Skip to main content

debugging production problems with git and go

What follows is an accounting of a debug session I just completed. In the end the issue was not in my code but in a 3rd party library that was in turn effected because a service that it depended on was not running... but this is how I go there. (the stack tract stupid)

Logging into my server I realized that CoreOS had updated my Alpha channel server. It's a pain in my ass when that happens... and there are a number of side effects that I have not yet accounted for.

The login:
Welcome to Secure Shell version 0.8.34.
Answers to Frequently Asked Questions:
Connecting to
Loading NaCl plugin... done.'s password: 
Last login: Fri Sep  4 03:40:27 2015 from
CoreOS alpha (794.0.0)
Failed Units: 6

Crap, my chargeback service did not run. That's going to create a backlog of work for me.  But what happened?
$ sudo journalctl -u ChargebacksYesterday.service -e

Looking at the last page of the log I see that there was a stack trace. This is not going to be good because the trace is going to give me line numbers that do not match the current state of the code.  I'll need to branch the deployed version (after the fact) and then review the code. I hope no changes are required that demand merging.

The the commit-id from the binary
$ ChargebacksYesterday --version

appname ChargebacksYesterday
commit id: 5600cc2
build date dev-20150901141054

ALL of my programs return the above string when the '--version' CLI option is provided.  This way I get to the state of the code in order to debug problems. Looking at the log info, including the stack trace, you'll most likely not be able to debug a project that is being heavily developed.

go to my source
cd zquery

create a branch from the commit-id and push to the remote server
$ git branch
$ git branch debug_nil_pointer 5600cc2
$ git push -u origin debug_nil_pointer
$ git branch

** notice I created the branch from the commit-id and did not actually switch local branch.  I hate branch switching locally as I've janked my projects more than once.  In the next step I switch the branch view in the web GUI.

go to github/bitbucket and switch branches
- this is a visual thing you'll have to do it yourself

find my file and view the code
- I found the exact line of code and it turned out that I was correct. The bosun server running on my local server must have terminated or failed to restart after the CoreOS update.


Popular posts from this blog

Entry level cost for CoreOS+Tectonic

CoreOS and Tectonic start their pricing at 10 servers. Managed CoreOS starts at $1000 per month for those first 10 servers and Tectonic is $5000 for the same 10 servers. Annualized that is $85K or at least one employee depending on your market. As a single employee company I'd rather hire the employee. Specially since I only have 3 servers.

The pricing is biased toward the largest servers with the largest capacities; my dual core 32GB i5 IntelNuc can never be mistaken for a 96-CPU dual or quad core DELL

If CoreOS does not figure out a different barrier of entry they are going to follow the Borland path to obscurity.

UPDATE 2017-10-30: With gratitude the CoreOS team has provided updated information on their pricing, however, I stand by my conclusion that the effective cost is lower when you deploy monster machines. The cost per node of my 1 CPU Intel NUC is the same as a 96 CPU server when you get beyond 10 nodes. I'll also reiterate that while my pricing notes are not currently…

eGalax touch on default Ubuntu 14.04.2 LTS

I have not had success with the touch drivers as yet.  The touch works and evtest also seems to report events, however, I have noticed that the button click is not working and no matter what I do xinput refuses to configure the buttons correctly.  When I downgraded to ubuntu 10.04 LTS everything sort of worked... there must have been something in the kermel as 10.04 was in the 2.6 kernel and 4.04 is in the 3.x branch.

One thing ... all of the documentation pointed to the wrong website or one in Taiwanese. I was finally able to locate the drivers again: (it would have been nice if they provided the install instructions in text rather than PDF)
Please open the document "EETI_eGTouch_Programming_Guide" under the Guide directory, and follow the Guidline to install driver.
download the appropriate versionunzip the fileread the programming manual And from that I'm distilling to the following: execute the answer all of the questio…

Prometheus vs Bosun

In conclusion... while Bosun(B) is still not the ideal monitoring system neither is Prometheus(P).


I am running Bosun in a Docker container hosted on CoreOS. Fleet service/unit files keep it running. However in once case I have experienced at least one severe crash as a result of a disk full condition. That it is implemented as part golang, java and python is an annoyance. The MIT license is about the only good thing.

I am trying to integrate Prometheus into my pipeline but losing steam fast. The Prometheus design seems to desire that you integrate your own cache inside your application and then allow the server to scrape the data, however, if the interval between scrapes is shorter than the longest transient session of your application then you need a gateway. A place to shuttle your data that will be a little more persistent.

(1) storing the data in my application might get me started more quickly
(2) getting the server to pull the data might be more secure
(3) using a push g…