Nov 13, 2014

There are many deployment tools, such as Puppet, Chef and Salt Stack, most of them are all pull-based. Which means, when you deploy to a machine, the provisioning code will be downloaded to the target machine and run locally. Unlike many others, Ansible is a push-based deployment tool, instead of pulling code, it pushes SSH commands to the target machine. It’s great to have push-based approach in many situations. For example, you don’t need to install Ansible runtimes on the target machine, you can simply provision it. However, there are also shortcomings of this approach. Say if you want to provision EC2 instances in an AWS auto-scaling group, you don’t know when a new instance will be launched, and when it happens, it needs to be provisioned immediately. In this case, Ansible’s pushing approach is not that useful, since you need to provision the target machine on demand.

There are many ways to solve that problem, namely, to run Ansible provisioning code in a pulling manner.

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Aug 11, 2014

Docker is something really hot recently. It allows you to run your software with linux container easily. It’s actually kind of OS level isolation rather than hardware simulation nor kernel simulation. So you won’t have too much performance penalty but still have pretty nice virtual machine features. I really like the analog used by Docker community, shipping software should be easier and Docker serves as just like the standard container in shipping industry.

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Feb 5, 2014

It’s always an hateful job to correct PEP8 warnings manually.

$ flake8 billy --ignore=E501,W293
billy/tests/integration/test_basic.py:401:45: W291 trailing whitespace
billy/models/processors/balanced_payments.py:116:44: W291 trailing whitespace
billy/models/processors/balanced_payments.py:133:30: W291 trailing whitespace

I bet you don’t like this either. Today I cannot take it anymore. I was wondering, why I should do this thing machine should do? So I seek solutions on the Internet, and I found an article looks helpful - Syntax+pep8 checking before committing in git. The basic idea is to add a pre-commit hook script to git for checking PEP8 syntax before commit. By doing that, you cannot commit code with PEP8 warnings anymore, when you do, you see errors like this

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Oct 7, 2013

When you buy a house, you raise a mortgage. When you buy a car, you raise an auto loan. Maybe you are rich enough to clear all the debts at once, but anyway, we all live with debts, more or less. In fact, for software developers, we all live with debts as well. They’re so called technical debts. I really like the debt analog, technical debts are similar to debts in real life. Funny enough, most of people know how real debts work, but technical debts are not well known by developers. However, it makes sense. People live with the idea of debts maybe for thousands years, but there are only few decades history of computer.

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