My Graphite has all the metrics I expect but shows no data for them. Communication between my app and Graphite clearly works otherwise the metrics would not have appeared in the list but why is there no data? Update: Graphite data gotchas that got me (These gotchas explain why I did not see any data.)Continue reading “Graphite Shows Metrics But No Data – Troubleshooting”
Category Archives: Tools
How to create and run Gatling 2.0 tests
Getting up and running with Gatling perf. tests as I would like so I record this for my future reference. 0. Create a project: (The trailing “:” in the filter is important.) 1. Import to IntelliJ In IntelliJ choose to import an object, instead of “from sources” select “from external model” and then Maven. YouContinue reading “How to create and run Gatling 2.0 tests”
Ansible: Best practices for deriving host-level var from a group var
I have a cluster and a group variable (in test/staging/prod) holding the hostname of the cluster master. For each host, I want to derive a variable which is set to either “slave” or “master” and use it in templates. This can be done with set_fact: We could simplify that by using more advanced Jinja:Continue reading “Ansible: Best practices for deriving host-level var from a group var”
Recursive Copy In Ansible 1.5 And –diff
Ansible 1.5 has partial support for recursive copy of files: the synchronize module, using rsync cons: does not support group=, owner= -C and –diff – it does not print diff of the files changed; when running ansible with -v, it will print output of rsync’s –itemize-changes, i.e., for each changed file/dir, something like “<f.st…… conf/httpd.conf\n” (< =Continue reading “Recursive Copy In Ansible 1.5 And –diff”
Ansible Troubleshooting Tips
Few tips for troubleshooting Ansible, based on my brief experiences with Ansible 1.4 (read: do not rely on this info too much). Run ansible-playbook in the verbose mode ansible-playbook -vvvv … will provide you with plenty of details of what is going on. (Notice that additional v:s, starting from none, add more detail.) Use ./hacking/test-module CheckContinue reading “Ansible Troubleshooting Tips”
Most interesting links of February ’14
Recommended Readings Development Falsehoods Programmers Believe About Names – summary: there are no rules that apply to names, do not assume anything (my favourite: 12 + 13) Nathan Marz: Principles of Software Engineering, Part 1 – Nathan has worked with Big Data at Twitter and other places and really knows the perils or large, distributed, real-time systems andContinue reading “Most interesting links of February ’14”
Demonstration of Ansible Features With Control & Test VMs
I have created a small project to demonstrate some features of Ansible, the new DevOps hotness, including Vagrant VMs for running Ansible and for testing the configuration. Either go straight to https://github.com/jakubholynet/ansible-example-with-vm or continue reading the copy & paste here. This project has three things of interest: A non-trivial Ansible configuration that demonstrates couple ofContinue reading “Demonstration of Ansible Features With Control & Test VMs”
Most interesting links of September ’13
Recommended Readings Stuff The Internet Says On Scalability For September 13, 2013 – a collection of interesting performance related articles with summaries (via @_dagi) Can you copy a culture? The NUMMI story (audio/transcript) – how the GM factory with the worst workforce has been turned around via a good application of Toyota Production System –Continue reading “Most interesting links of September ’13”
Most interesting links of August ’13
Sorry folks, this month it will be very brief. I have many more great stuff in the queue but haven’t managed to write it down yet. Next month will be heavy 🙂 Recommended Readings Interested in native vs. webapp? Check out Why mobile web apps are slow (mobile browser much slower, not much real improvements,Continue reading “Most interesting links of August ’13”
Most interesting links of July ’13
This month focuses on languages and approaches (reactive programming, F#, Erlang, FP talks etc.), agile (need for speed, recommended books), Clojure/Linux/cloud tools and libs. Recommended Readings Development, agile The Need For Speed – the top 10 reasons for fast development flow (with time to market being one of the less important) – more learning, focusContinue reading “Most interesting links of July ’13”
Moved to https://blog.jakubholy.net/ 
