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I don't understand the point of Docker. It seems like a great product. For any serious production grade containerization , I'd use a real virtualization solutio

I don't understand the point of Docker. It seems like a great product. For any serious production grade containerization , I'd use a real virtualization solution like KVM, or VMWare.

geofft 11y ago
It's containerization between trustworthy apps; it's not security containerization. What it gets you is, if you have one application that's designed to run well on RHEL 5 with /usr/bin/python pointing to Python 2.4, and another one that's designed to run well on Debian testing with a manual /usr/bin/python symlink to Python 3, you can give both of them what they want. This has nothing to do with security. If you want Docker + security isolation, I'm intrigued by Clear Containers, which is a lightweight KVM-based virtualization thing: https://lists.clearlinux.org/pipermail/dev/2015-September/000049.html https://lists.clearlinux.org/pipermail/dev/2015-September/00... https://lwn.net/Articles/644675/ https://lwn.net/Articles/644675/
- takeda 11y ago
  > It's containerization between trustworthy apps; it's not security containerization. Isn't that what a process is? The containers in Linux are based on Jails from FreeBSD and zones from Solaris. They are absolutely there for security. Regarding the remaining part of your post, I understand what you are trying to show but python is a really bad example. You absolutely can have python 2 and 3 side by side, or even different minor versions. And with virtualenv or pyvenv (that came with 3.4) you can even have multiple installation of the sane version. If you add setuptools to your application you can easily generate single file package (I personally like wheel) the deployment is as simple as writing pip install myawesomeapp-1.0.py2.py3.whl it downloads all dependencies. There is not much that Docker would help, it only makes things more complex.
  - rdtsc 11y ago
    Pretty much. It is marketing multiple exiting open source Linux technologies (overlay file systems, namespacing for processes, network sockets, chroots) under a set of tools and bam! -- hundreds of millions of dollars in valuation.
    - superuser2 11y ago
      Well, more than that, it's packaging them into user-friendly tools and promoting the shit out of it. Still Docker the company's core value proposition is a hosted registry, something many savvy corporations will never go for. Docker the product could probably do just fine if the company were to fold.
      - LoSboccacc 11y ago
        but the hosted registry is what your average distribution already provide under the form of packages. and with everything moving to services, I see the utility of actually using components diminishing fast (well except for those providing those services) but for everyone else, docker solves no actual problem that can't already be solved now.
        superuser2 11y ago
        Writing a Dockerfile and typing "docker run whatever" is a hell of a lot easier than configuring a chroot and LXC container.
  - azernik 11y ago
    virtualenv only works if you want an isolated Python environment. What if you have two things that each want a set of .so libraries with incompatible versions, and one wants node.js? In theory this could be managed with something like NixOS, but containerization is the much more mature and flexible solution.
    - takeda 11y ago
      In that situation you can use LD_LIBRARY_PATH, that's what it is for. But what you really want in that case is to link the application statically. If you don't want to have benefits of shared objects: - smaller binary - memory savings (if multiple programs are using the same library, it is loaded once) - less files to patch to fix a security vulnerability The share objects have these features but it comes at price of lower performance, so by putting all .so files into a single docker file instead of statically compiling your application you're getting worst out of both worlds.
      - icebraining 11y ago
        Loading .so files doesn't mean the language can be statically compiled.
    - xorcist 11y ago
      How is that a problem? That's bascially the same thing as installing a newer set of tools under your home directory, and using them for an application. This has been done since long before Linux. (Containers are still good, for isolating concerns and management. Multiple versions of the same library is just not it.)
  - geofft 11y ago
    > Isn't that what a process is? It's the level of isolation of a process, yes. Just as two processes can use their address spaces as they see fit without bothering each other, even loading different versions of the same library, under a Linux container, two applications can use their filesystem as they see fit without bothering each other, even using different versions of the same binary applications. But the security isolation between two processes running as the same user account is extremely weak. While it's true that one process can't write to another one's memory directly, it's not a fundamental breach of the security policy if it can do so indirectly. There may be things to increase defense-in-depth (like Yama) but fundamentally if you're the same UID there is no security boundary. The same rule applies to containers. > python is a really bad example Yeah, agreed. I was just trying to come up with something quick. If your app works with v(irtual)env, by all means just use that and stop messing with containers. However, if you've got some large closed-source app with a portion in Python, and it expects /usr/bin/python to both work and be some exact version, you need to virtualize the filesystem.
    - takeda 11y ago
      > It's the level of isolation of a process, yes. Just as two processes can use their address spaces as they see fit without bothering each other, even loading different versions of the same library, under a Linux container, two applications can use their filesystem as they see fit without bothering each other, even using different versions of the same binary applications. I'm sorry for disagreeing, but that's what chroot() or even chdir() supposed to do. It's not for security (process can fool it), but they do provide isolation assuming there are no malicious actors. Containers were created to provide security, perfect example is FreeBSD Jail which precedes Solaris zones. It supposed to be secure version of chroot() which should not be escapable. It was successfully used in early 2000 before VMs to provide shared hosting. > But the security isolation between two processes running as the same user account is extremely weak. While it's true that one process can't write to another one's memory directly, it's not a fundamental breach of the security policy if it can do so indirectly. There may be things to increase defense-in-depth (like Yama) but fundamentally if you're the same UID there is no security boundary. The same rule applies to containers. Agreed, except the last sentence. With processes the isolation is weak because same UID represent the same user, if you use a different UID the isolation is enforced. The containers (assuming they are correctly set up) allow you to actually have two root accounts that can't interfere with each other. > Yeah, agreed. I was just trying to come up with something quick. If your app works with v(irtual)env, by all means just use that and stop messing with containers. However, if you've got some large closed-source app with a portion in Python, and it expects /usr/bin/python to both work and be some exact version, you need to virtualize the filesystem. Assuming these are not malicious, you can just do: chroot /app1_root python myapp1.py chroot /app2_root python myapp2.py And as long as they don't use any tricks to get out, they won't step on each others teas.
- philips 11y ago
  If you want to try out Clear Containers we merged it into the rkt container runtime a few weeks ago. And since rkt can run both docker and appc container images you can run any existing app container from this runtime. This blog posts details Clear Containers in rkt: https://coreos.com/blog/rkt-0.8-with-new-vm-support/ https://coreos.com/blog/rkt-0.8-with-new-vm-support/
- LoSboccacc 11y ago
  so it's basically a complete set of workaround for enabling people to live with brain-damaged applications? and we are encouraging this now, instead of fixing the damned apps? sheesh this makes me feel old.
  - geofft 11y ago
    Yeah, the UNIX-Haters(tm) view of Docker is something like, this is what you get when you give up on static linking, give up on a UNIX spec, and make the mistake of telling people that chroots exist. We could have avoided all of this, and normal application deployment would have just worked with all the benefits Docker gives.
stephengillie 11y ago
Any virtualization solution is going to require you manage an operating system. One of the goals of contanerization is for developers to only work with the application.
- voltagex_ 11y ago
  Unfortunately most docker containers seem to bring along 200+mb of operating system with them.
  - stephengillie 11y ago
    The binaries have to run somewhere. Container evangelists love to espouse the purity of running any container on any dock OS, and this is as true as being able to migrate VMs between any host - it still comes down to what the application/VM needs from the underlying OS/hardware.
    - vidarh 11y ago
      Mostly it comes down to lack of experience with containers so far, and lack of tools. Most apps need very little from the underlying OS if you actually take the time to e.g. set up a toolchain with a build container that you then move the build artefacts out of to install into the final container. Instead you see a lot of containers that in effect include all the build dependencies and a nearly full OS pulled in by that. It is improving, though slowly.
  - xorcist 11y ago
    This. Only 2G, not 200M. I try to get people to package application plus dependencies yet this is what they do every time. Every single time. Plus they always base it on images from the Internet, so bascially we trust some stranger with root privileges to all our data. Not always on the same image of course.
  - davexunit 11y ago
    Yes, this is a fundamental issue with Docker and other container systems that work with raw disk images as their basic unit of information. I have implemented a container system for the GNU Guix package manager that doesn't have this image bloat problem because it doesn't use opaque disk images. We store packages in a content-addressable storage system, which allows us to know the precise dependency graph for any piece of software in the system. Since we know the full set of software needed for any container, we are able to share the same binaries amongst all containers on a single host via a bind mount.
AgentME 11y ago
Think of it like a tool for packaging and deploying applications with everything they need. Its purpose is closer to package managers than being a secure sandbox for running untrusted users' VMs.
- vezzy-fnord 11y ago
  Funny, an article got posted here just an hour ago advocating against treating Docker like a package manager: http://vilkeliskis.com/blog/2015/09/23/docker_is_not_a_package_management_tool.html http://vilkeliskis.com/blog/2015/09/23/docker_is_not_a_packa... I'd be inclined to agree. The reductionist sum of mechanisms that make a Linux container have always been about detaching, multiplexing and partitioning kernel resource subsystems. Docker was the first program that really hyped it into the idea of being about application deployment, but I fear this gives people wrong impressions and makes the mistake of treating an emergent property as if it were a fundamental.
  - KirinDave 11y ago
    The first part of your post made sense. I have no idea what point you're trying to convey with the second part. That applications are not business logic over kernel resources is a curious argument to make.
- doug1001 11y ago
  that was my initial impression i got from reading some posts on the Docker Site, and perhaps there is no consistent definition of "package manager"--to me though, the most difficult tasks a p/m must do are: reproducible builds, dependency management, conflict resolution among transitive dependencies, and the like. But Docker does none of these things as i understand it.
jkyle 11y ago
KVM & VMWare are not containerization, they're full virtualization. There are a lot of benefits to containers and they don't have to be insecure. More efficient resource utilization and orders of magnitude faster allocation and launching to name two. Google runs a significant portion of its internal operations in a container infrastructure and has for quite a while.[1] They're perfectly capable of deployment into production environments. I won't comment on docker as I haven't spent the time to fully grok all its warts. 1. http://research.google.com/pubs/pub43438.html http://research.google.com/pubs/pub43438.html
- _yy 11y ago
  > Google runs a significant portion of its internal operations in a container infrastructure and has for quite a while.[1] They use containers inside virtual machines. Virtualization for security, containers for deployment.
  - jkyle 11y ago
    I know from Joe Beda's talk [1] they run vm's inside containers for scenarios where they need a managed os. And that those containers run on bare metal. But I can't speak to the reverse not being an employee or authority on Google's internals. 1. https://speakerdeck.com/jbeda/containers-at-scale https://speakerdeck.com/jbeda/containers-at-scale
Pyxl101 11y ago
Containerization and virtualization serve different purposes. VMs run actual operating systems within them. A single operating system runs many different containers, that each act something like processes running on that same OS, in a way where they're highly sandboxed and segmented from each other. If your goal is strong isolation, then VMs are definitely better today. The purpose of Docker and similar container technologies is not that kind of isolation. It's to package up and distribute applications in a way that's more decoupled than simply installing them all on the same system.
- takeda 11y ago
  I'm not hiding that after I learned about Docker I became skeptic. It seems like yet another thing that people observed what Google was doing, and then implementing it wrong. Google is using containers instead of VMs. This still provides security isolation and allows them to use resources more efficiently (VM has overhead where you need a whole OS for every instance). This approach does not make much sense in public cloud, where you already run inside of VM and the overhead is really for Amazon not you. So I see Docker is now pivoting to be a package manager, but there are already tools that do that. You can argue that Docker is simpler but so was rpm when it started. As Docker will grow it will become more complex in order to support all functionality package format already provides. There might be an argument that you can run multiple Docker containers on a single host, but that's what processes are for. There is change happening, and looks like cloud companies want to create "cloud os", I guess Docker is step toward that direction, but at current state in don't see it offering anything valuable to the organization that uses it.
  - monkey26 11y ago
    Docker as a package manager somewhat matches my use, and I think it does its job well. As the packager, I can just create one "package" that any Linux distribution running Docker can install, instead of creating packages for multiple versions of many different distributions.
    - takeda 11y ago
vacri 11y ago
If your VMs are single-purpose, you don't necessarily need VMs. Containers are single-process things - they're not running syslog or cron or any of that overhead, for example. Docker is also big on ensuring you are using the literal same artifact in dev as on prod (assuming you change your team's workflow, of course). Which is the right thing to use is entirely dependent on your use case.
- insaneirish 11y ago
  > Containers are single-process things - they're not running syslog or cron or any of that overhead, for example. You're either being entirely too prescriptive or interchanging containers and Docker freely when they are not equivalent, though one is a particular implementation of the other. People have been running containers that emulate a full system for quite a while (see FreeBSD jails, illumos/Solaris zones, Linux OpenVZ, LXC, etc.).
tbronchain 11y ago
We[1] believe that the point of Docker is to provide "application packages" (called containers), which is a big step ahead to deliver applications (using their words: build, ship, run). However, we also do believe the isolation containers provide isn't sufficient for multi-tenant usages. This is the main motivation behind Hyper, which run groups of container images (Pods) as Virtual Machines. [1] https://hyper.sh https://hyper.sh

I don't understand the point of Docker. It seems like a great product. For any serious production grade containerization , I'd use a real virtualization solution like KVM, or VMWare.

geofft 11y ago

It's containerization between trustworthy apps; it's not security containerization. What it gets you is, if you have one application that's designed to run well on RHEL 5 with /usr/bin/python pointing to Python 2.4, and another one that's designed to run well on Debian testing with a manual /usr/bin/python symlink to Python 3, you can give both of them what they want. This has nothing to do with security. If you want Docker + security isolation, I'm intrigued by Clear Containers, which is a lightweight KVM-based virtualization thing: https://lists.clearlinux.org/pipermail/dev/2015-September/000049.html https://lists.clearlinux.org/pipermail/dev/2015-September/00... https://lwn.net/Articles/644675/ https://lwn.net/Articles/644675/

takeda 11y ago
> It's containerization between trustworthy apps; it's not security containerization. Isn't that what a process is? The containers in Linux are based on Jails from FreeBSD and zones from Solaris. They are absolutely there for security. Regarding the remaining part of your post, I understand what you are trying to show but python is a really bad example. You absolutely can have python 2 and 3 side by side, or even different minor versions. And with virtualenv or pyvenv (that came with 3.4) you can even have multiple installation of the sane version. If you add setuptools to your application you can easily generate single file package (I personally like wheel) the deployment is as simple as writing pip install myawesomeapp-1.0.py2.py3.whl it downloads all dependencies. There is not much that Docker would help, it only makes things more complex.
- rdtsc 11y ago
  Pretty much. It is marketing multiple exiting open source Linux technologies (overlay file systems, namespacing for processes, network sockets, chroots) under a set of tools and bam! -- hundreds of millions of dollars in valuation.
  - superuser2 11y ago
    Well, more than that, it's packaging them into user-friendly tools and promoting the shit out of it. Still Docker the company's core value proposition is a hosted registry, something many savvy corporations will never go for. Docker the product could probably do just fine if the company were to fold.
    - LoSboccacc 11y ago
      but the hosted registry is what your average distribution already provide under the form of packages. and with everything moving to services, I see the utility of actually using components diminishing fast (well except for those providing those services) but for everyone else, docker solves no actual problem that can't already be solved now.
      - superuser2 11y ago
        Writing a Dockerfile and typing "docker run whatever" is a hell of a lot easier than configuring a chroot and LXC container.
- azernik 11y ago
  virtualenv only works if you want an isolated Python environment. What if you have two things that each want a set of .so libraries with incompatible versions, and one wants node.js? In theory this could be managed with something like NixOS, but containerization is the much more mature and flexible solution.
  - takeda 11y ago
    In that situation you can use LD_LIBRARY_PATH, that's what it is for. But what you really want in that case is to link the application statically. If you don't want to have benefits of shared objects: - smaller binary - memory savings (if multiple programs are using the same library, it is loaded once) - less files to patch to fix a security vulnerability The share objects have these features but it comes at price of lower performance, so by putting all .so files into a single docker file instead of statically compiling your application you're getting worst out of both worlds.
    - icebraining 11y ago
      Loading .so files doesn't mean the language can be statically compiled.
  - xorcist 11y ago
    How is that a problem? That's bascially the same thing as installing a newer set of tools under your home directory, and using them for an application. This has been done since long before Linux. (Containers are still good, for isolating concerns and management. Multiple versions of the same library is just not it.)
- geofft 11y ago
  > Isn't that what a process is? It's the level of isolation of a process, yes. Just as two processes can use their address spaces as they see fit without bothering each other, even loading different versions of the same library, under a Linux container, two applications can use their filesystem as they see fit without bothering each other, even using different versions of the same binary applications. But the security isolation between two processes running as the same user account is extremely weak. While it's true that one process can't write to another one's memory directly, it's not a fundamental breach of the security policy if it can do so indirectly. There may be things to increase defense-in-depth (like Yama) but fundamentally if you're the same UID there is no security boundary. The same rule applies to containers. > python is a really bad example Yeah, agreed. I was just trying to come up with something quick. If your app works with v(irtual)env, by all means just use that and stop messing with containers. However, if you've got some large closed-source app with a portion in Python, and it expects /usr/bin/python to both work and be some exact version, you need to virtualize the filesystem.
  - takeda 11y ago
    > It's the level of isolation of a process, yes. Just as two processes can use their address spaces as they see fit without bothering each other, even loading different versions of the same library, under a Linux container, two applications can use their filesystem as they see fit without bothering each other, even using different versions of the same binary applications. I'm sorry for disagreeing, but that's what chroot() or even chdir() supposed to do. It's not for security (process can fool it), but they do provide isolation assuming there are no malicious actors. Containers were created to provide security, perfect example is FreeBSD Jail which precedes Solaris zones. It supposed to be secure version of chroot() which should not be escapable. It was successfully used in early 2000 before VMs to provide shared hosting. > But the security isolation between two processes running as the same user account is extremely weak. While it's true that one process can't write to another one's memory directly, it's not a fundamental breach of the security policy if it can do so indirectly. There may be things to increase defense-in-depth (like Yama) but fundamentally if you're the same UID there is no security boundary. The same rule applies to containers. Agreed, except the last sentence. With processes the isolation is weak because same UID represent the same user, if you use a different UID the isolation is enforced. The containers (assuming they are correctly set up) allow you to actually have two root accounts that can't interfere with each other. > Yeah, agreed. I was just trying to come up with something quick. If your app works with v(irtual)env, by all means just use that and stop messing with containers. However, if you've got some large closed-source app with a portion in Python, and it expects /usr/bin/python to both work and be some exact version, you need to virtualize the filesystem. Assuming these are not malicious, you can just do: chroot /app1_root python myapp1.py chroot /app2_root python myapp2.py And as long as they don't use any tricks to get out, they won't step on each others teas.
philips 11y ago
If you want to try out Clear Containers we merged it into the rkt container runtime a few weeks ago. And since rkt can run both docker and appc container images you can run any existing app container from this runtime. This blog posts details Clear Containers in rkt: https://coreos.com/blog/rkt-0.8-with-new-vm-support/ https://coreos.com/blog/rkt-0.8-with-new-vm-support/
LoSboccacc 11y ago
so it's basically a complete set of workaround for enabling people to live with brain-damaged applications? and we are encouraging this now, instead of fixing the damned apps? sheesh this makes me feel old.
- geofft 11y ago
  Yeah, the UNIX-Haters(tm) view of Docker is something like, this is what you get when you give up on static linking, give up on a UNIX spec, and make the mistake of telling people that chroots exist. We could have avoided all of this, and normal application deployment would have just worked with all the benefits Docker gives.

stephengillie 11y ago

Any virtualization solution is going to require you manage an operating system. One of the goals of contanerization is for developers to only work with the application.

voltagex_ 11y ago
Unfortunately most docker containers seem to bring along 200+mb of operating system with them.
- stephengillie 11y ago
  The binaries have to run somewhere. Container evangelists love to espouse the purity of running any container on any dock OS, and this is as true as being able to migrate VMs between any host - it still comes down to what the application/VM needs from the underlying OS/hardware.
  - vidarh 11y ago
    Mostly it comes down to lack of experience with containers so far, and lack of tools. Most apps need very little from the underlying OS if you actually take the time to e.g. set up a toolchain with a build container that you then move the build artefacts out of to install into the final container. Instead you see a lot of containers that in effect include all the build dependencies and a nearly full OS pulled in by that. It is improving, though slowly.
- xorcist 11y ago
  This. Only 2G, not 200M. I try to get people to package application plus dependencies yet this is what they do every time. Every single time. Plus they always base it on images from the Internet, so bascially we trust some stranger with root privileges to all our data. Not always on the same image of course.
- davexunit 11y ago
  Yes, this is a fundamental issue with Docker and other container systems that work with raw disk images as their basic unit of information. I have implemented a container system for the GNU Guix package manager that doesn't have this image bloat problem because it doesn't use opaque disk images. We store packages in a content-addressable storage system, which allows us to know the precise dependency graph for any piece of software in the system. Since we know the full set of software needed for any container, we are able to share the same binaries amongst all containers on a single host via a bind mount.

AgentME 11y ago

Think of it like a tool for packaging and deploying applications with everything they need. Its purpose is closer to package managers than being a secure sandbox for running untrusted users' VMs.

vezzy-fnord 11y ago
Funny, an article got posted here just an hour ago advocating against treating Docker like a package manager: http://vilkeliskis.com/blog/2015/09/23/docker_is_not_a_package_management_tool.html http://vilkeliskis.com/blog/2015/09/23/docker_is_not_a_packa... I'd be inclined to agree. The reductionist sum of mechanisms that make a Linux container have always been about detaching, multiplexing and partitioning kernel resource subsystems. Docker was the first program that really hyped it into the idea of being about application deployment, but I fear this gives people wrong impressions and makes the mistake of treating an emergent property as if it were a fundamental.
- KirinDave 11y ago
  The first part of your post made sense. I have no idea what point you're trying to convey with the second part. That applications are not business logic over kernel resources is a curious argument to make.
doug1001 11y ago
that was my initial impression i got from reading some posts on the Docker Site, and perhaps there is no consistent definition of "package manager"--to me though, the most difficult tasks a p/m must do are: reproducible builds, dependency management, conflict resolution among transitive dependencies, and the like. But Docker does none of these things as i understand it.

jkyle 11y ago

KVM & VMWare are not containerization, they're full virtualization. There are a lot of benefits to containers and they don't have to be insecure. More efficient resource utilization and orders of magnitude faster allocation and launching to name two. Google runs a significant portion of its internal operations in a container infrastructure and has for quite a while.[1] They're perfectly capable of deployment into production environments. I won't comment on docker as I haven't spent the time to fully grok all its warts. 1. http://research.google.com/pubs/pub43438.html http://research.google.com/pubs/pub43438.html

_yy 11y ago
> Google runs a significant portion of its internal operations in a container infrastructure and has for quite a while.[1] They use containers inside virtual machines. Virtualization for security, containers for deployment.
- jkyle 11y ago
  I know from Joe Beda's talk [1] they run vm's inside containers for scenarios where they need a managed os. And that those containers run on bare metal. But I can't speak to the reverse not being an employee or authority on Google's internals. 1. https://speakerdeck.com/jbeda/containers-at-scale https://speakerdeck.com/jbeda/containers-at-scale

Pyxl101 11y ago

Containerization and virtualization serve different purposes. VMs run actual operating systems within them. A single operating system runs many different containers, that each act something like processes running on that same OS, in a way where they're highly sandboxed and segmented from each other. If your goal is strong isolation, then VMs are definitely better today. The purpose of Docker and similar container technologies is not that kind of isolation. It's to package up and distribute applications in a way that's more decoupled than simply installing them all on the same system.

takeda 11y ago
I'm not hiding that after I learned about Docker I became skeptic. It seems like yet another thing that people observed what Google was doing, and then implementing it wrong. Google is using containers instead of VMs. This still provides security isolation and allows them to use resources more efficiently (VM has overhead where you need a whole OS for every instance). This approach does not make much sense in public cloud, where you already run inside of VM and the overhead is really for Amazon not you. So I see Docker is now pivoting to be a package manager, but there are already tools that do that. You can argue that Docker is simpler but so was rpm when it started. As Docker will grow it will become more complex in order to support all functionality package format already provides. There might be an argument that you can run multiple Docker containers on a single host, but that's what processes are for. There is change happening, and looks like cloud companies want to create "cloud os", I guess Docker is step toward that direction, but at current state in don't see it offering anything valuable to the organization that uses it.
- monkey26 11y ago
  Docker as a package manager somewhat matches my use, and I think it does its job well. As the packager, I can just create one "package" that any Linux distribution running Docker can install, instead of creating packages for multiple versions of many different distributions.
  - takeda 11y ago

vacri 11y ago

If your VMs are single-purpose, you don't necessarily need VMs. Containers are single-process things - they're not running syslog or cron or any of that overhead, for example. Docker is also big on ensuring you are using the literal same artifact in dev as on prod (assuming you change your team's workflow, of course). Which is the right thing to use is entirely dependent on your use case.

insaneirish 11y ago
> Containers are single-process things - they're not running syslog or cron or any of that overhead, for example. You're either being entirely too prescriptive or interchanging containers and Docker freely when they are not equivalent, though one is a particular implementation of the other. People have been running containers that emulate a full system for quite a while (see FreeBSD jails, illumos/Solaris zones, Linux OpenVZ, LXC, etc.).

tbronchain 11y ago

We[1] believe that the point of Docker is to provide "application packages" (called containers), which is a big step ahead to deliver applications (using their words: build, ship, run). However, we also do believe the isolation containers provide isn't sufficient for multi-tenant usages. This is the main motivation behind Hyper, which run groups of container images (Pods) as Virtual Machines. [1] https://hyper.sh https://hyper.sh