Pulumi Embraces Bun: Faster Infrastructure as Code

Bun Integration: A Performance Leap for IaC

Pulumi's integration of Bun as a fully supported runtime is a compelling advancement for developers seeking to optimize their Infrastructure as Code (IaC) workflows. The primary draw is the significant performance uplift, particularly in startup times and dependency installation, which directly translates to faster iteration cycles in CI/CD pipelines. Bun's native TypeScript execution, eliminating the need for ts-node or separate compilation steps, addresses a long-standing point of friction for TypeScript users of Pulumi, streamlining the development experience. Furthermore, Bun's commitment to Node.js compatibility ensures a smoother migration path for existing projects. The new pulumi new bun template and the simplification of async operations with top-level await in ESM are welcome ergonomic improvements that lower the barrier to entry and enhance developer productivity.

However, the current limitations regarding Pulumi's callback functions (magic lambdas) and dynamic providers are notable concerns. These features rely on specific Node.js internals that Bun does not yet fully replicate. Teams heavily dependent on these advanced capabilities will need to maintain their Node.js runtime for now. While Bun can still be used for package management with the Node.js runtime, this highlights that the full benefits of Bun are not yet universally applicable within the Pulumi ecosystem. The long-term viability of Bun for all Pulumi use cases will hinge on its continued development and its ability to achieve greater compatibility with Node.js's more intricate features. Nevertheless, for the majority of IaC use cases, this integration represents a substantial step forward in performance and developer experience.

Key Points

• Pulumi now fully supports Bun as an execution runtime, moving beyond its previous role as just a package manager.
• Developers can configure runtime: bun in Pulumi.yaml to have Bun execute their entire infrastructure program without requiring Node.js.
• Key benefits include significantly faster startup times (5-15ms vs 60-120ms) and package installs (6-35x faster) compared to Node.js.
• Native TypeScript execution in Bun eliminates the need for ts-node or separate compilation steps, simplifying workflows.
• Top-level await is now supported at the module level in Bun's ESM, simplifying async code structure.
• Migration for existing Node.js projects involves updating Pulumi.yaml, tsconfig.json, and package.json.
• Limitations exist for Pulumi's callback functions (magic lambdas) and dynamic providers due to reliance on Node.js v8/inspector modules not fully available in Bun.
• Bun 1.3+ and Pulumi 3.227.0+ are required for this integration.

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📖 Source: Pulumi Adds Full Bun Runtime Support