Docker

An Ubuntu 14.04 mail server configured with the guide from DigitalOcean or Linode. Any other MySQL configuration requires edits to PostMaster's database models. Paid support for this is available.
A working Docker host

Start by logging into the MySQL server that your mail server uses:
```
mysql -u root -p
```
Once you've logged into MySQL, create a PostMaster MySQL user that has privileges to edit the tables for the servermail database. Make sure to replace 'docker.postmaster.local' with your Docker host's IP address or DNS:
```
GRANT ALL PRIVILEGES ON servermail.* TO 'postmasteruser'@'docker.postmaster.local' IDENTIFIED BY 'password_changeme';
```
Exit from MySQL:
```
exit
```
If you are installing PostMaster on a server other than where your mail server's MySQL server is installed, make sure that bind-address is set 0.0.0.0 and not 127.0.0.1 in:
```
/etc/mysql/my.cnf
```

Find the URL to the latest tar.gz file containing the PostMaster source code at:
```
https://github.com/StackFocus/PostMaster/releases/latest
```

Then download PostMaster with the URL from the previous step:

wget https://github.com/StackFocus/PostMaster/archive/[release version].tar.gz -O ~/postmaster.tar.gz

Build the Docker image:

cd ~/PostMaster-*
docker build -t postmaster .

Create a directory on the Docker host to contain PostMaster's application and Apache logs:
```
mkdir -p /opt/postmaster_data/logs
```
Run a PostMaster Docker container from the created image. The -p has the Docker host serve port 80 of the PostMaster container. Change this to what suits your environment. The -e specifies the value of the DB_URI environment variable, which is the URI that PostMaster will use to connect to your mail server's MySQL server. The -v parameter specifies that the /opt/postmaster_data/logs should be mounted as a volume at /opt/postmaster/logs inside the container. Make sure to replace 'password_changeme' and 'docker.postmaster.local' with what you configured in step 2 of MySQL Preparation:
```
docker run \
     -p 0.0.0.0:80:8082 \
     -e DB_URI=mysql+pymysql://postmasteruser:password_changeme@docker.postmaster.local:3306/servermail \
     -v /opt/postmaster_data/logs:/opt/postmaster/logs \
     -d postmaster
```
Note: If you plan to deploy PostMaster behind a load-balancer, set the SECRET_KEY environment variable to a random string (preferably hex characters) that is the same across all running containers behind the load-balancer. This SECRET_KEY is used by Flask (the Python framework used for PostMaster) for cryptographic functions.
PostMaster should now be running. Simply use the username "admin" and the password "PostMaster" to login. You can change your username and password from Manage -> Administrators.