Use a final stage instead that never gets uploaded to the container registry.

LinuxGeneralCompiler/FinalStage/Dockerfile

@@ -0,0 +1,14 @@
+FROM git.zontreck.com/ariascreations/buildenvironments:linux
+
+WORKDIR /root/.gradle
+ADD ./secret/gradle.properties ./gradle.properties
+
+WORKDIR /root/.ssh
+ADD ./secret/id_rsa ./id_rsa
+ADD ./secret/id_rsa.pub ./id_rsa.pub
+
+RUN chmod 0600 id_rsa
+
+WORKDIR /
+
+ENTRYPOINT [ "/bin/bash", "/entrypoint.sh" ]