notes

When starting Varnish, add -p vsl_mask=+Hash argument to the command. Print varnish logs with this command:

sudo varnishlog -n /opt/varnish -q 'ReqURL ~ "my_request"'

Delete all images which contain build-cache in their name:

lxc image list -c l --format csv | grep build-cache | xargs -I % lxc image delete %

In order to enable mic on a bluetooth headphones, you need to change device configuration to Headset Head Unit in Settings > Sound menu. However, if you do so, the audio quality of the headphones will be quite bad.

Pipewire introduced support for the mSBC codec. This codec allows your headphones to enable microphone and still have okay-ish audio quality.

mSBC codec is disabled by default. To enable it, create ~/.config/pipewire/media-session.d/bluez-monitor.conf file with the following content:

properties = {
    bluez5.msbc-support = true
}

Restart Pipewire:

systemctl --user restart pipewire.service

HSP/HFP, codec mSBC option should be available in Settings > Sound menu

There is a special command git-subtree to merge / split repositories. It is not installed as a part of git package:

sudo dnf install git-subtree

The command to merge repository jsnjack/X to subfolder myfolder/new at branch master:

git subtree add -P myfolder/new [email protected]:jsnjack/X.git master

Add the following arguments to chrome options:

options = webdriver.ChromeOptions()
options.add_argument("headless")
options.add_argument("remote-debugging-address=0.0.0.0")
options.add_argument("remote-debugging-port=9222")
wd = webdriver.Chrome(chrome_options=options)

• start Chrome and navigate to chrome://inspect page
• make sure Discover network targets is checked
• click Configure button next to the previous option
• add a new target, for example (must be an IP address): 10.214.36.58:9222
• the remote browser should be automatically discovered and appear in Remote target list
• click Inspect

lxc config set core.https_address "[::]"
lxc config set core.trust_password new_password

After all clients are connected to the remote it is recommended to unset password:

lxc config unset core.trust_password

Traceback example: After update, kernel panic at boot with error: Unable to mount root fs on unknown-block(0,0)

Solution:

1. Restart your server and on the boot screen select any other boot option with older kernel
2. (optional, Leaseweb servers) Install missing dependency

sudo dnf install dracut-network

3. Navigate to /boot and verify that initramfs-file doesn’t exist for the latest kernel version
4. Generate it

# 4.18.0-338.el8.x86_64 is kernel version
dracut -f /boot/initramfs-4.18.0-338.el8.x86_64.img 4.18.0-338.el8.x86_64

5. Regenerate grub files

grub2-mkconfig -o /boot/grub2/grub.cfg

6. Restart

Sources:

• https://access.redhat.com/solutions/57018
• https://access.redhat.com/solutions/1958
• https://access.redhat.com/solutions/5672791

List all files installed by a specific package:

sudo dnf repoquery -l golang-bin