refs #31595: remove example, update README

README.md

@@ -2,7 +2,7 @@
 
 Available tags: [latest](https://github.com/eea/eea.docker.postfix/blob/master/Dockerfile), [eionet](https://github.com/eea/eea.docker.postfix/blob/master/eionet/Dockerfile).
 
-This image is a CentOS 6 container running postfix preconfigured for SMTP relay authentication. It runs as an open relay mail server inside the Docker Containers internal network, so it can be used by any container to send emails through the remote relay.
+This image is a CentOS 7 container running postfix preconfigured for SMTP relay authentication. It runs as an open relay mail server inside the Docker Containers internal network, so it can be used by any container to send emails through the remote relay.
 
 The hostname of the postfix server is set in the environment variable `MTP_HOST` and is mandatory. Postfix will run as an open relay server only if the variables below are also set.
 
@@ -23,37 +23,20 @@ Using the mount directive ```-v /etc/localtime:/etc/localtime:ro``` will make su
 
 ## Example usage
 
-In the `example` folder, there is an example centos container than can be used to test connectivity.
-    
-    cd example
-    docker build -t example .
-    docker run --rm -it -v /etc/localtime:/etc/localtime:ro --link=postfix:postfixcontainer example
-    
-    # from commandline:
-    $ mail test@example.com
-    
+From the postfix container ("postfix"):
+
     # from an application, python:
     $ python
-    Python 2.6.6 (r266:84292, Jan 22 2014, 09:42:36) 
-    [GCC 4.4.7 20120313 (Red Hat 4.4.7-4)] on linux2
-    Type "help", "copyright", "credits" or "license" for more information.
-    >>> import smtplib
-    >>> s = smtplib.SMTP('postfixcontainer')
+    >>> import smtplib, os
+    >>> s = smtplib.SMTP(os.getenv('HOSTNAME'))
     >>> s.sendmail('test@mydomain.com', ['user@example.com'], 'test')
-    {}
-
-## Existing container configuration
-
-If you have an existing container that makes use of `/usr/bin/sendmail` to send emails, and you want to use this postfix image instead, you must modify your `Dockerfile` to :
 
-Install mailx/ssmtp:
+From another application container ("app"):
 
-    # RUN apt-get install -y mailx ssmtp
-    or
-    # RUN yum install -y mailx ssmtp
-    
-Modify and copy / mount the `/etc/ssmtp.conf` file (see: https://github.com/eea/eea.docker.postfix/blob/master/example/ssmtp.conf). Change `mailhub` directive to the name of the postfixcontainer.
+    docker run --rm -it -v /etc/localtime:/etc/localtime:ro --name=app --link=postfix:postfixcontainer app_image
 
-    # ADD ssmtp.conf /etc/ssmtp.conf
-    
-You can check the example image for more details.
+    # from an application, python:
+    $ python
+    >>> import smtplib
+    >>> s = smtplib.SMTP('postfixcontainer')
+    >>> s.sendmail('test@mydomain.com', ['user@example.com'], 'test')

example/Dockerfile

-FROM centos:6
-
-RUN yum install -y mailx ssmtp
-
-ADD ssmtp.conf /etc/ssmtp/ssmtp.conf
-
-CMD ["bash"]

example/ssmtp.conf

-#
-# /etc/ssmtp.conf -- a config file for sSMTP sendmail.
-#
-# See the ssmtp.conf(5) man page for a more verbose explanation of the
-# available options.
-#
-
-# The person who gets all mail for userids < 500
-# Make this empty to disable rewriting.
-root=postmaster
-
-# The place where the mail goes. The actual machine name is required
-# no MX records are consulted. Commonly mailhosts are named mail.domain.com
-# The example will fit if you are in domain.com and your mailhub is so named.
-mailhub=postfixcontainer
-
-# Where will the mail seem to come from?
-#RewriteDomain=
-
-# The full hostname
-#Hostname=
-
-# Set this to never rewrite the "From:" line (unless not given) and to
-# use that address in the "from line" of the envelope.
-FromLineOverride=YES
-