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Includes

Use _include to merge additional config files. Includes load first, then the current file overrides. The merge strategy is:

• dicts merge recursively

• lists/scalars replace

_include:
  - base.yaml
  - prod.yaml

Paths are resolved relative to the including file.

Interpolation

Interpolation runs after includes and before resolution.

Resolution order

For each ${key} placeholder, Sygaldry resolves the value using the following priority:

1. Config path – if key exists as a dotted path in the merged config, that value is used.

2. Environment variable – if no config path matches, os.environ is checked.

3. Default – if a default is provided via ${key:-default} and neither config nor env matched, the default is used (and may itself contain nested placeholders).

If none of the above produce a value, an InterpolationError is raised.

Supported forms

• ${config.path} – value from merged config

• ${ENV_VAR} – environment variable (when not a config path)

• ${key:-default} – default when neither config nor env matches

• $${ – escape to a literal ${

• Nested placeholders are supported (e.g., ${DB_HOST:-${db.host}})

Type coercion

If the entire string is replaced by a single placeholder, Sygaldry will try to coerce the value to a scalar type (int, float, bool, or None).

Example

db:
  host: "localhost"
  port: "${DB_PORT:-5432}"
url: "postgres://${db.host}:${db.port}/app"