Darko Luketic

21. July 202321. July 2023

Copy large qcow2 image via rsync between 2 servers

Problem:
Very large (400GB+) .qcow2 file that needs to be copied from HostA to HostB, where HostB is behind an ISP that does 24 hour disconnection of the connection.
Also because other people live in that household that use TV streaming, the bandwidth consumed should be limited.
In this case I’m on a 100MBit/s connection, and I’ll limit the transfer speed to 4MB/s.

We will use rsync for this.

The command is simply,

rsync \
--sparse \
--bwlimit=4000 \
--info=progress2 \
--partial \
--append-verify \
source_server_address:/var/lib/libvirt/images/image_name.qcow2 \
./image_name.qcow2

rsync \

--sparse \

--bwlimit=4000 \

--info=progress2 \

--partial \

--append-verify \

source_server_address:/var/lib/libvirt/images/image_name.qcow2 \

./image_name.qcow2

sparse means, skip transfering zeroes or empty, unfilled data.
bwlimit=4000 means limit the transfer speed to 4000 kByte / second. aka 4Mbps.
info=progress2 shows a prettier progress than just --progress
partial and append-verify allows us the resume the transfer one the 24 hour disconnection kicks in, without needing to start from the beginning. It also verifies the transferred.

15. July 2023

Gibt es keinen Go / Golang Job ohne Cloud Native?

Ich bin extrem gefrustet.
Seit Jahren schaue ich mir Stellenanzeigen an.

Am Anfang wurden Java Jobs einfach als Go Jobs deklariert. Inzwischen nur noch Kubernetes Docker Microservices AWS GCP.

Ich hab kein Bock mehr.

3. July 20233. July 2023

Today I learned about NATS, microservice API and security

Actual security, as in identity, is still a 3rd party thing, aka you still need a OIDC IDP (or oauth2 in the broadest sense or similar).
All NATS security does is validate that the credentials you pass the a client are valid and enforce limits, if configured.

The microservice API was necessary, since simple request/reply structure was lacking errors, logging and statistics.
micro.Request actually has a convenience req.RespondJSON() function.

A small example?

func (h *Handler) Run() error {
	sigs := make(chan os.Signal, 1)
	signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)
	done := make(chan bool, 1)
	go func() {
		sig := <-sigs
		fmt.Println(sig)
		done <- true
	}()

	newsService, e := micro.AddService(h.nc, micro.Config{
		Name:        "news",
		Endpoint:    nil,
		Version:     "0.0.1",
		Description: "Group Service",
	})
	if e != nil {
		return e
	}
	groupGrp := newsService.AddGroup("group")

	if e := groupGrp.AddEndpoint(Create, micro.HandlerFunc(h.createGroup)); e != nil {
		return e
	}
	if e := groupGrp.AddEndpoint(FindAll, micro.HandlerFunc(h.findAllGroups)); e != nil {
		return e
	}
	if e := groupGrp.AddEndpoint(GetById, micro.HandlerFunc(h.getByID)); e != nil {
		return e
	}

	<-done
	return nil
}

func (h *Handler) Run() error {

sigs := make(chan os.Signal, 1)

signal.Notify(sigs, syscall.SIGINT, syscall.SIGTERM)

done := make(chan bool, 1)

go func() {

sig := <-sigs

fmt.Println(sig)

done <- true

}()

newsService, e := micro.AddService(h.nc, micro.Config{

Name: "news",

Endpoint: nil,

Version: "0.0.1",

Description: "Group Service",

})

if e != nil {

return e

}

groupGrp := newsService.AddGroup("group")

if e := groupGrp.AddEndpoint(Create, micro.HandlerFunc(h.createGroup)); e != nil {

return e

}

if e := groupGrp.AddEndpoint(FindAll, micro.HandlerFunc(h.findAllGroups)); e != nil {

return e

}

if e := groupGrp.AddEndpoint(GetById, micro.HandlerFunc(h.getByID)); e != nil {

return e

}

<-done

return nil

}

So right now I have, ent for the database stuff and nats over websocket for the service requests.
But I’m having big issues with NATS Jetstream.
The ws client is blocking, despite callbacks and async.

The micro package also has a long way to go.
Regular HTTP has middleware, micro doesn’t seem to have it, maybe I’m missing something. OTOH I could just pass the request to a next function, but it’s not very elegant.

28. June 2023

Keycloak ED25519 is being worked on

If you’re like me and trying to use NATS Jetstream with JWT auth and Keycloak…
Well right now you’re SOL, because Keycloak so far only supports RSA, HMAC and AES, and NATS requires ED25519 signatures.
But a certain individual named tnorimat aka Takashi Norimatsu is apparently working on ED25519 support.

EdDSA Keycloak Issue on Github

Godspeed I say.

13. June 2023

Diablo 4 is an unfinished bad game – don’t buy

There isn’t really much more to add.
70€ for this boring solofest.
What a waste of money.

Last Activison Blizzard product I’ll ever buy.

What pisses me off, I didn’t even want to buy it, but I got seduced by Twitch streamers.
Despite better knowledge.
The thing is, when there’s a charismatic Twitch streamer and you think “hey it’s a good game” because he is having fun or pretending to have fun, well it’s his job to have fun and sell the game, then you think you’ll have fun too.
But that’s a delusion.

1. Clan size is limited to 150 people.
So you can’t join the streamer’s clan, because it’s always full. And he doesn’t give a shit to create multiple clans.
2. No means of social interaction.
No LFG/M, no LFG channel, even chatting is “hard”, because it’s restricted to your immediate area.
So you can’t just find a group. People in town are mostly AFK.
And that’s in a forced online game.
3. Split game and endless grind
Before you complete the 6 acts of the story, the game is rather boring and it completely changes once you’ve finished it.
But in the end it’s all the same anyway. Grind to no end.
It’s just an awful, endless grind.

This game is hands down the worst Diablo title of them all.