info: To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/product/ux/technical-writing/#assignments
Next, you need to configure the test environment and write the k6 test.
The key performance metrics that the merge request widget shows after the test completes are:
- Checks: The percentage pass rate of the [checks](https://k6.io/docs/using-k6/checks) configured in the k6 test.
- TTFB P90: The 90th percentile of how long it took to start receiving responses, aka the [Time to First Byte](https://en.wikipedia.org/wiki/Time_to_first_byte) (TTFB).
- TTFB P95: The 95th percentile for TTFB.
- RPS: The average requests per second (RPS) rate the test was able to achieve.
NOTE:
If the Load Performance report has no data to compare, such as when you add the
Load Performance job in your `.gitlab-ci.yml` for the very first time,
the Load Performance report widget doesn't display. It must have run at least
once on the target branch (`main`, for example), before it displays in a
merge request targeting that branch.
## Configure the Load Performance Testing job
Configuring your Load Performance Testing job can be broken down into several distinct parts:
- Determine the test parameters such as throughput, and so on.
- Set up the target test environment for load performance testing.
- Design and write the k6 test.
### Determine the test parameters
The first thing you need to do is determine the [type of load test](https://k6.io/docs/test-types/introduction)
you want to run, and how it will run (for example, the number of users, throughput, and so on).
Refer to the [k6 docs](https://k6.io/docs/), especially the [k6 testing guides](https://k6.io/docs/testing-guides),
for guidance on the above and more.
### Test Environment setup
A large part of the effort around load performance testing is to prepare the target test environment
for high loads. You should ensure it's able to handle the
[throughput](https://k6.io/blog/monthly-visits-concurrent-users) it will be tested with.
It's also typically required to have representative test data in the target environment
for the load performance test to use.
We strongly recommend [not running these tests against a production environment](https://k6.io/our-beliefs#load-test-in-a-pre-production-environment).
### Write the load performance test
After the environment is prepared, you can write the k6 test itself. k6 is a flexible
tool and can be used to run [many kinds of performance tests](https://k6.io/docs/test-types/introduction).
Refer to the [k6 documentation](https://k6.io/docs/) for detailed information on how to write tests.
### Configure the test in GitLab CI/CD
When your k6 test is ready, the next step is to configure the load performance
testing job in GitLab CI/CD. The easiest way to do this is to use the
The above example creates a `load_performance` job in your CI/CD pipeline that runs
the k6 test.
NOTE:
For Kubernetes setups a different template should be used: [`Jobs/Load-Performance-Testing.gitlab-ci.yml`](https://gitlab.com/gitlab-org/gitlab/-/blob/master/lib/gitlab/ci/templates/Jobs/Load-Performance-Testing.gitlab-ci.yml).
k6 has [various options](https://k6.io/docs/using-k6/k6-options/reference/) to configure how it will run tests, such as what throughput (RPS) to run with,
GitLab only displays the key performance metrics in the MR widget if k6's results are saved
via [summary export](https://k6.io/docs/results-visualization/json#summary-export)
as a [Load Performance report artifact](../yaml/artifacts_reports.md#artifactsreportsload_performance).
The latest Load Performance artifact available is always used, using the
summary values from the test.
If [GitLab Pages](../../user/project/pages/index.md) is enabled, you can view the report directly in your browser.
### Load Performance testing in Review Apps
The CI/CD YAML configuration example above works for testing against static environments,
but it can be extended to work with [review apps](../review_apps/index.md) or
[dynamic environments](../environments/index.md) with a few extra steps.
The best approach is to capture the dynamic URL in a [`.env` file](https://docs.docker.com/compose/env-file/)
as a job artifact to be shared, then use a custom CI/CD variable we've provided named `K6_DOCKER_OPTIONS`
to configure the k6 Docker container to use the file. With this, k6 can then use any
environment variables from the `.env` file in scripts using standard JavaScript,
such as: ``http.get(`${__ENV.ENVIRONMENT_URL}`)``.
For example:
1. In the `review` job:
1. Capture the dynamic URL and save it into a `.env` file, for example, `echo "ENVIRONMENT_URL=$CI_ENVIRONMENT_URL" >> review.env`.
1. Set the `.env` file to be a [job artifact](../pipelines/job_artifacts.md).
1. In the `load_performance` job:
1. Set it to depend on the review job, so it inherits the environment file.
1. Set the `K6_DOCKER_OPTIONS` variable with the [Docker CLI option for environment files](https://docs.docker.com/engine/reference/commandline/run/#set-environment-variables--e---env---env-file), for example `--env-file review.env`.
1. Configure the k6 test script to use the environment variable in it's steps.
