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Exec Source

The Exec Source enables you to periodically execute a command and collect its stdout output. This is typically used in cases when Cribl Edge cannot accomplish collection with native Collectors or other Sources.

Type: System | TLS Support: N/A | Event Breaker Support: Yes

This Source is available in Cribl.Cloud on customer-managed hybrid Workers, but not on Cribl-managed Workers in Cribl.Cloud.

This Source allows you to run almost anything on the host system. Make sure you understand the security and other impacts of commands you plan to execute, before proceeding. To disable it on your Edge Nodes, see Disable the Exec Source below.

Especially for monitoring or polling, you’ll need to receive the command or script’s output periodically. For this reason, the Exec Source lets you specify when the command or script should run, by time interval or by cron-style schedule.

Here are a few examples of what you can run from an Exec Source:

  • Database queries.
  • Custom commands to poll databases or apps.
  • ping to check latency.
  • ps -ax to get a list of running processes.
  • SNMP GET requests to query an SNMP agent about network entities.
  • netstat -natp to get lists of sockets and TCP ports, and what they’re doing.
  • mtr -c 1 --report --json 8.8.8.8 to run a traceroute on a location (here, 8.8.8.8), and packaging up a report in JSON format.

Configure an Exec Source
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  1. On the top bar, select Products, and then select Cribl Edge. Under Fleets, select a Fleet. Next, you have two options:
    • To configure via QuickConnect, navigate to Routing > QuickConnect (Stream) or Collect (Edge). Select Add Source and select the Source you want from the list, choosing either Select Existing or Add New.
    • To configure via the Routes, select Data > Sources (Stream) or More > Sources (Edge). Select the Source you want. Next, select Add Source.
  2. In the New Source modal, configure the following under General Settings:
    • Enabled: Defaults to Yes.
    • Input ID: Enter a unique name to identify this Exec Source definition. If you clone this Source, Cribl Edge will add -CLONE to the original Input ID.
    • Command: Command to execute; supports Bourne shell syntax.
    • Schedule type: Use the buttons to select either Interval or Cron. For details, see Schedule Type below.
  3. Next, you can configure the following Optional Settings:
    • Max retries: Maximum number of retry attempts in the event that the command fails.
    • Tags: Optionally, add tags that you can use to filter and group Sources in Cribl Edge’s UI. These tags aren’t added to processed events. Use a tab or hard return between (arbitrary) tag names.
  4. Optionally, you can adjust the Processing and Advanced settings, or Connected Destinations outlined in the sections below.
  5. Select Save, then Commit & Deploy.

Schedule Type
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Customize the behavior in the corresponding field below the button.

  • Interval: Specify how often, in seconds, the command should run. Defaults to 60.
  • Schedule: Enter a cron expression. (You enter the cron expression in UTC time, but the resulting Estimated Schedule displays in local time.)

Processing Settings
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Event Breakers
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Event Breaker rulesets: A list of event breaking rulesets that will be applied to the input data stream before the data is sent through the Routes. Defaults to System Default Rule.

Event Breaker buffer timeout: How long (in milliseconds) the Event Breaker will wait for new data to be sent to a specific channel, before flushing out the data stream, as-is, to the Routes. Minimum 10 ms, default 10000 (10 sec), maximum 43200000 (12 hours).

Fields
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In this section, you can add Fields to each event, using Eval-like functionality.

Name: Field name.

Value: JavaScript expression to compute field’s value, enclosed in quotes or backticks. (Can evaluate to a constant.)

Pre-Processing
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In this section’s Pipeline drop-down list, you can select a single existing Pipeline to process data from this input before the data is sent through the Routes.

Advanced Settings
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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.

Connected Destinations
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Select Send to Routes to enable conditional routing, filtering, and cloning of this Source’s data via the Routing table.

Select QuickConnect to send this Source’s data to one or more Destinations via independent, direct connections.

Internal Fields
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Cribl Edge uses internal fields to assist in forwarding data to a Destination.

You can find the following event fields on the Live Data tab of the selected Exec Source, including the hostname and source of the event:

  • _raw
  • _time
  • cribl_breaker
  • host
  • source
Event fields
Event fields

Troubleshooting
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If a command isn’t running as expected, the Logs tab can help you identify issues by displaying the command executed, its elapsed time, and its exit code.

Event fields
Event fields

Disable the Exec Source on a Node
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To disable the Exec Source on a specific Edge Node, set the CRIBL_NOEXEC environment variable. This will override any configuration pushed from the Leader Node, ensuring the Exec Source remains disabled on that particular node.

The CRIBL_NOEXEC environment variable must be set outside of the Cribl product to disable the Exec Source. This variable cannot be modified within the product’s interface.

How to Disable the Exec Source on Different Platforms
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To disable the Exec Source, follow the platform-specific instructions below. Once you’ve set the CRIBL_NOEXEC environment variable, the Exec Source will be disabled. To re-enable it, remove or unset the variable.

Disable on Linux Platform
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To disable the Exec Source on a Linux system running as a Systemd service, edit the appropriate service definition file:

  • Cribl Edge: /etc/systemd/system/(cribl|cribl-edge).service
  • Cribl Stream: /etc/systemd/system/cribl.service

To ensure the CRIBL_NOEXEC environment variable is set when the Cribl Edge service starts, add CRIBL_NOEXEC=1 to the service’s configuration. If the service is currently running, a restart is required for the change to take effect.

Disable on Docker
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To disable the Exec Source on Docker, modify the docker run command (or equivalent) to include the -e CRIBL_NOEXEC=1 flag.

Disable on Kubernetes/Helm
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To disable the Exec Source on Kubernetes, add the --set env.CRIBL_NOEXEC=1 flag to your Helm install command or modify the values.yml file to include this setting.

Disable on Windows (For Cribl Edge)
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To add the CRIBL_NOEXEC environment variable to Cribl Edge on Windows, use the command prompt to execute the following command:

setx CRIBL_NOEXEC "1" /M

This command sets the environment variable for the current user account. The Cribl Edge service runs under LocalSystem user account by default.