We're making an important change to custom runtimes. On August 1st, 2025, we'll disable support for our microVM-backed custom runtimes and recommend that all users transition to our V8-based runtime engine.
Our V8-based custom runtimes offer significant improvements over those based on our microVM engine:
- Faster startup times - V8 runtimes spin up much quicker than microVM-based ones.
- Faster build times - Creating V8 custom runtimes is 10x faster than microVM runtimes.
- Easier self-hosting - V8-based runtimes run within our self-hosted offering.
What's changing
Starting today, July 2nd, 2025:
- New custom runtimes will default to the V8 engine instead of the microVM engine
Starting August 1st, 2025:
- Creating and using microVM runtimes will be disabled.
Migration timeline
Today - July 2nd: Organizations currently using microVM runtimes can continue using them while preparing for migration
August 1st: MicroVM runtimes will be disabled for all accounts except those in our transition program
How to migrate
We've prepared a migration guide to help you switch from microVM to V8 custom runtimes. The process involves:
- Reviewing your current custom runtime packages - Check which dependencies you're using in any microVM-based custom runtimes
- Creating new V8-based runtimes - Build equivalent runtimes using the V8 engine
- Testing your code - Ensure your applications work with the new runtime
- Updating your API calls - Switch to using the new runtime revision IDs
Need help?
We're here to support you through this transition. If you need assistance with migration, please send us a message on Discord or email us at hello@riza.io. We'll also proactively reach out to affected customers.
Wrapping up
We understand that deprecating features is often disruptive, and we don't take this decision lightly.
We're committed to making this transition as smooth as possible. If you have any questions or concerns, please don't hesitate to reach out.