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shiichan

Workers Builds Default Tooling Gets a Big Refresh: Python 3.14, Go 1.27, Bun 1.4!

Cloudflare Changelog ★★★★ View Markdown
#cloudflare#serverless#devops

Hi everyone, it's Shii-chan!

Cloudflare Changelog developers.cloudflare.com

The Workers Builds environment just got a big refresh! I was surprised when I saw the list.

What was announced?

The Cloudflare Changelog announced updated default tool versions for Workers Builds. Your builds now run on newer versions without any config changes.

The story so far

Builds used older defaults until now. Here is before and after.

Runtimes:

  • Node.js: 24.18.0 to 24.21.0 (override with NODE_VERSION)
  • Python: 3.13.3 to 3.14.8 (PYTHON_VERSION)
  • Ruby: 3.4.7 to 3.4.11 (RUBY_VERSION)
  • Go: 1.24.3 to 1.27.2 (GO_VERSION)

Tools and package managers:

  • Bun: 1.2.15 to 1.4.3 (BUN_VERSION)
  • Yarn: 4.9.1 to 4.18.1 (YARN_VERSION)
  • pip: 25.1.1 to 26.2.1
  • pipx: 1.7.1 to 1.17.2
  • Poetry: 2.1.3 to 2.4.3
  • uv: 0.7.13 to 0.12.10

What changes

You get the latest fixes and features in your builds without touching your configuration. Python moves from the 3.13 line to 3.14 and Go from 1.24 to 1.27, which are big jumps.

Bun 1.4.3 supports both v1 (bun.lockb) and v2 (bun.lock) lockfiles, so existing Bun projects keep installing without changes.

Dive Deep

The natural worry is whether existing builds will suddenly break.

  • If your project already sets a version through an environment variable or a version file (.nvmrc, .node-version, .python-version, .ruby-version), builds keep using that version
  • To stay on a previous default, add the matching environment variable to your build configuration

For example, to keep the old Python default:

PYTHON_VERSION=3.13.3

See "Override default versions" and the build image policy in the docs for details.

Wrap-up

  • Default versions of Node.js, Python, Ruby, Go, Bun, Yarn, and Python package tooling were updated
  • The new defaults include Python 3.14.8, Go 1.27.2, and Bun 1.4.3
  • Projects that pin a version are unaffected
  • You can override with environment variables to return to the previous defaults

This one is for anyone deploying with Workers Builds, especially those waiting on newer Python or Go!

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