Triggers

Triggers provide a way to automatically start specific Concord flows as a response to specific events.

• Common Syntax
• Supported Triggers
• Exclusive Triggers
• Limitations

Common Syntax

All triggers work by the same process:

• Concord matches the patterns you specify as triggers to event data.
• event data is typically external, but can be internally produced in the case of the cron triggers.
• for each matched trigger, it starts a new process.

You define triggers in the triggers section of a concord.yml file, as in this example:

triggers:
- eventSource:
    parameter1: ".*123.*"
    parameter2: false
    entryPoint: myFlow
    activeProfiles:
    - myProfile
    arguments:
      myValue: "..."
    exclusive:
      group: "myGroup"
      mode: cancel
...

When the API end-point /api/v1/events/ receives an event, Concord detects any existing matches with trigger names.

This allows you to publish events to /api/v1/events/eventSource for matching with triggers (where eventSource is any string).

Further:

• Concord detects any matches of parameter1 and parameter2 with the external event’s parameters;
• entryPoint is the name of the flow that Concord starts when there is a match;
• activeProfiles is the list of profiles to active for the process;
• arguments is the list of additional parameters that are passed to the flow;
• exclusive is the exclusivity info of the exclusive group.

Parameters can contain YAML literals as follows:

• strings
• numbers
• boolean values
• regular expressions

The triggers section can contain multiple trigger definitions. Each matching trigger is processed individually–each match can start a new process.

A trigger definition without match attributes is activated for any event received from the specified source.

In addition to the arguments list, a started flow receives the event parameter which contains attributes of the external event. Depending on the source of the event, the exact structure of the event object may vary.

Supported Triggers

• GitHub
• Cron
• Manual
• Generic
• OneOps

Exclusive Triggers

There is an option to make a triggered processes “exclusive”. This prevents the process from running, if there are any other processes in the same project with the same “exclusive group”:

flows:
  cronEvent:
    - log: "Hello!"
    - ${sleep.ms(65000)} # wait for 1m 5s

triggers:
- cron:
    spec: "* * * * *" # run every minute
    timezone: "America/Toronto"
    entryPoint: cronEvent

In this example, if the triggered process runs longer than the trigger’s period, then it is possible that multiple cronEvent processes can run at the same time. In some cases, it is necessary to enforce that only one trigger process runs at a time, due to limitation in target systems being accessed or similar reasons.

triggers:
- cron:
    spec: "* * * * *"
    timezone: "America/Toronto"
    entryPoint: cronEvent
    exclusive:
      group: "myGroup"
      mode: "cancel" # or "wait"

Any processes with the same exclusive value are automatically prevented from starting, if a running process in the same group exists. If you wish to enqueue the processes instead use mode: "wait".

See also Exclusive Execution section in the Concord DSL documentation.

Limitations

Trigger configuration is typically loaded automatically, but can be disabled globally or for specific types of repositories. For example, personal Git repositories can be treated differently from organizational repositories in GitHub. You can force a new parsing and configuration by manually reloading the repository content with the Refresh button beside the repository in the Concord Console or by using the API.