Analyzing .NET Core memory on Linux with LLDB

net-linux-memory

Most of the last week I’ve been experimenting with our .NET Windows project running on Linux in Kubernetes. It’s not as crazy as it sounds. We already migrated from .NET Framework to .NET Core, I fixed whatever was incompatible with Linux, tweaked here and there so it can run in k8s and it really does now. In theory.

In practice, there’re still occasional StackOverflow exceptions (zero segfaults, however) and most of troubleshooting experience I had on Windows is useless here on Linux. For instance, very quickly we noticed that memory consumption of our executable is higher than we’d expect. Physical memory varied between 300 MiB and 2 GiB and virtual memory was tens and tens of gigabytes. I know in production we could use much higher than that, but here, in container on Linux, is that OK? How do I even analyze that?

On Windows I’d took a process dump, feed it to Visual Studio or WinDBG and tried to google what’s to do next. Apparently, googling works for Linux as well, so after a few hours I managed learn several things about debugging on Linux and I’d like to share some of them today. Continue reading “Analyzing .NET Core memory on Linux with LLDB”

One-off Kubernetes jobs

Kubernetes jobsSo far all examples I made for Docker in Swarm Mode or Kubernetes blog posts were built around some sort of a service: web server, message queue, message bus. After all, “service” is a main concept in Swarm Mode, and even the whole micro-service application thing has, well, a “service” in it. But what about one-off jobs: maintenance tasks, scheduled events, or anything else, that we need to run just sometimes, not as a service?

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Dissecting Kubernetes example

ingress

Much to my surprise, starting from the last week Kubernetes became the part of my job description. It’s no longer something just interesting to try, I actually have to understand it now. And as you probably could tell from my older k8s post, I’m not quite there. The post sort of builds a logical example (containerized web server) but something just doesn’t click.

I was trying to understand what’s missing, and it seems like the problem is in the tooling. You see, there’re two and a half ways to run something in Kubernetes. One is through ad-hoc commands, like kubectl run or kubectl expose. They are simple, but they also skip few important concepts happening in the background, so the whole picture stays unclear. Continue reading “Dissecting Kubernetes example”

Autoscaling build servers with Gitlab CI

autoscaling builds

I’ve been using Gitlab CI for a while now and until certain point it worked really well. We had three build servers (GitLab runners) in the beginning, and when number of teammates or build steps and therefore commits and build jobs increased, I’d just add one more server to handle an extra load and felt that problem was solved.

Not for long. When number of servers climbed to more than ten, it became obvious that simply adding servers one by one doesn’t work anymore. It was both expensive to have all of them running all the time and it still wasn’t enough to handle occasional spikes of commits. Not to mention that during the nights and weekends those servers were doing absolutely nothing.

The whole thing needs to be dynamic and fortunately GitLab CI supports autoscaling out of the box. Documentation is a little bit confusing but in reality it’s very easy to get started. So here’s the plan: let’s try it!

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Another shiny toy – serverless application

Application deployment strategies are really evolving fast. While containerized applications still look hot, there’s something even more interesting happening. What if instead of dealing with application containers we’d got rid of redundant shell and send application functions directly to the cloud? Sounds insane, right? Yet all major cloud providers have function-as-a-service (FaaS) functionality, which along with object storage and database services is enough to build a fully functional web application without a server – a serverless application.

Of cause, there’s still a server somewhere. Maybe many of them. But this time we neither know, nor care about them. Continue reading “Another shiny toy – serverless application”

Keeping application secrets with Vault

Keeping application secrets with vault

I’ve been talking to one of our security guys recently about providing my piece of software with secret certificate and in the meanwhile keeping that certificate out of my hands. Apparently, managing application secrets is not an easy task. Later that day I checked out one of the tools that supposed to make such tasks simper – HashiCorp Vault – and was quite impressed. I didn’t realize how big the problem domain is, and how many tools and tricks you have to consider in order to build a solution for that. Today I want to go through the basics of managing secrets with Vault and hopefully highlight few things what impressed me the most.

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Provisioning cluster of VMs with Ansible

ansible cluster

Seeing how easy it was to provision one VM with Ansible, I can’t stop thinking: would it be as easy to deal with the whole cluster? After all, the original example I was trying to move to Ansible had three VMs: one Consul server and two worker machines. The server is ready, so adding two more machines sounds like an interesting exercise to do. So… let’s begin?

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Provisioning Vagrant VM with Ansible

Ansible Vagrant

I’m still looking for ways to automate hosts configuration. So far I’ve been using Vagrant + bash/PowerShell for configuring Linux or Windows hosts, but somehow I managed to miss the tool designed specifically for tasks like this – Ansible. It’s been around for last five years or so and became almost a synonym to “automatic configuration”. Today I’ll finally give it a try and see what difference it makes to use it comparing to provisioning with good old Bash.

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Easy continuous integration and deployment with GitLab CI

GitLab logo

Last month we finally finished migration from our previous CI/CD system to GitLab CE and that’s something that makes me extremely happy. It’s just so much easier to maintain our CI/CD monster, when repository, build configurations, build results, test results and even that “Approve” button that publishes the build to release repository – when they all are in the same place.

And what I particularly love about GitLab is how simple it is to configure all of that. So simple, that today I’ll show you how to setup fully functional CI/CD for demo project starting from installing GitLab and finishing with successful commit landing at “production” server. So, without further ado, let’s begin.

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Move existing WordPress site into Docker

Existing wordpress site in Docker

I’ve been running two WordPress blogs for some time and my biggest regret is that they are not running in Docker containers. If I did the right thing in the beginning, I wouldn’t have to worry about whether or not the server upgrade will be safe, or will I be able to recall server configuration when time to migrate comes. I actually would be able to spin up local blog replica, run some experiments on it (new settings, features or design change) and decide whether or not I want move that change into ‘production’.

However, it’s never too late. I’m reluctant to make a big change on the real server without prior tests, so today I’ll try to create local Docker replica of one of my blogs and see how that goes. Continue reading “Move existing WordPress site into Docker”