Plugins/docker git tag

Drone Support
1 
kind: pipeline
name: default

steps:
- name: publish
  image: plugins/docker
  settings:
    registry: registry.haitanyule.com
    repo: registry.haitanyule.com/b3log/pipe
    username:
      from_secret: REGISTRY_USER
    password:
      from_secret: REGISTRY_PASSWORD
    tags:
      - latest
      - ${DRONE_TAG}
  when:
    event:
    - tag

error logs

+ /usr/local/bin/docker build --rm=true -f Dockerfile -t . --pull=true --label org.label-schema.schema-version=1.0 --label org.label-schema.build-date=2018-12-14T17:02:47Z --label org.label-schema.vcs-ref= --label org.label-schema.vcs-url=http://git.haitanyule.com/docker/pipe.git
invalid argument "" for "-t, --tag" flag: invalid reference format
See 'docker build --help'.
time="2018-12-14T17:02:47Z" level=fatal msg="exit status 125"
2

What is the value of tag when you push it? I could be wrong, but try wrapping {DRONE_TAG} in quotes, in case it's being loaded as a number. `- "{DRONE_TAG}"`

3 
git tag 1.8.4
git push origian 1.8.4

or

git tag v1.8.4
git push origin v1.8.4

same error logs

WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled
+ /usr/local/bin/docker build --rm=true -f Dockerfile -t . --pull=true --label org.label-schema.schema-version=1.0 --label org.label-schema.build-date=2018-12-15T03:41:18Z --label org.label-schema.vcs-ref= --label org.label-schema.vcs-url=http://git.haitanyule.com/docker/pipe.git
invalid argument "" for "-t, --tag" flag: invalid reference format
See 'docker build --help'.
time="2018-12-15T03:41:18Z" level=fatal msg="exit status 125"