Lighttpd

I am currently struggling with the very same problem. In the meantime I've found out that the error output can be shown in the docker logs by omitting server.errorlog in lighttpd.conf. But for a useful debugging workflow, one needs also to be able to inspect the access logs when attaching to the container's log collector. Please kindly have another look at the issue.

Dockerfile:

FROM ubuntu:latest
RUN apt-get update && apt-get install -y --allow-unauthenticated --no-install-recommends lighttpd
COPY lighttpd.conf /etc/lighttpd/lighttpd.conf
CMD ["lighttpd", "-D", "-f", "/etc/lighttpd/lighttpd.conf", "2>&1"]

docker-compose.yml:

version: '2'
services:
  www:
    build: www
    ports:
      - "80:80" 

Relevant parts of lighttpd.conf:

#server.errorlog = "/dev/stderr" # omitting it makes error output work
server.modules += ( "mod_accesslog" )
$HTTP["host"] == "localhost" {
  accesslog.filename = "/dev/stderr" 
}

Creating network "lighttpd_default" with the default driver
Creating lighttpd_www_1
Attaching to lighttpd_www_1
www_1  | 2016-05-19 06:59:15: (log.c.118) opening errorlog '/dev/stderr' failed: Permission denied
www_1  | 2016-05-19 07:04:36: (server.c.1022) Configuration of plugins failed. Going down.
lighttpd_www_1 exited with code 255

willydee68: you're using the instructions I gave and you noted that server.errorlog should be commented out.

What is not working as you expect? Please be more specific.

Why aren't you using accesslog.filename = "/dev/stderr" at the global scope instead of only in $HTTP["host"] conditional?

Thanks for the tip about sending stuff to stderr. Works for me :-)

I guess you can close this as "not a defect" if you like since it's actually possible to do what I was requesting out of the box.

gstrauss: I cannot be more specific than pasting the error message (again):

2016-05-19 06:59:15: (log.c.118) opening errorlog '/dev/stderr' failed: Permission denied

acaron: would you mind posting your Docker config for willydee68?

willydee68: As you can see above, what I posted works for acaron. Did you google "docker and your error"?
Permission denied on /dev/stderr #6880
https://github.com/docker/docker/issues/6880
Perhaps you're running an old version of Docker? See the link for potential workarounds.
Also suggested: http://unix.stackexchange.com/questions/38538/bash-dev-stderr-permission-denied

acaron: Yes a dockerfile might be helpful; it seems I've missed something...

gstrauss: Docker version 1.11.1, should be the most recent release. I've found an approach on Stackexchange to launch Node.js in a container as nonprivileged user, but this also does not work for lighttpd, since it cannot bind to port 80 or 443 then.

willydee68: if you're starting as root, then once lighttpd drops privileges, it won't be able to open /dev/stderr

However, you can change the permissions (as root) before running lighttpd as root.
$ chown lighttpd /dev/stderr && /path/to/lighttpd -D -f /path/to/lighttpd.conf 2>&1

gstrauss: Understood. Created a docker-entrypoint.sh script doing that:

#!/bin/bash
/bin/chown www-data /dev/stderr && /usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf 2>&1

2016-05-20 11:57:57: (log.c.118) opening errorlog '/dev/stderr' failed: Permission denied
2016-05-20 11:57:57: (server.c.1022) Configuration of plugins failed. Going down.

Please test your script outside a docker environment to make sure it works outside Docker.

The usage here (which works for acaron) is similar to what I have seen posted for working with nginx inside Docker.

I'm sorry, but this isn't a Docker help forum, so I recommend the Docker forums. Please post a link here to your post so that we can all learn.

If all else fails, I suppose lighttpd could special case the string "/dev/stderr" when opening log files and simply dup2() STDERR_FILENO. That wouldn't be a difficult patch in log.c. Before doing that, I'd like to hear what the Docker forum recommends since what works for nginx logging should, in a similar fashion, also work for lighttpd logging.

Checked the same command line outside Docker under Ubuntu 16.04 LTS, running the given command line as root. Without the chown www-data /dev/stderr, it fails with permission denied, but with chown, it works indeed as expected, and both access and error log are echoed into the console. So it is a Docker-only problem. I will raise the issue there. Thanks for helping to track this down.

Yay, got it running! https://github.com/docker/docker/issues/6880#issuecomment-170214851 has the workaround.

docker-entrypoint.sh:

#!/bin/bash
mkfifo -m 600 /tmp/logpipe
cat <> /tmp/logpipe 1>&2 &
chown www-data /tmp/logpipe
/usr/sbin/lighttpd -D -f /etc/lighttpd/lighttpd.conf 2>&1

accesslog.filename = "/tmp/logpipe"