How to enable LDAP authentication in Azure Managed Instance for Apache Cassandra

Azure Managed Instance for Apache Cassandra provides automated deployment and scaling operations for managed open-source Apache Cassandra data centers. This article discusses how to enable LDAP authentication to your clusters and data centers.

Prerequisites

• If you don't have an Azure subscription, create a free account before you begin.
• An Azure Managed Instance for Apache Cassandra cluster. Review how to create an Azure Managed Instance for Apache Cassandra cluster from the Azure portal.

Deploy an LDAP Server in Azure

In this section, we'll walk through creating a simple LDAP server on a Virtual Machine in Azure. If you already have an LDAP server running, you can skip this section and review how to enable LDAP authentication.

1. Deploy a Virtual Machine in Azure using Ubuntu Server 18.04 LTS. You can follow instructions here.

2. Give your server a DNS name:

   

3. Install Docker on the virtual machine. We recommend this tutorial.

4. In the home directory, copy and paste the following text and hit enter. This command will create a file containing a test LDAP user account.

   mkdir ldap-user && cd ldap-user && cat >> user.ldif <<EOL
   dn: uid=admin,dc=example,dc=org
   uid: admin
   cn: admin
   sn: 3
   objectClass: top
   objectClass: posixAccount
   objectClass: inetOrgPerson
   loginShell: /bin/bash
   homeDirectory: /home/admin
   uidNumber: 14583102
   gidNumber: 14564100
   userPassword: admin
   mail: admin@example.com
   gecos: admin
   EOL 
   

5. Navigate back up to home directory

   cd ..
   

6. Run the below command, replacing <dnsname> with the dns name you created for your LDAP server earlier. This command will deploy an LDAP server with TLS enabled to a Docker container, and will also copy the user file you created earlier to the container.

   sudo docker run --hostname <dnsname>.uksouth.cloudapp.azure.com --name <dnsname> -v $(pwd)/ldap-user:/container/service/slapd/assets/test --detach osixia/openldap:1.5.0
   

7. Now copy out the certificates folder from the container (replace <dnsname> with the dns name you created for your LDAP server):

   sudo docker cp <dnsname>:/container/service/slapd/assets/certs certs
   

8. Verify that dns name is correct:

   openssl x509 -in certs/ldap.crt -text
   

   

9. Copy the ldap.crt file to clouddrive in Azure CLI for use later.

10. Add the user to the ldap (replace <dnsname> with the dns name you created for your LDAP server):

    sudo docker container exec <dnsname> ldapadd -H ldap://<dnsname>.uksouth.cloudapp.azure.com -D "cn=admin,dc=example,dc=org" -w admin -f /container/service/slapd/assets/test/user.ldif
    

Enable LDAP authentication

1. Currently, LDAP authentication is a public preview feature. Run the below command to add the required Azure CLI extension:

   az extension add --upgrade --name cosmosdb-preview
   

2. Set authentication method to "Ldap" on the cluster, replacing <resource group> and <cluster name> with the appropriate values:

   az managed-cassandra cluster update -g <resource group> -c <cluster name> --authentication-method "Ldap"
   

3. Now set properties at the data center level. Replace <resource group> and <cluster name> with the appropriate values, and <dnsname> with the dns name you created for your LDAP server.

   Note

   The below command is based on the LDAP setup in the earlier section. If you skipped that section because you already have an existing LDAP server, provide the corresponding values for that server instead. Ensure you have uploaded a certificate file like ldap.crt to your clouddrive in Azure CLI.

   ldap_search_base_distinguished_name='dc=example,dc=org'
   ldap_server_certificates='/usr/csuser/clouddrive/ldap.crt'
   ldap_server_hostname='<dnsname>.uksouth.cloudapp.azure.com'
   ldap_service_user_distinguished_name='cn=admin,dc=example,dc=org'
   ldap_service_user_password='admin'
   
   az managed-cassandra datacenter update -g `<resource group>` -c `<cluster name>` -d datacenter-1 --ldap-search-base-dn $ldap_search_base_distinguished_name --ldap-server-certs $ldap_server_certificates --ldap-server-hostname $ldap_server_hostname --ldap-service-user-dn $ldap_service_user_distinguished_name --ldap-svc-user-pwd $ldap_service_user_password
   

4. Once this command has completed, you should be able to use CQLSH (see below) or any Apache Cassandra open-source client driver to connect to your managed instance data center with the user added in the above step:

   export SSL_VALIDATE=false
   cqlsh --debug --ssl <data-node-ip> -u <user> -p <password>
   

Next steps

• LDAP authentication with Microsoft Entra ID
• Manage Azure Managed Instance for Apache Cassandra resources using Azure CLI
• Deploy a Managed Apache Spark Cluster with Azure Databricks