docker: add healthchecks

Author: MNThomson

Dockerfile

@@ -80,14 +80,14 @@ RUN adduser --system --home /var/lib/sqld --uid 666 --gid 666 sqld
 WORKDIR /var/lib/sqld
 USER sqld
 
-COPY docker-entrypoint.sh /usr/local/bin
-COPY docker-wrapper.sh /usr/local/bin
+COPY docker-entrypoint.sh docker-wrapper.sh docker-healthcheck.sh /usr/local/bin
 
 COPY --from=gosu /usr/local/bin/gosu /usr/local/bin/gosu
 COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
 COPY --from=builder /target/release/sqld /bin/sqld
 
 USER root
 
+HEALTHCHECK --interval=2s CMD /usr/local/bin/docker-healthcheck.sh
 ENTRYPOINT ["/usr/local/bin/docker-wrapper.sh"]
 CMD ["/bin/sqld"]

Dockerfile.dev

@@ -52,21 +52,22 @@ FROM debian:bullseye-slim
 RUN apt update
 
 EXPOSE 5001 8080
+
 VOLUME [ "/var/lib/sqld" ]
 
 RUN groupadd --system --gid 666 sqld
 RUN adduser --system --home /var/lib/sqld --uid 666 --gid 666 sqld
 WORKDIR /var/lib/sqld
 USER sqld
 
-COPY docker-entrypoint.sh /usr/local/bin
-COPY docker-wrapper.sh /usr/local/bin
+COPY docker-entrypoint.sh docker-wrapper.sh docker-healthcheck.sh /usr/local/bin
 
 COPY --from=gosu /usr/local/bin/gosu /usr/local/bin/gosu
 COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
 COPY --from=builder /sqld/bin /bin/sqld
 
 USER root
 
+HEALTHCHECK --interval=2s CMD /usr/local/bin/docker-healthcheck.sh
 ENTRYPOINT ["/usr/local/bin/docker-wrapper.sh"]
 CMD ["/bin/sqld"]

docker-healthcheck.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+SQLD_HTTP_LISTEN_ADDR="${SQLD_HTTP_LISTEN_ADDR:-"0.0.0.0:8080"}"
+SQLD_HTTP_LISTEN_ADDR="${SQLD_HTTP_LISTEN_ADDR//:/\/}"
+
+exec 3<>"/dev/tcp/$SQLD_HTTP_LISTEN_ADDR"
+echo -e "GET /health HTTP/1.1\r\nConnection: close\r\n\r\n" >&3
+RESPONSE=$(cat <&3)
+exec 3<&- && exec 3>&-
+
+if echo "$RESPONSE" | grep -q "HTTP/1.1 200 OK"; then
+    exit 0
+else
+    echo "Did not receive HTTP 200 response"
+    echo "$RESPONSE"
+    exit 1
+fi