Initial commit. Setup a centos7 image with postfix

Dockerfile

+FROM centos:centos7
+
+ENV MTP_HOST=fwd.example.com
+ENV MTP_PORT=25
+ENV MTP_USER=user
+ENV MTP_PASS=password
+
+RUN yum -y install postfix mailx cyrus-sasl cyrus-sasl-plain python-setuptools python-pip
+RUN curl https://bootstrap.pypa.io/get-pip.py | python -
+RUN pip install supervisor
+RUN mkdir -p /etc/supervisor.d/conf.d
+RUN echo_supervisord_conf > /etc/supervisord.conf
+RUN echo '[include]' >> /etc/supervisord.conf
+RUN echo 'files = supervisor/conf.d/*.conf' >> /etc/supervisord.conf
+
+RUN postconf -e "relayhost = [$MTP_HOST]:$MTP_PORT"
+RUN postconf -e 'smtp_sasl_auth_enable = yes'
+RUN postconf -e 'smtp_sasl_password_maps = hash:/etc/postfix/relay_passwd'
+RUN postconf -e 'smtp_sasl_security_options = noanonymous'
+RUN postconf -e 'smtp_tls_security_level = may'
+RUN touch /var/log/mail.log
+RUN mkdir -p /var/spool/postfix/public/
+RUN mkfifo /var/spool/postfix/public/pickup
+
+EXPOSE 25
+VOLUME ["/var/log", "/var/spool/postfix"]
+
+ADD postfix.sh /postfix.sh
+ADD supervisord.conf /etc/supervisor/conf.d/supervisord.conf
+CMD ["sh", "-c", "/usr/bin/supervisord""]
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postfix.sh

+#!/bin/bash
+
+# Set up user
+function setup_secret {
+    echo "$MTP_HOST   $MTP_USER:$MTP_PASS" > /etc/postfix/relay_passwd
+    postmap /etc/postfix/relay_passwd
+}
+
+setup_secret
+
+postfix start
+
+tail -f /var/log/mail.log

supervisord.conf

+[supervisord]
+nodaemon=true
+
+[program:postfix]
+command=/postfix.sh
+autostart=true
+autorestart=true
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