Over the last couple of months, we’ve transitioned away from callback-style error handling. Instead, we’re handling our errors with ES6 features (mainly promises and classes). In this post, I’ll talk about why we’ve made this transition.
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We run hundreds of thousands of containers across hundreds of servers a day. One of the biggest challenges we face is how to efficiently schedule containers. In this sense, scheduling is managing the allocation of containers to a set of servers in order to keep things running smoothly. Because the containers we schedule are components of our customers’ applications, we have to schedule them with no prior knowledge of their performance characteristics.
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Like any other generic solution, the microservices architecture has its tradeoffs; some things become easier and some become harder. When switching to microservices, one of the most common challenges is the question of where to put shared code.
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Promises are amazing! The concept has been around for decades, but they are finally here in ES6! Before we switched to promises, our code was full of confusing callback tricks and async. Switching to promises made our code easier to read, understand, and test. There are so many reasons to love promises, but here are my top five.
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One of the things that I found difficult when writing and refactoring in Ponos was maintaining the borders between the few classes and their functions. Some of the class methods returned values, some could throw errors, and others returned Promises. Relying on the inline documentation was insufficient because methods were changing faster than I was updating the documentation. Beyond these issues, I found myself moving or copying large chunks of testing code around for relatively small refactors, further fueling my motivation to find a better way.
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In my estimation, the most useful Unix command will always and forever be grep, but history is also high on my list. Combined, the two form a dynamic duo that can be used to answer the question, “what did I come up with to solve x, y or z hacky problem from the command line?”
We had a new feature request come down the pipeline while we were testing Runnable with some of our early users — to allow teams to opt-in to our elastic URL routing behavior, as opposed to having it enabled by default. (We have a fairly complex URL routing system which would take its own blog post to explain. In short, it handles routing all user traffic to their respective Docker containers.) This system was one of the earlier services written when building out our infrastructure, and has gone through several bug fixes and tuning to get it working just right.
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We work with Dockerfiles on a daily basis; all the code we run for ourselves and for our customers, we run from a set of Dockerfiles. In this article, we’ll talk about what mistakes people commonly make, and how to write them better. For those of you who are Docker experts, a lot of the tips in this article will probably be pretty obvious and will just provoke a lot of head-nodding. But for beginner to intermediate developers, this will be a useful guide that will hopefully help clean and speed up your workflow.
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