🚀 Announcing Agent Sandbox v0.5.1!

We're excited to announce the release of Agent Sandbox v0.5.1! This patch release brings significant reconciler performance optimizations, core stability improvements, new Go and Python SDK capabilities, expanded example workloads, and dependency upgrades including controller-runtime v0.24.0 (supporting Kubernetes 1.36).

Key Highlights

Core Stability & Reconciler Optimizations

Pod Cache Label Indexing (#1099): Indexed pod cache by sandbox label to eliminate $O(N)$ pod listing during reconcilePod, significantly reducing CPU overhead during high-scale reconciles.
Adoption-Completion Requeue (#1108): Implemented bounded requeue logic for SandboxClaim adoption completion to handle cache lag gracefully without falling back to exponential backoff.
Namespace Queue Partitioning (#813): Partitioned SimpleSandboxQueue by namespace to improve isolation and concurrency under heavy multi-tenant load.
Webhook Certificate Management Flag (#1093): Introduced --manage-webhook-certs to allow disabling in-binary certificate management and CRD patching for external cert-manager setups.
CRD Printer Columns & Status Updates (#964, #990, #1053): Added Desired printer column to SandboxWarmPool and updated computeReadyCondition for Sandbox CRD.
Shared Blueprint & Policy Injection (#995, #991): Introduced inlined SandboxBlueprint shared by Sandbox and SandboxTemplate, and fixed claim env injection rejection when templates specify EnvFrom.
NetworkPolicy Ownership (#828): Ensured SandboxTemplate controller explicitly verifies ownership of NetworkPolicy resources.

Go & Python SDK Enhancements

Go Sandbox-Router (#838, #1066): Introduced a high-performance Go implementation of sandbox-router as a drop-in replacement for the Python router, along with configurable MAX_KEEPALIVE_CONNECTIONS.
Python SDK Network & Gateway Improvements (#917, #1014, #756, #1035): Implemented Pod IP prioritization and normalization, RFC 3986 compliant IPv6 URL bracketing, enabled AsyncSandboxClient cleanup by default, and fixed gateway status address validation.
VolumeClaimTemplates in Claims (#961): Updated SDK to accept VolumeClaimTemplates directly via SandboxClaim.
Go Client Tagged Releases (#537): Established repository-tag-based release definitions for the Go client.

Examples, Load Testing & Workloads

GKE High-Density & Scale-to-Zero (#1005, #1048, #1023): Added GKE Swap example for high-density agent deployments, KEDA scale-to-zero example, and GKE late-binding user guide.
New Sandbox Workload Examples (#1068, #1043, #1040, #1049): Added nullclaw-sandbox, Playwright sandbox, Cilium identity-based egress e2e example, and RL instant-claim sizing.
Chrome Sandbox Stability (#1062, #1096): Cross-compiled chrome-sandbox entrypoint to prevent QEMU Go crashes and updated base images and readiness probes.

Infrastructure & Dependencies

Kubernetes 1.36 & Controller-Runtime (#779): Upgraded controller-runtime to v0.24.0 and Kubernetes dependencies to support Kubernetes 1.36.
Site & Docs (#1026, #785, #1075, #747): Upgraded Hugo to v0.163.3, documented agent skills in AGENTS.md, and added KEP for standardizing sandbox runtime interfaces.

Installation

Core & Extensions

# To install only the core components:
kubectl apply -f https://github.com/kubernetes-sigs/agent-sandbox/releases/download/v0.5.1/manifest.yaml

# To install the extensions components:
kubectl apply -f https://github.com/kubernetes-sigs/agent-sandbox/releases/download/v0.5.1/extensions.yaml

Python SDK

pip install k8s-agent-sandbox==0.5.1

Contributors

We extend our sincere thanks to all contributors to this release:
@Oneimu, @SHRUTI6991, @XbaoWu, @aditya-shantanu, @alexatakvelon, @amacaskill, @barney-s, @chw120, @dependabot, @dongjiang1989, @drogovozDP, @igooch, @janetkuo, @justinsb, @lauragalbraith, @lunarwhite, @mastersingh24, @moficodes, @mvanhorn, @prash2512, @pwoelfle-unique, @rayowang, @sairajp-rewind, @shrutiyam-glitch, @sudhanshu456, @tomergee, @volatilemolotov, @yuanwang04

New Contributors

@lunarwhite made their first contribution in #975
@prash2512 made their first contribution in #1053
@amacaskill made their first contribution in #1023
@sudhanshu456 made their first contribution in #1026
@XbaoWu made their first contribution in #1084
@yuanwang04 made their first contribution in #1005
@pwoelfle-unique made their first contribution in #1066
@alexatakvelon made their first contribution in #716

Full Changelog: v0.5.0...v0.5.1

kubernetes-sigs/agent-sandbox v0.5.1 on GitHub