Certificate signing request ca issuer

.spelling

@@ -30,12 +30,16 @@ boolean
 CAs
 CertificateRequest
 CertificateRequests
+CertificateSigningRequest
+CertificateSigningRequests
 Changelog
 ChartMuseum
 CloudDNS
 Cloudflare
 CloudFlare
 ClusterRole
+ClusterIssuer
+ClusterIssuers
 CNAME
 CNAMEs
 CNI
@@ -161,6 +165,7 @@ stdout
 subdomain
 (sub)domains
 subdomains
+SubjectAccessReview
 subresource
 templating
 Tiller

content/en/docs/usage/kube-csr.md

@@ -0,0 +1,125 @@
+---
+title: "Kubernetes CertificateSigningRequests"
+linkTitle: "Kubernetes CertificateSigningRequests"
+weight: 400
+type: "docs"
+---
+
+Kubernetes has an in-built
+[CertificateSigningRequest](https://kubernetes.io/docs/reference/access-authn-authz/certificate-signing-requests/)
+resource. This resource is similar to the cert-manager
+[CertificateRequest](../../concepts/certificaterequest/) in that it is used to
+request an X.509 signed certificate from a referenced Certificate Authority
+(CA).
+
+Using this resource may be useful for users who are using an application that
+supports this resource, and not the cert-manager CertificateRequest resource,
+but they still wish for certificates to be signed through cert-manager.
+
+#### Feature State
+
+This feature is currently in an _experimental_ state, and its behavior is
+subject to change in further releases.
+
+{{% pageinfo color="warning" %}}
+
+⛔️ This feature is only enabled by adding it to the `--feature-gates` flag on
+the cert-manager controller:
+
+```bash
+--feature-gates=ExperimentalCertificateSigningRequestControllers=true
+```
+
+Which can be added using Helm:
+
+```bash
+$ helm install \
+  cert-manager jetstack/cert-manager \
+  --namespace cert-manager \
+  --create-namespace \
+  --set featureGates="ExperimentalCertificateSigningRequestControllers=true" \
+  # --set installCRDs=true
+```
+
+> Note: cert-manager currently only supports signing CertificateSigningRequests
+> using the [CA issuer](../../configuration/ca/).
+
+> Note: cert-manager _will not_ automatically approve CertificateSigningRequests
+> that reference a cert-manager [Issuer](../../configuration/). Please refer to
+> the [Kubernetes documentation](https://kubernetes.io/docs/reference/access-authn-authz/certificate-signing-requests/#request-signing-process)
+> for the request process of CertificateSigningRequests.
+
+
+{{% /pageinfo %}}
+
+
+## Signer Name
+
+CertificateSigningRequests contain a
+[`spec.signerName`](https://kubernetes.io/docs/reference/access-authn-authz/certificate-signing-requests/#request-signing-process)
+field to reference a CA to sign the request. cert-manager Issuers or
+ClusterIssuers are referenced in the following form:
+
+```
+<resource type>.cert-manager.io/<signer namespace (if namespaced)>.<signer name>
+```
+
+For example, a namespaced Issuer in the namespace `sandbox` with the name
+`my-issuer` would be referenced via:
+
+```yaml
+    signerName: issuers.cert-manager.io/sandbox.my-issuer
+```
+
+A ClusterIssuer with the name `my-cluster-issuer` would be referenced via:
+
+```yaml
+    signerName: clusterissuers.cert-manager.io/my-cluster-issuer
+```
+
+### Referencing Namespaced Issuers
+
+Unlike CertificateRequests, CertificateSigningRequests are cluster scoped
+resources. To prevent users from requesting certificates from a namespaced
+Issuer in a namespace that they otherwise would not have access to, cert-manager
+performs a
+[SubjectAccessReview](https://kubernetes.io/docs/reference/access-authn-authz/authorization/#checking-api-access).
+This review ensures that the requesting user has the permission to `reference`
+the `signers` resource in the given namespace. The name should be either the
+name of the Issuer, or `"*"` to reference all Issuers in that namespace.
+
+An example Role to give permissions to reference Issuers in the `sandbox`
+namespace would look like the following:
+
+```yaml
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+  name: cert-manager-referencer:my-issuer
+  namespace: sandbox
+rules:
+- apiGroups: ["cert-manager.io"]
+  resources: ["signers"]
+  verbs:     ["reference"]
+  resourceNames:
+  - "my-issuer" # To give permission to _only_ reference Issuers with the name 'my-issuer'
+  - "*" # To give permission to reference Issuers with any name in this namespace
+```
+
+## Annotations
+
+To keep feature parity with CertificateRequests, annotations are used to store
+values that do not exist as `spec` or `status` fields on the
+CertificateSigningRequest resource. These fields are either set by the
+_requester_ or by the _signer_ as labelled below.
+
+- `experimental.cert-manager.io/request-duration`: **Set by the requester**. Accepts
+    a [Go time duration](https://golang.org/pkg/time/#ParseDuration) string
+    specifying the requested certificate duration. Defaults to 90 days.
+
+- `experimental.cert-manager.io/request-is-ca`: **Set by the requester**. If set to
+    `"true"`, will request for a CA certificate.
+
+- `experimental.cert-manager.io/ca`: **Set by the signer**. Once signed, the
+    signer will populate this annotation with the base 64 encode CA certificate
+    of the signing chain.