The 10-containerd-net.conflist file generated from the conf_template
should be written atomically so that partial writes are not visible to
CNI plugins. Use the new consistentfile package to ensure this on
Unix-like platforms such as Linux, FreeBSD, and Darwin.
Fixes https://github.com/containerd/containerd/issues/8607
Signed-off-by: Samuel Karp <samuelkarp@google.com>
Certain files may need to be written atomically so that partial writes
are not visible to other processes. On Unix-like platforms such as
Linux, FreeBSD, and Darwin, this is accomplished by writing a temporary
file, syncing, and renaming over the destination file name. On Windows,
the same operations are performed, but Windows does not guarantee that a
rename operation is atomic.
Partial/inconsistent reads can occur due to:
1. A process attempting to read the file while containerd is writing it
(both in the case of a new file with a short/incomplete write or in
the case of an existing, updated file where new bytes may be written
at the beginning but old bytes may still be present after).
2. Concurrent goroutines in containerd leading to multiple active
writers of the same file.
The above mechanism explicitly protects against (1) as all writes are to
a file with a temporary name.
There is no explicit protection against multiple, concurrent goroutines
attempting to write the same file. However, atomically writing the file
should mean only one writer will "win" and a consistent file will be
visible.
Signed-off-by: Samuel Karp <samuelkarp@google.com>
Several bits of code unmarshal image config JSON into an `ocispec.Image`, and then immediately create an `ocispec.Platform` out of it, but then discard the original image *and* miss several potential platform fields (most notably, `variant`).
Because `ocispec.Platform` is a strict subset of `ocispec.Image`, most of these can be updated to simply unmarshal the image config directly to `ocispec.Platform` instead, which allows these additional fields to be picked up appropriately.
We can use `tianon/raspbian` as a concrete reproducer to demonstrate.
Before:
```console
$ ctr content fetch docker.io/tianon/raspbian:bullseye-slim
...
$ ctr image ls
REF TYPE DIGEST SIZE PLATFORMS LABELS
docker.io/tianon/raspbian:bullseye-slim application/vnd.docker.distribution.manifest.v2+json sha256:66e96f8af40691b335acc54e5f69711584ef7f926597b339e7d12ab90cc394ce 28.6 MiB linux/arm/v7 -
```
(Note that the `PLATFORMS` column lists `linux/arm/v7` -- the image itself is actually `linux/arm/v6`, but one of these bits of code leads to only `linux/arm` being extracted from the image config, which `platforms.Normalize` then updates to an explicit `v7`.)
After:
```console
$ ctr image ls
REF TYPE DIGEST SIZE PLATFORMS LABELS
docker.io/tianon/raspbian:bullseye-slim application/vnd.docker.distribution.manifest.v2+json sha256:66e96f8af40691b335acc54e5f69711584ef7f926597b339e7d12ab90cc394ce 28.6 MiB linux/arm/v6 -
```
Signed-off-by: Tianon Gravi <admwiggin@gmail.com>
Co-authored-by: Sebastiaan van Stijn <github@gone.nl>
This commit fixes a broken link. This commit also updates the description about
the image handler. It now mentions about
`github.com/containerd/containerd/pkg/snapshotters` package.
Signed-off-by: Kohei Tokunaga <ktokunaga.mail@gmail.com>
To further some ongoing work in containerd to make as much code as possible
able to be used on any platform (to handle runtimes that can virtualize/emulate
a variety of different OSes), this change makes stats able to be handled on
any of the supported stat types (just linux and windows). To accomplish this,
we use the platform the sandbox returns from its `Platform` rpc to decide
what format the containers in a given sandbox are returning metrics in, then
we can typecast/marshal accordingly.
Signed-off-by: Danny Canter <danny@dcantah.dev>
Add new test cases for volumes on both Linux and Windows. These new
volumes will be used to test that we don't accidentally mangle volume
paths on Linux and that non-C volume mounts work properly when defined
in an image on Windows.
Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>
