uBuild: Fast and Safe Building of Thousands of Container Images

Rasmus Vestergaard, Andreas Lykke
12 min readadvanced
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Overview

The article discusses uBuild, Uber's platform for building container images efficiently and securely. It highlights the challenges of managing thousands of container builds and the architectural improvements made to optimize build times and ensure safety in the build process.

What You'll Learn

1

How to build container images at scale with uBuild

2

Why isolating privileged tasks is crucial in build processes

3

How to optimize build latency using caching strategies

Key Questions Answered

How does uBuild ensure the security of build processes?
uBuild runs build jobs in isolated containers, limiting privileges to only what is necessary. This prevents unauthorized access to sensitive information, such as secrets needed for pushing to container registries, thereby reducing the risk of malicious builds.
What optimizations were made to reduce build latencies in uBuild?
The introduction of a cache manager and optimizations in Git operations have significantly reduced build latencies. For instance, P95 build latencies for container images from the Go monorepo dropped from 29 minutes to 4 minutes after implementing these changes.
What role does Buildkite play in uBuild's architecture?
Buildkite serves as the job executor for uBuild, allowing for flexible CI job definitions while maintaining dedicated infrastructure for executing builds. This separation enables efficient scheduling and logging of build jobs without overloading the main system.
How does uBuild manage Git repositories for builds?
uBuild's cache manager maintains a pool of ready-to-use Git clones, allowing for quick access to the latest code without the delays of remote cloning. This setup ensures builds can start within seconds by resetting to the requested Git reference.

Key Statistics & Figures

P95 build latency for Go monorepo
29 minutes → 4 minutes
88% reduction
Weekly container image builds at Uber
100,000 builds
This high volume necessitates efficient build processes to maintain operational efficiency.

Technologies & Tools

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Key Actionable Insights

1
Implementing a centralized build service like uBuild can streamline the container image building process across teams.
By abstracting the complexities of the build system, teams can focus on their own domains without worrying about infrastructure, leading to faster development cycles.
2
Utilizing caching strategies can drastically improve build times.
By maintaining local caches and optimizing Git operations, Uber reduced build latencies significantly, which is crucial for a smooth developer experience.
3
Isolating privileged tasks during the build process enhances security.
This approach minimizes the risk of exposing sensitive information, ensuring that only necessary privileges are granted to build jobs.

Common Pitfalls

1
Failing to isolate build processes can lead to security vulnerabilities.
Without proper isolation, sensitive information could be exposed, allowing malicious users to exploit the build system.
2
Neglecting to manage Git references can slow down build processes.
Accumulating dangling references can degrade performance, making regular garbage collection essential to maintain efficiency.

Related Concepts

Containerization
Continuous Integration/Continuous Deployment (ci/Cd)
Microservices Architecture
Caching Strategies