This has started happening recently after a docker update on my Macbook. I am using Docker version 17.03.0-ce-mac2 on macos-sierra.
If I run a docker build -t . from a terminal I get a pop-up warning which says:
docker-credential-osxkeychain wants to use your confidential information stored in mydomain.com in your keychain.
Do you want to allow access to this item?
If I click 'deny' everything continues as normal without any issues. But I have to do this every time.
What does this mean ?
It looks like it was a bug in this particular release of Docker and that the new release 17.03.1-ce-mac5 is solving this issue. There is a reference in the release notes: https://github.com/docker/docker-credential-helpers/releases/tag/v0.5.0
I just installed this release and I don't have this behaviour on my El Capitan install.