Go for writing web servers
Summary: in my experience Go is a good language for building websites/web servers.
It’s easy to get excited about new technology like Go. The question is: how does it stand up to scrutiny after daily use?
I’ve written 3 web applications in Go, they’ve been running in production for over a month so I feel justified in publishing my opinion.
In the past I wrote web applications in Perl, PHP, Python (web.py, Tornado, App Engine) so those are the technologies I campare Go to.
Of the 3 websites, AppTranslator, is web service for crowd-sourcing translation for software and was written completely from scratch.
One reason to migrate from App Engine to my own server was to save money. At my levels of traffic (~3 requests per second) I was paying ~$80/month, mostly for the frontend instance hours.
Another reason was to do more complex processing (App Engine is great as long as you don’t have to do something that App Engine doesn’t support).
Finally, I wanted to see how Go will handle a real life project. The best way to test a new technology is on a project with a predictable (and relatively small) scope.
Things you need for building a web application
What functionality is typically needed for writing a web application and how does Go support it?
A very capable http server is part of standard library (net/http).
It parses incoming http requests, provides an easy way to send http responses back.
High-level web frameworks provide url routing i.e. a way to say "call this function to handle this url". Go has a simple built-in router. I also use mux which is built on top of the built-in router.
A lot of what web server does is returning html. Constructing this html is greatly simplified by using templates. Go has a powerful html/template library for that. To me it seems roughly equivalent of Django or Tornado templates.
There are other templating libraries for Go, but I found the above built-in package satisfactory, so I didn’t even try to use them.
Basic support for cookies is part of built-in http library. To generate cookies that cannot be spoofed or hi-jacked, I used securecookie library
There are Go libraries for all of the popular databases (MySQL, PostgreSQL, MongoDB, Redis etc.) but I haven’t used them.
I used what I call NoDB approach i.e. I wrote a very simple storage system that uses text files. Data is kept in memory and persisted in an append-only file.
This wouldn’t be the right approach for services that require more sophisticated functionality but was good enough for my needs and didn’t take long to implement.
There are three oauth libraries that I know of. I used this one. I didn’t have any particular reason to choose this one over the others. I only needed it for implementing Twitter-based authentication, this library worked so I used it.
Generating atom (rss) feeds
One cannot respect a blog engine that doesn’t provide full-text rss feed. I couldn’t find an existing package so I build a simple (and small) library for generating atom feeds
JSON and XML support
Go has a built-in support for JSON and XML.
There are APIs for raw parsing/serialization. If you know the shape of the data, you can serialize (marshal, in Go’s parlance) data structures to JSON or XML and de-serialize (unmarshal) from JSON or XML into a struct.
S3 access, support for zip files
This one is not universally needed. My web apps have built-in backup functionality which stores data, sometimes in the form of a .zip file, in s3.
Go has support for creating and decompressing zip and tar archives in the standard library. For s3 support I use goamz.
This is not specific to writing web server - all your important code should have unit tests.
Go has a built-in API and tool support for writing and running tests.
Deploying a new version of your code to the server is a pain in the ass regardless of the language used.
I wrote relatively short deployment script using Fabric (which is a python library and a tool for running deployment scripts). It copies the source files to the server, compiles them on the server, runs unit tests, shuts-down existing instance of the service and launches the new version. It stops if there’s anything wrong along the way.
It’s really important to be able to quickly deploy new versions of the software so those days I would write the deployment script as the first thing in the project. Doing all those deployment steps manually would be very annoying.
Server config and misc thoughts
The overall setup of the server is pretty standard: each service is running as a separate process on a local port. Nginx is running on port 80 and proxies the traffic to a given service based on Host header.
Show me the code
Feel free to learn from the code or use it in your own projects.
I think writing non-trivial web services is a sweet spot for Go.
Most of the needed functionality is part of standard library. For almost everything else there are 3rd party libraries.
Writing in Go is almost as fast and fluent as writing in Python but the code is order of magnitude faster and uses less memory.
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