Making containers was easy long before Docker came along:
- FreeBSD Jails
- Solaris Zones
- Proxmox (which was an abstraction over OpenVZ, back before LXC came along)
In fact because of all of the above, I was a latecomer to Docker and didn't understand the appeal.
What Docker changed was that it made containers "sexy", likely due to the git-like functionality. It took containers from a sysadmin world and into a developers world. But it certainly didn't make containers any easier in the process.
It did make it easier, at least the barrier to entry. I remember reading about jails years ago, when I had a lot less sysadmin knowledge, and I couldn't wrap my head around it.
With docker, many people still can't wrap their head around how it works and will do stupid things if they need to run them in a serious environment, but they can still run a bunch of containers to run some hard to install software easily on their local machine!
Sure, jails were easy in some ways, but boiling docker's success to sexyness, instead of usefulness, sounds a bit like yet another "Dropbox is just rsync". Docker wasn't solving the isolation issue (which had been obviously solved for years) but mostly the distribution issue.
So you mean you could take your FreeBSD Jails configuration, upload it on a well known public website like dockerhub, then get someone on Windows or Mac transparently install the image and run it with a few cmdlines ?
Because docker container are called container for this reason. That comes from the boat container analogy.
Many years before Linux containers, FreeBSD jails were easily packaged up via tar, deployed via scp, and started with minimal script. There wasn't much hype, it just worked. It was an excellent software packaging and distribution tool.
There wasn't a hub that I recall, nor was there tooling to use VMs so they could run on Windows/Mac. However, the main challenge, being able to distribute an "image" without requiring VM overhead, was solved elegantly. It just wasn't Linux, so it didn't make news.
Running Docker on non-Linux platforms requires a Linux VM to run in the background. It's not as cross platform as people make out. The other container technologies can be managed via code too, that code can be shared to public sites. And you can run those containers in a VM too, if you'd want.
What's more, with ZFS you could not only ship the container as code, but even the container as a binary snapshot, very much like Docker's push/pull but predating Docker. Even on Linux, for a long time before Docker, you could ship container snapshots as tarballs.
Also worth mentioning is that early versions of Proxmox even had (and likely still does) a friendly GUI to select which image you wanted to download, thus making even the task of image selection user friendly. This was more than 10 years ago, long before Docker's first release and something Docker Desktop still doesn't even have to this day.
> Because docker container are called container for this reason. That comes from the boat container analogy.
The term computer "container" predates Docker by a great many years. Containers were in widespread use on other UNIXes with Linux being late to the game. It was one of the reasons I preferred to run FreeBSD or Solaris on production in the 00s despite Linux being my desktop OS of choice. Even when Linux finally caught with containerisation, Docker was still a latecomer to Linux.
Furthermore, for a long time Docker wasn't even containers (still isn't strictly that now but it at least offers more in the way of process segregation than the original implementations did). Albeit this was a limitation of the mainline Linux kernel so I don't blame Docker for that. Whereas FreeBSD Jails and Solaris Zones offered much more separation, even at a network level.
If we are being picky about the term "container" (not something I normally like to do) then Docker is the least "container"-like of all containerisation technologies available. But honestly, I don't like to get hung up on jargon because it helps no-one. I only raise this because you credited the term to Docker.
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Now to be clear, I don't hate Docker. It may have it's flaws but there are aspects of it I do also really like; and thus I do use it regularly on my Linux hosts these days despite my original reluctance to move away from Jails (Jails is still much nicer if you need to do anything complicated with networking, but Docker is "good enough" for most cases). However what I really dislike is this rewriting of history where people seem to think Docker stood out as a better designed technology - either from a UX or engineering perspective.
I personally think what made Docker successful was being in the right place at the right time. Linux was already a popular platform, containers were beginning to become widely known outside of the sysadmin circles but Linux (at that time) still sucked for containerisation. So it got enough hype early on to generate the snowball effect that saw it become dominant. But lets also not forget just how unstable it was, for a long time it was frequently plagued with regression bugs from one release to another. Which caused a great many sysadmins to groan whenever a new release landed.
(sorry for the edits, the original post was a flow of thoughts without much consideration to readability. Hopefully I've tidied it up)
If anything this is testament to the failure of previous solutions to popularize it.
Docker invented absolutely zero on the OS side and reused what LXC did but the invention here is not "putting things in containers" but "making it easy to put things in containers" and "making it easy to run those containers. Every solution before that required a bunch more knowledge.
> Running Docker on non-Linux platforms requires a Linux VM to run in the background. It's not as cross platform as people make out.
Which people ? I never seen anyone saying Docker makes it easy to run cross platform stuff, and it was always one of it's pain points.
> If anything this is testament to the failure of previous solutions to popularize it.
Maybe. But I'd rather not argue about popularity in a conversation about technical merit. The two aren't mutually inclusive and popularity is a subjective quality. Nothing good ever comes from conversations about popularity and preference.
> Every solution before that required a bunch more knowledge.
I'm not sure I fully agree with that. Docker has a lot of bespoke knowledge whereas the previous solutions built on top of existing knowledge. Where they differed was that Docker was an easier learning curve for people with previously zero existing systems knowledge. Which is something I didn't really appreciate until reading these responses because (possibly because I'm an old timer developer. I want to understand how my code works at a systems level so made it my job to understand the OS and even hardware too - though that's gotten harder as tech has progressed. But that was expected of developers when I started out).
> Which people ? I never seen anyone saying Docker makes it easy to run cross platform stuff, and it was always one of it's pain points.
The comment I replied to said: "get someone on Windows or Mac transparently install the image and run it with a few cmdlines"
>> If anything this is testament to the failure of previous solutions to popularize it.
>Maybe. But I'd rather not argue about popularity in a conversation about technical merit. The two aren't mutually inclusive and popularity is a subjective quality. Nothing good ever comes from conversations about popularity and preference.
The popularity is directly related to technical merit of it being very easy to start, both to run and to create containers. It isn't "just" popular, it got popular because it was solution to the problem that near-zero infrastructure skill developer could apply. We have countless example of solutions winning almost purely on having low barrier to entry, and docker was just that for containers.
The previous solutions ignored that, and assumed the target audience is mildly competent sysadmin, not a developer that has no idea what UID is, let alone the rest of ops stuff.
And it got buy in on the other side of the fence too, as now sysadmin instead of installing a spider's net of PHP or Ruby deps just had to install docker and deploy a container.
>> Every solution before that required a bunch more knowledge.
> I'm not sure I fully agree with that. Docker has a lot of bespoke knowledge whereas the previous solutions built on top of existing knowledge. Where they differed was that Docker was an easier learning curve for people with previously zero existing systems knowledge.
Well, you got the point. At the point where you need that knowledge (and I'd argue debugging docker container is in every way harder than just having a process in system) you already bought into the ecosystem. There is no initial hurdle to go thru like there was with previous systems trying to do same thing, even if you end up with harder to debug end result.
Just like with other things, PHP got popular because it was easier than anything CGI related, "just write code inside your HTML", Ruby got popular off Rails and 15 minute blog engine demo, Python being just all around easy to learn.
> The previous solutions ignored that, and assumed the target audience is mildly competent sysadmin, not a developer that has no idea what UID is, let alone the rest of ops stuff.
But that doesn't mean that the previous solutions weren't popular for others outside of the developer community. The comments here are heavily developer orientated but that's only part of the story in terms of the wider container ecosystem.
> Just like with other things, PHP got popular because it was easier than anything CGI related, "just write code inside your HTML", Ruby got popular off Rails and 15 minute blog engine demo, Python being just all around easy to learn.
The point I was making wasn't that "Docker doesn't deserve popularity" nor any confusion as to why it's popular. It was saying that the stuff that came before it was also easy.
Your example about languages here is a apt because PHP is an easier language for people from a zero coding background. But if your background is in C then PHP is going to be much harder to use compared to learning Nim, Zig or Rust.
Saying the containerisation solutions that came before were garbage, as people have done, isn't accurate. I'm not being critical of Docker; I'm defending the elegance of Jails. It's just that elegance is exposed in a different way and for a different audience to who Docker targets.
i think a lot of previous solutions focused on the "5x" engineer that was willing to comb through manpages and dig through the source (or at least the Makefile) if something unexpected happened.
many, many, MANY engineers are not like that.
many just want to build and push their features, and that's fine.
Docker knew that LXC was onto something and focused on the latter audience; that combined with their VC funding after they hit a critical mass is why they are heralded as having "invented" containers (even though they didn't).
and what I really dislike is dissing a technology because piece of it had existed in other forms before.
yes, zones on solaris offered a lot of the modern SDN networking stuff. was it popular? no.
yes, with zfs, in theory, you could ship a binary file and the other side can load it nicely (if you're thinking send/recv). was it popular to ship things like that in the open, public, in an easy to use fashion? no.
just admit docker popularized a lot of these and let's move along. while the tech might have existed, the previous ecosystems sucked and docker changed this for good.
> and what I really dislike is dissing a technology because piece of it had existed in other forms before.
How am I "dissing" Docker here? The comments before me are saying other technologies weren't easy or as feature rich. I'm saying they were. That's not a criticism of Docker. It's just a fact about other technologies.
> yes, zones on solaris offered a lot of the modern SDN networking stuff. was it popular? no.
Popularity means jack shit about the quality of a product. Reddit, Twitter and Facebook are popular but the UX is appalling on each of them. Just as plenty of really well built technologies never gain traction.
I suspect the reason Zones wasn't popular was because Solaris wasn't popular. Had Zones or Jails existed in the Linux mainline kernel at the same time as they had in Solaris/FreeBSD then we might not have seen a need for Docker. Or maybe it might still be around and popular...who knows? It's pointless to speculate over why something is popular because it's unscientific and unprovable. But we can discuss the UX and capabilities.
> yes, with zfs, in theory, you could ship a binary file and the other side can load it nicely (if you're thinking send/recv). was it popular to ship things like that in the open, public, in an easy to use fashion? no.
I can't speak for others did or did not, but I certainly did. (also see my comment above regarding popularity).
> just admit docker popularized a lot of these and let's move along.
I wasn't arguing that Docker didn't popularise these things. I was arguing against the point that the other tools were sub-par.
> while the tech might have existed, the previous ecosystems sucked and docker changed this for good.
And here's the crux of problem: you're conflating popularity with technical excellence. They're two unrelated metrics.
Just for clarification, because zoltan isn't making very compelling arguments.
Docker made containers easy and effective. Solaris zones were not as good as Docker is, BSD jails are/were not as good or easy to use as Docker is. Popularity has nothing to do with it, except that the popularity is an indication of the fact that Docker was revolutionary in the way it made these technologies accessible to a very large professional audience.
Docker was not created in isolation, it was inspired by jails and zones and all the fancy new features that were added to the linux kernel at the time.
Using just the words FROM, ADD and CMD, you can make a container definition that effectively isolates a runtime for just about any application in a 3 lines. Beyond the couple simple keywords all you need to have is absolutely basic linux knowledge, the level you can teach any developer in an afternoon.
There's no need to pollute that developers mind with any other system administration garbage. Nothing about networking, policies, filesystems, whatever. Just basic bash and a couple keywords.
Then when you want to go to production, you just hand the shit your developers wrote over to a professional system administrator and they'll make it run perfect at any scale. It's magic. Before Docker the world was darkness and bullshit, and after Docker the world was drenched in light and all that is good.
The fact that it's 2022 and there's still people that are going "hur-dur Solaris zones, BSD jails amiright" as if any of those technologies have any relevance is ridiculous.
> The fact that it's 2022 and there's still people that are going "hur-dur Solaris zones, BSD jails amiright" as if any of those technologies have any relevance is ridiculous.
Having diversity in the computing ecosystem is a good thing, not bad.
I'll take your point that Docker brought containers to the developers (frankly, I made that point myself) but that doesn't mean that Jails doesn't solve some problems that Docker (currently) struggles with. Nor does Docker's success mean that a little competition isn't healthy for the wider industry.
Dismissing the stuff that went before it as "systems administration garbage" because it was targeted at a different audience to yourself is a really poor attitude in my opinion. Especially when there are countless examples of when audiences different from developers also need to make use of software. Frankly, I thought by now we were past the sysadmin vs developer flamewars. But clearly not.
Aside from that minor rant, I do want to thank for your post. It was an informative read.
My apologies, I meant relevance to the problem that Docker solves, which is enabling developers to neatly specify and package their dependencies. I am not trying to diminish jails and zones usefulness to system administrators. I'm just saying if you put Docker in a comparison list to other technologies, jails and zones wouldn't even be in that list.
The annoyance comes from system administrators looking at the set of technologies inside Docker and saying "we already have that", and then just assuming Docker must be some sort of marketing scheme. I deployed docker in my organisation within a week of its first (beta?) release, when all of its "marketing" was a single blog post.
Docker solved an enormous real problem in the software industry, even if from a system administrators perspective it's just a new way of packaging applications, as there have been many in the past and probably will be many in the future.
Oh I never meant any of my comments to undermine Docker. While I do have some specific frustrations with Docker, the same is true with any technology stack: Jails and Zones included.
I'd never describe Docker as being a marketing gimmick. It was definitely a "right time, right place" tool. But that speaks more about how the market (and particularly Linux) was yearning for something better.
Docker is the best because it did something its predecessors could not: made it accessible, easy to run and easy to share. On Linux. Now the technology has industry standardization and so much inertia it’s surviving the monetization drive by docker (the company). The existing software out there was sysadmin stuff because it was mostly DIY. Or required learning to administer and build tooling for another OS.
It's worth noting that Docker was primarily a godsend for people working in scripting languages like Ruby or Python, where they have very messy packaging systems, depend on tons of native Linux libraries and so on.
For people working on the JVM the world was in some sense already 'drenched in light'. You could just send the sysadmin a fat jar you developed on Windows or macOS and tell them to deploy it, done. Or maybe you'd use an app server, so you'd send a less fat jar and they'd deploy it via a GUI and it already gets high level services like db connections, backups, message queues etc.
Also, Docker doesn't really solve the common case of an app that depends on a DB, maybe email etc. Those are services that need administration, you can't just start up a random server and expect things to go well. At least you need backups, proper access control and so on.
So deployment difficulty was very much dependent on what ecosystem you were in.
That's certainly true and describes my circumstances at the time. But it's also good to note that it is great for C/C++ dependencies as well, our GIS applications require PROJ, and our machine learning projects various Nvidia cuda things.
Also, just last week I needed new smbd features, and the only way to deploy a recent smbd version whilst retaining sanity seems on Ubuntu seems to be to just use docker. Normally there's a PPA but there wasn't in this case for some reason.
popularity has won every single time in history over technical excellence. I know this is HN and a techbro echo chamber, but technical excellence is not even in the top 3 that people care about.
> Running Docker on non-Linux platforms requires a Linux VM to run in the background. It's not as cross platform as people make out. The other container technologies can be managed via code too, that code can be shared to public sites. And you can run those containers in a VM too, if you'd want.
right, and this is something else that Docker made incredibly easy to do as well. It's almost transparent now; so much so, that you need to use nsenter to connect to the underlying VM on Mac and Windows.
Jails and Zones are kernel mechanisms, they aren't easy any more than cgroups/namespaces are easy (to be fair, yes, they're easier than linux's tools by default, albeit less flexible). What docker changed was absolutely to make things "easy". A Dockerfile is really no more than a shell script, the docker command line is straightforward, the docker registry is filled with good stuff ready for use.
Yes: "What Docker changed was that it made containers "sexy", likely due to the git-like functionality.
Post cloud era and all those new markets to tap into. Jails etc: like a tool hammering nails. Why, when or how to build a city is something else entirely.
- FreeBSD Jails
- Solaris Zones
- Proxmox (which was an abstraction over OpenVZ, back before LXC came along)
In fact because of all of the above, I was a latecomer to Docker and didn't understand the appeal.
What Docker changed was that it made containers "sexy", likely due to the git-like functionality. It took containers from a sysadmin world and into a developers world. But it certainly didn't make containers any easier in the process.