Agent sandboxes / Azure Container Apps Sandboxes alternative

Azure Container Apps Sandboxes alternative

Azure Container Apps Sandboxes is a stateful programmable sandbox product with explicit lifecycle control, separate from Container Apps dynamic sessions. It snapshots full memory and disk state, supports persistent volumes and charges no CPU or memory fees while stopped. Compare its lifecycle, allocation and file-access contracts directly.

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

When Azure Container Apps Sandboxes fits

Choose Azure Sandboxes for Entra-governed isolated compute integrated with Azure networking, images, volumes and snapshot cloning. Its whole-state recovery is already a meaningful agent-runtime capability.

When to consider Sandbox0

Consider Sandbox0 for complete writable RootFS growth online and supported file operations while guest compute stays paused. Map Entra access, image compatibility, network rules and lifecycle policies explicitly when migrating.

Capabilities

Azure Container Apps Sandboxes and Sandbox0: what persists?

Feature comparison with documentation and verification status
Environment and runtime lifetimeAzure Container Apps SandboxesAuto-suspend and auto-delete are separate lifecycle policies. A full-state snapshot does not mean a stopped sandbox is retained indefinitely.View evidence ↗Sandbox0ttl 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 filesAzure Container Apps SandboxesStopped sandboxes retain a disk or full-state snapshot under lifecycle policy.View evidence ↗Sandbox0The writable RootFS survives successful checkpoints, including software, system configuration, dependencies, and user data.Read documentation →
Whole RootFSAzure Container Apps SandboxesFull snapshots include memory and disk of the sandbox root filesystem.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 stateAzure Container Apps SandboxesExplicit lifecycle and suspend/resume are documented.View evidence ↗Sandbox0Pause compute between tasks; resume on available capacity. Default resume starts fresh processes from the saved filesystem.Read documentation →
Memory and process stateAzure Container Apps SandboxesMemory suspension preserves memory and disk; disk mode is distinct.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.

Azure Sandboxes already offers full disk/memory snapshots and persistent volumes. The reviewed tier table lists captured disk capacities, but does not establish automatic online expansion of the whole writable RootFS without restarting agent processes.

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.

The data plane exposes file operations and snapshot lifecycle controls, but the reviewed overview does not establish whether full-RootFS reads or writes can run on a stopped sandbox without resuming compute. Verify that condition rather than inferring it from snapshot retention.

See paused file operations →

Choose memory or disk suspension deliberately

Memory mode captures a full memory-and-disk snapshot; disk mode preserves disk only. Snapshots can also seed cloned environments. Auto-suspend and auto-delete policies are separate controls, so a stopped environment is not automatically retained forever.

Source 1 ↗

The sandbox has its own resource tier and storage model

Current tiers range from XS with 20 GiB disk to 3XL with 320 GiB. OCI images become sandbox root filesystems. Data Disk volumes have one-sandbox attachment, while Azure Blob volumes can serve shared data. Initial tier sizing is not evidence of automatic online RootFS expansion.

Source 1 ↗

Compute pricing follows Consumption, with other meters separate

The Container Apps pricing page says Sandboxes follow Consumption pay-per-second pricing. The East US retail catalog lists active vCPU and active GiB-memory meters. The stopped-state CPU/memory exemption does not establish that snapshots, volumes, networking or other services have no charges.

Source 1 ↗Source 2 ↗Source 3 ↗

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.

Azure Container Apps Sandboxes

Pricing reviewed 2026-10-19

Consumption active CPU, East US
$0.000024 per vCPU-second
Standard active usage retail meter; verify effective region/account pricing.
Rate source ↗
Consumption active memory, East US
$0.000003 per GiB-second
Standard active memory meter; distinct from vCPU.
Rate source ↗
Stopped sandbox CPU and memory
$0
Applies to compute resources while stopped; other services/storage need their own budget.
Rate source ↗
Monthly Consumption free grant
180,000 vCPU-seconds and 360,000 GiB-seconds
Use applicable subscription/account terms; this is not unlimited sandbox or storage use.
Rate source ↗

The cited retail rates are East US USD Consumption meters. Entra ID is required; personal Microsoft accounts are unsupported. Sandbox, dynamic-session, Dedicated and request meters are different products/conditions. Confirm snapshot/volume and network charges before estimating the entire bill.

Check current Azure Container Apps Sandboxes 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 Azure Container Apps Sandboxes

  1. Record group/region, Entra access, images, resource tier, volumes, suspension mode and auto-delete policy.
  2. Export essential state and map compatible images, credentials, networking and lifecycle behavior to Sandbox0.
  3. Test system paths, online growth, memory versus fresh-process recovery, stopped-file behavior and full regional compute/storage/network costs.

Common questions

Is Sandbox0 a drop-in Azure Container Apps Sandboxes replacement?

Evaluate API compatibility and product scope. A shared sandbox category does not make SDKs, lifecycle semantics, or limits interchangeable.

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 ↗learn.microsoft.com/en-us/azure/container-apps/sandboxes-overview ↗azure.microsoft.com/en-us/pricing/details/container-apps/ ↗prices.azure.com/api/retail/prices ↗Sandbox0 RootFS capacity →

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