Restore SMTPHOST sendmail functionality

Author: decafdennis

Dockerfile

@@ -53,6 +53,12 @@ RUN apt-get update \
   && rm -rf /var/lib/apt/lists/* \
   && apt-get purge -y --auto-remove
 
+# TODO: Figure out why Debian's BusyBox does not include sendmail.
+# TODO: Verify integrity of this download.
+RUN curl https://www.busybox.net/downloads/binaries/1.26.2-defconfig-multiarch/busybox-x86_64 > /usr/local/bin/busybox \
+  && chmod a+x /usr/local/bin/busybox \
+  && ln -s /usr/local/bin/busybox /usr/local/bin/sendmail
+
 RUN curl -fL https://getcomposer.org/installer | php -- \
     --install-dir=/usr/local/bin \
     --filename=composer

README.md

@@ -4,6 +4,6 @@
 
 [Docker Hub](https://hub.docker.com/r/digdep/drupal-base/)
 
-This is a base image for running Drupal 8 in development. It does not come with Drupal itself, but it does come with a properly configured NGINX (stable), PHP-FPM (7.1), Composer, Drush, Terminus, dependencies for Cypress, and dependencies for CircleCI 2.0.
+This is a base image for running Drupal 8 in development. It does not come with Drupal itself, but it does come with a properly configured NGINX (stable), PHP-FPM (7.1), Composer, Drush, Terminus, BusyBox sendmail (so you can set the `SMTPHOST` env variable to e.g. a MailHog container) dependencies for Cypress, and dependencies for CircleCI 2.0.
 
 See `docker-compose.example.yml` for how to use.