Introducing Bun as a Runtime for Pulumi

Why It Matters

Eliminating the Node.js dependency streamlines tooling, cuts build times, and reduces infrastructure overhead, accelerating IaC delivery. Projects that rely on Lambda callbacks or dynamic providers must continue using Node.js, limiting full adoption for some enterprises.

Key Takeaways

• Bun runtime eliminates need for Node.js in Pulumi TypeScript projects.
• Native TypeScript support enables top‑level await without ts-node.
• Bun’s package manager installs dependencies up to 10× faster than npm.
• Dynamic providers and Lambda callbacks remain unsupported; Node.js still required for them.

Pulse Analysis

Bun, the all‑in‑one JavaScript runtime that bundles a fast package manager, bundler, and test runner, has gained traction among developers seeking speed and simplicity. Pulumi’s decision to adopt Bun as a first‑class runtime reflects a broader industry shift toward leaner toolchains that reduce the “node_modules” overhead and eliminate the need for separate compilation steps. By leveraging Bun’s native TypeScript execution, Pulumi users can run infrastructure‑as‑code scripts directly, benefiting from the runtime’s low‑latency startup and its promise of near‑100% Node.js API compatibility.

From a workflow perspective, the Bun integration removes the ts‑node layer, enabling top‑level await and ESM‑only projects without extra configuration. The built‑in package manager claims installation speeds up to ten times faster than npm, which translates to quicker CI pipelines and faster local iteration. Pulumi provides a one‑command starter (`pulumi new bun`) that scaffolds a TypeScript project pre‑configured with the appropriate `tsconfig.json` settings, allowing teams to migrate existing Node.js projects by simply swapping the runtime field and adjusting module resolution. This reduces the operational burden of maintaining multiple runtimes and aligns IaC development with modern JavaScript practices.

While the performance gains are compelling, the current limitation—lack of support for Lambda callback functions and dynamic providers—means that organizations with complex serverless or custom provider requirements must retain a Node.js runtime. As Bun continues to mature and close these gaps, Pulumi’s early adoption positions it to capture developers looking for faster, more integrated IaC pipelines. Enterprises should evaluate their existing Pulumi workloads, pilot the Bun runtime for non‑critical projects, and monitor Pulumi’s roadmap for expanded feature parity.