adds Healthcheck fixes #29 (#30)

Author: normanrz

Dockerfile

@@ -13,4 +13,14 @@ RUN groupadd -r fossildb \
   && chmod 777 . \
   && chown -R fossildb .
 
+RUN GRPC_HEALTH_PROBE_VERSION=v0.2.0 && \
+  wget -qO/bin/grpc_health_probe https://github.com/grpc-ecosystem/grpc-health-probe/releases/download/${GRPC_HEALTH_PROBE_VERSION}/grpc_health_probe-linux-amd64 && \
+  chmod +x /bin/grpc_health_probe
+
+EXPOSE 7155
+
+HEALTHCHECK \
+  --interval=2s --timeout=5s --retries=30 \
+  CMD /bin/grpc_health_probe -addr=:7155
+
 CMD [ "fossildb" ]