---
stage: Verify
group: Runner
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
---

# SaaS runners on Linux

When you run jobs on SaaS runners on Linux, the runners are on auto-scaled ephemeral virtual machine (VM) instances.
Each VM uses the Google Container-Optimized OS (COS) and the latest version of Docker Engine.
The default region for the VMs is `us-east1`.

## Machine types available for private projects (x86-64)

For the SaaS runners on Linux, GitLab offers a range of machine types for use in private projects.
For Free, Premium, and Ultimate plan customers, jobs on these instances consume the CI/CD minutes allocated to your namespace.

|                   | Small                     | Medium                    | Large                    |
|-------------------|---------------------------|---------------------------|--------------------------|
| Specs             | 1 vCPU, 3.75GB RAM        | 2 vCPUs, 8GB RAM          | 4 vCPUs, 16GB RAM        |
| GitLab CI/CD tags | `saas-linux-small-amd64` | `saas-linux-medium-amd64` | `saas-linux-large-amd64` |
| Subscription      | Free, Premium, Ultimate   | Free, Premium, Ultimate   | Premium, Ultimate        |

The `small` machine type is the default. Your job runs on this machine type if you don't specify
a [tags:](../../yaml/index.md#tags) keyword in your `.gitlab-ci.yml` file.

CI/CD jobs that run on `medium` and `large` machine types **will** consume CI minutes at a different rate than CI/CD jobs on the `small` machine type.

Refer to the CI/CD minutes [cost factor](../../../ci/pipelines/cicd_minutes.md#cost-factor) for the cost factor applied to the machine type based on size.

## Example of how to tag a job

To use a machine type other than `small`, add a `tags:` keyword to your job.
For example:

```yaml
stages:
  - Prebuild
  - Build
  - Unit Test

job_001:
 stage: Prebuild
 script:
  - echo "this job runs on the default (small) instance"

job_002:
 tags: [ saas-linux-medium-amd64 ]
 stage: Build
 script:
  - echo "this job runs on the medium instance"


job_003:
 tags: [ saas-linux-large-amd64 ]
 stage: Unit Test
 script:
  - echo "this job runs on the large instance"

```

## SaaS runners for GitLab projects

The `gitlab-shared-runners-manager-X.gitlab.com` fleet of runners are dedicated for
GitLab projects and related community forks. These runners are backed by a Google Compute
`n1-standard-2` machine type and do not run untagged jobs. Unlike the machine types used
for private projects, each virtual machine is re-used up to 40 times.

## SaaS runners on Linux settings

Below are the settings for SaaS runners on Linux.

| Setting                                                                 | GitLab.com       | Default |
|-------------------------------------------------------------------------|------------------|---------|
| Executor                                                                | `docker+machine` | -       |
| Default Docker image                                                    | `ruby:2.5`       | -       |
| `privileged` (run [Docker in Docker](https://hub.docker.com/_/docker/)) | `true`           | `false` |

- **Cache**: These runners share a
  [distributed cache](https://docs.gitlab.com/runner/configuration/autoscale.html#distributed-runners-caching)
  that's stored in a Google Cloud Storage (GCS) bucket. Cache contents not updated within
  the last 14 days are automatically removed, based on the
  [object lifecycle management policy](https://cloud.google.com/storage/docs/lifecycle).

- **Timeout settings**: Jobs handled by the SaaS Runners on Linux
  **time out after 3 hours**, regardless of the timeout configured in a
  project. For details, see issues [#4010](https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/4010)
  and [#4070](https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/4070).

NOTE:
The final disk space your jobs can use will be less than 25GB. Some disk space
allocated to the instance will be occupied by the operating system, the Docker image,
and a copy of your cloned repository.

## Pre-clone script

With SaaS runners on Linux, you can run commands in a CI/CD
job before the runner attempts to run `git init` and `git fetch` to
download a GitLab repository. The
[`pre_clone_script`](https://docs.gitlab.com/runner/configuration/advanced-configuration.html#the-runners-section)
can be used for:

- Seeding the build directory with repository data
- Sending a request to a server
- Downloading assets from a CDN
- Any other commands that must run before the `git init`

To use this feature, define a [CI/CD variable](../../../ci/variables/index.md#custom-cicd-variables) called
`CI_PRE_CLONE_SCRIPT` that contains a bash script.

NOTE:
The `CI_PRE_CLONE_SCRIPT` variable does not work on GitLab SaaS Windows or macOS runners.

### Pre-clone script example

This example was used in the `gitlab-org/gitlab` project until November 2021.
The project no longer uses this optimization because the
[pack-objects cache](../../../administration/gitaly/configure_gitaly.md#pack-objects-cache)
lets Gitaly serve the full CI/CD fetch traffic. See [Git fetch caching](../../../development/pipelines.md#git-fetch-caching).

The `CI_PRE_CLONE_SCRIPT` was defined as a project CI/CD variable:

```shell
(
  echo "Downloading archived master..."
  wget -O /tmp/gitlab.tar.gz https://storage.googleapis.com/gitlab-ci-git-repo-cache/project-278964/gitlab-master-shallow.tar.gz

  if [ ! -f /tmp/gitlab.tar.gz ]; then
      echo "Repository cache not available, cloning a new directory..."
      exit
  fi

  rm -rf $CI_PROJECT_DIR
  echo "Extracting tarball into $CI_PROJECT_DIR..."
  mkdir -p $CI_PROJECT_DIR
  cd $CI_PROJECT_DIR
  tar xzf /tmp/gitlab.tar.gz
  rm -f /tmp/gitlab.tar.gz
  chmod a+w $CI_PROJECT_DIR
)
```

The first step of the script downloads `gitlab-master.tar.gz` from Google Cloud Storage.
There was a [GitLab CI/CD job named `cache-repo`](https://gitlab.com/gitlab-org/gitlab/-/blob/5fb40526c8c8aaafc5f92eab36d5bbddaca3893d/.gitlab/ci/cache-repo.gitlab-ci.yml)
that was responsible for keeping that archive up-to-date. Every two hours on a scheduled pipeline,
it did the following:

1. Create a fresh clone of the `gitlab-org/gitlab` repository on GitLab.com.
1. Save the data as a `.tar.gz`.
1. Upload it into the Google Cloud Storage bucket.

When a job ran with this configuration, the output looked similar to:

```shell
$ eval "$CI_PRE_CLONE_SCRIPT"
Downloading archived master...
Extracting tarball into /builds/gitlab-org/gitlab...
Fetching changes...
Reinitialized existing Git repository in /builds/gitlab-org/gitlab/.git/
```

The `Reinitialized existing Git repository` message shows that
the pre-clone step worked. The runner runs `git init`, which
overwrites the Git configuration with the appropriate settings to fetch
from the GitLab repository.

`CI_REPO_CACHE_CREDENTIALS` must contain the Google Cloud service account
JSON for uploading to the `gitlab-ci-git-repo-cache` bucket.

Note that this bucket should be located in the same continent as the
runner, or [you can incur network egress charges](https://cloud.google.com/storage/pricing).

## `config.toml`

The full contents of our `config.toml` are:

NOTE:
Settings that are not public are shown as `X`.

**Google Cloud Platform**

```toml
concurrent = X
check_interval = 1
metrics_server = "X"
sentry_dsn = "X"

[[runners]]
  name = "docker-auto-scale"
  request_concurrency = X
  url = "https://gitlab.com/"
  token = "SHARED_RUNNER_TOKEN"
  pre_clone_script = "eval \"$CI_PRE_CLONE_SCRIPT\""
  executor = "docker+machine"
  environment = [
    "DOCKER_DRIVER=overlay2",
    "DOCKER_TLS_CERTDIR="
  ]
  limit = X
  [runners.docker]
    image = "ruby:2.5"
    privileged = true
    volumes = [
      "/certs/client",
      "/dummy-sys-class-dmi-id:/sys/class/dmi/id:ro" # Make kaniko builds work on GCP.
    ]
  [runners.machine]
    IdleCount = 50
    IdleTime = 3600
    MaxBuilds = 1 # For security reasons we delete the VM after job has finished so it's not reused.
    MachineName = "srm-%s"
    MachineDriver = "google"
    MachineOptions = [
      "google-project=PROJECT",
      "google-disk-size=25",
      "google-machine-type=n1-standard-1",
      "google-username=core",
      "google-tags=gitlab-com,srm",
      "google-use-internal-ip",
      "google-zone=us-east1-d",
      "engine-opt=mtu=1460", # Set MTU for container interface, for more information check https://gitlab.com/gitlab-org/gitlab-runner/-/issues/3214#note_82892928
      "google-machine-image=PROJECT/global/images/IMAGE",
      "engine-opt=ipv6", # This will create IPv6 interfaces in the containers.
      "engine-opt=fixed-cidr-v6=fc00::/7",
      "google-operation-backoff-initial-interval=2" # Custom flag from forked docker-machine, for more information check https://github.com/docker/machine/pull/4600
    ]
    [[runners.machine.autoscaling]]
      Periods = ["* * * * * sat,sun *"]
      Timezone = "UTC"
      IdleCount = 70
      IdleTime = 3600
    [[runners.machine.autoscaling]]
      Periods = ["* 30-59 3 * * * *", "* 0-30 4 * * * *"]
      Timezone = "UTC"
      IdleCount = 700
      IdleTime = 3600
  [runners.cache]
    Type = "gcs"
    Shared = true
    [runners.cache.gcs]
      CredentialsFile = "/path/to/file"
      BucketName = "bucket-name"
```