NFD

A unit file (nfd.service) should be enough, no scripts should be needed. Optionally we can (should) support on-demand socket-based activation, at least for the unix stream socket.

yes. nfd.service could be enough (may be nrd.service too, unless systemd cannot monitor two processes for the same service). I just don't know anything about it, so don't know exactly how to work with it. Are you familiar with it and can write a sample/readme?

I wouldn't go with ondemand approach. It is possible (even with upstart and launchd), but it is not entirely correct for us.

Alex Afanasyev wrote:

yes. nfd.service could be enough (may be nrd.service too, unless systemd cannot monitor two processes for the same service). I just don't know anything about it, so don't know exactly how to work with it. Are you familiar with it and can write a sample/readme?

Sure, I can do it.

I wouldn't go with ondemand approach. It is possible (even with upstart and launchd), but it is not entirely correct for us.

Why not? It actually makes a lot of sense for the local socket...

When an application connects to the socket, there is an assumption that someone already created faces, created correct routes so packet can be routed somewhere. So, it doesn't make much sense in starting nfd/nrd when an app tries to connect.

This is different from ssh/apache/etc. deamons, which are triggered by remote connection, do some local job, and after that they are useless. nfd is more like kernel's IP stack: it runs, somebody manages it with command interest, packets gets forwarded, etc.

So, 15.04 has switched to systemd and our PPA package no longer provides automatic start of nfd.

@Davide: Can you help creating systemd script that can be included in PPA?

I can work on this if needed.

From gerrit issue discussions:

Alex: Do you have any idea where systemd stores its journal on Ubuntu. I figured out that I can access nfd's logs (current logs) using journalctrl command, but I couldn't figure out where this information stored or whether or not this information is stored permanently (i.e., how to debug problems)

Eric: By default Ubuntu stores the journal in /run/log/journal. However, this is a temporary filesystem and is lost upon reboot.

Alex: is there a good way to make it "permanent"

Eric: This can be done by creating the /var/log/journal directory

So, just creating /var/log/journal folder and everything will work automatically? Or anything else to configure? What about log rotation, will this be handled automatically?

That's what the documentation says.

Rotation and other options can be configured in /etc/systemd/journald.conf:

http://www.freedesktop.org/software/systemd/man/journald.conf.html

I guess my question is going to Davide. How should we handle log files in nfd's PPA? Don't do anything and assume users will know what they are doing (this is kind of destructive...)? Create NFD-specific logging? Force creation of journal? Creating nfd-specific journal?

Alex Afanasyev wrote:

So, just creating /var/log/journal folder and everything will work automatically?

Yes, assuming Storage=auto in journald.conf (the default).

Or anything else to configure?

No, assuming Storage=auto in journald.conf (the default).

What about log rotation, will this be handled automatically?

Yes, if SystemMaxFileSize/RuntimeMaxFileSize and MaxFileSec are left to their default values (or set to any other reasonable values). In any case, these are system-wide settings that are configured by the admin, and should never be touched by us.

Alex Afanasyev wrote:

I guess my question is going to Davide. How should we handle log files in nfd's PPA? Don't do anything and assume users will know what they are doing (this is kind of destructive...)? Create NFD-specific logging? Force creation of journal? Creating nfd-specific journal?

What problem are you trying to solve? The volatility of the journal on Ubuntu? If that's the problem, then we don't need to do anything special. On Ubuntu journald is configured to forward all messages to syslog by default. So everything still goes to the rsyslog daemon and is handled according to the rsyslog rules and usually ends up being written to /var/log/syslog and friends.

THe problem is logging. Right now operators can see (without doing anything, except installing nfd package) all logs in /var/log/upstart/nfd.log. This log is automatically rotated and everything is fine.

With systemd I'm not seeing that the log is permanently stored. Should we enable something in the package to enable logging, e.g., adding syslog rule of some kind to the system?

So there are two problems (correct me if I'm wrong)

1. Writing nfd log messages to persistent storage (are you sure they don't get forwarded to syslog and saved like everything else?)

2. Logging nfd messages separately from everything else... this is rather vague, what is the exact requirement here? do you really need a separate log file stored on disk? otherwise, if you just want to easily skim or search through nfd messages without being disturbed by other output, the systemd way of doing this is e.g. journalctl _COMM=nfd, no configuration necessary.

Davide Pesavento wrote:

So there are two problems (correct me if I'm wrong)

1. Writing nfd log messages to persistent storage (are you sure they don't get forwarded to syslog and saved like everything else?)

2. Logging nfd messages separately from everything else... this is rather vague, what is the exact requirement here? do you really need a separate log file stored on disk? otherwise, if you just want to easily skim or search through nfd messages without being disturbed by other output, the systemd way of doing this is e.g. journalctl _COMM=nfd, no configuration necessary.

There only one problem, the first one you mentioned. I don't have issues with 2, as I already figured out how to use journalctl to extract nfd-specific info.

Well then you have to elaborate more on the first "problem" because I cannot reproduce it: as I said in comment #20, everything still ends up in /var/log/syslog on ubuntu.

Huh. Davide, the "problem" is that once somebody installs nfd from PPA, whether a week/month from now it would be possible to check logs about what have happened in the past. This is the only thing I want to have and I didn't notice /var/log/syslog originally, so I'm kind of ok right now. However, it would be even better if we had separated "permanent"+logrotated log files for NFD specifically, but I don't really care much.

Then add a config file in /etc/rsyslog.d/, systemd has nothing to do with this.