entrypoint: Launch our entrypoint via dumb-init

Even single process containers (which this one is actually not) should
have an init system. However most init systems are too big and complex
for containerization purposes. [Dumb-init][0] (and tini init) address
this problem _specifically_ for Docker containers.

See the [dumb-init][0] documentation for more details.

[0]: https://github.com/Yelp/dumb-init

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>

Author: oliv3r

Dockerfile-alpine-slim.template

@@ -99,6 +99,8 @@ RUN set -x \
 # forward request and error logs to docker log collector
     && ln -sf /dev/stdout /var/log/nginx/access.log \
     && ln -sf /dev/stderr /var/log/nginx/error.log \
+# Ensure we can run our entrypoint
+    && apk add --no-cache dumb-init \
 # create a docker-entrypoint.d directory
     && mkdir /docker-entrypoint.d
 

Dockerfile-alpine.template

@@ -75,4 +75,6 @@ RUN set -x \
     && if [ -n "/etc/apk/keys/abuild-key.rsa.pub" ]; then rm -f /etc/apk/keys/abuild-key.rsa.pub; fi \
     && if [ -n "/etc/apk/keys/nginx_signing.rsa.pub" ]; then rm -f /etc/apk/keys/nginx_signing.rsa.pub; fi \
 # Bring in curl and ca-certificates to make registering on DNS SD easier
-    && apk add --no-cache curl ca-certificates
+    && apk add --no-cache curl ca-certificates \
+# Ensure we can run our entrypoint
+    && apk add --no-cache dumb-init

Dockerfile-debian.template

@@ -82,6 +82,7 @@ RUN set -x \
                         $nginxPackages \
                         gettext-base \
                         curl \
+                        dumb-init \
     && apt-get remove --purge --auto-remove -y && rm -rf /var/lib/apt/lists/* /etc/apt/sources.list.d/nginx.list \
     \
 # if we have leftovers from building, let's purge them (including extra, unnecessary build deps)

entrypoint/docker-entrypoint.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/dumb-init /bin/sh
 # vim:sw=4:ts=4:et
 
 set -e