All articles tagged #linux

SSH is yet another example of an ancient technology that is still in wide use today. It may very well be that learning a couple of SSH tricks is more profitable in the long run than mastering a dozen Cloud Native tools destined to become deprecated next quarter.

One of my favorite parts of this technology is SSH Tunnels. With nothing but standard tools and often using just a single command, you can achieve the following:

• Access internal VPC endpoints through a public-facing EC2 instance.
• Open a port from the localhost of a development VM in the host's browser.
• Expose any local server from a home/private network to the outside world.

And more 😍

But despite the fact that I use SSH Tunnels daily, it always takes me a while to figure out the right command. Should it be a Local or a Remote tunnel? What are the flags? Is it a local_port:remote_port or the other way around? So, I decided to finally wrap my head around it, and it resulted in a series of labs and a visual cheat sheet 🙈

Full version 1.5MB

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GoogleContainerTools' distroless base images are often mentioned as one of the ways to produce small(er), fast(er), and secure(r) containers. But what are these distroless images, really? Why are they needed? What's the difference between a container built from a distroless base and a container built from scratch? Let's take a deeper look.

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There are many ways to create containers, especially on Linux and alike. Besides the super widespread Docker implementation, you may have heard about LXC, systemd-nspawn, or maybe even OpenVZ.

The general concept of the container is quite vague. What's true and what's not often depends on the context, but the context itself isn't always given explicitly. For instance, there is a common saying that containers are Linux processes or that containers aren't Virtual Machines. However, the first statement is just an oversimplified attempt to explain Linux containers. And the second statement simply isn't always true.

In this article, I'm not trying to review all possible ways of creating containers. Instead, the article is an analysis of the OCI Runtime Specification. The spec turned out to be an insightful read! For instance, it gives a definition of the standard container (and no, it's not a process) and sheds some light on when Virtual Machines can be considered containers.

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Go standard library makes it super easy to start an HTTP server:

package main

import "net/http"

func main() {
    http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
        w.Write([]byte("Hello there!\n"))
    })

    http.ListenAndServe(":8080", nil)
}

...or send an HTTP request:

package main

import "net/http"

func main() {
    resp, err := http.Get("http://example.com/")
    body, err := io.ReadAll(resp.Body)
}

In just ~10 lines of code, I can get a server up and running or fetch a real web page! In contrast, creating a basic HTTP server in C would take hundreds of lines, and anything beyond basics would require third-party libraries.

The Go snippets from above are so short because they rely on powerful high-level abstractions of the net and net/http packages. Go pragmatically chooses to optimize for frequently used scenarios, and its standard library hides many internal socket details behind these abstractions, making lots of default choices on the way. And that's very handy, but...

What if I need to fine-tune net/http sockets before initiating the communication? For instance, how can I set some socket options like SO_REUSEPORT or TCP_QUICKACK?

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