Writing TCP scanner in Go

Go is perfect for network applications. Its awesome standard library helps a lot in writing such software. In this article, we’ll write a simple TCP scanner in Go. The whole programm will take less than 50 lines of code. Before we’ll go to practice - a little theory. Of course, the TCP is more complicated than I describe but we need just basics. The TCP handshake is three-way. Firstly, the client sends the syn package which signals the beginning of a communication.

Golang Tips & Tricks #7 - private repository and proxy

In Go 1.13 all modules are provided using a proxy. The proxy caches dependencies what helps to make sure that the version of an external dependencies will never change. If the vendor remove the version and create a new one with the same version, only the first one will be provided. Proxy improves the performance of downloading dependencies as well so it’s useful to have such functionality in the ecosystem.

How I organize packages in Go

Structuring the source code can be as challenging as writing it. There are many approaches to do so. Bad decisions can be painful and refactoring can be very time-consuming. On the other hand, it’s almost impossible to perfectly design your application at the beginning. What’s more, some solutions may work at some application’s size and should the application develop over time. Our software should grow with the problem it’s solving.

Golang Tips & Tricks #6 - the _test package

Testing is one of the hardest stuff in programming. Today trick will help you organize your tests and the production code. Let’s assume you have a package called orders. When you want to separate the package for tests from the production code you can create a new folder and write tests there. It will work but there’s a more clearer way - put your tests to the folder with you package but suffix the package’s name in tests with _test.

Golang Tips & Tricks #5 - blank identifier in structs

While working with structures, there’s a possibility to initialize the structure without providing the keys of fields. type SomeSturct struct { FirstField string SecondField bool } // ... myStruct := SomeSturct{"", false} If we want to force other (or even ourselfs) to explicitly providing the keys, we can add _ struct{} in the end of the structure. type SomeSturct struct { FirstField string SecondField bool _ struct{} } // COMPILATION ERROR myStruct := SomeSturct{"", false} The code above will produce too few values in SomeSturct literal error.

GoGoConf 2019 - report

Recently I’ve been on the GoGoConf conference in Cracow. It was a cool opportunity to learn more and meet interesting persons. Today I’ll tell you about my thoughts regarding every talk from 2019 edition. Most of the talks don’t have video available yet but when the videos will be published I’ll update the post. Tackling contention: the monsters inside the ’sync.Locker’ - Roberto Clapis I personally like Roberto a lot for the way he behaves and how professional he is.

Software 2.0

There are, at least, two excellent articles about Software 2.0. Andrzej Karpathy and Carlos E. Perez wrote blog posts which cover the topic. In this article, I will explain how I understand the term “Software 2.0” what, I hope, will give you a different point of view on the main topic. Software 2.0 is a set of three things which combined complement each other: tools, people, and process. All of them relates to each other closely.

When you can lose messages in Kafka

Kafka is speedy and fault-tolerant distributed streaming platform. However, there are some situations when messages can disappear. It can happen due to misconfiguration or misunderstanding Kafka’s internals. In this article, I’ll explain when the data loss can happen and how to prevent it. Publisher: Acknowledgment When a message is sent to the publisher, the publisher waits for an acknowledgment (ACK) from the broker. There are three configuration options which can be used:

Golang Tips & Tricks #4 - internal folders

While developing a library, we create a directory structure to keep the code organized. However, some exported functions or struct should not be used by users of the library. The achieve that, call the package internal. . ├── bar │ ├── bar.go │ └── internal │ └── foobar.go ├── internal │ └── foo.go └── main.go In the example above, the foo.go can be included only in the main.go. What’s more, only the bar.

Learning On Mistakes

There are many situations which can cause unavailability. One of them can be a bug in a software, bad architecture design decisions or even a human error. Depending on how the numbers are calculated, from 22% to even 70% of outages are caused by human error. Software engineers, DevOps or administrators cannot prevent all the outages but we can learn from ourselves to improve the stability and reliability of systems we are creating.