An Aggregated APIServer for the Kubescape internal storage services.
Note: go-get or vendor this package as k8s.io/sample-apiserver
.
The Kubescape Storage APIServer serves custom resources that Kubescape defines for its operation. These custom reources might store internal Kubescape configuration, scan artifacts, computed snapshots etc that help the entire Kubescape in-cluster solution operate.
Like the rest of Kubernetes, sample-apiserver has used
godep and $GOPATH
for years and is now
adopting go 1.11 modules. While upstream mentions two alternative ways to go
about fetching the sample repository and its dependencies, we recommend and
primarily use only one: using native Go 1.11 modules and vendoring.
When using go 1.11 modules (GO111MODULE=on
), you first need to create the appropriate working directory:
mkdir ~/github.com/kubescape
cd ~/github.com/kubescape
Warning
Due to the specifics of the code generation script hack/update-codegen.sh
,
your working directory should always match your module path. That is,
~/github.com/kubescape/storage
for this specific repo. If the directories
don’t match and you store code in some other directory, you will write code
in whatever directory you chose, but once you run codegen, it will generate
the code only in ~/github.com/kubescape/storage
.
Once you have a working directory set up, issue the following commands in your working directory.
git clone https://github.com/kubescape/storage.git
cd storage
Note that when you need to generate code then you will
also need the code-generator repo to exist in an old-style location. One easy
way to do this is to use the command go mod vendor
to create and populate the
vendor
directory.
If you are developing Kubernetes according to
https://github.com/kubernetes/community/blob/master/contributors/guide/github-workflow.md
then you already have a copy of this demo in
kubernetes/staging/src/k8s.io/sample-apiserver
and its dependencies
--- including the code generator --- are in usable locations.
If you change the API object type definitions in any of the
pkg/apis/.../types.go
files then you will need to update the files generated
from the type definitions. To do this, first pull the dependencies and create
the vendor directory. Once you vendored the
dependencies, you will have the code generation scripts in your vendor
directory. To make code generation, you need to make them executable:
chmod +x vendor/k8s.io/code-generator/*.sh
Now you’re all set to generate the code for changed types. Do this with:
hack/update-codegen.sh
If you see any errors regarding GOPATH
, just provide it manually:
GOPATH=$(go env GOPATH) hack/update-codegen.sh
The code generation script will give you warnings about API rule violations. Don’t mind them. To address these warnings, add them to the exclusion list as show in the updated upstream repo.
You will also see a warning about generate-internal-groups.sh
being deprecated:
WARNING: generate-internal-groups.sh is deprecated.
WARNING: Please use k8s.io/code-generator/kube_codegen.sh instead.
This is valid, and upstream has also been updated to use the latest code
generation script — kube_codegen.sh
. However, as of now it breaks code
generation for us, and we had no opportunity to reconcile the changes.
Once the code generation finishes successfully, you should be able to run tests and build the binary with no errors:
go build -v ./...
go test -v -failfast -count=1 ./...
The normal build supports only a very spare selection of
authentication methods. There is a much larger set available in
https://github.com/kubernetes/client-go/tree/master/plugin/pkg/client/auth
. If you want your server to support one of those, such as oidc
,
then add an import of the appropriate package to
sample-apiserver/main.go
. Here is an example:
import _ "k8s.io/client-go/plugin/pkg/client/auth/oidc"
Alternatively you could add support for all of them, with an import like this:
import _ "k8s.io/client-go/plugin/pkg/client/auth"
With storage
as your current working directory, issue the
following command:
make binary
With storage
as your current working directory, issue the
following commands:
TAG=v1.2.3 make docker-build && TAG=v1.2.3 make docker-push
Take note that the Makefile targets use default values for the image tag and the Dockerfile path, so feel free to adjust them as environment variables as needed:
TAG=v1.2.3 IMAGE=quay.io/kubescape/storage make docker-build
TAG=v1.2.3 IMAGE=quay.io/kubescape/storage make docker-push
Edit artifacts/example/deployment.yaml
, updating the pod template's image
reference to match what you pushed and setting the imagePullPolicy
to something suitable.
If you’re running a Minikube cluster locally, build and tag an container image, use it in the artifacts/example/deployment.yaml
, set imagePullPolicy: Never
and this will let you use a local container image without having to push it to a container registry.
Then, make sure the appropriate namespace for the APIServer components exists:
kubectl apply -f artifacts/example/ns.yaml
Finally, create all the other Aggregated APIServer components:
kubectl apply -f artifacts/example
During development it is helpful to run the Storage APIServer stand-alone, i.e. without
a Kubernetes API server for authn/authz and without aggregation. This is possible, but needs
a couple of flags, keys and certs as described below. You will still need some kubeconfig,
e.g. ~/.kube/config
, but the Kubernetes cluster is not used for authn/z. A minikube or
hack/local-up-cluster.sh cluster will work.
Instead of trusting the aggregator inside kube-apiserver, the described setup uses local
client certificate based X.509 authentication and authorization. This means that the client
certificate is trusted by a CA and the passed certificate contains the group membership
to the system:masters
group. As we disable delegated authorization with --authorization-skip-lookup
,
only this superuser group is authorized.
-
First we need a CA to later sign the client certificate:
openssl req -nodes -new -x509 -keyout ca.key -out ca.crt
-
Then we create a client cert signed by this CA for the user
development
in the superuser groupsystem:masters
:openssl req -out client.csr -new -newkey rsa:4096 -nodes -keyout client.key -subj "/CN=development/O=system:masters" openssl x509 -req -days 365 -in client.csr -CA ca.crt -CAkey ca.key -set_serial 01 -out client.crt
-
As curl requires client certificates in p12 format with password, do the conversion:
openssl pkcs12 -export -in ./client.crt -inkey ./client.key -out client.p12 -passout pass:password
-
With these keys and certs in-place, we start the server:
etcd & sample-apiserver --secure-port 8443 --etcd-servers http://127.0.0.1:2379 --v=7 \ --client-ca-file ca.crt \ --kubeconfig ~/.kube/config \ --authentication-kubeconfig ~/.kube/config \ --authorization-kubeconfig ~/.kube/config
The first kubeconfig is used for the shared informers to access Kubernetes resources. The second kubeconfig passed to
--authentication-kubeconfig
is used to satisfy the delegated authenticator. The third kubeconfig passed to--authorized-kubeconfig
is used to satisfy the delegated authorizer. Neither the authenticator, nor the authorizer will actually be used: due to--client-ca-file
, our development X.509 certificate is accepted and authenticates us assystem:masters
member.system:masters
is the superuser group such that delegated authorization is skipped. -
Use curl to access the server using the client certificate in p12 format for authentication:
curl -fv -k --cert-type P12 --cert client.p12:password \ https://localhost:8443/apis/wardle.example.com/v1alpha1/namespaces/default/flunders
Or use wget:
wget -O- --no-check-certificate \ --certificate client.crt --private-key client.key \ https://localhost:8443/apis/wardle.example.com/v1alpha1/namespaces/default/flunders
Note: Recent OSX versions broke client certs with curl. On Mac try
brew install httpie
and then:http --verify=no --cert client.crt --cert-key client.key \ https://localhost:8443/apis/wardle.example.com/v1alpha1/namespaces/default/flunders
Kubescape Storage changes are tracked on the release page.