How to decrease workload in my Kubernetes cluster at night? (and save money 🤑)

As users of cloud resources, we are concerned by the cost of resources we use. The goal is to use the minimum required resource we need, everytime, and that’s why orchestrators are very useful.

Kubernetes with its automatic mechanismcs to scale (pods and nodes autoscaling) is very good for that. Here we will not take about how it works but how we can use this in concret use case to downscale easily when we don’t need resources more.

Setup Grafana OnCall @Home

Hello visitor! I hope you are fine.

It’s nice to meet you here.

Oh, you are passionate about alerting? Like me! What a coincidence!

OK, I knew, you are here because of the title…

I’m so happy to share with you my passion. What to say to start… hum… did you hear about Grafana OnCall?!

Will it continue like this for long?

It’s totally awesome, let’s talk about it. Come on, take a lemonade and be prepare for the fun!

Jé pa l'temps #33 - Clean big files in git

Basically the job is done with a command called git filter-branch

1git filter-branch --force --index-filter "git rm --cached --ignore-unmatch static/\*" --prune-empty --tag-name-filter cat -- --all

1git filter-repo --strip-blobs-bigger-than 10M

Sources

• https://docs.gitlab.com/ee/user/project/repository/reducing_the_repo_size_using_git.html

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La série « Jé pa l’temps » est une série de tutoriels rapides en mode “prise de note” pour avoir une trace de tout ce dont je ne peux me rappeler et pourquoi pas le partager à d’autre. On va à l’essentiel, laissons les jolis pavés à d’autres sites comme medium… LOL !

Jé pa l'temps #32 - Cloudinit

With Proxmox

Disk auto resize on boot

• Issue when you have several partition, if the order is disk,boot,swap; The last partition is Swap. It works well with only one big partition. Let’s try with several
  • Works with legacy partition, not LVM. LVM is another step of complexity.

Cloud init (Hostname)

There are “three configs” for the cloud init

• Network
• Vendor
• User

With this command, we can see the user config setup by Proxmox.

Jé pa l'temps #31 - Flush DNS

On Linux

sudo systemd-resolve --flush-caches
sudo resolvectl flush-caches

Fun commands

sudo systemd-resolve --statistics

Sources

• https://devconnected.com/how-to-flush-dns-cache-on-linux/

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La série « Jé pa l’temps » est une série de tutoriels rapides en mode “prise de note” pour avoir une trace de tout ce dont je ne peux me rappeler et pourquoi pas le partager à d’autre. On va à l’essentiel, laissons les jolis pavés à d’autres sites comme medium… LOL !

Jé pa l'temps #30 - Firewalls

Firewall package rules explanations

When you have openwrt, the server is the router.

INPUT: packets coming from the network and going to your server. OUTPUT: packets originating from your server and going to the network. FORWARD: packets forwarded by your server, if/when it acts as a router between different networks <= When the packet comes one zone to another without being addressed to the router

So basically when you want to host a wireguard peer on the router, your block all input traffic but you have to open wireguard port (think about it, it’s logic). So you do a specific rule on INPUT.