| Elektra 0.11.0

Use Case: Create simple specification for dockerd configuration file (daemon.json)

# Summary

- Scope: `spec`
- Level: Developer Goal
- Actors: Dev-Ops Engineer
- Brief: This use case introduces a simple specification for a part of the dockerd configuration file (daemon.json).

# Scenarios

- Precondition: The Dev-Ops Engineer has a working setup for `docker` and the daemon `dockerd`.
- Main success scenario:
  - The Dev-Ops Engineer wants to write a specification for the `default runtime` in the `dockerd` configuration.
  - The configuration key is `default/runtime`.
  - The configuration key uses `type`, `description` and `default` as metakeys.
  - The keys are all stored for the `spec` namespace.
- Alternative scenario: None.
- Error scenario:
  - Wrong metakeys are used (yielded as error to the user).
- Postcondition: The keys are all stored for the `spec` namespace..
- Non-functional Constraints: None.

# Example

The `default runtime` configuration for the `dockerd` could look like:

[default/runtime]
meta:/type = string
meta:/description = Default OCI runtime for containers
meta:/default = runc

In case the key `default/runtime` does not exist, `spec` plugin creates a `default` key with value `runc` in the default namespace.

For the full specification of the `dockerd` configuration file see dockerd-spec.