make docker-build and make docker do not work on 9.0.2 branch

[werdnum]

make docker-build does not work, because it is hardcoded to Go 1.10, which doesn't seem to have support for pulling dependencies. Updating GOVERSION to 1.14.2 in Makefile does the trick.

make docker does not work because there is no Dockerfile.

A minimal working Dockerfile might look like this (if you add the static target as a dependency for docker in Makefile)

FROM alpine:3.11
ADD bin/keycloak-gatekeeper /usr/bin/keycloak-gatekeeper
ENTRYPOINT /usr/bin/keycloak-gatekeeper

[jangaraj]

You don't even need FROM alpine:3.11. Make static binary and you can use FROM scratch.

[ASzc]

Should be addressed by #638