This feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of theService Specific Terms. Pre-GA features are available "as is" and might have limited support. For more information, see thelaunch stage descriptions.

Eventarc supports applying a path pattern when filtering. The pathpattern syntax lets you define an expression that matches events. This letsyou control the granularity of the Eventarc trigger you arecreating, and to capture and act on certain events. For example, you can createa trigger that applies to a single event, such as a change to a specific file,or you can extend the scope of the pattern and create a trigger that appliesmore broadly.

Apply a path pattern

You can apply a path pattern to filter events when you create a triggerusing the Eventarc Google Cloud console page or by runningagcloud command.

For example, you can apply a path pattern when filtering onresource names ordatabase instances (a single instance or a path).

• Specifying aresource name path pattern applies when creating a triggerforCloud Audit Logs events and toresourceName values. A resourcename indicates the resource being audited through an audit log.Resource names are organized hierarchically using identifiers made up of theID of the resource itself and the IDs of any parent resources, all separated byforward slashes, like this:/projects/project-1/datasets/dataset-id.The filtering done by Eventarc matches patterns based on thevalues of these identifiers. For more information, in this document, seeResource name format.

• Specifying adatabase instance path pattern applies when creating atrigger forFirebase Realtime Database events and toinstance orrefvalues. A database instance indicates a Firebase Realtime Databaseinstance. You can apply a path pattern to the instance name of the databaseinstance, or a document path for which you want to receive events when data iscreated, updated, or deleted in that path, or any of its children.

• Specifying aresource ID path pattern applies when creating a triggerforCloud IoT events and toregistry anddevice values.You can apply a path pattern to filter changes in registries, and devices in aregistry, with wildcard matching.

For details, see the instructions tocreate a trigger for a specific provider, event type, and destination.

Identify if you can apply a path pattern

To confirm if you can apply a path pattern to an attribute of an event from aprovider, describe the event provider. For example:

gcloudeventarcprovidersdescribecloudaudit.googleapis.com--location=us-central1

The output is similar to the following and apathPatternSupported value oftrue indicates that you can apply a path pattern:

displayName:CloudAuditLogseventTypes:-description:Anauditlogiscreatedthatmatchesthetrigger's filter criteria.  filteringAttributes:  - attribute: methodName    description: The identifier of the service'soperation.required:true-attribute:resourceNamedescription:Thecompletepathtoaresource.Usedtofiltereventsforaspecificresource.pathPatternSupported:true-attribute:serviceNamedescription:TheidentifieroftheGoogleCloudservice.required:true-attribute:typerequired:truetype:google.cloud.audit.log.v1.writtenname:projects/project-name/locations/us-central1/providers/cloudaudit.googleapis.com

Or, for example:

gcloudeventarcprovidersdescribefirebasedatabase.googleapis.com--location=us-central1

Where the output is similar to the following:

displayName:FirebaseRealtimeDatabaseeventTypes:-description:Newdatahasbeencreatedinthedatabase.filteringAttributes:-attribute:instancedescription:Asingledatabaseinstance.pathPatternSupported:truerequired:true-attribute:refdescription:Patterntomatchforthedatabaseinstance.pathPatternSupported:truerequired:true-attribute:typerequired:truetype:google.firebase.database.ref.v1.created[...]

For more information, seegcloud eventarc providers describe.

Path pattern syntax

The path pattern syntax is defined as follows:

Legend:

Expressions

An expression can be one of the following segment types and cannot be empty:

• A single segmentWildcard defined as* matches zero or more charactersin the pattern.
• AMultiSegmentWildcard defined as** matches zero or more segmentsin the pattern.
• ANameSegmentconsists of zero or one* and other characters. Thiscombination lets you filter by prefix, suffix, or file extension; forexample,file-*.txt.

Note that a path can contain many single segment wildcards, but onlyone multiple segment wildcard. For example, the following path is invalid:/projects/**/buckets/**.

Resource regionality

Resource names can contain location identifiers. For example:

/projects/$PROJECT_ID/locations/$REGION/triggers/my-trigger

However, path pattern matching is constrained by resource regionality. Forexample, for Cloud Audit Logs triggers, location wildcards only matchtriggers from the Cloud Audit Logs region, or global triggers.

Capture groups

ACaptureGroup lets you capture the content of an expression. You do thisby assigning the value to a variable name in braces; for example,buckets/{path=**}/files/{filename=file-*.txt}. A single segment wildcard canomit=* in a capture group; for example,/projects/_/buckets/{bucket}/objects/file.*

The following table provides examples of full resource names for commonly usedGoogle Cloud services.It is not a complete list. To learn more about howfull resource names are formatted, see theResource names section of the API design guide.

¹ For Cloud Firestore, don't specify a leading slashwhen creating a trigger(seeexamples).For more information, seeCloud Firestore data model.

² For Cloud Storage, resource names contain anunderscore (_) rather than a project ID. Youcannot replace the underscorewith a project ID, project name, or project number.

³ For Cloud Storage, use the entire object name, includingforward slashes. These characters arepart of the object name, not path separators.

Examples

The following examples demonstrate how you can and can't use the syntax.

Valid patterns

Invalid patterns

Pattern matching

What's next

• For a list of the events supported by Eventarc, seeGoogle event types supported by Eventarc.