Docs » Configure your tests » Private locations

Private locations 🔗

A private location is a software package that offers a quick and easy deployment of Splunk Synthetic Monitoring solutions beyond the public network so that you can find, fix, and prevent web performance defects on any internal web application, in any environment - whether inside or outside of your firewalls. Private locations allow Splunk Synthetics Monitoring users to test sooner in the development cycle and against internal sites or applications that aren’t available to the public.

Customers can, through the Splunk Synthetics Monitoring web interface, create new private locations and open a runner to run any checks assigned to them.

What is a runner? 🔗

A runner is a Docker container set up to run tests from a particular private location. A single private location can have one or more runners.

A location consists of a queue of tests assigned to a particular private location. Runners pick up runs from the queue, so the more active runners you have, the faster the queue of tests is processed.

Splunk Synthetic Monitoring doesn’t track how many runners there are for a given location. It is up to you to manage your own fleet of runners.

Use cases for private locations 🔗

  • Test private applications that aren’t exposed to the public.

  • Test pre-production applications which don’t have public staging sites.

  • Gain a higher level of flexibility in giving Splunk Synthetic Monitoring access to applications.

  • Test from locations not currently supported by Splunk Synthetic Monitoring’s public locations.

Requirements 🔗




  • The Docker container requires the host have the ifb kernel module installed.

  • The Docker container needs outbound internet access; however it doesn’t need inbound access.


  • runner.<realm>

  • *

  • *


Operating system

Linux, Windows1, or OSX1

For optimal performance when running Browser tests:

  • Linux

  • 2.3 GHz Dual-Core Intel Xeon (or equivalent) processor

  • 8 GB RAM, 2 cores

Set up a new private location 🔗

Follow these steps to set up a new private location:

  1. In Splunk Synthetic Monitoring, select the settings gear icon, then Private locations.

  2. Select + Add and add a name.

  3. Follow the steps in the guided setup to set up your runner.

  4. Save your private location.

What you can do with your private location ID 🔗

Each private location has a corresponding private location ID. With this ID, you can:

  • Build charts or dashboards

  • Search for metrics by private location

  • Refer to your private location ID if you’re interacting with the Splunk Synthetics Monitoring APIs.

Manage your tokens 🔗

It is your responsibility to update and manage your tokens. For added security, create a secret environment variable for your token in Docker. Consider creating a second token to provide coverage before your first token expires.

Working with Docker 🔗

Here is some guidance for working with Docker.

Limit logging in Docker 🔗

Follow these steps to limit logging:

  1. Create a file in a directory like this: /etc/docker/daemon.json.

  2. In the file, add:

  "log-driver": "local",
  "log-opts": {
    "max-size": "10m",
    "max-file": "3"
  1. Restart your docker service: sudo systemctl docker.service restart.

Adding certificates in Synthetics 🔗

Splunk Synthetic Monitoring supports injecting custom root CA certificates for any tests running from your private locations. Client keys and certificates aren’t supported at this time.

  1. Create a folder called certs on your host machine and place the CA Certificate (in CRT format) in the folder.

  2. Add the certs folder as a volume to the container (-v ./certs:/usr/local/share/ca-certificates/my_certs/).

  3. Modify the command you use when launching the container to update the CA Certificate cache before starting the agent binary (bash -c "sudo update-ca-certificates && bundle exec bin/start_runner).

For example, here is what a command might look like after you modify it to fit your environment:

docker run -e "RUNNER_TOKEN=<insert-token>" --volume=`pwd`/certs:/usr/local/share/ca-certificates/my_certs/ bash -c "sudo update-ca-certificates && bundle exec bin/start_runner"

Assess the health of your private location 🔗

A private location’s health depends on three factors:




Active runner

At least one runner is actively checking in.

If no runners are checking in, set up new runners for the private location.

Used in tests

The private location is currently being used in one or more tests.

If you need to delete a private location, you need to first delete it from all tests.

Clear queue

The queue for a given location is being cleared periodically and is not backed up.

If the queue is backed up, add new runners to the private location.

Troubleshoot queue length and latency 🔗

If both the queue latency and length increase over time, then add more runners to improve performance.

If your queue latency increases but your queue length doesn’t, then try these troubleshooting methods:

  • Check to see if a step is delaying the rest of the test

  • Investigate whether you have the sufficient resources to run private location runners on your machines.

The maximum number of runs in a queue is 100,000.

Any runners older than one hour are removed from the queue.