How to log output to log file using runit

Question

I am running program using runit to run at startup. I want all the output by from the program that is run by runit to be logged to a file.

I have looked at svlogd but I cannot figure out how to get it running.

Answer 1

I cannot figure out how to get it running.

In the daemontools family world, log services are just services like any other. So you run svlogd with a run program just like you would run a "main" service with a run program.

The special things about "log" services are merely that:

• The "log" service directory is located using a symbolic link from (or a straight subdirectory beneath) the "main" service directory.
• Some, but not all, daemontools family toolsets tightly bind "log" and "main" services and operate upon the twain as a unit. This is to a degree the case with runit.

Otherwise, they are just like everything else.

So make a "log" service to run svlogd just like you would make any other service, put it into the right place relative to your "main" service, and set things off.

Further reading

• Jonathan de Boyne Pollard (2015). "Logging". The daemontools family. Frequently Given Answers.
• Gerrit Pape. "How do I create a new service directory with an appendant log service?". runit Frequently Asked Questions.
• Daniel J. Bernstein. "How do I create a service directory with a log?". daemontools Frequently Asked Questions.

Answer 2

The first thing you have to do is to find out where runit files are on your system. Usually it's /etc/runit/. There, you'll find a directory called sv in which one directory per service is created.

Let's say you want to create a new service called food. You would create create a directory called food in /etc/runit/sv/.

# mkdir /etc/runit/sv/food

Create a run script in /etc/runit/sv/food. Let's say that your service's program is an executable at /opt/bin/foo. In that case your run script will be this.

#!/bin/sh
exec /opt/bin/foo 2>&1

For logging, you should create another directory in /etc/runit/sv/food called log. And in it another run script.

#!/bin/sh
exec svlogd -tt <logs-directory>

Make sure the <logs-directory> exits. And don't forget to make both run scripts executables.

# chmod +x /etc/runit/sv/food/run
# chmod +x /etc/runit/sv/food/log/run

Make a symbolic link of your food directory inside /etc/runit/runsvdir/default

# ln -s /etc/runit/sv/food /etc/runit/runsvdir/default/

To manually start/stop your service simply run:

# sv start food
# sv stop food

Take a loot at this quick start guide for more details.

Notice that unlike the guide, I didn't use chpst in my example. In this case the food service will run as root. Use chpst as suggested by the guide if you want your service to run as a specific user.