wheezy web: deploy nginx + uwsgi + memcached

wheezy.web is a lightweight, high performance, high concurrency WSGI web framework with the key features to build modern, efficient web. Here we will deploy quick start with nginx, uwsgi and memcached to clean debian stable installation.

memcached statistics status

Here is a "top" emulator for memcached statistics:

watch -n 5 "echo stats | socat unix-connect:/var/tmp/memcached.sock -"

The screen will be refreshed every 5 seconds and display results of memcached stats command.

How to build Python deb package from source

You need a newer python version that is not available with the Debian package management system. You can compile it from source and install but that usually takes a lot of time. It would be better to build a deb instead and install it on as many machines as you need. You can use checkinstall for this.

apt-get install checkinstall

The instruction how to compile python from source is here. Once you compiled python here is a simple command that does the rest for you:

checkinstall -y --pkgname=python2.7

Once it finishes you will get a deb file in the current directory. You can install it this way:

dpkg -i python2.7_2.7.6-1_i386.deb

Here is how to remove it:

apt-get remove --purge python2.7

Note, packages built with checkinstall are not updated by OS package management system, thus updates need to be provided manually.

PostgreSQL Streaming Replication Hot Standby

Streaming replication allows a standby server to stay up-to-date with primary. The standby connects to the primary, which streams WAL records to the standby as they're generated.

Hot standby is the term used to describe the ability to connect to the server and run read-only queries.

This method of replication is completely transparent to the client, it doesn't require any changes to database, allows query information from standby server and requires minimum administrative effort.

Python HTTP Client API

The modern web services expose public API to the world and JSON is de-facto standard in this communication. Here is a simple use case that integrates with buildbot public API.

Lets setup a virtual environment and install wheezy.core package:

virtualenv env
env/bin/easy_install wheezy.core

Launch python from virtual environment (env/bin/python) and try this:

>>> from wheezy.core.httpclient import HTTPClient
>>> c = HTTPClient('http://buildbot.buildbot.net/json/')
>>> c.get('project')
200
>>> project = c.json
>>>> str(project.title)
Buildbot

Here is another example that demonstarates etag handling (the second time we request events the server responds with HTTP status code 304, not modified):

>>> base = 'https://api.github.com/repos/python/cpython/'
>>> c = HTTPClient(base)
>>> c.get('events')
200
>>> c.headers['content-encoding']
['gzip']
>>> c.get('events')
304

The HTTPClient supports HTTP(S) GET/HEAD/POST verbs, follows redirects, handles cookies and etags between requests, gzip content decoding.