add a healthcheck to the image and an HEALTHCHECK_PATH env var

Dockerfile

@@ -4,6 +4,7 @@ FROM php:${BASE_VERSION}-fpm-alpine
 
 # port to for the webserver
 ENV WEBSERVER_PORT=8080
+ENV HEALTHCHECK_PATH=""
 
 COPY start-container.sh /usr/local/bin/start-container
 
@@ -32,6 +33,9 @@ RUN apk add --no-cache \
     && docker-php-ext-install filter pdo_mysql \
     && chmod +x /usr/local/bin/start-container
 
+HEALTHCHECK --interval=5m --timeout=3s --start-period=5m --start-interval=10s \
+  CMD curl -f http://localhost/${HEALTHCHECK_PATH} || exit 1
+
 EXPOSE ${WEBSERVER_PORT}
 
 WORKDIR /var/www/html