The dummy provider implements an environment provider for testing purposes, registered with environs under the name "dummy".
The configuration YAML for the testing environment must specify a "controller" property with a boolean value. If this is true, a controller will be started when the environment is bootstrapped.
The configuration data also accepts a "broken" property of type boolean. If this is non-empty, any operation after the environment has been opened will return the error "broken environment", and will also log that.
The DNS name of instances is the same as the Id, with ".dns" appended.
To avoid enumerating all possible series and architectures, any series or architecture with the prefix "unknown" is treated as bad when starting a new instance.