slackd is a very simple daemon that simply watches a text file (usually a log file) and pushes any lines which match a specific criteria to a Slack channel. slackd allows you to specify a line_includes and/or a line_excludes regular expression to watch for, if both are provided they will both trigger a post to Slack.

slackd is a completely stand alone application and has no external dependencies. It does not need to be installed, it can simply be run in-place.

In this example I am using the slackd_linux_amd64 binary, but you can change it to whichever flavor you need to use.

wget -O slackd https://github.com/swill/slackd/raw/master/bin/slackd_linux_amd64
chmod +x slackd

Configure the Service

cp slackd.service.example /etc/systemd/system/slackd.service
vim /etc/systemd/system/slackd.service
# Edit the environment variables and location of the binary to fit your needs.

Enable the Service

sudo systemctl enable slackd

Start the Service

sudo systemctl start slackd

Stop the Service

sudo systemctl stop slackd

View the Logs

journalctl -u slackd

wget -O slackd https://github.com/swill/slackd/raw/master/bin/slackd_linux_amd64
vim config.ini
    # create config according to usage section and save
sudo vim /etc/rc.local
	# add the following before the `exit 0`
	# cd /path/to/slackd && nohup ./slackd -config=config.ini &
nohup ./slackd -config=config.ini &

The application is self documented, so you can review the usage at any time.

Note: All uppercase flags can be set via environment variables in addition to the config file and the CLI.

$ ./slackd -h
Usage of slackd:
  -CHANNEL string
      The ID of the Slack channel to post to. EG: C0XXXXXXXXX
  -config string
      Path to ini config for using in go flags. May be relative to the current executable path.
  -configUpdateInterval duration
      Update interval for re-reading config file set via -config flag. Zero disables config file re-reading.
  -dumpflags
      Dumps values for all flags defined in the app into stdout in ini-compatible syntax and terminates the app.
  -FILE string
      The file path to watch for changes.
  -LINE_EXCLUDES string
      Post line if this regexp DOES NOT match.
  -LINE_INCLUDES string
      Post line if this regexp DOES match.
  -REOPEN
      Reopen the file if it disappears. Useful with log rotation.
  -TOKEN string
      Your Slack token.

With this config I want to watch the /var/log/application.log file. I want to post lines from the log file to the Slack channel with ID C0XXXXXXXXX for either of the following conditions:

• The line includes the case insensitive text error.
• The line does not start with a date in the specified format (useful for stack traces).

token = ####-##########-##########-##########-######
channel = C0XXXXXXXXX
file = /var/log/application.log
line_includes = (?i)error
line_excludes = ^[0-9]{4}/[0-9]{2}/[0-9]{2}
reopen = true