Collection of system containers images
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azure azure: Add nodocs to yum command Oct 10, 2017
kubernetes-apiserver fix uid/gid, bind mount /var/run/kubernetes in apiserver Oct 23, 2017
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kubernetes-master kubernetes-master: Update for lint Oct 10, 2017
kubernetes-proxy make uid/gid 0 explicit Dec 19, 2017
kubernetes-scheduler fix uid/gid, bind mount /var/run/kubernetes in apiserver Oct 23, 2017
lint lint: Works on Python 2 and 3 Oct 11, 2017
net-snmp Add `[Install]` section to net-snmp service template Jan 16, 2018
open-vm-tools-centos Update May 7, 2018
ovirt-guest-agent-fedora ovirt-guest-agent: Update capability syntax Oct 28, 2017
.papr.yml .papr.yml: use distro-sync for the workaround Sep 19, 2017 doc: Add with blurbs about expected files May 30, 2017 Fix the example for in Oct 11, 2017 doc: Add and blog links Oct 4, 2017 doc: Add and blog links Oct 4, 2017 use the preprocessed config.json.template file Aug 22, 2017

System Containers

As part of our effort to reduce the number of packages that are shipped with the Atomic Host image, we faced the problem of how to containerize services that are needed to be run before a container runtime, like the upstream docker daemon, is running. The result: system containers: a way to run containers in production using read only images.

A system container is a container that is executed out of an systemd unit file early in boot, using runc. The specified IMAGE must be a system image already fetched. If it is not already present, atomic will attempt to fetch it assuming it is an oci image. Installing a system container consists of checking it the image by default under /var/lib/containers/atomic/ and generating the configuration files for runc and systemd. OSTree and runc are required for this feature to be available.

System containers use different technologies:

  • We use the atomic tool to install system containers.
  • Labels can influence how the atomic tool uses a system container
  • Specific files are required to be part of a valid system image
  • For storage system containers do not need to use COW File systems, since they are in production. We default to using OSTree for storage of the container images.
  • The atomic tool does not use upstream docker to pull the container images, instead we use the Skopeo tool to pull images from a container registry.
  • When you atomic install a system container the tool will look for a systemd unit file template in /exports directory and will create a systemd unit file to run the container on the host.
  • The unit files uses runc to create and run the containers.
  • systemd manages the lifecycle of the container.

To use system containers you must have Atomic CLI version 1.12 or later and the ostree utility installed.

For more information on system containers see: