John Siu Blog

Docker - Postfix with sasldb2 support

Build

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git clone https://github.com/J-Siu/docker_postfix.git
cd docker_postfix
docker build -t jsiu/postfix .

Usage

Host Directories and Volume Mapping

Postfix Configuration

Configuration Volume

Container will automatically exit if no configuration volume (${POSTFIX_CNF}), or if configuration volume is empty.

The permission and ownership of ${POSTFIX_CNF} is not important. Container start.sh copies /postfix to /etc/ and applies ownership and permission to /etc/postfix accordingly.

Postfix configuration come with Alpine package install is included in the container at /postfix.pkg.tgz. Retrieve it with following commands:

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docker run -d -it --rm --name tmp jsiu/postfix sh
docker cp tmp:/postfix.pkg.tgz .
docker stop tmp

aliases

If aliases is used, it should be placed at ${POSTFIX_CNF}/aliases. Container start.sh script will execute newaliases.

In main.cf:

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alias_maps = hash:/etc/postfix/aliases
alias_database = hash:/etc/postfix/aliases

sasldb2

If sasldb2 is to be used, sasldb2 and smtpd.conf should be placed in ${POSTFIX_CNF}/sasl2/. Container start.sh script will copy them to /etc/sasl2/.

Sample smtpd.conf content:

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pwcheck_method: auxprop
auxprop_plugin: sasldb
mech_list: PLAIN LOGIN

Logs

There are two ways to log to journald.

/dev/log

Mount host /dev/log to container /dev/log to enable postfix logs to host logging system.

/dev/stdout

To have postfix log to stdout:

Add following to master.cf

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postlog   unix-dgram n  -       n       -       1       postlogd

Add following to main.cf

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maillog_file = /dev/stdout

Show postfix log from journald:

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journalctl -t <postfix container name>
journalctl -t postfix

Run

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docker run \
-d \
-e P_TZ=America/New_York \
-v /home/jsiu/postfix:/postfix \
-v /dev/log:/dev/log
-p 25 \
-p 587 \
jsiu/postfix

Compose

Get docker-compose template from image:

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docker run --rm jsiu/postfix cat /docker-compose.yml > docker-compose.yml
docker run --rm jsiu/postfix cat /env > env

Fill in .env according to your environment.

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docker-compose up

Repository

• docker_postfix

Contributors

• John Sing Dao Siu

Change Log

• 1.0
  • Initial commit.
• 1.1
  • Dockerfile remove apk update
  • start.sh
    • Use exec so start.sh can exit
• 3.5.3-r0
  • Adopt Postfix version
  • Postfix version 3.5.3-r0
• 3.5.4-r0
  • Auto update to 3.5.4-r0
• 3.5.4-r0-p0
  • Remove cyrus-sasl-plain
• 3.5.6-r0
  • Auto update to 3.5.6-r0
• 3.5.7-r0
  • Auto update to 3.5.7-r0
• 3.5.7-r2
  • Auto update to 3.5.7-r2
• 3.5.8-r0
  • Auto update to 3.5.8-r0
• 3.5.8-r0-p1
  • Create /etc/sasl2 directory
• 3.5.8-r0-p2
  • Fix start.sh
• 3.5.9-r0
  • Auto update to 3.5.9-r0
• 3.5.9-r0-p0
  • Force rebuild to use cyrus-sasl 2.1.27-r12
• 3.6.0-r0
  • Auto update to 3.6.0-r0
• 3.6.1-r0
  • Auto update to 3.6.1-r0
• 3.7.0-r2
  • Auto update to 3.7.0-r2
• 3.7.0-r2-p1
  • Add docker push github workflow
• 3.7.1-r1
  • Auto update to 3.7.1-r1
• 3.7.2-r0
  • Auto update to 3.7.2-r0

License

The MIT License

Copyright (c) 2022

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.