Now from docker client you can simply search your private registry directly without using the HTTP APIs or any extra tools:

e.g. searching for centos image:

docker search localhost:5000/centos

So I know this is a rapidly changing field but (as of 2015-09-08) I found the following in the Docker Registry HTTP API V2:

Listing Repositories (link)

GET /v2/_catalog

Listing Image Tags (link)

GET /v2/<name>/tags/list

Based on that the following worked for me on a local registry (registry:2 IMAGE ID 1e847b14150e365a95d76a9cc6b71cd67ca89905e3a0400fa44381ecf00890e1 created on 2015-08-25T07:55:17.072):

$ curl -X GET http://localhost:5000/v2/_catalog{"repositories":["ubuntu"]}$ curl -X GET http://localhost:5000/v2/ubuntu/tags/list{"name":"ubuntu","tags":["latest"]}

As of v 0.7.0 of the private registry you can do:

$ curl -X GET http://localhost:5000/v1/search?q=postgresql

and you will get a json payload:

{"num_results": 1, "query": "postgresql", "results": [{"description": "", "name": "library/postgresql"}]}

to give more background here is how I started my registry:

docker run \        -e SETTINGS_FLAVOR=local \        -e STORAGE_PATH=/registry \        -e SEARCH_BACKEND=sqlalchemy \        -e LOGLEVEL=DEBUG \        -p 5000:5000 \        registry