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Google Cloud Pub/Sub

Cribl Edge supports sending data to Google Cloud Pub/Sub, a managed real-time messaging service for sending and receiving messages between applications.

Type: Streaming | TLS Support: Yes | PQ Support: Yes

Configuring Cribl Edge to Output to Pub/Sub
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From the top nav, click Manage, then select a Fleet to configure. Next, you have two options:

To configure via the graphical QuickConnect UI, click Routing > QuickConnect (Stream) or Collect (Edge). Next, click Add Destination at right. From the resulting drawer’s tiles, select Google Cloud > Pub/Sub. Next, click either Add Destination or (if displayed) Select Existing. The resulting drawer will provide the options below.

Or, to configure via the Routing UI, click Data > Destinations (Stream) or More > Destinations (Edge). From the resulting page’s tiles or the Destinations left nav, select Google Cloud > Pub/Sub. Next, click Add Destination to open a New Destination modal that provides the options below.

General Settings
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Output ID: Enter a unique name to identify this Pub/Sub output definition.

Topic ID: ID of the Pub/Sub topic to send events to.

Optional Settings
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Create topic: Toggle to Yes if you want Cribl Edge to create the topic on Pub/Sub if it does not exist.

Ordered delivery: Toggle to Yes if you want Cribl Edge to send events in the order that they arrived in the queue. For ordered delivery to work correctly, ensure that both the process receiving events and the subscription from which messages are read have ordered delivery enabled.

Region: Region to publish messages to. Select default to allow Google to auto-select the nearest region. (If you’ve enabled Ordered delivery, the selected region must be allowed by message storage policy.)

Backpressure behavior: Whether to block, drop, or queue events when all receivers are exerting backpressure. Defaults to Block.

Tags: Optionally, add tags that you can use to filter and group Destinations in Cribl Edge’s Manage Destinations page. These tags aren’t added to processed events. Use a tab or hard return between (arbitrary) tag names.

Authentication
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Use the Authentication method drop-down to select one of these options:

  • Auto: This option uses the environment variables PUBSUB_PROJECT and PUBSUB_CREDENTIALS, and requires no configuration here.

  • Manual: This default option displays a Service account credentials field for you to enter the contents of your service account credentials file (a set of JSON keys), as downloaded from Google Cloud.
    To insert the file itself, click the upload button at this field’s upper right. As an alternative, you can use environment variables, as outlined here.

  • Secret: This option exposes a drop-down in which you can select a stored secret that references the service account credentials described above. A Create link is available to store a new, reusable secret.

Persistent Queue Settings
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This tab is displayed when the Backpressure behavior is set to Persistent Queue.

On Cribl-managed Cribl.Cloud Workers (with an Enterprise plan), this tab exposes only the destructive Clear Persistent Queue button (described below in this section). A maximum queue size of 1 GB disk space is automatically allocated per PQ‑enabled Destination, per Worker Process. The 1 GB limit is on outbound uncompressed data, and no compression is applied to the queue.

This limit is not configurable. If the queue fills up, Cribl Edge will block outbound data. To configure the queue size, compression, queue-full fallback behavior, and other options below, use a hybrid Group.

Max file size: The maximum data volume to store in each queue file before closing it. Enter a numeral with units of KB, MB, etc. Defaults to 1 MB.

Max queue size: The maximum amount of disk space that the queue is allowed to consume on each Worker Process. Once this limit is reached, this Destination will stop queueing data and apply the Queue‑full behavior. Required, and defaults to 5 GB. Accepts positive numbers with units of KB, MB, GB, etc. Can be set as high as 1 TB, unless you’ve configured a different Max PQ size per Worker Process in Fleet Settings.

Queue file path: The location for the persistent queue files. Defaults to $CRIBL_HOME/state/queues. To this value, Cribl Edge will append /<worker‑id>/<output‑id>.

Compression: Codec to use to compress the persisted data, once a file is closed. Defaults to None; Gzip is also available.

Queue-full behavior: Whether to block or drop events when the queue is exerting backpressure (because disk is low or at full capacity). Block is the same behavior as non-PQ blocking, corresponding to the Block option on the Backpressure behavior drop-down. Drop new data throws away incoming data, while leaving the contents of the PQ unchanged.

Clear Persistent Queue: Click this “panic” button if you want to delete the files that are currently queued for delivery to this Destination. A confirmation modal will appear - because this will free up disk space by permanently deleting the queued data, without delivering it to downstream receivers. (Appears only after Output ID has been defined.)

Strict ordering: The default Yes position enables FIFO (first in, first out) event forwarding. When receivers recover, Cribl Edge will send earlier queued events before forwarding newly arrived events. To instead prioritize new events before draining the queue, toggle this off. Doing so will expose this additional control:

  • Drain rate limit (EPS): Optionally, set a throttling rate (in events per second) on writing from the queue to receivers. (The default 0 value disables throttling.) Throttling the queue’s drain rate can boost the throughput of new/active connections, by reserving more resources for them. You can further optimize Workers’ startup connections and CPU load at Fleet Settings > Worker Processes.

Processing Settings
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Post‑Processing
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Pipeline: Pipeline to process data before sending the data out using this output.

System fields: A list of fields to automatically add to events that use this output. By default, includes cribl_pipe (identifying the Cribl Edge Pipeline that processed the event). Supports wildcards. Other options include:

  • cribl_host – Cribl Edge Node that processed the event.
  • cribl_input – Cribl Edge Source that processed the event.
  • cribl_output – Cribl Edge Destination that processed the event.
  • cribl_route – Cribl Edge Route (or QuickConnect) that processed the event.
  • cribl_wp – Cribl Edge Worker Process that processed the event.

Advanced Settings
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Batch size: The maximum number of items the Google API should batch before it sends them to the topic. Defaults to 10 items.

Batch timeout (ms): The maximum interval (in milliseconds) that the Google API should wait to send a batch (if the configured Batch size limit has not been reached).. Defaults to 100 ms.

Max queue size: Maximum number of queued batches before blocking. Defaults to 100.

Max batch size (KB): Maximum size for each sent batch. Defaults to 256 KB.

Max concurrent requests: The maximum number of in-progress API requests before Cribl Edge applies backpressure. Defaults to 10.

Environment: If you’re using GitOps, optionally use this field to specify a single Git branch on which to enable this configuration. If empty, the config will be enabled everywhere.

Google Cloud Roles and Permissions
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Your Google Cloud service account should have at least the following roles on topics:

  • roles/pubsub.publisher
  • roles/pubsub.viewer or roles/viewer

To enable Cribl Edge’s Create topic option, your service account should have one of the following (or higher) roles:

  • roles/pubsub.editor
  • roles/editor

Either editor role confers multiple permissions, including those from the lower viewer, subscriber, and publisher roles. For additional details, see the Google Cloud Access Control topic.

Proxying Requests
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If you need to proxy HTTP/S requests, see System Proxy Configuration.

Let’s Change the Topic
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The Pub/Sub Destination supports alternate topics specified at the event level in the __topicOut field. So (for example) if a Pub/Sub Destination is configured to send to main topic topic1, and Cribl Edge receives an event with __topicOut: topic2, then Cribl Edge will override the main topic and send this event to topic2.

However, a topic specified in the event’s __topicOut field must already exist on Pub/Sub. If it does not, Cribl Edge cannot dynamically create the topic, and will drop the event. On the Destination’s Status tab, the Dropped metric tracks the number of events dropped because a specified alternate topic did not exist.