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

Summary

• Scope: spec
• Level: Developer Goal
• Actors: Dev-Ops Engineer
• Brief: This use case introduces a enum 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 log level in the dockerd configuration.
  • The configuration key is log/level.
  • The configuration key uses description, default and enum as metakeys.
  • The specification strictly defines all enum values debug, info, warn, error and fatal.
  • 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 log level configuration for the dockerd could look like:

[log/level]
meta:/description = Set the logging level
meta:/enum/check = #4
meta:/enum/check/#0 = debug
meta:/enum/check/#1 = info
meta:/enum/check/#2 = warn
meta:/enum/check/#3 = error
meta:/enum/check/#4 = fatal
meta:/default = info

In case the key log/level does not exist, spec plugin creates a default key with value info in the default namespace.

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