It’s impossible to work with docker containers without docker images. In this post I want to talk about what makes docker images possible: the overlay filesystems.
I’ll start with a brief description of overlay filesystems. Then we will see how it applies to docker images and how docker builds an image from a dockerfile. I’ll conclude with layers cache and OCI format for container images.

As usual I’ll try to make the blog post as practical as possible.

What’s an overlay filesystems

Overlay filesystems (also called union filesystems) allow creating a union of two or more directories: a list of lower directories and an…


Photo by Michael Dziedzic on Unsplash

When we think about distributed systems, we picture multiple machines communicating to each other to fulfill a request, perhaps a cluster of nodes storing data in a distributed database, or more abstract concepts like consistency in the CAP theorem[1].

But have you have ever seen a distributed system with your eyes? I do not mean an architecture diagram, I mean REALLY seeing it.
I bet you do and it is likely the thing you are using to read this post, your laptop. If the last sentence surprised you, keep reading and we shall see why.

Consistency

As you already know, memory…


In the past few years, the DevOps reports have shown how high-performance teams use monitoring to quickly detect errors, reduce downtime and costs.
Monitoring a complex application is a significant engineering endeavor in and of itself, but thanks to effort of cloud providers, developers can instrument their system with few clicks or configurations.

When it comes to your system health, monitoring your dependencies is just as important as monitoring your system. If your system is experiencing issues, your system dashboards and alarms should highlight if one of your dependency is having a bad time.
In the rest of the article…


Hi everyone!

Today I am going to discuss about a topic very close to me:
Accessibility (or a11y for short).

I have worked a little over one year in the Accessibility team, experience that helped me grow, both personally and professionally. I have recently moved to another team, so before I will partly override what I learned with new information, I though to flush out the main memory on the disk and write down the main pointers for later reference.

Hopefully with this post I am going to to kill two birds with one stone, both document and share couple…

Nicola Apicella

Software dev engineer at Amazon. Golang, Java and container enthusiast. Love automation in general. Opinions are my own.

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