CI and test infrastructure / WarpBuild GitHub Actions Runners alternative

WarpBuild alternative for returning agent runtime state

WarpBuild offers GitHub Actions runners across operating systems, and its Cloud Ubuntu runners can reuse full-disk snapshots. Those snapshots already include installed system packages and workspace state. They have an explicit lifetime and reboot-based restore, while the macOS, Windows and BYOC offerings have different support.

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Reviewed 2026-10-19 · Published by the Sandbox0 team

When WarpBuild GitHub Actions Runners fits

Choose WarpBuild for GitHub Actions integration, clean CI jobs, runner resource classes and Ubuntu snapshot acceleration. Keep native Mac/Windows and specialized Docker builder jobs on the appropriate runner product.

When to consider Sandbox0

Consider Sandbox0 for compatible Linux agents that should return to one durable growing RootFS and use supported files during compute pauses. Retain required CI triggers, artifact publication and native OS build stages separately.

Capabilities

WarpBuild GitHub Actions Runners and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeWarpBuild GitHub Actions RunnersNot established in this reviewSandbox0ttl and hard_ttl default to 0 (disabled). Configure idle pause and deletion policies for the same persistent sandbox identity; an idle running sandbox still accrues compute charges.Read documentation →
Persistent filesWarpBuild GitHub Actions RunnersCloud Ubuntu disk snapshots preserve captured state across jobs for up to 15 days; other runner surfaces do not support them.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSWarpBuild GitHub Actions RunnersUbuntu snapshots capture installed system and workspace filesystem state; /tmp is cleaned and separate job identity resets.View evidence ↗Sandbox0Persistence extends beyond /workspace to paths such as /usr/local, /etc, and /home. Runtime tmpfs and virtual filesystems are excluded.Read documentation →
Release compute, keep stateWarpBuild GitHub Actions RunnersBooting a new CI job from a saved disk does not establish in-place process-preserving pause/resume.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateWarpBuild GitHub Actions RunnersSnapshot restore drops memory and restarts from disk; previous services/processes are not running.View evidence ↗Sandbox0Experimental memory checkpoints can preserve compatible process state. Use memory: true on both pause and resume on a compatible deployment. A filesystem checkpoint alone does not preserve running processes.Read documentation →

Online RootFS growth

On growth-enabled images, Sandbox0 automatically expands the writable RootFS as free space runs low, within a configured sparse logical ceiling up to 64 TiB. Agent processes keep running. Growth is enabled in the qualified Cloud region; confirm activation for other regions. Existing images and snapshots retain their captured storage geometry. The ceiling is logical capacity, not preallocated host disk.

WarpBuild Cloud Ubuntu snapshots can preserve a complete captured system filesystem, with /tmp and memory exceptions and a fifteen-day lifetime. Resource-class and image sizing differ from automatic online low-space growth of an indefinitely retained agent RootFS.

Files while compute is paused

Sandbox0's Files API reads persistent files without resuming compute. Filesystem-only pauses also permit edits; retained-memory pauses are read-only and reject mutations with 409. SSH, SFTP, file watching, and runtime-only mounts require running compute.

Snapshots retain disk state for booting later CI jobs. The cited feature does not establish a native arbitrary file API spanning that saved runner filesystem without starting a guest job; caches/artifacts expose a separate selected-data scope.

See paused file operations →

Ubuntu snapshots retain more than a dependency cache

A snapshot saves the runner filesystem, including installed packages, toolchains, workspace and pulled Docker images. Memory and running processes are dropped, and /tmp is cleaned on reboot. Restored jobs start services again; filesystem reuse is not process continuation.

Source 1 ↗

Snapshot support and expiry have hard boundaries

Only WarpBuild Cloud Ubuntu runners support snapshots. macOS, Windows and BYOC silently ignore snapshot labels. Snapshots are deleted after fifteen days, and a missing or expired alias falls back to the base image. That fallback must be compatible with the workflow’s setup steps.

Source 1 ↗Source 2 ↗

Snapshot costs are additional to runner minutes

Runner use is billed per minute, with separate snapshot-restore and retained-snapshot storage charges. BYOC has a management fee plus underlying cloud capacity; its snapshot support differs. Compare the actual OS/class and saved-image lifetime, not only the smallest Linux runner price.

Source 1 ↗Source 2 ↗

Pricing

Compare billing models, then price your workload

CPU allocation, memory, billing minimums, disk, plan fees, and supported workload differ. These meters are not equal-performance machine quotes. Confirm region, resource units, and included allowances before estimating a total.

WarpBuild GitHub Actions Runners

Pricing reviewed 2026-10-19

Cloud Linux x64 entry reference
$0.004/minute
2 vCPU / 8 GB RAM; other OS/resource classes differ.
Rate source ↗
Cloud macOS M4 Pro entry reference
$0.08/minute
6 vCPU / 14 GB RAM; Ubuntu snapshots are unsupported on macOS.
Rate source ↗
Snapshot restore
$0.04 per job
Additional to runner minutes.
Rate source ↗
Retained snapshot storage
$0.025/hour per snapshot
Separate storage meter; snapshots expire after 15 days.
Rate source ↗

Cloud cache storage/operations, Docker builders and BYOC have separate meters and feature scope. Do not assign Ubuntu snapshot guarantees to macOS/Windows or infer equal performance from nominal cores. Include current runner minutes, saved-image storage/restore, caches and any underlying BYOC cloud costs.

Check current WarpBuild GitHub Actions Runners pricing ↗

Sandbox0

$0.015/GiB-hour compute (billed by the second at approximately $0.000004167/GiB-second), plus $0.02/GiB-month of retained incremental RootFS and memory checkpoint data. Shared base images and platform recovery retention are excluded; paused sandboxes accrue storage charges only.

Compute / GiB-hour
$0.015
Retained data / GiB-month
$0.02
Paused compute
$0.00

A 4 GiB agent, 100 running hours

$6.00 compute

4 GiB × 100 hours, billed by the second. Keeping 20 GiB of billable incremental data for a full billing month adds $0.40. CPU is derived from memory by the platform; choose a tier that fits your workload.

Understand storage billing →

Before migrating from WarpBuild GitHub Actions Runners

  1. Inventory OS/cloud/BYOC surface, snapshot labels/aliases, expiry fallback, secret cleanup, runner sizes and all snapshot/cache meters.
  2. Export required system/user data and port compatible agent commands and policy; retain required CI/native OS stages and artifact integrations.
  3. Test recurring tasks, service restart versus required memory state, online growth, paused files and total runner, snapshot, cache and Linux runtime costs.

Common questions

Is Sandbox0 a drop-in WarpBuild GitHub Actions Runners replacement?

Evaluate API compatibility and product scope. These products serve different core workflows, so a change may require a different architecture.

Does keeping files also keep a running agent?

Filesystem state and volatile process state are separate. Sandbox0 requires explicit compatible memory checkpoints to preserve running processes; its default filesystem resume starts fresh processes.

Sources and review scope

The Boat team's Battleships directory is the discovery source. References below describe the product and plan discussed on this page. Check current availability, regional terms and billing units before migrating. Where the cited material does not establish a capability or price, the comparison identifies that uncertainty.

Battleships research record ↗www.warpbuild.com/runners/snapshot ↗www.warpbuild.com/docs/ci/features/snapshot-runners ↗www.warpbuild.com/pricing ↗Sandbox0 RootFS capacity →

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