The Open Container Initiative is a lightweight, open governance structure, to be formed under the auspices of the Linux Foundation, for the express purpose of creating open industry standards around container formats and runtime.
The Cloud Native Computing Foundation will create and drive the adoption of a new set of common container technologies informed by technical merit and end user value, and inspired by Internet-scale computing.
App Container (appc) is an open specification that defines several aspects of how to run applications in containers: an image format, runtime environment, and discovery protocol.
Systemd is a suite of basic building blocks for a Linux system. It provides a system and service manager that runs as PID 1 and starts the rest of the system. If you write a container solution, please consider supporting the following interfaces.
Run Docker containers on Google Cloud Platform, powered by Kubernetes. Google Container Engine actively schedules your containers, based on declared needs, on a managed cluster of virtual machines.
* [Mesosphere](https://mesosphere.com/)
The Mesosphere Datacenter Operating System (DCOS) is a new kind of operating system that spans all of the machines in your datacenter or cloud. It provides a highly elastic, and highly scalable way of deploying applications, services and big data infrastructure on shared resources.
Daemon based on liblxc offering a REST API to manage LXC containers.
* [OpenVZ](https://openvz.org/Main_Page)
OpenVZ is container-based virtualization for Linux. OpenVZ creates multiple secure, isolated Linux containers (otherwise known as VEs or VPSs) on a single physical server enabling better server utilization and ensuring that applications do not conflict.
rkt (pronounced "rock-it") is a CLI for running app containers on Linux. rkt is designed to be composable, secure, and fast. Based on AppC specification.
* [LXC](https://github.com/lxc/lxc)
LXC is the well known set of tools, templates, library and language bindings. It's pretty low level, very flexible and covers just about every containment feature supported by the upstream kernel.
* [Vagga](https://github.com/tailhook/vagga)
Vagga is a fully-userspace container engine inspired by Vagrant and Docker, specialized for development environments.
* [libct](https://github.com/xemul/libct)
Libct is a containers management library which provides convenient API for frontend programs to rule a container during its whole lifetime.
* [libvirt](https://libvirt.org/drvlxc.html)
A big toolkit to interact with the virtualization capabilities of recent versions of Linux (and other OSes).
Firejail is a SUID sandbox program that reduces the risk of security breaches by restricting the running environment of untrusted applications using Linux namespaces, seccomp-bpf and Linux capabilities.
* [NsJail](https://github.com/google/nsjail)
NsJail is a process isolation tool for Linux. It makes use of the the namespacing, resource control, and seccomp-bpf syscall filter subsystems of the Linux kernel.
Snappy Ubuntu Core is a new rendition of Ubuntu with transactional updates - a minimal server image with the same libraries as today’s Ubuntu, but applications are provided through a simpler mechanism.
- [Introduction to Linux Containers](https://access.redhat.com/articles/1353593)
- [What’s Next for Containers? User Namespaces](http://rhelblog.redhat.com/2015/07/07/whats-next-for-containers-user-namespaces/#more-1004)
- [Architecting Containers Part 1: Why Understanding User Space vs. Kernel Space Matters](http://rhelblog.redhat.com/2015/07/29/architecting-containers-part-1-user-space-vs-kernel-space/)
- [Architecting Containers Part 2: Why the User Space Matters](http://rhelblog.redhat.com/2015/09/17/architecting-containers-part-2-why-the-user-space-matters-2/)
* leak to another container (bug in namespaces, filesystem) -> user namespaces with different uid inside for each cotainer: 1000 in container - 14293 and 15398 outside; security modules like selinux or apparmor
2) system services like cron, ssh
* run as root -> isolate via bastion host or vm
* using /dev -> "devices" control group
The following device nodes are created in the container by default.
The Docker images are also mounted with nodev, which means that even if a device node was pre-created in the image, it could not be used by processes within the container to talk to the kernel.
Here is the current list of capabilities that Docker uses: chown, dac_override, fowner, kill, setgid, setuid, setpcap, net_bind_service, net_raw, sys_chroot, mknod, setfcap, and audit_write.
Docker removes several of these capabilities including the following:
CAP_SETPCAP Modify process capabilities
CAP_SYS_MODULE Insert/Remove kernel modules
CAP_SYS_RAWIO Modify Kernel Memory
CAP_SYS_PACCT Configure process accounting
CAP_SYS_NICE Modify Priority of processes
CAP_SYS_RESOURCE Override Resource Limits
CAP_SYS_TIME Modify the system clock
CAP_SYS_TTY_CONFIG Configure tty devices
CAP_AUDIT_WRITE Write the audit log
CAP_AUDIT_CONTROL Configure Audit Subsystem
CAP_MAC_OVERRIDE Ignore Kernel MAC Policy
CAP_MAC_ADMIN Configure MAC Configuration
CAP_SYSLOG Modify Kernel printk behavior
CAP_NET_ADMIN Configure the network
CAP_SYS_ADMIN Catch all
uses /proc, /sys -> remount ro, drop cap_sys_admin; security modules like selinux or apparmor; some part of this fs are "namespace-aware"
Docker mounts these file systems into the container as "read-only" mount points.
. /sys
. /proc/sys
. /proc/sysrq-trigger
. /proc/irq
. /proc/bus
Copy-on-write file systems
Docker uses copy-on-write file systems. This means containers can use the same file system image as the base for the container. When a container writes content to the image, it gets written to a container specific file system. This prevents one container from seeing the changes of another container even if they wrote to the same file system image. Just as important, one container can not change the image content to effect the processes in another container.
* uid 0 -> user namespaces, uid 0 mappet to random uid outside
3) system services like devices, network, filesystems
* root -> more of services should work on host outside; isolate sensitive functions, run as non-privilaged context
Things are better. For example, most modern container technologies can make use of Linux's built-in security tools such as:
[AppArmor](http://wiki.apparmor.net/index.php/Main_Page), [SELinux](http://selinuxproject.org/page/Main_Page) and [Seccomp](http://man7.org/linux/man-pages/man2/seccomp.2.html) policies;
[Grsecurity](https://grsecurity.net/);
[Control groups (cgroups)](https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/ch01.html);
Sure, you're deploying seccomp, but you can't use selinux inside your container, because the policy isn't per-namespace (?? lxc uses apparmore for each container...)
[sVirt](http://selinuxproject.org/page/SVirt) - selinux for kvm
The ecosystem of awesome new technologies emerging around containers and microservices can be a little overwhelming, to say the least. We thought we might be able to help: welcome to the Container Ecosystem Project.
This page is an attempt to document the ins and outs of containers on Linux. This is not just restricted to programmers looking to implement containers or use container like features in their own code but also Sysadmins and Users who want to get more of a handle on how containers work 'under the hood'.
