Add 'tini' as init process for docker

Author: mrdimidium

Dockerfile

@@ -58,11 +58,18 @@ RUN make build
 
 FROM debian:stable-slim
 
+RUN apt-get update -yq && \
+    apt-get install -yq tini
+
 # copy ca certificates
 COPY --from=0 /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
 
 COPY --from=0 /browser/zig-out/bin/lightpanda /bin/lightpanda
 
 EXPOSE 9222/tcp
 
+# Lightpanda install only some signal handlers, and PID 1 doesn't have a default SIGTERM signal handler.
+# Using "tini" as PID1 ensures that signals work as expected, so e.g. "docker stop" will not hang.
+# (See https://github.com/krallin/tini#why-tini).
+ENTRYPOINT ["/usr/bin/tini", "--"]
 CMD ["/bin/lightpanda", "serve", "--host", "0.0.0.0", "--port", "9222"]