wesley tanaka

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Testing Ansible roles with test-kitchen and Docker using the Ansible Role Tester

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Preparing an Ansible role to be distributed can be time consuming and error prone. Ideally, you should test it against many versions of Ansible and many operating system versions. However, doing this is time consuming.

Enter the Ansible Role Tester.

In its simplest form, you simply add this to your CI script after making sure that docker and bundler are available:

wget -O- bit.ly/ansibletest | sh

Structured log files in Python using python-json-logger

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One approach for transferring events from your software into a log indexer software like logstash or splunk is to output them to disk in a structured format like JSON. Structured logs have some advantages over plain text logs, and the API of the Python logging module is flexible enough to output them with a custom Formatter.

Structured log files

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Historically, logs on unix systems have been line-based. Each event is represented by a single line appended to a file. Fields of the event are separated by spaces. These logs are compact, human readable, somewhat machine readable, and easily analyzed with pipelines of command line tools like cut, sort, uniq, awk, sed etc.

Erlang Cheat Sheet

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beam process: erlang virtual machine

.beam files: erlang binaries

erlang module is a file and the unit of compilation

erlang application is a unit of composition of functionality.  its interface is a start() and stop() function.

Importing a module from a local directory into a Puppetfile or a Gemfile

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In a Gemfile:

gem "my-module", :path => File.join("..", "my-module")

Accessible Introduction to Software Transactional Memory (STM)

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Fatal Error: Unable to find package java.lang in classpath or bootclasspath

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This error: Fatal Error: Unable to find package java.lang in classpath or bootclasspath can occur when /usr/lib/jvm/default-java is missing

This can be worked around with:

cd /usr/lib/jvm
sudo ln -s java-8-oracle default-java

Using Amazon Glacier as a cheap backup solution from the command line

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Set up the bucket and lifecycle rules:

Using Docker in Mac OSX with VMWare Fusion and docker-machine

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Although Docker uses Linux kernel features, it is possible to run docker containers in Mac OSX by installing a linux virtual machine and running the docker containers inside the virtual machine.

Create virtual machine called osxdocker:

docker-machine create --driver vmwarefusion osxdocker --vmwarefusion-memory-size=2048

Set environment variables to let the docker command line program connect to boot2docker

eval `docker-machine env osxdocker`

Run docker commands

How to catch up vmware clock to accurate time after a virtual machine pause/un-pause

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When you pause a VMWare Fusion virtual machine on a Mac OSX host and resume it after a long time, your system clock will sometimes be behind. ntpd won't catch the clock up if it's too far behind. One manual solution is to run ntpdate in the guest operating system once the virtual machine unpauses:

sudo ntpdate pool.ntp.org

Another approach which I am currently trying, is to set your clocksource to use acpi_pm instead of tsc. You can check which clocksources you have available with:

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by Wesley Tanaka