WSL 2 keeps overwriting resolv.conf

[Rimobul]

Environment

Windows build number: Microsoft Windows [Version 10.0.19041.264]
Your Distribution version: Ubuntu 18.04
Whether the issue is on WSL 2 and/or WSL 1: WSL 2

Steps to reproduce

Previously, I had my WSL in version 1 and everything worked fine. Then I decided to upgrade to WSL 2 and - similar to many others - I lost internet connection. Thankfully, I could easily bring it back by running:

sudo bash -c 'echo "nameserver 8.8.8.8" > /etc/resolv.conf'

Apparently, it was just a DNS issue. I could live with that. However, then I restarted my WSL and the nameserver was set back to 172.31.208.1. So I decided to do exactly what was written in the comments in /etc/resolv.conf:

# This file was automatically generated by WSL. To stop automatic generation of this file, add the following entry to /etc/wsl.conf:
# [network]
# generateResolvConf = false

And ran the following lines:

sudo bash -c 'echo "[network]" > /etc/wsl.conf'
sudo bash -c 'echo "generateResolvConf = false" >> /etc/wsl.conf'

I was proud that I resolved the issue so elegantly until I restarted my WSL again. Now, resolv.conf was in red and not accessible from Ubuntu. When I tried to access it from Windows, I saw just an empty file.

Expected behavior

After restarting WSL, resolv.conf keeps the user-defined values.

Actual behavior

After restarting WSL, resolv.conf is empty or not accessible at all.

[0xbadfca11]

/etc/resolv.conf is symlink to /run/resolvconf/resolv.conf, and /run is tmpfs.
You have to delete symlink before editing.

[Rimobul]

@0xbadfca11 That did not help. I ran:

sudo rm /etc/resolv.conf
sudo bash -c 'echo "nameserver 8.8.8.8" > /etc/resolv.conf'
sudo bash -c 'echo "[network]" > /etc/wsl.conf'
sudo bash -c 'echo "generateResolvConf = false" >> /etc/wsl.conf'

But after restarting WSL, I see the following:

[Rimobul]

Ok, so I finally found solution in an old ticket: #1908 (comment)

So the full set of commands that have to be run is:

sudo rm /etc/resolv.conf
sudo bash -c 'echo "nameserver 8.8.8.8" > /etc/resolv.conf'
sudo bash -c 'echo "[network]" > /etc/wsl.conf'
sudo bash -c 'echo "generateResolvConf = false" >> /etc/wsl.conf'
sudo chattr +i /etc/resolv.conf

[vctsvz]

sudo tee /etc/wsl.conf > /dev/null << EOF
[network]
generateResolvConf=false
EOF

echo -e 'nameserver 8.8.8.8\nnameserver 8.8.4.4' | sudo tee /etc/resolv.conf > /dev/null;
sudo chattr -f +i /etc/resolv.conf;

[jnawk]

There's no point mucking about with /etc/wsl.conf - it's utterly ignored, and the chattr +i part of the solution amounts to "make the file completely immutable", thereby preventing whatever WSL nonsense is clobbering the file at startup from doing what it pleases. The note in /etc/resolv.conf about how to prevent /etc/resolv.conf from being clobbered is just total fabrication.

[d4v3y0rk]

There's no point mucking about with /etc/wsl.conf - it's utterly ignored, and the chattr +i part of the solution amounts to "make the file completely immutable", thereby preventing whatever WSL nonsense is clobbering the file at startup from doing what it pleases. The note in /etc/resolv.conf about how to prevent /etc/resolv.conf from being clobbered is just total fabrication.

I can confirm that the wsl.conf does nothing and that using the solution mention above with the +i attribute does work.

[ahickey-sfdc]

wsl --shutdown

It seems that changes to wsl.conf are only read when the subsystem completely restarts. I kept trying to get /etc/resolv.conf to stick around and it was overwritten every time I started a new wsl instance even with the +i attribute on /etc/resolv.conf. The only way to get it to stay for me was to do a wsl --shutdown once.