dockerfile - How does Docker name repositories? -


in directory called ringer i've created simple dockerfile install stuff , mount app... have never explicitly set name.

i used docker-compose.yml file define web , pointed @ dockerfile mentioned above.

when run docker images see following:

$ docker images repository                     tag                 image id            created             virtual size ringer_web                     latest              bf9b931e1030        8 minutes ago       938.9 mb 

it looks docker named image's repository after local directory , image name... question is, how docker choose name image's repository? (and if applicable, why)

from docs:

compose_project_name

sets project name, prepended name of every container started compose. defaults basename of current working directory.

btw, not docker, docker-compose deciding on name. change it, set compose_project_name before running docker-compose:

compose_project_name=myprefix docker-compose