Add sites-enabled ENV variable interpolation

All credit to shepmaster/nginx-template-image for the implementation

README.md

@@ -12,6 +12,7 @@ Docker image for nginx. Both [mainline and stable][mainline-vs-stable] releases
 
 Differences from the [official Docker image][official-image]:
 
+* Enables environment variable interpolation in config files (thanks to scripts taken from [`shepmaster/nginx-template-image`][nginx-template-image])
 * Provides a *stable* tag (the official Docker nginx image only provides the mainline/development version of nginx).
 * Uses the Ubuntu PPA installation path, so there are some extra compiled modules available.
 * Sets `worker_processes` to `auto`. This value should typically be set to the number of cores on the machine.  Because the Debian/Ubuntu installers set this at install-time to a static value equal to the detected number of cores on the machine, many Docker images get this wrong.  `auto` means nginx will attempt to detect the number of cores when nginx starts up.
@@ -62,6 +63,8 @@ example.com
 $ docker run -v /tmp/sites-enabled:/data/sites-enabled:ro abevoelker/nginx
 ```
 
+If you need environment variable interpolation in your site configs, put the files in `/data/sites-templates` with a `.tmpl` extension and they will be copied to `/data/sites-enabled/` with the `.tmpl` extension removed.  See [`shepmaster/nginx-template-image`][nginx-template-image] for more info.
+
 ### nginx.conf
 
 If you have a custom `nginx.conf`, just mount it to `/data/conf/nginx.conf`:
@@ -102,3 +105,4 @@ MIT license.
 
 [mainline-vs-stable]: http://nginx.com/blog/nginx-1-6-1-7-released/
 [official-image]: https://github.com/nginxinc/docker-nginx
+[nginx-template-image]: https://github.com/shepmaster/nginx-template-image

mainline/Dockerfile

@@ -4,6 +4,9 @@ MAINTAINER Abe Voelker <[email protected]>
 # Provide a custom nginx.conf, tweaked for Docker use
 COPY nginx.conf /data/conf/
 
+# Add nginx templating helper scripts
+COPY bin/ /usr/sbin/
+
 # Ensure UTF-8 locale
 COPY locale /etc/default/locale
 RUN \
@@ -20,13 +23,17 @@ RUN \
   DEBIAN_FRONTEND=noninteractive apt-get install -y nginx &&\
 # Copy default config files to /data
   /bin/bash -c "cp -a /etc/nginx/{conf.d,sites-enabled} /data/" &&\
+# Create /data/sites-templates directory
+  mkdir /data/sites-templates &&\
+  chmod 0755 /data/sites-templates &&\
 # Clean up APT and temporary files when done
   apt-get clean &&\
   DEBIAN_FRONTEND=noninteractive apt-get remove --purge -y software-properties-common &&\
   rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
 VOLUME ["/var/cache/nginx", "/var/log/nginx"]
 
+ENTRYPOINT ["entrypoint.sh"]
 CMD ["nginx", "-c", "/data/conf/nginx.conf"]
 
 EXPOSE 80 443

mainline/bin/entrypoint.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+set -eu
+
+render-templates.sh /data/sites-templates /data/sites-enabled
+exec $@

mainline/bin/render-templates.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+set -eu
+
+indir="${1}"
+outdir="${2}"
+
+function template_files() {
+    find "${indir}" \
+        -mindepth 1 \
+        -maxdepth 1 \
+        -name '*.tmpl' \
+        -print0
+}
+
+function non_template_files() {
+    find "${indir}" \
+        -mindepth 1 \
+        -maxdepth 1 \
+        -not \
+        -name '*.tmpl' \
+        -print0
+}
+
+rm -rf "${outdir}"
+mkdir -p "${outdir}"
+template_files | xargs -0 substitute-env-vars.sh "${outdir}"
+non_template_files | xargs -0 -I{} ln -s {} "${outdir}"

mainline/bin/substitute-env-vars.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+set -eu
+
+output_dir=$1
+shift
+files=$@
+
+function fill_in() {
+    perl -p -e 's/\$\{([^}]+)\}/defined $ENV{$1} ? $ENV{$1} : "\${$1}"/eg' "${1}"
+}
+
+function output_filename {
+    local destname=$(basename "${1}" '.tmpl')
+    echo "${output_dir}/${destname}"
+}
+
+for file in $files; do
+    fill_in "${file}" > $(output_filename "${file}")
+done

stable/Dockerfile

@@ -4,6 +4,9 @@ MAINTAINER Abe Voelker <[email protected]>
 # Provide a custom nginx.conf, tweaked for Docker use
 COPY nginx.conf /data/conf/
 
+# Add nginx templating helper scripts
+COPY bin/ /usr/sbin/
+
 # Ensure UTF-8 locale
 COPY locale /etc/default/locale
 RUN \
@@ -20,13 +23,17 @@ RUN \
   DEBIAN_FRONTEND=noninteractive apt-get install -y nginx &&\
 # Copy default config files to /data
   /bin/bash -c "cp -a /etc/nginx/{conf.d,sites-enabled} /data/" &&\
+# Create /data/sites-templates directory
+  mkdir /data/sites-templates &&\
+  chmod 0755 /data/sites-templates &&\
 # Clean up APT and temporary files when done
   apt-get clean &&\
   DEBIAN_FRONTEND=noninteractive apt-get remove --purge -y software-properties-common &&\
   rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*
 
 VOLUME ["/var/cache/nginx", "/var/log/nginx"]
 
+ENTRYPOINT ["entrypoint.sh"]
 CMD ["nginx", "-c", "/data/conf/nginx.conf"]
 
 EXPOSE 80 443

stable/bin/entrypoint.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+set -eu
+
+render-templates.sh /data/sites-templates /data/sites-enabled
+exec $@

stable/bin/render-templates.sh

@@ -0,0 +1,28 @@
+#!/bin/bash
+
+set -eu
+
+indir="${1}"
+outdir="${2}"
+
+function template_files() {
+    find "${indir}" \
+        -mindepth 1 \
+        -maxdepth 1 \
+        -name '*.tmpl' \
+        -print0
+}
+
+function non_template_files() {
+    find "${indir}" \
+        -mindepth 1 \
+        -maxdepth 1 \
+        -not \
+        -name '*.tmpl' \
+        -print0
+}
+
+rm -rf "${outdir}"
+mkdir -p "${outdir}"
+template_files | xargs -0 substitute-env-vars.sh "${outdir}"
+non_template_files | xargs -0 -I{} ln -s {} "${outdir}"

stable/bin/substitute-env-vars.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+
+set -eu
+
+output_dir=$1
+shift
+files=$@
+
+function fill_in() {
+    perl -p -e 's/\$\{([^}]+)\}/defined $ENV{$1} ? $ENV{$1} : "\${$1}"/eg' "${1}"
+}
+
+function output_filename {
+    local destname=$(basename "${1}" '.tmpl')
+    echo "${output_dir}/${destname}"
+}
+
+for file in $files; do
+    fill_in "${file}" > $(output_filename "${file}")
+done