Bitbucket Pipelines is rolling out a cutting-edge runtime upgrade that vastly improves build performance and capacity. Debuting larger 4x and 8x step sizes with scalable CPU and memory resources, this update promises accelerated continuous integration workloads without downtime.
- New runtime supports 4x and 8x step sizes with scalable CPU and memory
- Upcoming migration of 1x and 2x steps to new runtime planned for September
- IP allow-lists may require updating due to new cloud infrastructure addresses
What happened
Atlassian announced a major upgrade to the underlying runtime powering Bitbucket Pipelines. The new runtime leverages microVM technology and runc to better allocate compute resources, allowing larger build steps with more CPU cores and increased memory. This enables developers to run faster and more demanding CI/CD workloads.
The initial rollout focuses on 4x and 8x sized steps, available starting in June. Smaller step sizes (1x and 2x) will be transitioned to the new runtime in September. This phased migration ensures there is no downtime and that users can benefit from the performance improvements without service interruptions.
Why it matters
Previously, scaling step sizes in Bitbucket Pipelines only increased memory, not CPU, limiting the speed gains available for more intensive builds. With this update, CPU resources now scale alongside memory for larger steps, delivering significantly faster build times and allowing for larger builds to run efficiently in the cloud.
This advancement supports the evolving needs of development teams who require robust CI/CD infrastructure to accelerate software delivery. Additionally, the migration to AWS-managed IP addresses improves the reliability and security of pipeline executions, although it requires some users to update their firewall and network policies.
What to watch next
Users should prepare for the September migration when 1x and 2x steps will move to the new runtime and start using AWS-associated IP ranges. Organizations with strict network access controls will need to adjust their allow-lists accordingly to avoid disruptions.
Atlassian plans to introduce dedicated node pools for 4x and 8x steps with restricted persistent IP address ranges to accommodate sensitive security environments. Further enhancements like ARM and multi-architecture builds are also expected to build on this new runtime, expanding Bitbucket Pipelines' capabilities in the near future.