EngFlow CI Runners: Bazel CI startup in seconds, not minutes

Efficiently Speed up your CI with Warm Bazel, Autoscaling and reliable infrastructure.
In our benchmark, time to first action dropped from about 3 minutes to about 30 seconds.

The cold-start tax

A new CI runner starts empty. Before it executes a single action, it clones the repository, starts a Bazel server, parses the build graph, and fetches dependencies. On large codebases that is minutes of setup; paid on every job, on every runner, no matter how small the change.

Measured startup time

CI provider	Cold runner	EngFlow CI Runner
Buildkite	~3 min	~30s
GitHub Actions	~3 min 10s	~40s

Measured on the EngFlow repository, 2025, Bazel 9 rolling release. Cold-runner time is 20s for the Git clone plus 2 min 30s for Bazel initialization; warm time is total time to first action. Your numbers will vary with snapshot size, machine acquisition and boot time (about 12s on GCP, about 25 s on AWS), and disk bandwidth, which bounds snapshot download speed.

Works with the pipelines you have

CI Runners execute GitHub Actions and Buildkite jobs. Point a job label at a Bento. No workflow rewrites, no new CI system to adopt.

Warm Bazel, not just a warm cache

Remote caching skips re-executing actions. Warm Bazel also skips the work before the first action: server startup, build-graph analysis, dependency fetching. The snapshot restores Bazel’s in-memory state, so jobs go straight to executing actions.

Runners inside your EngFlow cluster

CI Runners are native EngFlow workers, co-located with your remote execution and cache. Traffic between runner, executors, and CAS stays inside the cluster instead of crossing networks between your CI vendor and your build cluster.

Autoscaling instead of idle VMs

The runner pool autoscales with your EngFlow cluster: it grows under load and shrinks when queues drain. You stop paying for runners that sit idle between jobs.

Managed CI Runners

EngFlow provisions and manages the runners. There is no self-hosted runner fleet for your team to patch, upgrade, or capacity-plan.

Compatibility

CI providers: GitHub Actions and Buildkite
Host platform: Linux, on x86-64 and arm64
Cloud providers: AWS and GCP
Full requirements and current limitations are in the CI Runners docs.
https://docs.engflow.com/ci-runners/ci-runners-bazel-overview.html

See it against your own repository

Read the docs for setup, requirements, and benchmark details or request a trial and measure startup time on your codebase.