Buildkite Agent job queues

Each pipeline has the ability to separate its jobs (define by the pipeline's steps) using queues. This allows you to isolate a set of jobs and/or agents, making sure that only specific agents will run jobs that are intended for them.

Common use cases for queues include deployment agents, and pools of agents for specific pipelines or teams.

Setting an agent's queue

An agent's queue is configured using an agent tag as a queue tag. This configuration can be set at the command line when starting the agent, the agent's configuration file, or through an environment variable.

Agents can only be configured to listen on a single queue within a cluster.

In the following example, the --tags flag of the buildkite-agent start command is used to configure this agent to listen on the linux-medium-x86 queue, which is part of the Testing cluster:

buildkite-agent start --token "TESTING-AGENT-TOKEN-VALUE" --tags "queue=linux-medium-x86"

Ensure you have already configured your cluster's agent tokens and queues

Your clusters and queues should already be configured before starting your agents to target these queues.

Setting up queues for unclustered agents

This section documents a deprecated Buildkite feature

Learn more about unclustered agents and their tokens in Unclustered agent tokens.

For unclustered agents, queues are configured when starting a Buildkite agent. An unclustered agent can listen on a single queue or on multiple queues. For multiple queues, add as many extra queue tags as are required.

In the following example, the --tags flag of the buildkite-agent start command is used to configure this unclustered agent to listen on both the development and testing queues:

buildkite-agent start --token "UNCLUSTERED-AGENT-TOKEN-VALUE" --tags "queue=development,queue=testing"

The default queue

If you don't configure a queue for your agent by setting the queue tag (for example, queue=linux-medium-x86), the agent will accept jobs from the default queue as if you had set (that is, queue=default).

Clusters without a default queue configured

If you start your agent without explicitly specifying an existing queue in your cluster and a default queue is not configured in this cluster, then your agent will fail to start.

You must either explicitly specify an existing queue within in your cluster when starting the agent, or have a default queue already configured in this cluster for the agent to start successfully.

Targeting a queue

Target specific queues using the agents attribute on your pipeline steps or at the root level for the entire pipeline.

For example, the following pipeline would run on the priority queue as determined by the root level agents attribute (and ignores the agents running the default queue). The build step matches only agents running on the linux-medium-x86 queue.

  queue: "priority"

  - command: echo "hello"

  - command:
      queue: "linux-medium-x86"

Alternative methods

Branch patterns are another way to control what work is done. You can use branch patterns to determine which pipelines and steps run based on the branch name.