Docker is the buzz these days, right? Package your application with a Dockerfile, build, push to a registry and somehow get it to your cloud provider. There are a million ways to skin this cat. 🐱
The reality of it is, someone sets up a container somewhere that “just works” and often forgets about it. I’ve seen a single container run for months on end. This results in missing functionality from newer versions of an application or—even worse—can lead to potential security vulnerabilities, all because somebody was too lazy to update the image and recreate the container on their on-prem server or in the cloud.
Container Orchestration
The proper way to handle such a scenario is to utilize rolling updates using Kubernetes or Docker Swarm, but to most developers, these are black boxes that “only ops people know how to use.” So what happens now? Usually a developer will just issue a docker run... and say, “Cool, my app is deployed, now consumers can quit hounding me.”
It’s not ideal… but again… the reality.
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Automate the Process
There’s a popular open source project called Watchtower that has the ability to “watch” running Docker containers on either the same local or remote host, check if there is a newer image in the remote registry, and then update the container with the new image using the same configuration options it was instantiated with. Pretty cool right?
Absolutely.
This application really intrigued me, so naturally I started digging through the source, which is written in Go. The issue was I couldn’t follow a lot of what was going on in the application due to its lack of readability. I’m not a Go expert, but can still follow logic in most cases. This was not one of those cases…
I thought it was natural that it was written in Go since, well, Docker is. I knew there were two Docker SDK options available in Go and Python, so I thought to myself, “OK, Watchtower is the Go version of auto-updating containers, where’s the Python version?” Well, guess what… it didn’t exist.
Reinventing the Wheel
Why?
I was somewhat shocked to see someone had not done a similar thing using the Docker Python SDK. And so went the thought process, “Hey, I dig Python. I’ll try my hand at it.” It is the Hacktoberfest season after all.
After a weekend of playing with Docker Python SDK, I saw how feasible the implementation would be and had something minimal working.
Next, if we look closer we can see there are 4 requests being generated to fonts.gstatic.com. And this is to load Google fonts, which is included in the default WordPress theme. In our example, it is loading different font weights for Merriweather and Montserrat.
It always better to reduce the number of external DNS lookups and also focus on having a single HTTP/2 connection if possible. Every external lookup introduces its own set of latency issues, content download times, TLS negotiations, etc. So what we are going to do is move the Google fonts to our CDN. This way they load from the same place as the rest of our assets.
You can check out our in-depth tutorial on how to migrate Google Fonts to your CDN. This can also be used to simply host them directly on your web server as well, if you aren’t using a CDN. We quickly download the following Google fonts from https://google-webfonts-helper.herokuapp.com and host them on our server in a folder called “fonts.”
As you can see we are almost down to a single HTTP/2 connection with no external DNS lookups. The only thing left is that call to gravatar.com. Thankfully they are using HTTP/2 now, but unless you really want avatars, you can disable them.
This can easily be remove by un-checking the “show avatars” in the discussion setting of your WordPress dashboard.
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By removing the call to gravatar.com we are now down to 11 HTTP requests and are using a single HTTP/2 connection for external assets on our CDN.
