Debugging .NET Core app from a command line on Linux

command line debugging

Million years ago, way before the ice age, I was preparing small C++ project for “Unix Programming” university course and at some point had to debug it via command line. That was mind blowing. And surprisingly productive. Apparently, when nothing stands in the way, especially UI, debugging can become incredibly focused.

Since .NET Framework got his cross platform twin brother .NET Core, I was looking forward to repeat the trick and debug .NET Core app on Ubuntu via command line. Few days ago it finally happened and even though it wasn’t a smooth ride, that was quite an interesting experience. So, let’s have look.

Continue reading “Debugging .NET Core app from a command line on Linux”

Sending proactive messages with Microsoft Bot Framework

Futurama rebellion

I was thinking again about that bot, who supposedly will monitor unreliable tests for me, and suddenly realized one thing. All examples I dealt with were dialog based. You know, user sends the first message, bot responds, etc. But the bot I’m thinking about is different. Initial conversation indeed starts like a dialog. But once bot starts monitoring unit test statistics and finds something that I should take a look at, he needs to talk first! Microsoft calls such scenario sending proactive messages and there’re few tricks how to make that possible. Continue reading “Sending proactive messages with Microsoft Bot Framework”

Playing with Microsoft Bot Framework

Little Bender

Part of my job description is our CI/CD and it kind of implies that I’m interested in keeping the build green. It doesn’t mean that I immediately jump in whenever some unit test fails, but I’m definitely keeping an eye on unreliable ones.

Whenever master branch stays red long enough, this is what starts to happen to each failed test in it:

  1. Look for test failures history in Google BigQuery (select Name, Result, count(*)...).
  2. If test behaves like a random results generator, create a case for that.
  3. Skip the test in master branch and put the case number as a reason.
  4. Find out who created the test (git blame) and assign it back to the author.

Pretty simple. And boring. I can automate that, but it’s not always clear who is the author of the test. After all, people resign, update each other’s tests, refactor and destroy git history on special occasions. I was thinking about doing something with machine learning to solve that, but it feels like an overkill. Creating a bot, on the other hand, who would ask me to double check when it’s uncertain, sounds more interesting and actually doable. Even if I’m never going to finish it.

However, I’ve never wrote any bots before, so for starters I’d like to check what it actually feels like. Continue reading “Playing with Microsoft Bot Framework”

Caveman’s brief look into modern front-end

modern front-end

Well, it might seem surprising, given what this blog is usually about, but during most of my career my main focus was… in front-end development. Yup, JavaScript and friends. It wasn’t the only thing I did, but definitely the biggest one. After moving to Canada focus shifted a little bit: I still do occasional front-end tasks for our web project, which started back in 2009, but basically last 2 years I’m on a server side. Continue reading “Caveman’s brief look into modern front-end”

Web application firewalls

Our company is obsessed with IT security, so even though that’s not really my area, every other week I hear something new about the subject, whether I like it or not. However, sometimes interesting thing happen, when I learn about something I’ve been using for years, but only now realized that it actually has a name. I’m talking about Web Application Firewalls. Continue reading “Web application firewalls”

Quick intro to etcd

etcd logo

It feels like last months I focused way too much on debugging and .NET Core  and stopped paying attention to topic I enjoyed to blog about over the last year – DevOps and distributed applications. That doesn’t feel right and in order to fix that I’ll play with something new today. For instance, with etcd.

During my romance with distributed apps, etcd always was somewhere near. It came up as alternative to Consul when I was experimenting with service discovery and configuration management. At some point etcd also comes up as a storage where Kubernetes stores its cluster data. Etcd is everywhere! So I think it worth understanding what that is and how it looks like.

Continue reading “Quick intro to etcd”

Examining NodeJS core dump with llnode and lldb

Learning how to analyze .net core dumps on Linux with lldb and SOS plugin was really rewarding experience. It just feels good knowing that I can see managed stacks, objects and threads in something that looks very native and unmanaged. I saw there are also lldb plugins for Python and Java, but… can I do the same for NodeJS and JavaScript? Well,

OfCourse

There’s llnode plugin which does exactly that. Today I’m not going to go deeply into how it works – it’s not in the focus of my daily job now. But it’s still interesting to get a feeling of it. So, let’s dive right in. Continue reading “Examining NodeJS core dump with llnode and lldb”

The mystery of “Debug adapter process has terminated unexpectedly”

VS Code

Interesting story happened to me the other day. Visual Studio Code, my primary C# editor on Linux, suddenly stopped working. Well, it’s debugger did. Whenever I put a breakpoint and started debugging, nice friendly message would appear in the top of the editor, saying:

Debug adapter process has terminated unexpectedly

And it all worked just fine before. As recently I installed a whole bunch of new tools on my Ubuntu, such as lldb, perf and lttng, I played with removing and re-adding them again, reinstalling VS Code itself, but nothing seemed to help. Surprisingly, another C# IDE that supports Linux – JetBrains Rider – also failed to debug the projects I needed (worked fine with few others, though), so I had no other choice but try to get to the bottom of it, or at least make VS Code work again. Continue reading “The mystery of “Debug adapter process has terminated unexpectedly””

Sending .NET Core app metrics to Graphite with StatsD

time valueIt’s been more than a year since I connected a small piece of JavaScript to collectd plugin and started to gather our CI’s monitoring data and store it in Graphite. Surprisingly, the whole thing worked like a charm. Even the JavaScript component.

However, the time comes when I need to collect even more data coming from inside of long running apps, so JavaScript + collectd pair is no longer an option. What might work is those apps sending their metrics directly to Graphite server. After all, it can accept data in plain string format via TCP, so that shouldn’t be hard. Continue reading “Sending .NET Core app metrics to Graphite with StatsD”

How to unit test.. a server with goss

Unit test server with gossI’ve been looking through the latest Technology Radar issue and here’s what I found in its new Techniques section: “TDD’ing containers”. Wow. Mentally, I’m not yet ready to connect TDD to containers, but I took a look at the tools used for that, and those are quite interesting.

The first one is serverspec, which allows running BDD-like tests against local or remote servers or containers. It looks pretty solid, supports multiple OSs and its only downside (for me) is that serverspec is written in Ruby and therefore doesn’t really fit in the stack I normally work with.

The other one – goss – leaves an impression of a multitool, which usually worries me, but here… I’m kind of curious, so let’s have a look. Continue reading “How to unit test.. a server with goss”