
"description": "Simple workflow to show the workflowExecTimeout working",
"start": "PrintStartMessage",
"timeouts": {
"workflowExecTimeout": "PT1H"
} ...
}6.7.2. Event timeout
When you define a state in a workflow, you can use the timeouts property to configure the maximum time to complete this state. When that time is overdue, the state is considered timed-out, and the engine continues the execution from this state. The execution flow depends on the state type, for instance, a transition to a next state might be executed.
Event-based states can use the sub-property eventTimeout to configure the maximum time to wait for an event to arrive. This is the only property that is supported in current implementation.
Event timeouts support callback state timeout, switch state timeout, and event state timeout.
6.7.2.1. Callback state timeout
The Callback state can be used when you must execute an action in general to call an external service, and wait for an asynchronous response in the form of an event.
Once the response event is consumed, the workflow continues the execution, in general moving to the next state defined in the transition property.
Since the Callback state halts the execution until the event is consumed, you can configure an eventTimeout for it, and in case the event does not arrive in the configured time duration, the workflow continues the execution moving to the next state defined in the transition.
Example of Callback state with timeout
{
"name": "CallbackState",
"type": "callback",
"action": {
"name": "callbackAction",
"functionRef": {
"refName": "callbackFunction",
"arguments": {
"input": "${\"callback-state-timeouts: \" + $WORKFLOW.instanceId + \" has executed the callbackFunction.\"}"
}
}
},
"eventRef": "callbackEvent",
"transition": "CheckEventArrival",
"onErrors": [
{
"errorRef": "callbackError",
"transition": "FinalizeWithError"
}
],
"timeouts": {
"eventTimeout": "PT30S"
}
}6.7.2.2. Switch state timeout
You can use the Switch state when you need to take an action depending on certain conditions. These conditions can be based on the workflow data, dataConditions, or on events, eventConditions.
When you use the eventConditions, the workflow execution waits to make a decision until any of the configured events arrives and matches a condition. In this situation, you can configure an event timeout, that controls the maximum time to wait for an event to match the conditions.
If this time expires, the workflow moves to the state defined in the defaultCondition property.
Example of Switch state with timeout
{
"name": "ChooseOnEvent",
"type": "switch",
"eventConditions": [
{
"eventRef": "visaApprovedEvent",
"transition": "ApprovedVisa"
},
{
"eventRef": "visaDeniedEvent",
"transition": "DeniedVisa"
}
],
"defaultCondition": {
"transition": "HandleNoVisaDecision"
},
"timeouts": {
"eventTimeout": "PT5S"
}
}6.7.2.3. Event state timeout
The Event state is used to wait for one or more events to be received by the workflow, execute a set of actions, and then continue the execution. If the Event state is a starting state, a new workflow instance is created.
The timeouts property is used for this state to configure the maximum time the workflow should wait for the configured events to arrive.
If this time is exceeded and the events are not received, the workflow moves to the state defined in the transition property or ends the workflow instance, in case of an end state, without performing any actions.
Example of Event state with timeout
{
"name": "WaitForEvent",
"type": "event",
"onEvents": [
{
"eventRefs": [
"event1"
],
"eventDataFilter": {
"data": "${ \"The event1 was received.\" }",
"toStateData": "${ .exitMessage }"
},
"actions": [
{
"name": "printAfterEvent1",
"functionRef": {
"refName": "systemOut",
"arguments": {
"message": "${\"event-state-timeouts: \" + $WORKFLOW.instanceId + \" executing actions for event1.\"}"
}
}
}
]
},
{
"eventRefs": [
"event2"
],
"eventDataFilter": {
"data": "${ \"The event2 was received.\" }",
"toStateData": "${ .exitMessage }"
},
"actions": [
{
"name": "printAfterEvent2",
"functionRef": {
"refName": "systemOut",
"arguments": {
"message": "${\"event-state-timeouts: \" + $WORKFLOW.instanceId + \" executing actions for event2.\"}"
}
}
}
]
}
],
"timeouts": {
"eventTimeout": "PT30S"
},
"transition": "PrintExitMessage"
}
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