Cloud Run services by default operate within the first generation execution environment, which features fast cold start times and emulation of most, but not all operating system calls. Originally, this was the only execution environment available to services in Cloud Run.
The second generation execution environment provides full Linux compatibility rather than system call emulation. This execution environment provides:
- Faster CPU performance
- Faster network performance, especially in the presence of packet loss
- Full Linux compatibility, including support for all system calls, namespaces, and cgroups
- Network file system support
Although the second generation execution environment generally performs faster under sustained load, it has longer cold start times than first generation for most services.
You can select the execution environment for your Cloud Run service when you deploy a new service or a new revision of your service. If you don't specify an execution environment, first generation is used by default.
How to choose an execution environment
You should use first generation if any of the following apply:
- Your Cloud Run service has bursty traffic, and needs to scale out fast to many instances, or your service is sensitive to cold start times.
- Your Cloud Run service has infrequent traffic that causes frequent scale out from zero.
- You want to use less than 512 MiB of memory. The second generation execution environment requires at least 512 MiB of memory.
You should use second generation if any of the following apply to your Cloud Run service:
- Your service needs to use a network file system, which is only supported by second generation.
- Your service has fairly steady traffic and is tolerant of somewhat slower cold starts.
- Your service has CPU-intensive workloads.
- Your service could benefit from faster network performance.
- Your service needs to use software that has issues running in first generation due to unimplemented system calls.
- Your service needs Linux cgroup functionality.
Best practices when using the second generation execution environment
We recommend that your container install a SIGTERM handler, especially if you are using the CPU On-Demand billing model.
Handling SIGTERM gives your container a chance to perform any necessary cleanup tasks such as flushing logs before exiting. If your container does not catch SIGTERM, it will still be given 10 seconds to perform these tasks; those 10 seconds are billable.
How to check whether your container handles SIGTERM
To determine whether your container has a SIGTERM handler installed:
Start Cloud Shell. You can find Activate Cloud Shell in the header of the documentation page you're on. You may need to authorize it and wait for it to provision. Alternatively, start a standalone session.
Run the container locally in Cloud Shell:
docker run IMAGE_URL
Replace IMAGE_URL with a reference to the container image, for example,
us-docker.pkg.dev/cloudrun/container/hello:latest. If you use Artifact Registry, the repository REPO_NAME must already be created. The URL has the shape
Open another tab in Cloud Shell and get a list of the containers running in the current Cloud Shell session:
docker container ls
You need to locate the container ID returned from the command.
Using the container ID, send your container a SIGTERM signal
docker kill -s SIGTERM CONTAINER_ID
Return to the tab where you invoked
docker runto see whether the container has exited (stopped). If the SIGTERM signal caused your container to exit, your container is handling SIGTERM.
How to handle SIGTERM
If your container does not handle SIGTERM, the simplest way to add a SIGTERM
handler is to wrap your service with
tini. Doing this makes your service run
as a subprocess of
tini, which takes on the role of the container init process.
Refer to the Docker instructions
Alternatively, you can change your application to directly handle SIGTERM.
- To specify an execution environment for your Cloud Run services, refer to Select an execution environment.
- To specify memory for your for your Cloud Run services, refer to Memory limits.
- To use Filestore with Cloud Run, refer to Using Filestore with Cloud Run.
- To use Cloud Storage FUSE with Cloud Run, refer to Using Cloud Storage FUSE with Cloud Run.
- To use use network file systems such as NFS, NDB, 9P, CIFS/Samba, and Ceph
with Cloud Run, refer to Using network file systems