> ## Documentation Index
> Fetch the complete documentation index at: https://porter-gk-forward-auth.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# App metadata environment variables

> Reference for default environment variables Porter injects into every app, including CPU, RAM, replicas, pod IP, image tag, and domains

Porter injects some default environment variables in all Porter-provisioned apps, containing basic metadata around your app and the current deployment revision. A full list of these environment variables may be found here:

1. `PORTER_RESOURCES_RAM` - The amount of RAM assigned to the current service.
2. `PORTER_RESOURCES_CPU` - The number of vCPU cores assigned to the current service.
3. `PORTER_RESOURCES_REPLICAS` - The static replica count for the current service. Note that this may differ from the actual number of replicas running, if you have autoscaling enabled.
4. `PORTER_NODE_NAME` - The node the current service replica is running on.
5. `PORTER_NODE_IP` - The internal IP of the node the current service replica is running on.
6. `PORTER_POD_NAME` - This is the same as the internal hostname for the current service replica.
7. `PORTER_POD_IP` - The internal private IP assigned to the current service replica.
8. `PORTER_POD_IMAGE_TAG` - The image tag being used to run the current service replica. This is typically the same as `PORTER_IMAGE_TAG`.
9. `PORTER_IMAGE_TAG` - The image tag being used for the current app. This is typically the same as `PORTER_POD_IMAGE_TAG`.
10. `PORTER_POD_REVISION` - The revision ID assigned to the latest app deployment by Porter.
11. `PORTER_APP_SERVICE_NAME` - A portmanteau of the app name and service name: `<APP>-SERVICE`.
12. `PORTER_DOMAINS` - A comma-separated list of the domains assigned to your service.

The following environment variables are only injected into [preview environments](/preview-environments/overview):

13. `PORTER_PR_BRANCH` - The git branch (head ref) of the pull request that created the preview environment.
14. `PORTER_PR_NUMBER` - The number of the pull request that created the preview environment.
15. `PORTER_PR_NAMESPACE` - The Kubernetes namespace of the preview environment. Use this when constructing in-cluster DNS names for services in the same preview, e.g. `<service>.$PORTER_PR_NAMESPACE.svc.cluster.local`. Prefer this over `PORTER_PR_BRANCH`, which is the raw branch name and is not a valid DNS label for long or non-conforming branch names.

If you're looking at adding more metadata to logs or traces, these environment variables can be used to inject metadata about the origin of a log/trace into your observability tooling.