Docker build with Git command running in CircleCI failing with: Fatal: No names found, cannot describe anything, invalid argument, for "-t, --tag" flag: invalid reference format

Introduction

Context: Docker, CircleCI, Github.

The Docker build command 

docker build -f .circleci/Dockerfile -t $AWS_ACCOUNT_ID.ecr.$AWS_DEFAULT_REGION.amazonaws.com/${CIRCLE_PROJECT_REPONAME}:`git describe --tags` -t $AWS_ACCOUNT_ID.ecr.$AWS_DEFAULT_REGION.amazonaws.com/${CIRCLE_PROJECT_REPONAME}:${CIRCLE_BUILD_NUM} -t $AWS_ACCOUNT_ID.ecr.$AWS_DEFAULT_REGION.amazonaws.com/${CIRCLE_PROJECT_REPONAME}:${CIRCLE_SHA1} .

was failing with this message:

fatal: No names found, cannot describe anything.

invalid argument "********************************************/my-project:" for "-t, --tag" flag: invalid reference format

See 'docker build --help'.

Exited with code exit status 125

Solution

You'd expect the Docker command maybe being syntactically incorrect. But the error message is referring to something else: it turns out the git describe --tags command gave the fatal message.

The cause was that there was no git-tag set at all on the Github project yet.   After manually creating a release (including a tag) on Github and running the above build command again, the docker build command succeeded.