KMS issuer is a cert-manager Certificate Request controller that uses AWS KMS to sign the certificate request.
In this guide, we assume that you have a Kubernetes environment with a cert-manager version supporting CertificateRequest issuers, cert-manager v0.11.0 or higher.
For any details on Cert-Manager, check the official documentation.
You can install the controller using the official helm chart:
helm repo add kms-issuer 'https://skyscanner.github.io/kms-issuer'
helm repo updateTo install the chart with the release name kms-issuer:
helm upgrade --install kms-issuer kms-issuer/kms-issuer --namespace kms-issuer-system --create-namespace- Install cert-manager. The operator has been tested with version v0.15.1
kubectl apply --validate=false -f https://github.com/jetstack/cert-manager/releases/download/v0.15.1/cert-manager.yaml- Install and run the kms-issuer
Install the kms-issuer Kubernetes Custom Resources and start the controller.
# Install CRD
make install
# Run the controller (you must have have a role able to create/access KMS keys)
make run- Create a KMS Key
You need a valid KMS asymetric key that as the ability to SIGN_VERIFY messages. Currently, Cloudformation does not support KMS SIGN_VERIFY keys. To simply the provisioning process, the kms-issuer operator provides a dedicated controller for provisioning a valid KMS key.
cat << EOF | kubectl apply -f -
---
apiVersion: cert-manager.skyscanner.net/v1alpha1
kind: KMSKey
metadata:
name: kmskey-sample
spec:
aliasName: alias/kms-issuer-example
description: a kms-issuer example kms key
customerMasterKeySpec: RSA_2048
tags:
project: kms-issuer
deletionPolicy: Delete
deletionPendingWindowInDays: 7
EOF- Create a KMS issuer object
cat << EOF | kubectl apply -f -
---
apiVersion: cert-manager.skyscanner.net/v1alpha1
kind: KMSIssuer
metadata:
name: kms-issuer
namespace: default
spec:
keyId: alias/kms-issuer-example # The KMS key id or alias
commonName: My Root CA # The common name for the root certificate
duration: 87600h # 10 years
EOFAt this point, the operator geneates a public root certificate signed using the provided KMS key. You can inspect it with the following command:
kubectl get kmsissuer kms-issuer -o json | jq -r ".status.certificate" | base64 --decode | openssl x509 -noout -text- Finally, create a Certificate request that will be signed by our KMS issuer.
cat << EOF | kubectl apply -f -
---
apiVersion: cert-manager.io/v1
kind: Certificate
metadata:
name: example-com
namespace: default
spec:
# Secret names are always required.
secretName: example-com-tls
duration: 8760h # 1 year
renewBefore: 360h # 15d
subject:
organizations:
- skyscanner
# The use of the common name field has been deprecated since 2000 and is
# discouraged from being used.
commonName: example.com
isCA: false
privateKey:
algorithm: RSA
encoding: PKCS1
size: 2048
usages:
- server auth
- client auth
# At least one of a DNS Name, URI, or IP address is required.
dnsNames:
- example.com
- www.example.com
uris:
- spiffe://cluster.local/ns/sandbox/sa/example
ipAddresses:
- 192.168.0.5
# Issuer references are always required.
issuerRef:
name: kms-issuer
# We can reference ClusterIssuers by changing the kind here.
# The default value is Issuer (i.e. a locally namespaced Issuer)
kind: KMSIssuer
# This is optional since cert-manager will default to this value however
# if you are using an external issuer, change this to that issuer group.
group: cert-manager.skyscanner.net
EOFYou now have a key pair signed by KMS
kubectl get secret example-com-tlsA KMSKey resource is used to create an AWS KMS asymetric key compatible with the KMS issuer.
| Field | Type | Description |
|---|---|---|
apiVersion |
string | cert-manager.skyscanner.net/v1alpha1 |
kind |
string | KMSKey |
metadata |
object | Refer to the Kubernetes API documentation for metadata fields. |
spec |
object | Desired state of the KMSKey resource. |
spec.aliasName |
string | the alias name for the kms key. This value must begin with alias/ followed by a name, such as alias/ExampleAlias. |
spec.description |
string | Description for the key. (optional) |
spec.customerMasterKeySpec |
string | Determines the signing algorithms that the CMK supports. Only RSA_2048 is currently supported. (optional, default=RSA_2048) |
spec.policy |
string | The key policy to attach to the CMK. (optional) |
spec.tags |
object | A list of tags for the key. (optional) |
spec.deletionPolicy |
string | Policy to deletes the alias and key on object deletion. Either Retain or Delete. (optional, default=Retain). |
spec.deletionPendingWindowInDays |
int | Number of days before the KMS key gets deleted. If you include a value, it must be between 7 and 30, inclusive. If you do not include a value, it defaults to 30. (optional) |
A KMSIssuer resource configures a new Cert-Manager external issuer.
| Field | Type | Description |
|---|---|---|
apiVersion |
string | cert-manager.skyscanner.net/v1alpha1 |
kind |
string | KMSIssuer |
metadata |
object | Refer to the Kubernetes API documentation for metadata fields. |
spec |
object | Desired state of the KMSIssuer resource. |
spec.keyId |
string | The unique identifier for the customer master key |
spec.commonName |
string | The common name to be used on the Certificate. |
spec.duration |
duration | Certificate default Duration. (optional, default=26280h aka 3 years) |
spec.renewBefore |
duration | The amount of time before the certificate’s notAfter time that the issuer will begin to attempt to renew the certificate. If this value is greater than the total duration of the certificate (i.e. notAfter - notBefore), it will be automatically renewed 2/3rds of the way through the certificate’s duration. The NotBefore field on the certificate is set to the current time rounded down by the renewal interval. For example, if the certificate is renewed every hour, the NotBefore field is set to the beggining of the hour. If the certificate is renewed every day, the NotBefore field is set to the beggining of the day. This allows the generation of consistent certificates regardless of when it has been generated during the renewal period, or recreate the same certificate after a backup/restore of your kubernetes cluster. For more details on the computation, check the time.Truncate function. |
The KMS Issuer will wait for CertificateRequests to have an approved condition
set before
signing. If using an older version of cert-manager (pre v1.3), you can disable
this check by supplying the command line flag -enable-approved-check=false to
the Issuer Deployment.
Kms-Issuer is built using the Kubebuilder framework. See the official documentation to get started and check CONTRIBUTING.md for more details.
Check SECURITY.md.