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

Summary

• Scope: spec
• Level: Developer Goal
• Actors: Dev-Ops Engineer
• Brief: This use case introduces an underline 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 runtimes in the dockerd configuration file.
  • The underline specification configuration keys are runtimes/_, runtimes/_/path, runtimes/_/runtimeArgs/#.
  • The specification uses type, description and example as metakeys.
  • The underline configuration is defined by the wildcard character _.
  • The keys are all stored for the spec namespace.
• Alternative scenario:
  • Define the storage type with an array specification.
  • The array specification configuration keys are runtimes/#, runtimes/#/path, runtimes/#/runtimeArgs/#.
  • The configuration key runtimes/# uses array/min, description and example as metakeys.
  • The configuration key runtimes/#/path uses type, description and example.
  • The configuration key runtimes/#/runtimeArgs/# still uses array/min, description and example.
• 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 runtimes configuration for the dockerd could look like:

[runtimes/_]
meta:/type = string
meta:/description = Additional OCI compatible runtime
meta:/example = custom
 
[runtimes/_/path]
meta:/type = string
meta:/description = The path to the OCI compatible runtime
meta:/example = /usr/local/bin/my-runc-replacement
 
[runtimes/_/runtimeArgs/#]
meta:/array/min = 0
meta:/description = The runtime arguments for the OCI compatible runtime
meta:/example = --debug

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