Interpolation

how it works

Any string value in confit.toml can reference other values using {dotted.path} syntax:

[project]
name = "my-project"
domain = "example.com"

[services.web]
url = "https://{project.domain}"
description = "{project.name} web service"

When confit resolves services.web.url, it:

1. Finds the raw value: "https://{project.domain}"
2. Looks up project.domain in the config: "example.com"
3. Returns: "https://example.com"

recursive references

References can chain through multiple levels:

[vaults]
prod = "my-vault-production"

[credentials]
api_key = "op://{vaults.prod}/api-key/credential"

Resolving credentials.api_key:

1. Raw: "op://{vaults.prod}/api-key/credential"
2. Looks up vaults.prod: "my-vault-production"
3. Result: "op://my-vault-production/api-key/credential"

The interpolated value then goes through provider evaluation if providers are declared.

lazy evaluation

confit only interpolates the path you ask for. If you run:

confit resolve project.name

It does not interpolate credentials.api_key or any other value in the config. This means you can have values that reference unset variables, and they won’t cause errors unless you actually try to resolve them.

lists

List values stay as lists internally. When referenced in a string context, they’re joined with spaces:

[project]
users = ["admin", "deploy", "dev"]

[ansible]
user_list = "{project.users}"

$ confit resolve ansible.user_list
admin deploy dev

$ confit resolve project.users
admin deploy dev

cycle detection

Circular references are caught and reported:

[a]
x = "{b.y}"

[b]
y = "{a.x}"

$ confit resolve a.x
Error: Circular reference: a.x

regex

The interpolation token pattern is:

\{([a-zA-Z0-9_.]+)\}

Tokens must contain only letters, digits, underscores, and dots. This means {path.to.value} works but {path-to-value} does not match and is left as a literal string.