Implemented a simple mail notification after backups using mailx. This can be used to send mail via an external SMTP server. Syntax uniformity is questionable.

Dockerfile

@@ -11,7 +11,7 @@ FROM alpine:3.10.1
 COPY --from=build /etc/ssl/certs /etc/ssl/certs
 COPY --from=build /bin/restic /bin/restic
 
-RUN apk add --update --no-cache fuse openssh-client
+RUN apk add --update --no-cache fuse openssh-client heirloom-mailx
 
 RUN \
     mkdir -p /mnt/restic /var/spool/cron/crontabs /var/log; \
@@ -25,6 +25,7 @@ ENV \
     BACKUP_CRON="0 */6 * * *" \
     RESTIC_FORGET_ARGS="" \
     RESTIC_JOB_ARGS=""
+    MAILX_ARGS=""
 
 # /data is the dir where you have to put the data to be backed up
 VOLUME /data

README.md

@@ -60,7 +60,7 @@ docker logs
 ```
 Shows `/var/log/cron.log`
 
-Additionally you can see the the full log, including restic output, of the last execution in `/var/log/backup-last.log`. When the backup fails the log is copied to `/var/log/restic-error-last.log`.
+Additionally you can see the the full log, including restic output, of the last execution in `/var/log/backup-last.log`. When the backup fails the log is copied to `/var/log/restic-error-last.log`. If configured, you can find the full output of the mail notification in `/var/log/mail-last.log`.
 
 # Customize the Container
 
@@ -77,6 +77,7 @@ The container is setup by setting [environment variables](https://docs.docker.co
 * `RESTIC_JOB_ARGS` - Optional. Allows to specify extra arguments to the back up job such as limiting bandwith with `--limit-upload` or excluding file masks with `--exclude`.
 * `AWS_ACCESS_KEY_ID` - Optional. When using restic with AWS S3 storage.
 * `AWS_SECRET_ACCESS_KEY` - Optional. When using restic with AWS S3 storage.
+* `MAILX_ARGS` - Optional. If specified, the content of `/var/log/backup-last.log` is sent via mail after each backup using an *external SMTP*. To have maximum flexibility, you have to specify the mail/smtp parameters by 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 backup 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'"`.
 
 ## Volumes
 

backup.sh

@@ -1,6 +1,7 @@
 #!/bin/sh
 
 lastLogfile="/var/log/backup-last.log"
+lastMailLogfile="/var/log/mail-last.log"
 
 copyErrorLog() {
   cp ${lastLogfile} /var/log/backup-error-last.log
@@ -11,7 +12,7 @@ logLast() {
 }
 
 start=`date +%s`
-rm -f ${lastLogfile}
+rm -f ${lastLogfile} ${lastMailLogfile}
 echo "Starting Backup at $(date +"%Y-%m-%d %H:%M:%S")"
 echo "Starting Backup at $(date)" >> ${lastLogfile}
 logLast "BACKUP_CRON: ${BACKUP_CRON}"
@@ -50,3 +51,12 @@ fi
 
 end=`date +%s`
 echo "Finished Backup at $(date +"%Y-%m-%d %H:%M:%S") after $((end-start)) seconds"
+
+if [ -n "${MAILX_ARGS}" ]; then
+    sh -c "mailx -v -S sendwait ${MAILX_ARGS} < ${lastLogfile} > ${lastMailLogfile} 2>&1"
+    if [ $? == 0 ]; then
+        echo "Mail notification successfully sent."
+    else
+        echo "Sending mail notification FAILED. Check ${lastMailLogfile} for further information."
+    fi
+fi