Nguyen Quy Hy's blog – What I've learnt in the technical world

Offsite backup with Unraid, Tailscale, Backrest/Restic and Tailvault

November 27, 2025January 19, 2026 nguyenquyhy Leave a comment

Restic and its companion UI Backrest already allow you to back up to many different locations. However, getting it setup to back up from one Unraid NAS to another might not be straight forward. Here I will go into details on the steps I have used to to make it work.

The goals of this setup are:

Sender will use Backrest while receiver will use Tailvault app in Unraid.
Both apps will have Tailscale integration enabled, and connectivity will be via Tailscale.

Tailvault is a very simple Alpine container that enables SFTP. However, Restic doesn’t support SFTP with password, hence the need for additional setup for key pairs between the 2 containers.

Generate a keypair with PuTTYgen, choose EdDSA and Ed25519
Install TailVault app in the Community Store with the following modifications:
Open TailVault container log and login to Tailscale using the link in log
Open appdata/TailVault and download ssh_host_ed25519_key.pub
Install Backrest app in the Community Store with Tailscale enabled
Open Backrest container log and login to Tailscale using the link in log
Create known_hosts file on your computer with the following content:
Upload id_ed25519 from step 1 and known_hosts from step 5 to appdata/backrest
Select id_ed25519, click Permissions, change Group and Other to No Access
Edit backrest app in Unraid’s Docker and add the following:
Open backrest URL
Add repo. For Repository URL, use sftp:<username set in step 2>@<tailvault domain from Tailscale>:/backups

References

Guide from backrest: Using SSH (SFTP) Remotes with Docker Compose · Backrest

Dev Drive and Dotnet Tools

December 31, 2023December 31, 2023 nguyenquyhy 1 Comment

I recently tried out Dev Drive of Windows 11, where a ReFS partition can be created for your code and packages. It went smoothly and most of my projects were built successfully until it came to my Monogame project.

For your context, Monogame is a game engine written in .NET and allows you to write your game entirely in C#. It has a content pipeline to convert your audio and images assets to certain format, and the pipeline is written as local dotnet tools.

Turns out dotnet tools stop working after I moved Nuget package cache folder to the Dev Drive (with NUGET_PACKAGES environment variable). I tried to trigger the tool manually, but the error message is confusing an unhelpful:

❯ dotnet mgcb
Run "dotnet tool restore" to make the "mgcb" command available.
❯ dotnet tool restore
Skipping NuGet package signature verification.
Tool 'dotnet-mgcb' (version '3.8.1.303') was restored. Available commands: mgcb
❯ dotnet mgcb
Run "dotnet tool restore" to make the "mgcb" command available.

I tried to check my Dev Drive and I can see dotnet-mgcb had been restored correctly. Looking a bit further, I realized that .NET is still trying to look for the tool in the old path in %userprofile%\.nuget (even after computer restart).

I might have guessed the issue by now: there must be a cache somewhere pointing to the old paths. Turned out local dotnet tools cache the package information (including the path) in %userprofile%\.dotnet\toolResolverCache.

The fix is obvious now:

Empty %userprofile%\.dotnet\toolResolverCache
Run dotnet tool restore again and double check toolResolverCache to ensure the files are recreated.

I think ideally, since dotnet tool restore can already get the package to the new cache folder in Dev Drive, it should also try to update this toolResolverCache folder automatically instead of requiring a manual wipe like this.

New country and a new PC

November 21, 2020November 21, 2020 nguyenquyhy Leave a comment

It has been a while since I last published a new post here. I still have quite a number of drafts lining up, but has never managed to come around to finish them. Probably I should restart writing with some update on my life and some interesting things I learned recently.

A couple months ago I moved to a new country halfway around the world with a new job (or actually same old job in a different company), and I took this chance to learn to build a new PC. I have had a bit of experience with PC hardware before, but mainly from replacing part from a complete build, rather than building from an empty case, so this would be my first time having to work with a new case and mainboard.

Delegating authentication in ASP.NET 5 (or Core 3)

August 7, 2020September 15, 2020 nguyenquyhy Leave a comment

Most web applications nowadays need some authentication mechanism to differentiate their users for various levels of personalization. However, user authentication tends to get more sophisticated due to the variety of client platforms as well as the susceptibility to attacks.

As a user, I no longer want to create a new credential for each site I am visiting. Giving my password to a site requires a certain amount of trust in the site’s security since not all sites implements proper amount of protection to password (or credential in general) with standard mechanisms of password hashing or 2FA.

As a system developer, protecting users’ passwords and users’ credentials in general becomes a big burden due to the growing list of attack techniques. This is also a source of distraction when signing in is certainly not the focus of most web application.

A better way to tackle authentication would be to leave this part to the “professional,” or in other words, to delegate user authentication to popular identity services such as Google Account or Microsoft Account. Our web application now only needs to take care of authorization and managing users’ data. This has become a major trend thanks to the introduction of JWT and OIDC protocol.

In this post, I’ll go through what I have done to incorporate Signing in with Microsoft Account into my ASP.NET 5 web applications. This should be directly applicable for ASP.NET Core 3 thanks to similar authentication setup. Authentication mechanism in this post is using open standards such as JWT and OIDC, so it should be able to extend to many other identity providers such as Google Account.

Javascript Module Loaders

January 20, 2020January 20, 2020 nguyenquyhy Leave a comment

Javascript has a long history with so many changes over the years. One area that has so much improvements yet might still be so confusing is its support for modularization.

This blog post discusses a part of this area, specifically on how to your Javascript source files can be loaded into your application. This blog post also focuses on Javascript on browser instead of other native environment such as NodeJS.

References

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