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Brendon Jones's blog




Fixed up the rabbit queues/bindings that I had broken when I accidentally used a queue resource in place of a routing key when exploring the erlang commands. Figured out the syntax I needed to properly create the binding to an existing queue and now have all the configuration sorted.

Spent the rest of the week packaging the remaining software that we deploy on the AMP servers - ampweb, ampy, nntsc, ampsave, netevmon. Quite a few of them have progressed a lot since they were last packaged, so lots of dependencies needed to be updated, users created, databases created and populated, etc. Almost have all the packages built and ready for a test deployment now.




Spent some time working on issues a new user had installing the amplet client on a new Ubuntu machine. The Jessie packages almost work fine, though there seems to be a change in behaviour (or a bug) in the libcurl-gnutls library which prevents curl from working with any of our SSL sites. In the end after a lot of chasing things around, the easiest workaround seems to be to build against the OpenSSL flavour of libcurl instead.

Got the amplet client building on Centos again so that I could update a server used as an endpoint for cooperative tests. It is now running throughput and udpstream tests to get sample data for prophet, as well as testing out the new client build.

Started to look over all the old Debian packaging I had done for the server side software to get it all working for the current versions. Updated packages for the simple parts (pywandevent, libnntsc, amppki). Got stuck writing erlang to declare queues, exchanges and bindings on the server because the default tools can't do that (and I don't want to install extra tools). Currently have declarations working fine but in creating the bindings I've created a broken queue that breaks the web interface.




Spent most of the week working on installing the server-side components of AMP, which took a lot longer than I thought it would. Ran into issues with deploying ampweb when it's not at the root of the website - a lot of URLs were absolute and URL parsing was expecting a particular layout or number of elements which was no longer the case. Fixed all the obvious ones, but more were still showing up a few days later and have also been fixed.

Found and fixed a few small edge cases in recent ampweb/ampy features that hadn't been tested with the sort of data I was wanting to look at. Also had issues with trying to test the changes I had made to make sure they worked elsewhere, as the influx database on prophet was misbehaving and making it difficult to fetch data in some circumstances.




Spent some time tidying up control messages and configuration when scheduling tests that require cooperation from the server. As part of the previous changes the port number was no longer being sent to tests, which meant it could only operate using the default port - this is now fixed and works for both scheduled and standalone tests. Also fixed up some parameter parsing when running standalone tests where empty parameter lists were not being created properly.

Wrote some basic unit tests for the udpstream test and it's control messages. Fixed a possible memory leak when failing to send udpstream packets. Made sure documentation and protobuf files agreed on default values of test parameters.

Started to install the server-side components of AMP on another machine for a test deployment so that I can use the documentation I write as I go to help build/update the packaging for the most recent versions.




Added a latency measure to the udpstream test by reflecting probe packets at the receiver. The original sender can combine the RTT information with jitter and loss to calculate Mean Opinion Scores, which was slightly annoying as (depending on the test direction) the remote end of the test now has to collate and send back partial result data. Updated the ampsave function to reflect the new data reported by the test.

Updated the display of tcpping test information in the scheduling website to reflect the new packet size options. Worked with Shane to update the lamp deployment to the newest version of all the event detection and web display/management software.

Tidied up some more documentation and sent it to a prospective AMP user. Will hopefully get some feedback next week as they try to install it and I can see which areas of the documentation are still lacking.




Lots of minor fixes this week. Fixed the commands to properly kill the entire process group when stopping the AMP client using the init scripts. Still need a cleaner way to do this as part of the main process. Updated the AMP schedule fetching to follow HTTP redirects, which was required to make it work on the Lightwire deployment. Fixed the tcpping test to properly match response packets when the initial SYN contains payload. Different behaviour was observed in some cases where RSTs would acknowledge a different sequence number compared to a SYN ACK, and only one of these was being checked for.

Updated all the tests to report the DSCP settings that they used. They are not currently saved into the database, but they are being sent to the collector now.

Set the default packet interval of the udpstream test to 20ms, which is closer to VoIP than the global AMP minimum interval that it was using. Also wrote most of the code for the test to calculate Mean Opinion Scores based on the ITU recommendations, just need to add a latency measure to complete the calculation.




Did some reading around calculating mean opinion scores for VoIP and started to add code to the udpstream test to calculate it both the Cisco way and the ITU E-model way. Neither of them explicitly take into account jitter which seems unusual, my best guess so far is that they count jitter as part of the delay. Other models I've found do include jitter as part of the delay calculation.

Spent some time writing more documentation about installing and configuring an amplet client. Install process, configuration options and schedule file options all get a first draft description, hopefully enough to help people install monitors with minimal assistance but I expect they will need to be expanded. Updated example configuration files to agree with the new documentation.

Various small fixes, including updating the standalone icmp and tcpping tests to print human readable icmp errors rather than printing the type and code, and using Python .egg format in the ampsave packages.

Merged my scheduling parts of the website back into the main branch so that others can start using the features I've added.




Worked with Brad to get access to the Netspace amplet and bring it slightly more up to date (site firewalls had been interfering with us making changes until now). That's the last amplet that was reporting to erg now upgraded.

Merged my amplet client control socket changes back into the main branch without too much apparent trouble. Need to do some more testing to make sure everything is sensible. After merging, added options to set DSCP bits for the new udpstream test like all the existing tests had.

Continued working on documentation and tidied up the sample program showing how to read data from a RabbitMQ queue and extract the AMP messages.

Had a quick visit to Lightwire on Thursday which generated some more interesting ideas, especially for me around automation of test target selection. Some of these line up nicely with wishlist items I already had, so hopefully I might be able to find time to work on those features soon.




Short week due to Easter holidays.

Went through the protocol buffer descriptions for all of the AMP test formats and wrote some short documentation about the fields, and some sample code to fetch, unpack and understand test result messages.

While working on the documentation I found a few instances of test options that were inconsistent or didn't quite behave correctly. In particular I made the TCP ping size parameter behave the same as the ICMP one (total packet size rather than payload size), and made sure that setting just the UDP payload size in the DNS test would correctly add an EDNS header.




Updated some of the signals used with the amplet client to provide
better management - as well as being able to reload configuration from
disk, it can now force a refetch of remote schedule files with a SIGUSR2.

Also made sure that all children (tests, servers, etc) have their
signals unblocked and the signal handler restored to the default.
Libwandevent sets all these in the main process, which was being
propagated to the children and causing some unexpected behaviour. The
init scripts now try to kill the entire process group of the amplet
client, which means children should now get the signal too.

Renamed server processes in ps so that it was obvious what task they
were performing.

Refactored some more of the repeated server code out of the
udpstream/throughput tests so they are now a lot cleaner. Moved some of
the test server control message code around so that it was grouped
together in a sensible place.