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ACM Private CA Policy

Amazon Certificate Manager Private CA Backend

The default mTLS policy in Kong Mesh supports the following backends:

• builtin: Kong Mesh automatically generates the Certificate Authority (CA) root certificate and key that will be used to generate the data plane certificates.
• provided: the CA root certificate and key can be provided by the user.

Kong Mesh adds:

• vault: Kong Mesh generates data plane certificates using a CA root certificate and key stored in a HashiCorp Vault server.
• acmpca: Kong Mesh generates data plane certificates using Amazon Certificate Manager Private CA.
• certmanager: Kong Mesh generates data plane certificates using Kubernetes cert-manager certificate controller.

ACM Private CA mode

In acmpca mTLS mode, Kong Mesh communicates with the Amazon Certificate Manager, which generates the data plane proxy certificates automatically. Kong Mesh does not retrieve any CA private keys, which means that the private key of the CA is secured by Amazon ACM and not exposed to third parties.

In acmpca mode, you point Kong Mesh to the ACM resource and optionally provide an authentication method. Kong Mesh will use the default AWS credential chain to authenticate.

When Kong Mesh is running in acmpca mode, the backend communicates with AWS ACM and ensures data plane certificates are issued and rotated for each proxy.

Configure ACM Private CA

The acmpca mTLS backend requires a configured ACM Private CA resource to be accessible.

The following steps show how to configure ACM Private CA for Kong Mesh with a mesh named default. For your environment, replace default with the appropriate mesh name.

Kong Mesh works with a Root CA or an Intermediate CA.

See ACM Private CA documentation to learn how to create an ACM Private CA in AWS.

Once created, you will need the ARN of the Private CA and the Root Certificate Chain to configure Kong Mesh.

Configure Mesh

Authentication and AWS Client Configuration

kuma-cp communicates directly with ACM Private CA. kuma-cp will use the default ordering of AWS credential chain to authenticate. It will search for credentials in environment variables, configuration files and EC2 / IRSA roles. In addition to credentials, AWS configuration may be specified in standard environment variables, such as AWS_REGION.

AWS credentials may also be supplied as secrets stored by Kong Mesh.

ACMPCA mTLS Configuration

AWS credentials and CA Certificate may be supplied inline, as a path to a file on the same host as kuma-cp, or contained in a secret. Inline specification of credentials should be used for testing purposes only. When using a secret, it should be a mesh-scoped secret. On Kubernetes, this mesh-scoped secret should be stored in the system namespace (kong-mesh-system by default) and should be configured as type: system.kuma.io/secret.

Here’s an example of a configuration with a acmpca-backed CA:

apiVersion: kuma.io/v1alpha1
kind: Mesh
metadata:
  name: default
spec:
  mtls:
    enabledBackend: acmpca-1
    backends:
      - name: acmpca-1
        type: acmpca
        dpCert:
          rotation:
            expiration: 1d
        conf:
          arn: "arn:aws:acm-pca:region:account:certificate-authority/12345678-1234-1234-1234-123456789012" # AWS ARN of the Private CA
          commonName: '{{ tag "kuma.io/service" }}.mesh' # optional. If set, then commonName is added to the certificate. You can use "tag" directive to pick a tag which will be base for commonName. If unset, a Subject Alternative Name may be duplicated as Common Name.
          caCert:             # caCert is used to verify the TLS certificate presented by ACM.
            secret: sec-1     # one of file, secret or inline.
          auth: # Optional AWS authentication keys. If unset, default credential chain locations are searched.
            awsCredentials:
              accessKey:
                secret: sec-2  # one of file, secret or inline.
              accessKeySecret:
                file: /tmp/accesss_key.txt # one of file, secret or inline.

type: Mesh
name: default
mtls:
  enabledBackend: acmpca-1
  backends:
  - name: acmpca-1
    type: acmpca
    dpCert:
      rotation:
        expiration: 24h
    conf:
      arn: "arn:aws:acm-pca:region:account:certificate-authority/12345678-1234-1234-1234-123456789012" # AWS ARN of the Private CA
      commonName: '{{ tag "kuma.io/service" }}.mesh' # optional. If set, then commonName is added to the certificate. You can use "tag" directive to pick a tag which will be base for commonName. If unset, a Subject Alternative Name may be duplicated as Common Name.
      caCert:              # caCert is used to verify the TLS certificate presented by ACM.
        secret: sec-1      # one of file, secret or inline.
      auth:  # Optional AWS authentication keys. If unset, default credential chain locations are searched.
        awsCredentials:
          accessKey:
            secret: sec-2  # one of file, secret or inline.
          accessKeySecret:
            file: /tmp/accesss_key.txt # one of file, secret or inline.

Apply the configuration with kumactl apply -f [..].

If you’re running in Universal mode, you can also use the HTTP API to apply configuration.

multi-zone and ACM Private CA

In a multi-zone environment, the global control plane provides the Mesh to the zone control planes. However, you must make sure that each zone control plane can communicate with ACM Private CA. This is because certificates for data plane proxies are requested from ACM Private CA by the zone control plane, not the global control plane.

You must also make sure the global control plane can communicate with ACM Private CA. When a new acmpca backend is configured, Kong Mesh validates the connection by issuing a test certificate. In a multi-zone environment, validation is performed on the global control plane.