paas-config.yaml file

The optional paas-config.yaml file configures runtime behavior in experimental 12-factor app charms targeting Ubuntu 26.04 LTS. Place the file in the charm folder right beside charmcraft.yaml.

When the file exists, the extension adds a config part that stages paas-config.yaml into the charm. When the file doesn’t exist, the extension doesn’t generate the part. For bases 24.04 LTS and 22.04 LTS, the extension doesn’t stage the file through a separate config part.

Charmcraft validation

Charmcraft validates the following properties when it expands the extension with base 26.04 LTS during charmcraft pack or charmcraft expand-extensions:

  • The file contains valid YAML.

  • The top-level value is a mapping.

  • framework_logging_format: json is used only with Flask, Django, or FastAPI.

  • port and metrics-port are integers from 1 through 65535.

  • metrics-path is a string that starts with / and is a valid RFC 3986 URL path.

The public top-level spellings are port, metrics-port, and metrics-path. Charmcraft doesn’t validate other paas-charm settings beyond YAML structure and the framework logging compatibility check.

For example:

paas-config.yaml
port: 8080
metrics-port: 9102
metrics-path: /metrics
framework_logging_format: json

The paas-config reference defines runtime defaults, framework behavior, and the rest of the schema.