This document discusses the available options for upgrading a system running Intel® Clear Containers.
There are currently two implementations of Clear Containers:
-
Clear Containers 2.x (or just 2.x) refers to the previous implementation of Clear Containers which uses a runtime called
cc-oci-runtime. 2.x code is available at: https://github.com/01org/cc-oci-runtime -
Clear Container 3.x (or just 3.x) refers to the current implementation which uses a runtime called
cc-runtime. 3.x code is available at: https://github.com/clearcontainers/runtime
The 2.x codebase is no longer being developed. Only new releases will be considered for significant bug fixes.
The main development focus is now on the 3.x branch. All 2.x users are encouraged to switch to the 3.x implementation.
Clear Containers 2.x and 3.x share certain architectural elements. Both
use a shim process called cc-shim and a proxy process called
cc-proxy. However, the 2.x versions of these elements are
incompatible with their 3.x counterparts.
This section details supported operations and configurations.
For operating systems with pre-built packages (such as Fedora* and Ubuntu*), upgrading is possible with the following conditions:
- Configuration files are not migrated (see Configuration files).
- It is necessary to perform a few cleanup steps as outlined in the subsections below.
Once the cleanup steps have been performed, simply follow the 3.x installation guides and any existing packaged versions of the 2.x components will be removed and the new 3.x components installed in their place.
Assuming the system was installed by following the CC 2.x Ubuntu installation guide:
-
Perform the following cleanup steps:
$ sudo rm -f /etc/systemd/system/docker.service.d/clr-containers.conf $ sudo apt-get purge -y docker-engine $ sudo rm -f /etc/apt/sources.list.d/cc-oci-runtime.list
-
Follow the CC 3.x Ubuntu installation guide.
Assuming the system was installed by following the CC 2.x Fedora installation guide:
-
Perform the following cleanup steps:
$ sudo rm -f /etc/systemd/system/docker.service.d/clr-containers.conf $ sudo rm -f /etc/yum.repos.d/home:clearlinux:preview:clear-containers-2.1.repo
-
Follow the CC 3.x Fedora installation guide.
Since the CentOS installation instructions require the user to manually build and install various packages, upgrading must also be performed manually. This is not a recommended strategy: instead, consider installing 3.x on a system which does not have 2.x installed.
This section details operations and configurations that are not supported.
Running both 2.x and 3.x on the same system is explicitly not supported due to the incompatible elements between the two systems.
If you are using the pre-built packages, installing the 3.x elements will remove the 2.x ones (see Systems using pre-built packages).
The 2.x runtime supported three different configuration files
(vm.json, hypervisor.args and cc-oci-runtime.sh.cfg for the
cc-oci-runtime.sh helper script).
The 3.x runtime uses a single configuration file (configuration.toml).
Note:
None of the 2.x configuration files are migrated or read by the 3.x runtime. Any changes made to the 2.x configuration files will not be carried over to the 3.x runtime.
Systems using packaged versions of 3.x cannot be downgraded to 2.x simply by following the 2.x installation instructions.
However, it should be possible to switch back to 2.x by first fully removing 3.x and then following the 2.x installation instructions.
Using 2.x is now discouraged since it is no longer being developed (see Maintenance warning).