Check if image:tag combination already exists on docker hub
Update: Docker-Free solution see below
Using Docker
This is the solution I use with gitlab using the docker:stable image.
Login
docker login -u $USER -p $PASSWORD $REGISTRY
Check whether it's there:
docker manifest inspect $IMGNAME:$IMGTAG > /dev/null ; echo $?
docker will return 0 on success or 1 on failure.
If you get a warning: Update Docker or enable experimental client-features:
Set the environment variable DOCKER_CLI_EXPERIMENTAL
to enabled
(See Matěj's answer below)
Alternatively adjust the config (original answer):
echo '{"experimental": "enabled"}' > ~/.docker/config.json
This will also overwrite your config. If that is not an option you need to do that manually or use jq
, sed
or whatever you have available.
Update:If you don't have access to a docker-daemon, e.g. because you are building a docker image using kaniko within a docker, you can use the registry-api scripts provided by harbor. Note that they are python2.
Please try this one
function docker_tag_exists() { curl --silent -f -lSL https://index.docker.io/v1/repositories/$1/tags/$2 > /dev/null}if docker_tag_exists library/nginx 1.7.5; then echo existelse echo not existsfi
Update:
In case of usage Docker Registry v2 (based on this):
# set username and passwordUNAME="user"UPASS="password"function docker_tag_exists() { TOKEN=$(curl -s -H "Content-Type: application/json" -X POST -d '{"username": "'${UNAME}'", "password": "'${UPASS}'"}' https://hub.docker.com/v2/users/login/ | jq -r .token) curl --silent -f --head -lL https://hub.docker.com/v2/repositories/$1/tags/$2/ > /dev/null}if docker_tag_exists library/nginx 1.7.5; then echo existelse echo not existsfi
To build on morty's answer, notice that docker supports setting the experimental flag using environment variable:
DOCKER_CLI_EXPERIMENTAL
Enable experimental features for the cli (e.g.enabled
ordisabled
)
The snippet therefore becomes:
tag=somethingif DOCKER_CLI_EXPERIMENTAL=enabled docker manifest inspect $image:$tag >/dev/null; then Do nothingelse Build and push docker image with that tagfi