send emails using a sidecar container with msmtpd

README.md

@@ -35,6 +35,7 @@ ___
   * [Use fail2ban-client](#use-fail2ban-client)
   * [Global jail configuration](#global-jail-configuration)
   * [Custom jails, actions and filters](#custom-jails-actions-and-filters)
+  * [Sending email using a sidecar container](#sending-email-using-a-sidecar-container)
 * [Contributing](#contributing)
 * [License](#license)
 
@@ -169,7 +170,7 @@ through the container. Here is an example if you want to ban an IP manually:
 
 ```console
 $ docker exec -t <CONTAINER> fail2ban-client set <JAIL> banip <IP>
-``` 
+```
 
 ### Global jail configuration
 
@@ -202,6 +203,12 @@ exists, it will be overriden.
 > [!WARNING]
 > Container has to be restarted to propagate changes
 
+### Sending email using a sidecar container
+
+If you want to send emails using a sidecar container, see the example in
+[examples/smtp](examples/smtp). It uses the [smtp.py action](https://github.com/fail2ban/fail2ban/blob/1.1.0/config/action.d/smtp.py)
+and [msmtpd SMTP relay](https://github.com/crazy-max/docker-msmtpd) image.
+
 ## Contributing
 
 Want to contribute? Awesome! The most basic way to show your support is to star

examples/smtp/compose.yml

@@ -0,0 +1,29 @@
+name: fail2ban
+
+services:
+  msmtpd:
+    image: crazymax/msmtpd:latest
+    container_name: fail2ban_msmtpd
+    env_file:
+      - "./msmtpd.env"
+    ports:
+      - "127.0.0.1:2500:2500"
+    environment:
+      - "TZ"
+    restart: always
+
+  fail2ban:
+    image: crazymax/fail2ban:latest
+    container_name: fail2ban
+    depends_on:
+      - msmtpd
+    network_mode: "host"
+    cap_add:
+      - NET_ADMIN
+      - NET_RAW
+    volumes:
+      - "./data:/data"
+      - "/var/log:/var/log:ro"
+    env_file:
+      - "./fail2ban.env"
+    restart: always

examples/smtp/data/jail.d/00-jail.local

@@ -0,0 +1,2 @@
+[DEFAULT]
+action = smtp.py[host=localhost:2500, sendername=Fail2Ban, [email protected], [email protected]]

examples/smtp/fail2ban.env

@@ -0,0 +1,5 @@
+TZ=Europe/Paris
+
+F2B_LOG_TARGET=STDOUT
+F2B_LOG_LEVEL=INFO
+F2B_DB_PURGE_AGE=1d

examples/smtp/msmtpd.env

@@ -0,0 +1,10 @@
+# https://github.com/crazy-max/docker-msmtpd
+SMTP_HOST=smtp.gmail.com
+SMTP_PORT=587
+SMTP_TLS=on
+SMTP_STARTTLS=on
+SMTP_TLS_CHECKCERT=on
+SMTP_AUTH=on
+SMTP_USER=foo
+SMTP_PASSWORD=bar
+SMTP_FROM=[email protected]