The daemon has made a habit of mutating the DefaultRuntime and Runtimes
values in the Config struct to merge defaults. This would be fine if it
was a part of the regular configuration loading and merging process,
as is done with other config options. The trouble is it does so in
surprising places, such as in functions with 'verify' or 'validate' in
their name. It has been necessary in order to validate that the user has
not defined a custom runtime named "runc" which would shadow the
built-in runtime of the same name. Other daemon code depends on the
runtime named "runc" always being defined in the config, but merging it
with the user config at the same time as the other defaults are merged
would trip the validation. The root of the issue is that the daemon has
used the same config values for both validating the daemon runtime
configuration as supplied by the user and for keeping track of which
runtimes have been set up by the daemon. Now that a completely separate
value is used for the latter purpose, surprising contortions are no
longer required to make the validation work as intended.
Consolidate the validation of the runtimes config and merging of the
built-in runtimes into the daemon.setupRuntimes() function. Set the
result of merging the built-in runtimes config and default default
runtime on the returned runtimes struct, without back-propagating it
onto the config.Config argument.
Signed-off-by: Cory Snider <csnider@mirantis.com>
The existing runtimes reload logic went to great lengths to replace the
directory containing runtime wrapper scripts as atomically as possible
within the limitations of the Linux filesystem ABI. Trouble is,
atomically swapping the wrapper scripts directory solves the wrong
problem! The runtime configuration is "locked in" when a container is
started, including the path to the runC binary. If a container is
started with a runtime which requires a daemon-managed wrapper script
and then the daemon is reloaded with a config which no longer requires
the wrapper script (i.e. some args -> no args, or the runtime is dropped
from the config), that container would become unmanageable. Any attempts
to stop, exec or otherwise perform lifecycle management operations on
the container are likely to fail due to the wrapper script no longer
existing at its original path.
Atomically swapping the wrapper scripts is also incompatible with the
read-copy-update paradigm for reloading configuration. A handler in the
daemon could retain a reference to the pre-reload configuration for an
indeterminate amount of time after the daemon configuration has been
reloaded and updated. It is possible for the daemon to attempt to start
a container using a deleted wrapper script if a request to run a
container races a reload.
Solve the problem of deleting referenced wrapper scripts by ensuring
that all wrapper scripts are *immutable* for the lifetime of the daemon
process. Any given runtime wrapper script must always exist with the
same contents, no matter how many times the daemon config is reloaded,
or what changes are made to the config. This is accomplished by using
everyone's favourite design pattern: content-addressable storage. Each
wrapper script file name is suffixed with the SHA-256 digest of its
contents to (probabilistically) guarantee immutability without needing
any concurrency control. Stale runtime wrapper scripts are only cleaned
up on the next daemon restart.
Split the derived runtimes configuration from the user-supplied
configuration to have a place to store derived state without mutating
the user-supplied configuration or exposing daemon internals in API
struct types. Hold the derived state and the user-supplied configuration
in a single struct value so that they can be updated as an atomic unit.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Ensure data-race-free access to the daemon configuration without
locking by mutating a deep copy of the config and atomically storing
a pointer to the copy into the daemon-wide configStore value. Any
operations which need to read from the daemon config must capture the
configStore value only once and pass it around to guarantee a consistent
view of the config.
Signed-off-by: Cory Snider <csnider@mirantis.com>
`docker run -v /foo:/foo:ro` is now recursively read-only on kernel >= 5.12.
Automatically falls back to the legacy non-recursively read-only mount mode on kernel < 5.12.
Use `ro-non-recursive` to disable RRO.
Use `ro-force-recursive` or `rro` to explicitly enable RRO. (Fails on kernel < 5.12)
Fix issue 44978
Fix docker/for-linux issue 788
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
Kubernetes only permits RuntimeClass values which are valid lowercase
RFC 1123 labels, which disallows the period character. This prevents
cri-dockerd from being able to support configuring alternative shimv2
runtimes for a pod as shimv2 runtime names must contain at least one
period character. Add support for configuring named shimv2 runtimes in
daemon.json so that runtime names can be aliased to
Kubernetes-compatible names.
Allow options to be set on shimv2 runtimes in daemon.json.
The names of the new daemon runtime config fields have been selected to
correspond with the equivalent field names in cri-containerd's
configuration so that users can more easily follow documentation from
the runtime vendor written for cri-containerd and apply it to
daemon.json.
Signed-off-by: Cory Snider <csnider@mirantis.com>
Raspberry Pi allows to start system under overlayfs.
Docker is successfully fallbacks to fuse-overlay but not starting
because of the `Error starting daemon: rename /var/lib/docker/runtimes /var/lib/docker/runtimes-old: invalid cross-device link` error
It's happening because `rename` is not supported by overlayfs.
After manually removing directory `runtimes` docker starts and works successfully
Signed-off-by: Illia Antypenko <ilya@antipenko.pp.ua>
Since runtimes can now just be containerd shims, we need to check if the
reference is possibly a containerd shim.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Contrary to popular belief, the OCI Runtime specification does not
specify the command-line API for runtimes. Looking at containerd's
architecture from the lens of the OCI Runtime spec, the _shim_ is the
OCI Runtime and runC is "just" an implementation detail of the
io.containerd.runc.v2 runtime. When one configures a non-default runtime
in Docker, what they're really doing is instructing Docker to create
containers using the io.containerd.runc.v2 runtime with a configuration
option telling the runtime that the runC binary is at some non-default
path. Consequently, only OCI runtimes which are compatible with the
io.containerd.runc.v2 shim, such as crun, can be used in this manner.
Other OCI runtimes, including kata-containers v2, come with their own
containerd shim and are not compatible with io.containerd.runc.v2.
As Docker has not historically provided a way to select a non-default
runtime which requires its own shim, runtimes such as kata-containers v2
could not be used with Docker.
Allow other containerd shims to be used with Docker; no daemon
configuration required. If the daemon is instructed to create a
container with a runtime name which does not match any of the configured
or stock runtimes, it passes the name along to containerd verbatim. A
user can start a container with the kata-containers runtime, for
example, simply by calling
docker run --runtime io.containerd.kata.v2
Runtime names which containerd would interpret as a path to an arbitrary
binary are disallowed. While handy for development and testing it is not
strictly necessary and would allow anyone with Engine API access to
trivially execute any binary on the host as root, so we have decided it
would be safest for our users if it was not allowed.
It is not yet possible to set an alternative containerd shim as the
default runtime; it can only be configured per-container.
Signed-off-by: Cory Snider <csnider@mirantis.com>
The io/ioutil package has been deprecated in Go 1.16. This commit
replaces the existing io/ioutil functions with their new definitions in
io and os packages.
Signed-off-by: Eng Zer Jun <engzerjun@gmail.com>
This fixes a panic when an admin specifies a custom default runtime,
when a plugin is started the shim config is nil.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
The previous default runtime `io.containerd.runtime.v1.linux` is being deprecated (https://github.com/containerd/containerd/issues/4365)
`io.containerd.runc.v2` is available since containerd v1.3.0.
Using v1.3.5 or later is recommended. v1.3.0-v1.3.4 doesn't pass `TestContainerStartOnDaemonRestart`.
Fix#41107
Replace #41115
Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
In dockerd we already have a concept of a "runtime", which specifies the
OCI runtime to use (e.g. runc).
This PR extends that config to add containerd shim configuration.
This option is only exposed within the daemon itself (cannot be
configured in daemon.json).
This is due to issues in supporting unknown shims which will require
more design work.
What this change allows us to do is keep all the runtime config in one
place.
So the default "runc" runtime will just have it's already existing shim
config codified within the runtime config alone.
I've also added 2 more "stock" runtimes which are basically runc+shimv1
and runc+shimv2.
These new runtime configurations are:
- io.containerd.runtime.v1.linux - runc + v1 shim using the V1 shim API
- io.containerd.runc.v2 - runc + shim v2
These names coincide with the actual names of the containerd shims.
This allows the user to essentially control what shim is going to be
used by either specifying these as a `--runtime` on container create or
by setting `--default-runtime` on the daemon.
For custom/user-specified runtimes, the default shim config (currently
shim v1) is used.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
