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by Jiří {x2} Činčura

Running ASP.NET Core app on Azure B1ls VM (penny pinching)

27 Aug 2020 3 mins .NET Core, Azure, Azure VMs

Although I usually try to avoid IaaS services as much as possible, for this side project I needed to expose Kestrel webserver directly and hence the obvious choice for hosting web app – the App Service – wasn’t an option. So I went for a VM. And given it’s a side project, I also wanted to run it cheaply. And why not to try to go all out with B1ls VM using Linux.

About the VM

The B1ls using Linux is a cheapest option at the moment on Azure. Around €3-4. You get 1 vCPU, 0,5 GB of RAM and 160 IOPS/10MBps of uncached disk throughput. Not much, but at least on paper it should be capable of running ASP.NET Core app (not a huge one, obviously) without any hacking.


I went for a Debian distribution, only because from all the options it’s what I liked the most. Instead of installing just the runtime I installed the whole SDK, since I also wanted to try compiling the app directly on the VM. The installation was smooth and in a short amount of time I was able to run dotnet -info

.NET Core SDK (reflecting any global.json):
 Version:   3.1.401
 Commit:    39d17847db

Runtime Environment:
 OS Name:     debian
 OS Version:  10
 OS Platform: Linux
 RID:         debian.10-x64
 Base Path:   /usr/share/dotnet/sdk/3.1.401/

Host (useful for support):
  Version: 3.1.7
  Commit:  fcfdef8d6b

.NET Core SDKs installed:
  3.1.401 [/usr/share/dotnet/sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.App 3.1.7 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 3.1.7 [/usr/share/dotnet/shared/Microsoft.NETCore.App]


Compiling a basically empty ASP.NET Core app on this machine takes a lot of time, like between 1 and 3 minutes. The reason is the nature of B-series burstable VMs and the size/IOPS of B1ls. But it’s possible.


Running the application is pretty easy too. On my machine I executed dotnet publish -c Release -r linux-64 --self-contained false and copied the result onto the VM using scp. Set +x for the binary and off I go. My application is fairly small (just an ASP.NET Core (no MVC, no Razor Pages, etc.) and everything goes from memory (no disk, no database, etc.)), but I was still surprised how quickly it started (my expectation was something like Raspberry Pi 2/3/4 that I use for running .NET Core apps too).

Resources usage

This is the summary snapshot from top command while my application is running.

Tasks:  84 total,   1 running,  83 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.3 us,  0.0 sy,  0.0 ni, 99.3 id,  0.0 wa,  0.0 hi,  0.3 si,  0.0 st
MiB Mem :    397.5 total,     22.1 free,    250.9 used,    124.6 buff/cache
MiB Swap:      0.0 total,      0.0 free,      0.0 used.    131.2 avail Mem


It is absolutely possible to run an ASP.NET Core on a B1ls VM, but it needs to be a slim one. The B1s might be a better option for a “reasonable” ASP.NET Core app with still a very favorable pricing (about double the price of B1ls).

Profile Picture Jiří Činčura is an independent developer focusing on data and business layers, language constructs, parallelism and databases. Specifically Entity Framework, asynchronous and parallel programming, cloud and Azure. He's Microsoft Most Valuable Professional and you can read his articles, guides, tips and tricks at