# Sitar-agent: Building a reliable dynamic configuration sidecar at scale

DevFeed: [Sitar-agent: Building a reliable dynamic configuration sidecar at scale](<https://devfeed.tech/articles/sitar-agent-building-a-reliable-dynamic-configuration-sidecar-at-scale-1223.md>)

Original publisher: [Read original article](<https://medium.com/airbnb-engineering/sitar-agent-building-a-reliable-dynamic-configuration-sidecar-at-scale-b7e00c152068?source=rss----53c7c27702d5---4>)

Author: Bo Teng

Published: 2026-06-04T17:01:04Z

Content type: article

Language: en

Sources: [The Airbnb Tech Blog - Medium](<https://devfeed.tech/sources/the-airbnb-tech-blog-medium.md>)

Topics: [configuration](<https://devfeed.tech/topics/configuration.md>), [Kubernetes](<https://devfeed.tech/topics/kubernetes.md>), [Amazon S3](<https://devfeed.tech/topics/amazon-s3.md>)

Tags: [agent](<https://devfeed.tech/tags/agent.md>), [architecture](<https://devfeed.tech/tags/architecture.md>), [distributed-systems](<https://devfeed.tech/tags/distributed-systems.md>), [engineering](<https://devfeed.tech/tags/engineering.md>), [infrastructure](<https://devfeed.tech/tags/infrastructure.md>), [kubernetes](<https://devfeed.tech/tags/kubernetes.md>), [s3](<https://devfeed.tech/tags/s3.md>), [scale](<https://devfeed.tech/tags/scale.md>), [software-architecture](<https://devfeed.tech/tags/software-architecture.md>), [software-development](<https://devfeed.tech/tags/software-development.md>), [sync](<https://devfeed.tech/tags/sync.md>)

## AI overview

Airbnb describes Sitar-agent, a Kubernetes sidecar that reliably delivers dynamic configuration to service pods. It bootstraps from S3 snapshots, then synchronizes newer configuration from the Sitar Service.

## Source excerpt

How Airbnb built a Kubernetes sidecar to deliver dynamic configuration reliably at scale. By: Bo Teng, Cosmo Qiu, Siyuan Zhou, Ankur Soni, Xin Huang, Willis Harvey Introduction In our previous post, we explored Airbnb's dynamic configuration system, Sitar, with a focus on service architecture and configuration change safety. Now for the harder question: once a config change is committed, which happens several times each minute, how does it actually reach the thousands of Airbnb's service instances reliably, quickly, and without redeploying the services? This post describes sitar agent: a lightweight Kubernetes sidecar that runs alongside every subscribed service pod, continuously synchronizing the latest configurations from the service backend and making them available on the local filesystem for reads. In this post, we will first go through the configuration delivery life cycle, and then discuss some key design choices for the sitar-agent sidecar. Config delivery life cycle The diagram below illustrates the end-to-end journey of a configuration change, from the developer-facing layer to the production service fleet. Sitar config delivery lifecycle Step 1 -- Config creation/update Developers create or update configuration values through either Git flow or the web UI. These changes are committed to the Sitar Service, where they are stored with full versioning, change logs, and ACL enforcement. Step 2 -- Hourly snapshot upload The Snapshot Service periodically packages the full state of all config groups and uploads compressed snapshots to AWS S3. Step 3.1 -- Preload snapshot from S3 (on pod startup) When a production service pod starts, the sitar-agent sidecar runs first. It downloads the latest snapshot for each subscribed tenant's configs from S3 to the mounted disk (shared between sitar-agent and the main container). This allows the agent to bootstrap from a known-good state without fetching every config from the Sitar Service from scratch on every restart. Preloadin