Not OP, but, seriously asking, why should I? I usually still use VMs for every app i need. Much more work I assume, but besides saving time (and some overhead and mayve performance) what would I gain from docker or other containers?
Comment on Should I move to Docker?
onlinepersona@programming.dev 9 months ago
Why wouldn’t you want to use containers? I’m curious. What do you use now? Ansible? Puppet? Chef?
Dyskolos@lemmy.zip 9 months ago
MostlyGibberish@lemm.ee 9 months ago
One of the things I like about containers is how central the IaC methodology is. There are certainly tools to codify VMs, but with Docker, right out of the gate, you’ll be defining your containers through a Dockerfile, or docker-compose.yml, or whatever other orchestration platform. With a VM, I’m always tempted to just make on the fly config changes directly on the box, since it’s so heavy to rebuild them, but with containers, I’m more driven to properly update the container definition and then rebuild the container. Because of that, you have an inherent backup that you can easily push to a remote git server or something similar. Maybe that’s not as much of a benefit if you have a good system already, but containers make it easier imo.
Dyskolos@lemmy.zip 9 months ago
Actually only tried a docker container once tbh. Haven’t put much time into it and was kinda forced to do. So, if I got you right, I do define the container with like nic-setup or ip or ram/cpu/usage and that’s it? And the configuration of the app in the container? is that IN the container or applied “onto it” for easy rebuild-purpose? Right now I just have a ton of (big) backups of all VMs. If I screw up, I’m going back to this morning. Takes like 2 minutes tops. Would I even see a benefit of docker? besides saving much overhead of cours.
felbane@lemmy.world 9 months ago
You don’t actually have to care about defining IP, cpu/ram reservations, etc. Your docker-compose file just defines the applications you want and a port mapping or two, and that’s it.
Example:
--- version: "2.1" services: adguardhome-sync: image: lscr.io/linuxserver/adguardhome-sync:latest container_name: adguardhome-sync environment: - CONFIGFILE=/config/adguardhome-sync.yaml volumes: - /my/appdata/config:/config ports: - 8080:8080 restart: - unless-stopped
That’s it, you run
docker-compose upand the container starts, reads your config from your config folder, and exposes port 8080 to the rest of your network.
SpaceCadet@feddit.nl 9 months ago
what would I gain from docker or other containers?
Reproducability.
Once you’ve built the Dockerfile or compose file for your container, it’s trivial to spin it up on another machine later. It’s no longer bound to the specific VM and OS configuration you’ve built your service on top of and you can easily migrate containers or move them around.
Dyskolos@lemmy.zip 9 months ago
But that’s possible with a vm too. Or am I missing something here?
twei@feddit.de 9 months ago
If you update your OS, it could happen that a changed dependency breaks your app. This wouldn’t happen with docker, as every dependency is shipped with the application in the container.
uzay@infosec.pub 9 months ago
Apart from the dependency stuff, what you need to migrate when you use docker-compose is just a text file and the volumes that hold the data. No full VMs that contain entire systems because all that stuff is just recreated automatically in seconds on the new machine.
pete_the_cat@lemmy.world 9 months ago
VMs have a ton of overhead compared to Docker. VMs replicate everything in the computer while Docker just uses the host for everything, except it sandboxes the apps.
In theory, VMs are far more secure since they’re almost entirely isolated from the host system (assuming you don’t have any of the host’s filesystems attached), they are also OS agnostic whereas Docker is limited to the OS it runs on.
Dyskolos@lemmy.zip 9 months ago
Ah ok thanks, the security-aspect is indeed important to me. So I shouldn’t really use it for critical things. Especially those with external access.
pete_the_cat@lemmy.world 9 months ago
Docker is still secure, it’s just less secure than Virtualization. It’s like a standard door knob lock (the twist/push button kind) vs a deadbolt. Both will keep 90% of bad-actors out but those who really want to get in can based on how high the security is.
criticalimpact@lemm.ee 9 months ago
Saves time, minimal compatibility, portability and you can update with 2 commands There’s really no reason not to use docker
Dyskolos@lemmy.zip 9 months ago
But I can’t really tinker IN the docker-image, right? It’s maintained elsewhere and I just get what i got. But with way less tinkering? Do I have control over the amount/percentage of resources a container uses? And could I just freeze a container, move it to another physical server and continue it there? So it would be worth the time to learn everything about docker for my “just” 10 VMs to replace in the long run?
xcjs@programming.dev 9 months ago
You can tinker in the image in a variety of ways, but make sure to preserve your state outside the container in some way:
- Extend the image you want to use with a custom Docker file
- Execute an interactive shell session, example
docker exec -it containerName /bin/bash - Replace or expose filesystem resources using host or volume mounts.
Yes, you set a variety of resources constraints, including but not limited to processor and memory utilization.
There’s no reason to “freeze” a container, but if your state is in a host or volume mount, destroy the container, migrate your data, and resume it with a run command or docker-compose file. Different terminology and concept, but same result.
It may be worth it if you want to free up overhead used by virtual machines on your host, store your state more centrally, and/or represent your infrastructure as a docker-compose file or set of docker-compose files.
GreatBlueHeron@lemmy.ca 9 months ago
Currently no virtualisation at all - just my OS on bare metal with some apps installed. Remember, this is a single machine sitting in my basement running Samba and a couple of other things - there’s not much to orchestrate :-)
onlinepersona@programming.dev 9 months ago
Oh, I thought you had multiple machines.
I use docker because each service I use requires different libraries with different versions. With containers, that doesn’t matter. It also provides some rudimentary security. If an attacker gets in, they’ll have to break out of the container first to get at the rest of the system. Each container can run with a different user, so even if they do get out of the container, at worst they’ll be able to destroy the data they have access to - well, they’ll still see other stuff in the network, but I think it’s better than being straight pwned.
pete_the_cat@lemmy.world 9 months ago
It makes deployments a lot easier once you have the groundwork laid (writing your compose files). If you ever need to nuke the OS reinstalling and configuring 20+ apps can only take a few minutes (assuming you still have the config data, which should live outside of the container).
For example, setting up my mediaserver, webserver, SQL server, and usenet suit of apps can take a few hours to do natively. Using Docker Compose it takes one command and about 5-10 minutes. Granted, I had to spend a few hours writing the compose files and testing everything, along with storing the config data, but just simply backing up the compose files with git means I can pull everything down quickly. Even if I don’t have the config files anymore it probably only takes like an hour or less to configure everything.