Rotate certificate Azure Arc-enabled SQL Managed Instance (indirectly connected)

This article describes how to rotate user-provided Transport Layer Security(TLS) certificate for Azure Arc-enabled SQL Managed Instances in indirectly connected mode using Azure CLI or kubectl commands.

Examples in this article use OpenSSL. OpenSSL is an open-source command-line toolkit for general-purpose cryptography and secure communication.

Prerequisite

Generate certificate request using openssl

If the managed instance uses a self-signed certificate, add all needed Subject Alternative Names (SANs). The SAN is an extension to X.509 that allows various values to be associated with a security certificate using a subjectAltName field, the SAN field lets you specify additional host names (sites, IP addresses, common names, and etc.) to be protected by a single SSL certificate, such as a multi-domain SAN or extended validation multi-domain SSL certificate.

To generate certificate on your own, you need to create a certificate signing request (CSR). Verify the configuration for the certificate has a common name with required SANs and has a CA issuer. For example:

openssl req -newkey rsa:2048 -keyout your-private-key.key -out your-csr.csr

Run the following command to check the required SANs:

openssl x509 -in /<cert path>/<filename>.pem -text

The following example demonstrates this command:

openssl x509 -in ./mssql-certificate.pem -text

The command returns the following output:

Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 7686530591430793847 (0x6aac0ad91167da77)
        Signature Algorithm: sha256WithRSAEncryption
        Issuer: CN = Cluster Certificate Authority
        Validity
            Not Before: Mmm dd hh:mm:ss yyyy GMT
            Not After: Mmm dd hh:mm:ss yyyy GMT
        Subject: CN = mi4-svc
        Subject Public Key Info:
            Public Key Algorithm: rsaEncryption
                RSA Public-Key: (2048 bit)
                Modulus:
                    00:ad:7e:16:3e:7d:b3:1e: ...
                Exponent: 65537 (0x10001)
        X509v3 extensions:
            X509v3 Extended Key Usage: critical
                TLS Web Client Authentication, TLS Web Server Authentication
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Subject Alternative Name:
                DNS:mi4-svc, DNS:mi4-svc.test.svc.cluster.local, DNS:mi4-svc.test.svc
    Signature Algorithm: sha256WithRSAEncryption
         7a:f8:a1:25:5c:1d:e2:b4: ...
-----BEGIN CERTIFICATE-----
MIIDNjCCAh6gAwIB ...==
-----END CERTIFICATE-----

Example output:

X509v3 Subject Alternative Name:
DNS:mi1-svc, DNS:mi1-svc.test.svc.cluster.local, DNS:mi1-svc.test.svc

Create Kubernetes secret yaml specification for your service certificate

  1. Encode a file using the following command with base64 in any Linux distribution, data are encoded and decoded to make the data transmission and storing process easier.

    base64 /<path>/<file> > cert.txt 
    

    For Windows users, use certutil utility to perform Base64 encoding and decoding as the following command:

    $certutil -encode -f input.txt b64-encoded.txt
    

    Remove the header in the output file manually, or use the following command:

    $findstr /v CERTIFICATE b64-encoded.txt> updated-b64.txt 
    
  2. Add the base64 encoded cert and private key to the yaml specification file to create a Kubernetes secret:

    apiVersion: v1
    kind: Secret
    metadata:
      name: <secretName>
    type: Opaque
    data:
      certificate.pem: < base64 encoded certificate >
      privatekey.pem: < base64 encoded private key >
    

Rotating certificate via Azure CLI

Use the following command by providing Kubernetes secret that you created previously to rotate the certificate:

az sql mi-arc update -n <managed instance name> --k8s-namespace <arc> --use-k8s --service-cert-secret <your-cert-secret>

For example:

az sql mi-arc update -n mysqlmi --k8s-namespace <arc> --use-k8s --service-cert-secret mymi-cert-secret

Use the following command to rotate the certificate with the PEM formatted certificate public and private keys. The command generates a default service certificate name.

az sql mi-arc update -n <managed instance name> --k8s-namespace arc --use-k8s --cert-public-key-file <path-to-my-cert-public-key> --cert-private-key-file <path-to-my-cert-private-key> --k8s-namespace <your-k8s-namespace>

For example:

az sql mi-arc update -n mysqlmi --k8s-namespace arc --use-k8s --cert-public-key-file ./mi1-1-cert --cert-private-key-file ./mi1-1-pvt

You can also provide a Kubernetes service cert secret name for --service-cert-secret parameter. In this case, it's taken as an updated secret name. The command checks if the secret exists. If not, the command creates a secret name and then rotates the secret in the managed instance.

az sql mi-arc update -n <managed instance name> --k8s-namespace <arc> --use-k8s --cert-public-key-file <path-to-my-cert-public-key> --cert-private-key-file <path-to-my-cert-private-key> --service-cert-secret <path-to-mymi-cert-secret>

For example:

az sql mi-arc update -n mysqlmi --k8s-namespace arc --use-k8s --cert-public-key-file ./mi1-1-cert --cert-private-key-file ./mi1-1-pvt --service-cert-secret mi1-12-1-cert-secret

Rotate the certificate with kubectl command

Once you created the Kubernetes secret, you can bind it to the SQL Managed Instance yaml definition security section where serviceCertificateSecret located as follows:

  security:
    adminLoginSecret: <your-admin-login-secret>
    serviceCertificateSecret: <your-cert-secret>

The following .yaml file is an example to rotate the service certificate in SQL instance named mysqlmi, update the spec with a Kubernetes secret named my-service-cert:

apiVersion: sql.arcdata.microsoft.com/v1
kind: sqlmanagedinstance
metadata:
  name: mysqlmi
  namespace: my-arc-namespace
spec:
spec:
  dev: false
  licenseType: LicenseIncluded
  replicas: 1
  security:
    adminLoginSecret: mysqlmi-admin-login-secret
    # Update the serviceCertificateSecret with name of the K8s secret
    serviceCertificateSecret: my-service-cert
  services:
    primary:
      type: NodePort
  storage:
    data:
      volumes:
      - size: 5Gi
    logs:
      volumes:
      - size: 5Gi
  tier: GeneralPurpose

You can use the following kubectl command to apply this setting:

   kubectl apply -f <my-sql-mi-yaml-file>

Next steps