I have initialized https://hub.docker.com/r/jboss/keycloak/ on my Digital Ocean Docker Droplet.
$docker run -e KEYCLOAK_USER=admin -e -p 8080:8080 KEYCLOAK_PA
The following sequence of commands worked for me
On the host VM:
docker run --name key -d -p 8080:8080 -e KEYCLOAK_USER=admin -e KEYCLOAK_PASSWORD=admin jboss/keycloak
docker exec -it key bash
Inside the container:
cd keycloak/bin/
./kcadm.sh config credentials --server http://localhost:8080/auth --realm master --user admin
Logging into http://localhost:8080/auth as user admin of realm master
Enter password: admin
./kcadm.sh update realms/master -s sslRequired=NONE