fix: Send mail notifications via msmtp

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Changed
+* BREAKING: Added `msmtp` package to be used to send mail via SMTP, since Alpine's `mail` no longer supports
+  providing external server configurations via `-S` parameters.
+
 ## v1.3.2 (restic 0.16.0)
 
 ### Changed

Dockerfile

@@ -6,10 +6,12 @@ RUN unzip rclone-current-linux-amd64.zip && mv rclone-*-linux-amd64/rclone /bin/
 
 FROM restic/restic:0.16.0
 
-RUN apk add --update --no-cache curl mailx
+RUN apk add --update --no-cache curl mailx msmtp
 
 COPY --from=rclone /bin/rclone /bin/rclone
 
+RUN ["ln", "-sf", "/usr/bin/msmtp", "/usr/sbin/sendmail"]
+
 RUN \
     mkdir -p /mnt/restic /var/spool/cron/crontabs /var/log; \
     touch /var/log/cron.log;

README.md

@@ -131,7 +131,7 @@ The container is set up by setting [environment variables](https://docs.docker.c
 * `AWS_ACCESS_KEY_ID` - Optional. When using restic with AWS S3 storage.
 * `AWS_SECRET_ACCESS_KEY` - Optional. When using restic with AWS S3 storage.
 * `TEAMS_WEBHOOK_URL` - Optional. If specified, the content of `/var/log/backup-last.log` and `/var/log/check-last.log` is sent to your Microsoft Teams channel after each backup and data integrity check.
-* `MAILX_ARGS` - Optional. If specified, the content of `/var/log/backup-last.log` and `/var/log/check-last.log` is sent via mail after each backup and data integrity check using an *external SMTP*. To have maximum flexibility, you have to specify the mail/smtp parameters on your own. Have a look at the [mailx manpage](https://linux.die.net/man/1/mailx) for further information. Example value: `-e "MAILX_ARGS=-r 'from@example.de' -s 'Result of the last restic run' -S smtp='smtp.example.com:587' -S smtp-use-starttls -S smtp-auth=login -S smtp-auth-user='username' -S smtp-auth-password='password' 'to@example.com'"`.
+* `MAILX_ARGS` - Optional. If specified, the content of `/var/log/backup-last.log` and `/var/log/check-last.log` is sent via mail after each backup and data integrity check using an *external SMTP*. To have maximum flexibility, you have to specify the mail/smtp parameters on your own. Have a look at the [mailx manpage](https://linux.die.net/man/1/mailx) for further information. Example value: `-e "MAILX_ARGS=-r 'from@example.de' -s 'Result of the last restic run' 'to@example.com'"`. ***ATTENTION: A [msmtp](https://wiki.alpinelinux.org/wiki/Relay_email_to_gmail_(msmtp,_mailx,_sendmail)) config file must be provided (by mounting `/config/msmtprc`) for the mail sending to work using an external SMTP server/relay***
 * `OS_AUTH_URL` - Optional. When using restic with OpenStack Swift container.
 * `OS_PROJECT_ID` - Optional. When using restic with OpenStack Swift container.
 * `OS_PROJECT_NAME` - Optional. When using restic with OpenStack Swift container.
@@ -146,6 +146,7 @@ The container is set up by setting [environment variables](https://docs.docker.c
 ## Volumes
 
 * `/data` - This is the data that gets backed up. Just [mount](https://docs.docker.com/engine/reference/run/#volume-shared-filesystems) it to wherever you want.
+* `/config/msmtprc` - Optional. If specified, the file is copied to `/etc/msmtprc` and used for sending mails via an external SMTP server/relay. ***ATTENTION: The file must be provided for the mail sending to work using an external SMTP server/relay***
 
 ## Set the hostname
 
@@ -211,13 +212,15 @@ services:
       - ./post-backup.sh:/hooks/post-backup.sh:ro     # Run script post-backup.sh after every backup
       - ./post-check.sh:/hooks/post-check.sh:ro       # Run script post-check.sh after every check
       - ./ssh:/root/.ssh                              # SSH keys and config so we can login to "storageserver" without password
+      - ./msmtprc:/config/msmtprc:ro                  # Mail config for sending mails via an external SMTP server/relay
     environment:
       - RESTIC_REPOSITORY=sftp:storageserver:/storage/nas  # Backup to server "storageserver" 
       - RESTIC_PASSWORD=passwordForRestic                  # Password restic uses for encryption
       - BACKUP_CRON=0 22 * * 0                             # Start backup every Sunday 22:00 UTC
       - CHECK_CRON=0 22 * * 3                              # Start check every Wednesday 22:00 UTC
       - RESTIC_DATA_SUBSET=50G                             # Download 50G of data from "storageserver" every Wednesday 22:00 UTC and check the data integrity
       - RESTIC_FORGET_ARGS=--prune --keep-last 12          # Only keep the last 12 snapshots
+      - MAILX_ARGS=-r 'from@example.de' -s 'Result of the last restic run' 'to@example.com'
 ```
 
 # Versioning

backup.sh

@@ -71,8 +71,8 @@ if [ -n "${TEAMS_WEBHOOK_URL}" ]; then
     fi
 fi
 
-if [ -n "${MAILX_ARGS}" ]; then
-    sh -c "mail -v -S sendwait ${MAILX_ARGS} < ${lastLogfile} > ${lastMailLogfile} 2>&1"
+if [ -n "${MAILX_ARGS}" ] && [ -f /config/msmtprc ]; then
+    sh -c "mail -v ${MAILX_ARGS} < ${lastLogfile} > ${lastMailLogfile} 2>&1"
     if [ $? == 0 ]; then
         echo "Mail notification successfully sent."
     else

check.sh

@@ -59,8 +59,8 @@ if [ -n "${TEAMS_WEBHOOK_URL}" ]; then
     fi
 fi
 
-if [ -n "${MAILX_ARGS}" ]; then
-    sh -c "mail -v -S sendwait ${MAILX_ARGS} < ${lastLogfile} > ${lastMailLogfile} 2>&1"
+if [ -n "${MAILX_ARGS}" ] && [ -f /config/msmtprc ]; then
+    sh -c "mail -v ${MAILX_ARGS} < ${lastLogfile} > ${lastMailLogfile} 2>&1"
     if [ $? == 0 ]; then
         echo "Mail notification successfully sent."
     else

entry.sh

@@ -35,6 +35,16 @@ if [ -n "${CHECK_CRON}" ]; then
     echo "${CHECK_CRON} /usr/bin/flock -n /var/run/backup.lock /bin/check >> /var/log/cron.log 2>&1" >> /var/spool/cron/crontabs/root
 fi
 
+# Copy msmtp config file from volume to /etc/msmtprc if exists and chown
+# ATTENTION: E-mail notification will only work if this files exists
+if [ -f /config/msmtprc ]; then
+    echo "Found msmtp config file in /config/msmtprc"
+    cp /config/msmtprc /etc/msmtprc
+    chmod 600 /etc/msmtprc
+else
+    echo "No msmtp config file found in /config/msmtprc"
+fi
+
 # Make sure the file exists before we start tail
 touch /var/log/cron.log
 

msmtprc.example

@@ -0,0 +1,18 @@
+# Set default values for all following accounts.
+defaults
+auth           on
+tls            on
+tls_trust_file /etc/ssl/certs/ca-certificates.crt
+syslog         on
+
+# Gmail
+account        gmail
+host           smtp.gmail.com
+port           587
+from           from@gmail.com
+user           user@gmail.com
+password       XXXXXXXXXXXXXXXXXXXXX 
+
+# Set a default account
+account default : gmail
+aliases        /etc/aliases