Chore(env) - Use nginx:mainline-alpine-slim instead of nginx:latest

Author: tarlepp

docker/nginx/Dockerfile

@@ -1,10 +1,10 @@
-FROM nginx:latest
+FROM nginx:mainline-alpine-slim
 
 ADD nginx.conf /etc/nginx/conf.d/default.conf
 ADD php-upstream.conf /etc/nginx/conf.d/upstream.conf
 
 # https://cloud.google.com/monitoring/agent/plugins/nginx
-RUN apt-get update && apt-get install -y curl
+RUN apk update && apk add curl
 RUN cd /etc/nginx/conf.d/ \
     && curl -O https://raw.githubusercontent.com/Stackdriver/stackdriver-agent-service-configs/master/etc/nginx/conf.d/status.conf \
-    && rm -rf /var/lib/apt/lists/*
+    && rm -rf /var/cache/apk/*

docker/nginx/Dockerfile_dev

@@ -1,4 +1,4 @@
-FROM nginx:latest
+FROM nginx:mainline-alpine-slim
 
 # Note that this `nginx-dev.conf` is also mounted within `compose.yaml`
 # so you don't need to build containers if you change something there, restart
@@ -7,7 +7,7 @@ ADD nginx-dev.conf /etc/nginx/conf.d/default.conf
 ADD php-upstream.conf /etc/nginx/conf.d/upstream.conf
 
 # https://cloud.google.com/monitoring/agent/plugins/nginx
-RUN apt-get update && apt-get install -y curl
+RUN apk update && apk add curl
 RUN cd /etc/nginx/conf.d/ \
     && curl -O https://raw.githubusercontent.com/Stackdriver/stackdriver-agent-service-configs/master/etc/nginx/conf.d/status.conf \
-    && rm -rf /var/lib/apt/lists/*
+    && rm -rf /var/cache/apk/*