Errata

( OR = O'Reilly Online )

I followed along in your book on a new Centos VM ( CentOS Linux release 7.3.1611 (Core) ) -- admittedly, after I had tried a number of tutorials on the web to install it on virtual metal after seeing quirky results when running a docker container from https://hub.docker.com/r/hopsoft/graphite-statsd/ .

I was happy to see that you endorsed a virtual environment. That was really how I had wanted to set graphite up in this VM.

I had a number of issues, many because I was trying to do this behind a corporate firewall.

But I had one issue pop up that took me a while to figure out .. as it was so subtle.

Example 4-18:
$ sudo -E carbon-cache.py --instance=1 start

When I ran this, I got this result:

ImportError: No module named twisted.python.util

Actually, what it really means is that it can't find any part of twisted in my environment, and that just happens to be the first time it tried. But I didn't know that at the time.

When I googled for this, I found instances where the same language had popped up, and I found "solutions" ranging from running Graphite in a docker container with a static version of carbon that didn't import twisted, using a lesser version of twisted (<13, I think it was), and someone even managed to get it working by installing the system version of twisted-core.

None of these are really the right answer. But the last one offers a clue. ( I didn't find it that way, though. ) -- I found it by running python directly in my virtual environment, and importing twisted.python.util. And then adding print statements to carbon-cache.py, where I noticed that the sys.path was the system path, and not the virtual env path.

head /opt/graphite/bin/carbon-cache.py
#!/usr/bin/python

I believe that line, along with running 'carbon-cache' is responsible for this behavior. carbon-cache.py is found in the usual spot, but the first line means that it uses the python interpreter that is at /usr/bin/python, rather than the python interpreter built into the virtual environment.

$ sudo -E python /opt/graphite/bin/carbon-cache.py --instance=1 stop

... works.

$ sudo -E /opt/graphite/bin/carbon-cache.py --instance=1 stop

... does not.

All of this seems consistent with the wrong python interpreter being invoked.

Thanks for writing this book. I look forward to going through your troubleshooting section and actually reading the first 2 chapters about how Graphite works. But for now, I'm off to figure out how to implement nginx instead of httpd. .. because httpd just isn't working. ( Even though run-graphite-devel-server.py does. ... something I haven't seen in your book yet. )

Hope you have a great day!

First sentence of first paragraph does not make sense; seems like a sentence-fragment, missing the Subject. It reads as if it is the predicate, or perhaps was part of a bulleted list. Were I to guess, it should read "A composable monitoring system includes all of the features..."