Docker error: invalid reference format: repository name must be lowercase

Question

Ran into this Docker error with one of my projects:

invalid reference format: repository name must be lowercase

What are the various causes for

Answer 1

Let me emphasise that Docker doesn't even allow mixed characters.

Good: docker build -t myfirstechoimage:0.1 .

Bad: docker build -t myFirstEchoImage:0.1 .

Answer 2

On MacOS when your are working on an iCloud drive, your $PWD will contain a directory "Mobile Documents". It does not seem to like the space!

As a workaround, I copied my project to local drive where there is no space in the path to my project folder.

I do not see a way you can get around changnig the default path to iCloud which is ~/Library/Mobile Documents/com~apple~CloudDocs

The space in the path in "Mobile Documents" seems to be what docker run does not like.

Answer 3

For me the issue was with the space in volume mapping that was not escaped. The jenkins job which was running the docker run command had a space in it and as a result docker engine was not able to understand the docker run command.

Answer 4

In my case, the image name defined in docker-compose.yml contained uppercase letters. The fact that the error message mentioned repository instead of image did not help describe the problem and it took a while to figure out.