What's the deal with Docker?
I never understood how to use Docker, what makes it so special? I would really like to use it on my Rapsberry Pi 3 Model B+ to ease the setup process of selfhosting different things.
I'm currently running these things without Docker:
- Mumble server with a Discord bridge and a music bot
- Maubot, a plugin-based Matrix bot
- FTP server
- Two Discord Music bots
All of these things are running as systemd services in the background. Should I change this? A lot of the things I'm hosting offer Docker images.
It would also be great if someone could give me a quick-start guide for Docker. Thanks in advance!
IMHO with docker and containerization in general you are trading drive space for consistency and relative simplicity.
a hypothetical:
You set up your mumble server and it requires the leftpad 3.7 package to run. you install it and everything is fine.
Now you install your ftp server but it needs leftpad 5.5. what do you do? hope the function that mumble uses in 3.7 still exists in 5.5? run each app in its own venv?
Docker and containerization resolve this by running each app in its own mini virtual machine. A container running mumble and leftpad 3.7 can coexist on host that also has a container running a ftp server with leftpad 5.5.
Here is a good video on what hole docker and containerization looks to fill
https://www.youtube.com/watch?v=Nm1tfmZDqo8
Docker containers aren't running in a virtual machine. They're running what amounts to a fancy chroot jail... It's just an isolated environment that takes advantage of several kernel security features to make software running inside the environment think everything is normal despite being locked down.
This is a very important distinction because it means that docker containers are very light weight compared to a VM. They use but a fraction of the resources a VM would and can be brought up and down in milliseconds since there's no hardware to emulate.
FYI docker engine can use different runtimes and there is are lightweight vm runtimes like kata or firecracker. I hope one day docker will default with that technology as it would be better for the overall security of containers.
To put it in simpler terms, I'd say that containers virtualise only the operating system rather than the whole underlying machine.I guess not then.
It virtualises only parts of operating system (namely processes and network namespaces with ability to passthru devices and mount points). It is still using host kernel, for example.
I wouldn't say that namespaces are virtualization either. Container don't virtualize anything, namespaces are all inherited from the root namespaces and therefore completely visible from the host (with the right privileges). It's just a completely different technology.
The word you’re all looking for is sandboxing. That’s what containers are - sandboxes. And while they a different approach to VMs they do rely on some similar principals.
I never said that it is a virtualization. Yet for easy understanding I named created namespaces "virtualized". Here I mean "virtualized" = "isolated". Systemd able to do that with every process btw.
Also, some "smart individuals" called comtainerization as type 3 hypervisors, that makes me laugh so hard :)
The operating system is explicitly not virtualised with containers.
What you've described is closer to paravirtualisation where it's still a separate operating system in the guest but the hardware doesn't pretend to be physical anymore and is explicitly a software interface.
Not exactly IMO, as containers themselves can simultaneously access devices and filesystems from the host system natively (such as VAAPI devices used for hardware encoding & decoding) or even the docker socket to control the host system's Docker daemon.
They also can launch directly into a program you specify, bypassing any kind of init system requirement.
OC's suggestion of a chroot jail is the closest explanation I can think of too, if things were to be simplified
I would also add security, or at least accessible security. Containers provide a number of isolation features out-of-the-box or extremely easy to configure which other systems require way more effort to achieve, or can't achieve.
Ironically, after some conversation on the topic here on Lemmy I compiled a blog post about it.
Tbf, systemd also makes it relatively easy to sandbox processes. But it's opt-in, while for containers it's opt-out.
Yeah, and it also requires quite many options, some with harder-to-predict outcomes. For example RootDirectory can be used to effectively chroot the process, but that carries implications such as the application not having access to CA certificates anymore, which in general in containers is a solved problem.
Doesn’t that mean that docker containers use up much more resources since you’re installing numerous instances & versions of each program like mumble and leftpad?
Kinda, but it depends on the size of the dependencies, with drive space bing so cheap these days do you really worry about 50Mb of storage being wasted on 4 different versions of glib or leftpad
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While what you've written is technically wrong, I get why you did the comparison that way. Now there are tons of other containerization solutions that can exactly what you're describing without the dark side of Docker.
There have been some great answers on this so far, but I want to highlight my favourite part of Docker: the disposability.
When you have a running Docker container, you can hop in, fuck about with files, break stuff as you try to figure something out, and then kill the container and all of the mess you've created is gone. Now tweak your config and spin up a fresh one exactly the way you need it.
You've been running a service for 6 months and there's a new upgrade. Delete your instance and just start up the new one. Worried that there might be some cruft left over from before? Don't be! Every new instance is a clean slate. Regular, reproducible deployments are the norm now.
As a developer it's even better: the thing you develop locally is identical to the thing that's built, tested, and deployed in CI.
I <3 Docker!
What about your preferences/configs/files (when you spun up a fresh one)?
The most popular way of configuring containers are by using environment variables that live outside the container. But for apps that use files to store configuration, you can designate directories on your host that will be available inside the container (called "volumes" in Docker land). It's also possible to link multiple containers together, so you can have a database container running alongside the app.
If you have all of that set up then, what benefit is there to blowing away your container and spinning up a 'fresh' one? I've never been able to wrap my head around docker, and I think this is a big part of it.
There's a lot more to an application than its configuration. It may require certain specific system libraries, need a certain way of starting up, or a whole host of other special things. With a container, the app dev can precreate a perfect environment for their program and save you LOADS of hassle trying to set it up.
The benefit of all this is that you can know exactly where application state is stored, know that you're running the app in it's right environment, and it becomes turbo easy to install updates, or roll back if needed.
Totally spin up a VM, install docker on it, and deploy 2-3 web apps. You'll notice that you use the same way of configuring them, starting and stopping them, and you might not want to look back ;)
I've played with it a bit. I think I was using something called DockStarter and Portainer. Like I said though, I could never quite grasp what was going on. Now for my home webapps I use Yunohost, and for my media server I use Swizzin CE. I've found these to be a lot easier, but I will try Docker again sometime.
It's virtual machines but faster, more configurable with a considerably larger set of automation, and it consumes less computer resources than a traditional VM. Additionally, in software development it helps solve a problem summarized as "works on my machine." A lot of traditional server creation and management relied on systems that need to be set up perfectly identical every deployment to prevent dumb defects based on whose machine was used to write it on. With Docker, it's stupid easy to copy the automated configuration from "my machine" to "your machine." Now everyone, including the production systems, are running from "my machine." That's kind of a big deal, even if it could be done in other ways naturally on Linux operating systems. They don't have the ease of use or the same shareability.
What you're doing is perfectly expected. That's a great way of getting around using Docker. You aren't forced into using it. It's just easier for most people
This is exactly the answer.
I'd just expand on one thing: many systems have multiple apps that need to run at the same time. Each app has its own dependencies, sometimes requiring a specific version of a library.
In this situation, it's very easy for one app to need v1 of MyCleverLibrary (and fails with v2) and another needs v2 (and fails with v1). And then at the next OS update, the distro updates to v2.5 and breaks everything.
In this situation, before containers, you will be stuck, or have some difficult workrounds including different LD_LIBRARY_PATH settings that then break at the next update.
Using containers, each app has its own libraries at the correct and tested versions. These subtle interdependencies are eliminated and packages 'just work'.
I can also add that if you want to run multiple programs that each have a web interface it's easy to direct each interface to the port you want instead of having to go through various config files that are different for each program or worst case having to change a hardcoded port in some software. With docker you have the same easy config options for each service you want to run. Same with storage paths. Various software stores their files at seemingly random places. With docker you just map a folder and all you files are stored there without any further configs.
I approve of this expanded answer. I may have been too ELI5 in my post.
If the OP has read this far, I'm not telling you to use docker, but you could consider it if you want to store all of your services and their configurations in a backup somewhere on your network so if you have to set up a new raspberry pi for any reason, now it's a simple sequence of docker commands (or one docker-compose command) to get back up and running. You won't need to remember how to reinstall all of the dependencies.
This blog post explains it well:
https://cosmicbyt.es/posts/demistifying-containers-part-1/
Essentially, containers are means of creating environments in which you can run software, and those environments are:
It is essentially a way for you to run a program without having to worry how to set up the environment, why it didn't work as expected, what dependencies you're missing, etc.
I feel that a lot of people here are missing the point. Docker is popular for selfhosted services for a few main reasons:
Docker also has lots of downsides. I would generally say that if your distribution packages software I would prefer the distribution's package over the docker image. A good distribution package will also solve all of these problems. The main issue you will see with distribution packages is a longer delay before new versions are made available.
What Docker completely dominates was previous cross-distribution packaging options which typically took one of the previous strategies.
Sorry if I’m about 10 years behind Linux development, but how does Docker compare with the latest FlatPak trend in application distribution? How you have described it sounds somewhat similar, outside of also getting segmented access to data and networks.
For desktop apps Flatpak is almost certainly a better option than Docker. Flatpak uses the same core concepts as Docker but Flatpak is more suited for distributing graphical apps.
Generally I would still default to my distro's packages where possible, but if they are unsuitable for whatever reason (not available, too old, ...) then a Flatpak is a great option.
Docker is to servers, as flatpak is to desktop apps.
I would probably run away if i saw flatpak on a headless server
Flatpak has better security features than docker. While its true it's not designed with server apps in mind, it is possible to use its underlying "bubblewrap" to create isolated environments. Maybe in the future, tooling will improve its features and bridge the gap.
For your use case, consider it to be a packaging format (like AppImage, Flatpak, Deb, RPM, etc.) that includes all the dependencies (including services, not just libraries) for the app in question.
If it's not broken don't fix it.
Use Podman (my preferred - the SystemD approach is awesome), containerd, or Incus. Docker is a graveyard of half-finished pet projects that have no reason for existing. Podman has a Docker-compatible socket, so 100% of Docker tooling will work with it.
I can add, podman was ignored in previous years at my day job because there were some reliability issues either with GPU access or networking I forget, however these issues have been resolved and we're reimplementing it pretty much effortlessly
Yep, we're reconsidering it at work as well. it's grown pretty nicely
Try to run something that requires php7 and something else that requires php8 on the same web server; or python 2 and python 3.
You actually can, but it's not pretty.
(The thing about a declarative setup isn't much of a difference, you can do it for any popular Linux distro.)
Doesn't that mean that docker containers use up much more resources since you're installing numerous instances & versions of each program like PHP?
Oh, sure, the bloat on your images requires resources from the host.
There is the option of sharing things. But, obviously that conflicts a bit with maintaining your environments isolated.
I have a reason I don't think is covered. A few programs I have come across that I want to try recommend docker and some only provide instructions for docker. They can spend less time trying to help you with dependencies and installations knowing they've included everything you need in the docker file. I don't have a background in Linux or programming so unless they tell you exactly how to install something, I can struggle. Their installation page is then just the docker compose file with a note on the environment variables you can change.
One of the the main reasons why docker and kubernetes take off is they standardized the deployment process. Say, you have 20 services running on your servers. It's much easier to maintain those 20 services as a set of yaml files that follow certain standard than 20 config files each with different format. If you only have a couple of services, the advantage is probably not apparent. But as you add more and more services, you'll start to appreciate it.
Yep, I couldn't run half of the services in my homelab if they weren't containerized. Running random, complex installation scripts and maintaining multiple services installed side-by-side would be a nightmare.
The thing that confused me when first learning about docker was, that everybody compares it to a virtual machine. It's not. Containers dont virtualize anything. They take a (single) process from the host OS and separate that into its own environment. All system calls, memory access, file writes etc are still handled by the same os (same kernel). However the process is separated both on the file system and process level. It can't see other processes outside of the container and it also doesn't see the real filesystem. It sees a filesystem provided by the container. This also means it sees different file and user permissions. When you run a alpine Linux docker container on an Ubuntu system, the container only containes the (few) files for alpine but no Linux kernel no desktop environment. A process inside that container only sees the alpine files and not the Ubuntu files. It also means all containers see a filesystem independent of each other and can use libraries and dependencies of different versions (they are only files after all).
For administration it makes running complex services easy. You define how to setup that service (what base Linux distro to use, what packages to install, what commands to run, and how to start the process). You can then be save to assume the setup of that service did not interfere with the setup of any other service. "Service 1 needs a certain system wide config changed? Service 2 needs that config in the default state? And both need a different version of the same library?" In containers you can have all at the same time because they each see a different version of the same config and library.
And all this is provided by the kernel itself. All docker does is provide an "easy" way to create and manage containers but could could do all of that using chroot, runc and a few other.
As a note, containers usually don't come with systemd as they don't need an init system. You would run the service directly inside the container and then use systemd outside the container to make sure the container is started/restarted, or just docker as it can already do that.
I found a great article demystifying containers recently
While you are technically right there is very little logical difference between containers and VMs. Really the only fundamental difference is that containers use the same kernel while VMs run their own. (let's not even worry about para-virtualization right now).
In practice I would say the biggest difference is that there is better memory sharing so total memory usage will often be less. But honestly this mostly comes down to the fact that the average container bundles less software than the average VM image. Easier management of volumes is also nice because typically you will just bind-mount a host directory, but it also isn't hard to mount a block device on a Linux host.
Install Portainer, it helps you get used to managing docker images and containers before going full command line.
I actually prefer dockge, I only have a few containers and its a lot simpler while still able to do all the basics of docker management. Portainer was overkill for me.
I have a pile of containers both for selfhosting and for dev builds, and still wouldn't use Portainer.
Lazydocker, FTW
I learned on portainer. I just wish it worked better. Dockge is a much better solution anyways
One benefit that might be overlooked here is that as long as you don’t use any Docker Volumes (and instead bind mount a local directory) and you’re using Docker Compose, you can migrate a whole service, tech stack and everything, to a new machine super easily. I just did this with a Minecraft server that outgrew the machine it was on. Just tar the whole directory, copy it to the new host, untar, and
docker compose up -d.This
docker compose up -dthing is something I don't understand at all. What exactly does it do? A lot of README.md files from git repos include this command for Docker deployment. And another question: How can you automatically start the Docker container? Do you need a systemd service to rundocker compose up -d?Docker Compose is basically designed to bring up a tech stack on one machine. So rather than having an Apache machine, a MySQL machine, and a Redis machine, you set up a Docker Compose file with all of those services. It’s easier than using individual Docker commands too. It sets up a network so they can all talk to each other, then opens the ports you tell it to. It’s isolated from other Docker Compose networks, so things won’t interfere with each other. So you can basically isolate a bunch of services with their own tech stacks all on the same machine. I’ve got my Jellyfin server running on the same machine as my Mastodon instance, thanks to Docker Compose.
As long as Docker is configured to run automatically at boot (which it usually is when you install it), it will bring containers back up that are set to be restarted. You can use the “always” or the “unless-stopped” values for the restart option, depending on your needs, then Docker will bring that container back up after a reboot.
Docker Compose is also useful in this context, because you can define dependencies for services. So I can say that the Mastodon container depends on the Postgres container, and Docker Compose will always start the Postgres container first.
You just need the docker and docker-compose packages. You make a
docker-compose.ymlfile and there you define all settings for the container (image, ports, volumes, ...). Then you rundocker-compose up -din the directory where that file is located and it will automatically create the docker container and run it with the settings you defined. If you make changes to the file and run the command again, it will update the container to use the new settings. In this commanddocker-composeis just the software that allows you to do all this with thedocker-compose.ymlfile,upmeans it's bringing the container up (which means starting it) and-dis for detached, so it does that in the background (it will still tell you in the terminal what it's doing while creating the container).I started self-hosting a bit prior to when Docker took off, and getting multiple services running was much harder. Service A wants a certain version of PHP installed with certain plugins while Service B wants a different version. You'd follow a tutorial for installing Service C and desperately hope that it wouldn't somehow break Service A or B. You installed Service D for a bit despite all the installation pain and now want to uninstall it - I hope you tracked exactly what config changes you made throughout the system so you can undo it.
Docker fixed all of this by making each service independent through containers which made self-hosting 10x easier. I'd also add that I love how easy it is to transfer my setup to a new server - I keep all of my container volumes in a specific directory and my docker-compose files in another and that's all I need to backup / transfer. Without Docker you'd have to specifically handle each & every configuration file and database location, and if you later upgrade to a newer version of the OS or a different distro you'd have to handle possible conflicts between your versions and what the distro expects.
A lot of people here really do be describing docker like flatpak
They're similar under the good, but flatpak is optimized for desktop use. Docker targets server applications.
I've used Docker a fair bit over the years because it's a simple line of code I can copy/paste to get a simple web server running.
I ran Home Assistant Supervised in Docker for many years. It was a few lines of code and then I basically had Home Assistant OS running on my Pi without it taking over the whole Pi, meaning I could run other things on it too.
That ended when HA just died one day and I had no clue how to get it running again. I spent a day trying, then just installed HA OS on the Pi instead.
Anyway I now have a Dell Optiplex and Proxmox and I've gone back to Docker. Why? Well I discovered that I could make a Linux VM and install Docker on it, then add the Docker code to install a Portainer client to it, then make that into a template.
Meaning I can clone that template and type the IP address into Portainer and now I have full access to that Docker instance from my original Portainer container. That means I can bang a Docker Compose file into the "Stack" and press go, then tinker with the thing I wanna tinker with. If I get it working it can stay, if I don't then I just delete the VM and I've lost nothing.
Portainer has made Docker way more accessible for me. I love a webui
I use proxmox to run debian VMs to run docker compose "stacks".
Some VMs are dedicated to an entire servicecs docker compose stack.
Some VMs are for a docker compose of a bunch of different services.
Some services are run across multiple nodes with HA VIPs and all that jazz for "guaranteed" uptime.
I see the guest VM as a collection, but there is only ever 1 compose file per host.
Has a bit of overhead, but makes it really easy to reason about, separate VLANs and firewall rules etc
What is Portainer? You've said that it's a web UI, but what exactly does it provide you with?
Well the webui provides me with a list of containers, whether they're running or not, the ports that are opened by the containers. There's Stacks which are basically Docker Compose files in a neat UI. The ability to move these stacks to other instances. There's the network options and ability to make more networks, the files that are associated with the containers.
And not just for the instance I'm in, but for all the instances I've connected.
In my previous experience with Docker these are all things that I need to remember code to find, meaning I most often have to Google the code to find out what I'm after. Here is neatly packaged in a web page.
Oh and the logs, which are really useful when tinkering to try get something up and running
Sounds awesome! I've taken a look at Portainer and got confused on the whole Business Edition and Community Edition. What are you running?
Community edition. It's free!
Docker can be many things - and portainer is a nice replacement for those using docker for running services. It’s got a great web interface. For automation and most development docker and compose is my pick. Also a good fit for those that only use X to spawn terminals.
Does portainer, and docker in turn, allow taking/accessing something like point in time snapshots of containers like VM software do? They make it easy to tinker with stuff, knowing that if I mess up, I can go back to a snapshot and be good again.
Not to my knowledge no
If you're already using systemd, do not switch to Docker. Use Podman instead. Docker runs all your services under the Docker service. Podman can both run the same containers as systemctl services.
Quadlets with podman have completely replaced compose files for me. I use the kuberentes configs. Then I run a tailscale container in the pod and BAM, all of my computers can access that service without have to expose any ports.
Then I have an ansible playbook to log in to the host and start a detached tmux session so my user systemd services keep running. Its all rootless, and just so dang easy.
I used to run systemd units that just start docker-compose files, that's also a thing, I suppose. Also generally it's easy to manage the container directly (killing/restarting) without the needed lifecycle a systemd unit gives, I would say.
How’s the Pi 3? I was considering the idea of getting one to avoid the crazy prices for newer models
If you're OK with a little more power usage (like 10W instead of 3-5W), you can buy a mini PC from Dell/Lenovo/HP with a 7th gen Intel CPU for about $50-70 on ebay, with storage and RAM included. As a bonus you also get a case, power supply, cooling, etc.. which you have to buy extra for the Pi.
It'll be significantly faster in every way, with a lot more options for expansion if needed. The Pi 3 is very slow for even the most basic tasks, even just running
apt upgradecan take several minutes or more for a few package updates.i’ve got a used dell optiplex laying around for any bigger projects so a pi would be for tinkering with and small scale stuff. I didn’t have a good grasp of how slow it would run though thank you
A mini-pc with an Intel N100 will be a little more expensive (I bought one for ~150€) but it's about 5-6 times faster than the Pi and mine also came with 16gb of RAM and a 500gb SSD. It requires very little power and because of that, it's also very quiet. AV1 decode is also great if you plan to run something like Kodi on it or you want to do transcoding from an AV1 video with Jellyfin (I haven't migrated those to it yet, so I don't know how well it works in practice). I'm not sure but it might not even be a lot more expensive than a Pi with 8gb of RAM and an additional 500gb SSD.
A little slower by today's standards, but if your needs are light, it'll do the job. Keep in mind it only has a gigglebyte of RAM, so its capacity for running things may be limited, especially as docker applications go (since they bring a copy of each dependency). You won't be able to run something as large as GitLab or Nextcloud, but a smattering of small apps should be within its capabilities
IMO, Pis are for tinkering or anything that needs the GPIO.
Everything else should be some cheapo PC without the GPIO, or something embeded designed for the GPIO.
Pis are great for hobby/fun things and for prototyping.
It's great for my needs. If you think about picking one up today, I wouldn't really recommend it. It just offers too little resources to be actually viable in the regular day. I use mine because I had it laying in the dust for a couple of years. Well, it's enough for my Mumble server and the bots I use for Discord and Matrix.
Dockers documentation is actually pretty good, I’d recommend taking a look at it because it’s written really well and can be used as a decent primer on learning to read documentation.
I would recommend learning docker / containerization. For your use case you likely won’t see a big benefit HOWEVER it is a good technology to know.
As far as the “why” you’d use it there are too many to list but for your use case the why I’d argue is “just so you know how to do it” and you’ll come up with your own why along the way.
Simplest why beyond “it’s a good technology to know” is that updating an app is as simple as pulling a new container and relaunching it.
Docker is amazing but not needed. You can compare it to a simpler VM. You can take a docker and run it on any machine. You have an environment that is separate from your host and you and the container can only access it via defined points (volumes and ports).
Imagine you need to run a 2nd Mumble Server. I never set on up but its often that a 2nd instance is not that easy. With docker its easy. The only difference is that you need to use different ports, when you have only one network access or you use a reverse proxy. You can create a 2nd instance to test stuff, without interrupting your productive system. Its a security benefit, because its isolated to some degree and you can remove one easily.
I started using it with MSSQL Server, because I hated how invasive it is on a windows machine, especially I just needed it temporarily to do stuff with it. I'm not a microsoft admin and I know that Servers from Microsoft are a different level. Docker allowed me to start and stop it and remove it very easily. After that I started using it for a lot of and brought my NAS on the next level.
Also one thing worth mentioning are Linux Containerx (LXC). They are in Proxmox but I have less knowledge. It feels more like a full VM than docker but uses less resources. This is the reason why containers in general are more popular. They are less resource hungry than a full VM but have some benefits than running everything on one machine. LXC feels more like a full system, than docker. With docker you rarely get into the system. You may execute some commands, like a create user command or a one time job but don't access it via a shell from the inside (its possible). LXC on the other hand, you use the shell.
Docker of one version of software that uses Linux containers to encapsulate software and that software's dependencies, while limiting that software's access to the underlying OS. It's chroot, but for more of the system. It can make running software that has a lot of moving parts and dependencies easier. It can also improve your security running that software.
For how-tos, watch one of the 875,936 YouTube tutorials, or read one of the 3 million text tutorials. Or ask ChatGPT, if you really need hand-holding.
Vs. LXD?
Recent video that explains Docker very well: https://www.youtube.com/watch?v=rIrNIzy6U_g
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Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
~ | High Availability IP | Internet Protocol LXC | Linux Containers NAS | Network-Attached Storage SBC | Single-Board Computer SSD | Solid State Drive mass storage SSL | Secure Sockets Layer, for transparent encryption
9 acronyms in this thread; the most compressed thread commented on today has 15 acronyms.
[Thread #592 for this sub, first seen 11th Mar 2024, 17:25] [FAQ] [Full list] [Contact] [Source code]
The thing with Docker is that people don't want to learn how to use Linux and are buying into an overhyped solution that makes their life easier without understanding the long term consequences. Most of the pro-Docker arguments go around security and that's mostly BS because 1) systemd can provide as much isolation a docker containers and 2) there are other container solutions that are at least as safe as Docker and nobody cares about them.
Companies such as Microsoft and GitHub are all about re-creating and reconfiguring the way people develop software so everyone will be hostage of their platforms. We see this in everything now Docker/DockerHub/Kubernetes and GitHub actions were the first sign of this cancer. We now have a generation that doesn’t understand the basic of their tech stack, about networking, about DNS, about how to deploy a simple thing into a server that doesn’t use some Docker BS or isn’t a 3rd party cloud xyz deploy-from-github service.
Before anyone comments that Docker isn’t totally proprietary and there’s Podman consider the following: It doesn’t really matter if there are truly open-source and open ecosystems of containerization technologies. In the end people/companies will pick the proprietary / closed option just because “it’s easier to use” or some other specific thing that will be good on the short term and very bad on the long term.
Docker may make development and deployment very easy and lowered the bar for newcomers have the dark side of being designed to reconfigure and envelope the way development gets done so someone can profit from it. That is sad and above all set dangerous precedents and creates generations of engineers and developers that don’t have truly open tools like we did. There's LOT of money into transitioning everyone to the "deploy-from-github-to-cloud-x-with-hooks" model so those companies will keep pushing for it.
Note that technologies such as Docker keep commoditizing development - it’s a negative feedback loop that never ends. Yes I say commoditizing development because if you look at it those techs only make it easier for the entry level developer and companies instead of hiring developers for their knowledge and ability to develop they’re just hiring “cheap monkeys” that are able to configure those technologies and cloud platforms to deliver something. At the end of the they the business of those cloud companies is transforming developer knowledge into products/services that companies can buy with a click.
Actually Docker and the success of containers is mostly due to the ease of shipping code that carries its own dependencies and can be run anywhere. Security is a side-effect and definitely not the reason why containers picked-up.
Yes, and it's much harder to achieve the same. In systemd you need to use 30 different options to get what using containers you achieve almost instantly and with much less hussle. I made an example on my blog where I decided to run
blockyin Systemd and not in Docker. It's just less convenient and accessible, harder to debug and also relies on each individual user to do it, while with containers a lot gets packed into the image and therefore harder to mess up.There are a many container runtimes (CRI-O, podman, mirantis, containerd, etc.). Docker is just a convenient API, containers are fully implemented just with Linux native features (namespaces, seccomp, capabilities, cgroups) and images follow an open standard (OCI).
I will avoid comment what looks like a rant, but I want to simply remind you that containers are the successor of VMs (virtualize everything!), platforms that were completely proprietary and in the hands of a handful of vendors, while containers use only native OS features and are therefore a step towards openness.
I don't disagree with you, but that also shows that most modern software is poorly written. Usually a bunch of solutions that hardly work and nobody is able to reproduce their setup in a quick, sane and secure way.
Yes, that's exactly point point. There are many options, yet people stick with Docker and DockerHub (that is everything but open).
Yes... maybe we just need some automation/orchestration tool for that. This is like saying that it's way too hard to download the rootfs of some distro, unpack it and then use
unshareto launch a shell on a isolated namespace... Docker as you said provides a convenient API but it doesn't mean we can't do the same for systemd.Completely proprietary... like QEMU/libvirt? :P
Does it? I mean, this is especially annoying with old software, maybe dynamically linked or PHP, or stuff like that. Modern tools (go, rust) don't actually even have this problem. Dependencies are annoying in general, I don't think it's a property of modern software.
Who are these people? There are tons of registries that people use, github has its own, quay.io, etc. You also can simply publish Dockerfiles and people can build themselves. Ofc Docker has the edge because it was the first mainstream tool, and it's still a great choice for single machine deployments, but it's far from the only used. Kubernetes abandoned Docker as default runtime for years, for example... who are you referring to?
But Systemd also uses unshare, chroot, etc. They are at the same level of abstraction. Docker (and container runtimes) are simply specialized tools, while systemd is not. Why wouldn't I use a tool that is meant for this when it's available. I suppose bubblewrap does something similar too (used by Flatpak), and I am sure there are more.
Right, because organizations generally run QEMU, not VMware, Nutanix and another handful of proprietary platforms... :)
I use ghcr, i have no issues pulling images from amazon ECR or wherever.
Docker got there first with the adoption and marketing.
Automation tools like ansible and terraform have existed for ages, and are great for running things without containers.
OCI just makes it a hell of a lot easier and portable
I’ve been using ansible as well and it’s great.
Successor implies replacement. I think containers are another tool in the toolkit of servers/hosting, but not a replacement for VMs
Well, I did not mean replacement (in fact, most orgs run in clouds which uses VMs) but I meant that a lot of orgs moved from VMs as the way to slice their compute to containers/kubernetes. Often the technologies are combined, so you are right.
Docker makes sense if you are deploying thousands of machines in the cloud. I don't think it makes as much sense if you have your own hardware.
Some services do have 1-line installers with docker, so those might be useful. But they usually have 1-line non-docker installers too.
Docker still makes sense on your own hardware. Especially if you're the type of person to try out different programs often
Avoid Docker as much as possible. It gives you a quick way to run apps, but in a way that you can't see what is going to be installed.
It is also double resource heater.
And it has many frequent vulnerabilities.
You can look at the Dockerfile and see every single step that goes into building a particular image.
That's patently false.
Dawg have you ever actually used docker?
False.