Create a temporary admin user for Keycloak running on Docker

If you lose your admin password, these steps will create a new temporary user that will allow you to login:

$ docker exec -it keycloak-keycloak-1 bash
bash-5.1$ find / -name kc.sh
/opt/keycloak/bin/kc.sh
bash-5.1$ export PASS_VAR=somepassword
bash-5.1$ /opt/keycloak/bin/kc.sh bootstrap-admin user --username tmpadm --password:env PASS_VAR