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Installing the CircleCI Runner

Prerequisites

The installation process assumes you have installed the following utilities on your system:

  • CircleCI CLI

  • curl (installed by default on macOS)

  • sha256sum (installed as part of coreutils on Linux apt/yum, macOS via brew)

  • systemd version 235+ (Linux only)

  • permissions to create a user, and create directories under /opt.

Authentication

These commands can only be run by an owner/admin of your organization.

In order to complete this process you will need to create a namespace and authentication token by performing the steps listed below:

  1. Create a namespace for your organization’s runner resources.

    Each organization can only create a single namespace. If you already use orbs, this namespace will be the same namespace as the orbs use. Use the following command: circleci namespace create <name> <vcs-type> <org-name> (e.g. if your GitHub URL is https://github.com/circleci, then use: circleci namespace create my-namespace github circleci.

  2. Create a resource class for your runner for your namespace using the following command: circleci runner resource-class create <resource-class> <description> (e.g. circleci runner resource-class create my-namespace/my-resource-class my-description)

    To create resource classes and tokens you need to be an organization administrator in the VCS provider.

  3. Create a token for authenticating the above resource-class by using the following command: circleci runner token create <resource-class> <nickname> (e.g. circleci runner token create my-namespace/my-resource-class my-token). This will print a generated Runner configuration including the authentication token.

The token cannot be retrieved again, so be sure to store it safely.

Job running requirements

Running jobs requires you have the following tools available on your machine:

  • tar

  • gzip

  • coreutils (Linux only)

  • git (recommended, but not required)

Installation

Download the Launch Agent Binary and Verify the Checksum

The launch agent can be installed using the following script, which will use opt/circleci as the base install location.

First, set one of these variables as appropriate for for your installation target.

Installation Target Variable

For Linux x86_64

platform=linux/amd64

For Linux ARM64

platform=linux/arm64

For macOS x86_64

platform=darwin/amd64

For macOS M1

platform=darwin/arm64

Run the following steps to download, verify and install the binary.

prefix=/opt/circleci
sudo mkdir -p "$prefix/workdir"
base_url="https://circleci-binary-releases.s3.amazonaws.com/circleci-launch-agent"
echo "Determining latest version of CircleCI Launch Agent"
agent_version=$(curl "$base_url/release.txt")
echo "Using CircleCI Launch Agent version $agent_version"
echo "Downloading and verifying CircleCI Launch Agent Binary"
curl -sSL "$base_url/$agent_version/checksums.txt" -o checksums.txt
file="$(grep -F "$platform" checksums.txt | cut -d ' ' -f 2 | sed 's/^.//')"
mkdir -p "$platform"
echo "Downloading CircleCI Launch Agent: $file"
curl --compressed -L "$base_url/$agent_version/$file" -o "$file"
echo "Verifying CircleCI Launch Agent download"
grep "$file" checksums.txt | sha256sum --check && chmod +x "$file"; sudo cp "$file" "$prefix/circleci-launch-agent" || echo "Invalid checksum for CircleCI Launch Agent, please try download again"

Platform-specific instructions

Please refer to the platform-specific installation instructions:

CircleCI Runner Installation (Linux)

Create the CircleCI runner configuration

The recommended CircleCI runner configuration for Linux is:

api:
  auth_token: AUTH_TOKEN
runner:
  name: RUNNER_NAME
  command_prefix: ["sudo", "-niHu", "circleci", "--"]
  working_directory: /opt/circleci/workdir/%s
  cleanup_working_directory: true

Replace AUTH_TOKEN with the token created in the Authentication step. RUNNER_NAME can be anything you’d like.

Install the CircleCI runner configuration

Once created, save the configuration file to /opt/circleci/launch-agent-config.yaml owned by root with permissions 600.

sudo chown root: /opt/circleci/launch-agent-config.yaml
sudo chmod 600 /opt/circleci/launch-agent-config.yaml

Create the circleci user & working directory

These will be used when executing the task agent. These commands must be run as a user with permissions to create other users (e.g. root). For information about GECOS, see the wiki page.

Ubuntu/Debian

id -u circleci &>/dev/null || adduser --uid 1500 --disabled-password --gecos GECOS circleci

mkdir -p /opt/circleci/workdir
chown -R circleci /opt/circleci/workdir

CentOS/RHEL

id -u circleci &>/dev/null || adduser --uid 1500 -c GECOS circleci

mkdir -p /opt/circleci/workdir
chown -R circleci /opt/circleci/workdir

Enable the systemd unit

Create /opt/circleci/circleci.service owned by root with permissions 755.

You must ensure that TimeoutStopSec is greater than the total amount of time a task will run for - which defaults to 5 hours.

If you want to configure the CircleCI runner installation to start on boot, it is important to note that the launch agent will attempt to consume and start jobs as soon as it starts, so it should be configured appropriately before starting. The launch agent may be configured as a service and be managed by systemd with the following scripts:

[Unit]
Description=CircleCI Runner
After=network.target
[Service]
ExecStart=/opt/circleci/circleci-launch-agent --config /opt/circleci/launch-agent-config.yaml
Restart=always
User=root
NotifyAccess=exec
TimeoutStopSec=18300
[Install]
WantedBy = multi-user.target

You can now enable the service:

systemctl enable /opt/circleci/circleci.service

Start the service

When the CircleCI runner service starts, it will immediately attempt to start running jobs, so it should be fully configured before the first start of the service.

systemctl start circleci.service

Verify the service is running

The system reports a very basic health status through the Status field in systemctl. This will report Healthy or Unhealthy based on connectivity to the CircleCI APIs.

You can see the status of the agent by running:

systemctl status circleci.service --no-pager

Which should produce output similar to:

circleci.service - CircleCI Runner
   Loaded: loaded (/opt/circleci/circleci.service; enabled; vendor preset: enabled)
   Active: active (running) since Fri 2020-05-29 14:33:31 UTC; 18min ago
 Main PID: 5592 (circleci-launch)
   Status: "Healthy"
    Tasks: 8 (limit: 2287)
   CGroup: /system.slice/circleci.service
           └─5592 /opt/circleci/circleci-launch-agent --config /opt/circleci/launch-agent-config.yaml

You can also see the logs for the system by running:

journalctl -u circleci

CircleCI Runner Installation (macOS)

Create a CircleCI runner configuration

Choose a user to run the CircleCI agent. These instructions refer to the selected user as USERNAME.

Complete the template shown below, with the various capitalized parameters filled in. When complete, save the template as launch-agent-config.yaml.

api:
    auth_token: AUTH_TOKEN
runner:
    name: RUNNER_NAME
    command_prefix : ["sudo", "-niHu", "USERNAME", "--"]
    working_directory: /tmp/%s
    cleanup_working_directory: true
logging:
    file: /Library/Logs/com.circleci.runner.log

Install the CircleCI Runner configuration

Create a directory as root to hold the CircleCI runner configuration:

sudo mkdir -p '/Library/Preferences/com.circleci.runner'

Copy the previously created launch-agent-config.yaml into the directory:

sudo cp 'launch-agent-config.yaml' '/Library/Preferences/com.circleci.runner/launch-agent-config.yaml'

Install the launchd .plist

Copy the following to /Library/LaunchDaemons/com.circleci.runner.plist, owned by root, with permissions 644:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
    <dict>
        <key>Label</key>
        <string>com.circleci.runner</string>

        <key>Program</key>
        <string>/opt/circleci/circleci-launch-agent</string>

        <key>ProgramArguments</key>
        <array>
            <string>circleci-launch-agent</string>
            <string>--config</string>
            <string>/Library/Preferences/com.circleci.runner/launch-agent-config.yaml</string>
        </array>

        <key>RunAtLoad</key>
        <true/>

        <!-- The agent needs to run at all times -->
        <key>KeepAlive</key>
        <true/>

        <!-- This prevents macOS from limiting the resource usage of the agent -->
        <key>ProcessType</key>
        <string>Interactive</string>

        <!-- Increase the frequency of restarting the agent on failure, or post-update -->
        <key>ThrottleInterval</key>
        <integer>3</integer>

        <!-- Wait for 10 minutes for the agent to shut down (the agent itself waits for tasks to complete) -->
        <key>ExitTimeOut</key>
        <integer>600</integer>

        <!-- The agent uses its own logging and rotation to file -->
        <key>StandardOutPath</key>
        <string>/dev/null</string>
        <key>StandardErrorPath</key>
        <string>/dev/null</string>
    </dict>
</plist>

Enable the launchd service

If you are following these instructions for a second time, you should unload the following existing service:

sudo launchctl unload '/Library/LaunchDaemons/com.circleci.runner.plist'

Now you can load the service:

sudo launchctl load '/Library/LaunchDaemons/com.circleci.runner.plist'

Verify the service is running

The macOS application console can be used to view the logs for the CircleCI agent. Look under "Log Reports" for the logs called com.circleci.runner.log.

Configuration file reference

A YAML file is used to configure the launch agent, how it communicates with our servers and how it will launch the task agent.

The configuration file uses the following format with the various parameters explained in more detail below:

api:
  auth_token: AUTH_TOKEN
runner:
  name: RUNNER_NAME

runner.name

RUNNER_NAME is a unique name assigned to this particular running launch agent. CircleCI recommends using the hostname of the machine so that it can be used to identify the agent when viewing statuses and job results in the CircleCI UI.

api.auth_token

This is a token used to identify the launch agent to CircleCI and can be generated by circleci command-line tool. An existing token may be shared among many installations, but this token only allows a particular resource_class to be specified.

runner.command_prefix

This prefix enables you to customize how the task agent process is launched. Using a custom script here can allow you to execute arbitrary commands before and after the task runner. You should take care to ensure the supplied arguments are executed, and the correct exit code is returned from the script upon completion.

runner.working_directory

This directory allows you to control the default working directory used by each job. If the directory already exists, task agent will need permissions to write to the directory. If the directory does not exist, then the task agent will need permissions to create the directory. If %s is present in the value, this value will be replaced with a different value for each job. Note that these directories will not be automatically removed.

runner.cleanup_working_directory

This directory enables you to control the working directory cleanup after each job. The default value is false.

runner.max_run_time

This value can be used to override the default maximum duration the task agent will run each job. Note that the value is a string with the following unit identifiers h, m or s for hour minute and seconds respectively:

Here are few valid examples:

  • 72h - 3 days

  • 1h30m - 1 hour 30 minutes

  • 30s - 30 seconds

  • 50m - 50 minutes

  • 1h30m20s - An overly specific (yet still valid) duration.

The default value is 5 hours.
Customizing job timeouts and drain timeouts

If you would like to customize the job timeout setting, you can "drain" the job by sending the Launch Agent a termination (TERM) signal, which then causes the Launch Agent to attempt to gracefully shutdown. When this TERM signal is received, the launch agent enters 'draining' mode, preventing the Launch Agent from accepting any new jobs, but still allowing any current active job to be completed. At the end of "draining," the Launch Agent then signals the Task Agent to cancel any active job (by sending it a TERM signal).

If the Task Agent does not exit a brief period after the TERM, the Launch Agent will manually kill it by sending it a KILL signal.

Draining can end in one of two ways:

  • The task has been in the draining state for longer than the configured max_run_time.

  • An additional TERM signal is received by the Launch Agent during "draining".

Docker Installation

The host needs to have Docker installed. Once the runner container is started, the container will immediately attempt to start running jobs. The container will be reused to run more jobs indefinitely until it is stopped.

The number of containers running in parallel on the host is constrained by the host’s available resources and your jobs' performance requirements.

Create a Dockerfile that extends the CircleCI Runner image

In this example, python3 is installed on top of the base image.

Dockerfile.runner.extended

FROM circleci/runner:launch-agent
RUN apt-get update; \
    apt-get install --no-install-recommends -y \
        python3

Build the Docker image

docker build --file ./Dockerfile.runner.extended .

Start the Docker container

The environment variable values are not to the docker command, so these environment variables are not visible in ps output. 
CIRCLECI_RESOURCE_CLASS=<resource-class> CIRCLECI_API_TOKEN=<runner-token> docker run --env CIRCLECI_API_TOKEN --env CIRCLECI_RESOURCE_CLASS --name <container-name> <image-id-from-previous-step>

When the container starts, it will immediately attempt to start running jobs.

Stopping the Docker container

docker stop <container-name>

Additional Resources