This commit implements the changes necessary to start up a graphite carbon Cache
with twisted and start the corresponding graphiteWeb service.
Dependencies need to be included via python buildEnv to include all recursive
implicit dependencies.
Additionally cairo is a requirement of graphiteWeb and pycairo is not a standard
python package (buildPythonPackage) and therefore cannot be included via
buildEnv. It also needs cairo in the Library PATH.
- add missing types in module definitions
- add missing 'defaultText' in module definitions
- wrap example with 'literalExample' where necessary in module definitions
The advantage of putting the PID file under the ephemeral /run is that
when the machine crashes /run gets cleared allowing graphite to start
once the machine is rebooted.
We also set the PIDFile systemd option so that systemd knows the correct
PID and enables systemd to remove the file after service shut down.
I'm not sure what exactly this user is needed for, i.e. under what circumstances
it must exist or not, but creating it unconditionally seems like the wrong thing
to do. I complained to @offlinehacker about this on Github, but got no response
for a week or so. I'm disabling the extraUsers bit to put out the fire, and now
hope that someone who actually knows about Graphite implements a proper solution
later.
Currently, the restartTriggers are abusing the systemd unit file in that
the cfg.carbon.config/storageAggregation/... option text is pasted into
the unit file. Even though this sort-of works (the service is restarted
if the config changes) this causes systemd to print error messages about
invalid sections (rightfully so!).
The correct use of restartTriggers is to list storage paths, which is
what this change does. If any of the
cfg.carbon/config/storageAggregation/... options change, configDir will
get a new hash. It is not as "fine grained" as the current version, but
it is not abusing the interface.
Also, remove unneeded 'waitress' in one of the restartTriggers, because
it is already listed as part of the service config.
It's "aggregation" with two 'g's.
Fixes this:
carbon-cache[9363]: [console] /nix/store/drxq4jj92sjk3cjik2l4hnsndbray3i4-graphite-config/storage-aggregation.conf not found, ignoring.
mkdir -m will only set the permissions if it *creates* the directory.
Existing directories, with possibly wrong permissions, will not be
updated.
Use explicit chmod so permissions will always be correct.
The preStart snippets (graphite, carbon) try to create directories under
/var/db/. That currently fails because the code is run as user
"graphite". Fix by setting "PermissionsStartOnly = true" so that the
preStart stuff is run as 'root'.
Further:
* graphite-web-0.9.12/bin/build-index.sh needs perl, so add it to PATH.
* Now that preStart runs as root, we must wait with "chown graphite"
until we're done creating files/directories.
* Drop needless check for root (uid 0) before running chown.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
(systemd service descriptions that is, not service descriptions in "man
configuration.nix".)
Capitalizing each word in the description seems to be the accepted
standard.
Also shorten these descriptions:
* "Munin node, the agent process" => "Munin Node"
* "Planet Venus, an awesome ‘river of news’ feed reader" => "Planet Venus Feed Reader"
Twisted provides option to log with syslog, this enables nicer logging.
Imagine what happens in a case of exception. If logs are written to stdout,
traceback won't be merged thus giving ugly logs. This commit fixes that.
This is also one of the official ways of starting carbon, so no worries.
