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Task Page for Verifying Signed Images (#32184)

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* Add container image signing docs

Signed-off-by: Sascha Grunert <sgrunert@redhat.com>

* Creates a task page to verify signed control plane container images

* Added info about cosigned and why we need cosign in experimental mode

Updates based on PR review

Apply suggestions from code review

Co-authored-by: Tim Bannister <tim@scalefactory.com>

* Uses K8s SBoM to get list of signed images

Apply suggestions from code review

Co-authored-by: Qiming Teng <tengqm@outlook.com>
Co-authored-by: Chris Negus <cnegus@redhat.com>

* Add current scope of sign/verify

Co-authored-by: Sascha Grunert <sgrunert@redhat.com>
Co-authored-by: Tim Bannister <tim@scalefactory.com>
Co-authored-by: Qiming Teng <tengqm@outlook.com>
Co-authored-by: Chris Negus <cnegus@redhat.com>
This commit is contained in:
Pushkar Joglekar
2022-04-12 08:29:23 -07:00
committed by GitHub
parent f440c609e9
commit ba6776b2a6
2 changed files with 89 additions and 1 deletions
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content/en/docs/tasks/administer-cluster/verify-signed-images.md
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---
title: Verify Signed Container Images
content_type: task
min-kubernetes-server-version: v1.24
---
<!-- overview -->
{{< feature-state state="alpha" for_k8s_version="v1.24" >}}
## {{% heading "prerequisites" %}}
These instructions are for Kubernetes {{< skew currentVersion >}}. If you want
to check the integrity of components for a different version of Kubernetes,
check the documentation for that Kubernetes release.
You will need to have the following tools installed:
- `cosign` ([install guide](https://docs.sigstore.dev/cosign/installation/))
- `curl` (often provided by your operating system)
## Verifying image signatures
For a complete list of images that are signed please refer
to [Releases](/releases/download/).
Let's pick one image from this list and verify its signature using
the `cosign verify` command:
```shell
COSIGN_EXPERIMENTAL=1 cosign verify k8s.gcr.io/kube-apiserver-amd64:v1.24.0
```
{{< note >}}
`COSIGN_EXPERIMENTAL=1` is used to allow verification of images signed
in `KEYLESS` mode. To learn more about keyless signing, please refer to
[Keyless Signatures](https://github.com/sigstore/cosign/blob/main/KEYLESS.md#keyless-signatures)
. {{< /note >}}
### Verifying images for all control plane components
To verify all signed control plane images, please run this command:
```shell
curl -Ls https://sbom.k8s.io/$(curl -Ls https://dl.k8s.io/release/latest.txt)/release | grep 'PackageName: k8s.gcr.io/' | awk '{print $2}' > images.txt
input=images.txt
while IFS= read -r image
do
COSIGN_EXPERIMENTAL=1 cosign verify "$image"
done < "$input"
```
Once you have verified an image, specify that image by its digest in your Pod
manifests as per this
example: `registry-url/image-name@sha256:45b23dee08af5e43a7fea6c4cf9c25ccf269ee113168c19722f87876677c5cb2`
.
For more information, please refer
to [Image Pull Policy](/docs/concepts/containers/images/#image-pull-policy)
section.
## Verifying Image Signatures with Admission Controller
For non-control plane images (
e.g. [conformance image](https://github.com/kubernetes/kubernetes/blob/master/test/conformance/image/README.md))
, signatures can also be verified at deploy time using
[cosigned](https://docs.sigstore.dev/cosign/kubernetes/#cosigned-admission-controller)
admission controller. To get started with `cosigned` here are a few helpful
resources:
* [Installation](https://github.com/sigstore/helm-charts/tree/main/charts/cosigned)
* [Configuration Options](https://github.com/sigstore/cosign/tree/main/config)
content/en/releases/download.md
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type: docs
---
# Core Kubernetes components
Kubernetes ships binaries for each component as well as a standard set of client
applications to bootstrap or interact with a cluster. Components like the
Kube API Server are capable of running within container images inside of a
@@ -68,7 +70,21 @@ container image name, for example
[`k8s.gcr.io/kube-apiserver-arm64:{{< param "fullversion" >}}`][0-arm64]. All
those derivations are signed in the same way as the multi-architecture manifest lists.
<!-- TODO: describe how to use the signed images -->
The Kubernetes project publishes a list of signed Kubernetes container images
in SBoM (Software Bill of Materials) format.
You can fetch that list using:
```shell
curl -Ls https://sbom.k8s.io/$(curl -Ls https://dl.k8s.io/release/latest.txt)/release | grep 'PackageName: k8s.gcr.io/' | awk '{print $2}'
```
For Kubernetes v{{< skew currentVersion >}}, the only kind of code artifact that
you can verify integrity for is a container image, using the experimental
signing support.
To manually verify signed container images of Kubernetes core components, please refer to
[Verify Signed Container Images](/docs/tasks/administer-cluster/verify-signed-images).
## Binaries