cql-proxy

Table of Contents

• What is the cql-proxy?
• When to use cql-proxy
• Configuration
• Getting started
  • Locally build and run
  • Run a cql-proxy docker image
  • Use Kubernetes
• Known issues
  • Token-aware load balancing

What is cql-proxy?

cql-proxy is designed to forward your application's CQL traffic to an appropriate database service. It listens on a local address and securely forwards that traffic.

When to use cql-proxy

The cql-proxy sidecar enables unsupported CQL drivers to work with DataStax Astra. These drivers include both legacy DataStax drivers and community-maintained CQL drivers, such as the gocql driver and the rust-driver.

cql-proxy also enables applications that are currently using Apache Cassandra or DataStax Enterprise (DSE) to use Astra without requiring any code changes. Your application just needs to be configured to use the proxy.

If you're building a new application using DataStax drivers, cql-proxy is not required, as the drivers can communicate directly with Astra. DataStax drivers have excellent support for Astra out-of-the-box, and are well-documented in the driver-guide guide.

Configuration

Use the -h or --help flag to display a listing all flags and their corresponding descriptions and environment variables (shown below as items starting with $):

$ ./cql-proxy -h
Usage: cql-proxy

Flags:
  -h, --help                                              Show context-sensitive help.
  -b, --astra-bundle=STRING                               Path to secure connect bundle for an Astra database. Requires '--username' and '--password'. Ignored if using the
                                                          token or contact points option ($ASTRA_BUNDLE).
  -t, --astra-token=STRING                                Token used to authenticate to an Astra database. Requires '--astra-database-id'. Ignored if using the bundle path
                                                          or contact points option ($ASTRA_TOKEN).
  -i, --astra-database-id=STRING                          Database ID of the Astra database. Requires '--astra-token' ($ASTRA_DATABASE_ID)
      --astra-api-url="https://api.astra.datastax.com"    URL for the Astra API ($ASTRA_API_URL)
  -c, --contact-points=CONTACT-POINTS,...                 Contact points for cluster. Ignored if using the bundle path or token option ($CONTACT_POINTS).
  -u, --username=STRING                                   Username to use for authentication ($USERNAME)
  -p, --password=STRING                                   Password to use for authentication ($PASSWORD)
  -r, --port=9042                                         Default port to use when connecting to cluster ($PORT)
  -n, --protocol-version="v4"                             Initial protocol version to use when connecting to the backend cluster (default: v4, options: v3, v4, v5, DSEv1,
                                                          DSEv2) ($PROTOCOL_VERSION)
  -m, --max-protocol-version="v4"                         Max protocol version supported by the backend cluster (default: v4, options: v3, v4, v5, DSEv1, DSEv2)
                                                          ($MAX_PROTOCOL_VERSION)
  -a, --bind=":9042"                                      Address to use to bind server ($BIND)
  -f, --config=CONFIG                                     YAML configuration file ($CONFIG_FILE)
      --debug                                             Show debug logging ($DEBUG)
      --health-check                                      Enable liveness and readiness checks ($HEALTH_CHECK)
      --http-bind=":8000"                                 Address to use to bind HTTP server used for health checks ($HTTP_BIND)
      --heartbeat-interval=30s                            Interval between performing heartbeats to the cluster ($HEARTBEAT_INTERVAL)
      --idle-timeout=60s                                  Duration between successful heartbeats before a connection to the cluster is considered unresponsive and closed
                                                          ($IDLE_TIMEOUT)
      --readiness-timeout=30s                             Duration the proxy is unable to connect to the backend cluster before it is considered not ready
                                                          ($READINESS_TIMEOUT)
      --idempotent-graph                                  If true it will treat all graph queries as idempotent by default and retry them automatically. It may be
                                                          dangerous to retry some graph queries -- use with caution ($IDEMPOTENT_GRAPH).
      --num-conns=1                                       Number of connection to create to each node of the backend cluster ($NUM_CONNS)
      --proxy-cert-file=STRING                            Path to a PEM encoded certificate file with its intermediate certificate chain. This is used to encrypt traffic
                                                          for proxy clients ($PROXY_CERT_FILE)
      --proxy-key-file=STRING                             Path to a PEM encoded private key file. This is used to encrypt traffic for proxy clients ($PROXY_KEY_FILE)
      --rpc-address=STRING                                Address to advertise in the 'system.local' table for 'rpc_address'. It must be set if configuring peer proxies
                                                          ($RPC_ADDRESS)
      --data-center=STRING                                Data center to use in system tables ($DATA_CENTER)
      --tokens=TOKENS,...                                 Tokens to use in the system tables. It's not recommended ($TOKENS)

To pass configuration to cql-proxy, either command-line flags, environment variables, or a configuration file can be used. Using the docker method as an example, the following samples show how the token and database ID are defined with each method.

Using flags

docker run -p 9042:9042 \
  --rm datastax/cql-proxy:v0.1.3 \
  --astra-token <astra-token> --astra-database-id <astra-datbase-id>

Using environment variables

docker run -p 9042:9042  \
  --rm datastax/cql-proxy:v0.1.3 \
  -e ASTRA_TOKEN=<astra-token> -e ASTRA_DATABASE_ID=<astra-datbase-id>

Using a configuration file

Proxy settings can also be passed using a configuration file with the --config /path/to/proxy.yaml flag. This can be mixed and matched with command-line flags and environment variables. Here are some example configuration files:

contact-points:
  - 127.0.0.1
username: cassandra
password: cassandra
port: 9042
bind: 127.0.0.1:9042
# ...

or with a Astra token:

astra-token: <astra-token>
astra-database-id: <astra-database-id>
bind: 127.0.0.1:9042
# ...

All configuration keys match their command-line flag counterpart, e.g. --astra-bundle is astra-bundle:, --contact-points is contact-points: etc.

Setting up peer proxies

Multi-region failover with DC-aware load balancing policy is the most useful case for a multiple proxy setup.

When configuring peers: it is required to set --rpc-address (or rpc-address: in the yaml) for each proxy and it must match is corresponding peers: entry. Also, peers: is only available in the configuration file and cannot be set using a command-line flag.

Multi-region setup

Here's an example of configuring multi-region failover with two proxies. A proxy is started for each region of the cluster connecting to it using that region's bundle. They all share a common configuration file that contains the full list of proxies.

Note: Only bundles are supported for multi-region setups.

cql-proxy --astra-bundle astra-region1-bundle.zip --username token --password <astra-token> \
  --bind 127.0.0.1:9042 --rpc-address 127.0.0.1 --data-center dc-1 --config proxy.yaml

cql-proxy ---astra-bundle astra-region2-bundle.zip --username token --password <astra-token> \
  --bind 127.0.0.2:9042 --rpc-address 127.0.0.2 --data-center dc-2 --config proxy.yaml

The peers settings are configured using a yaml file. It's a good idea to explicitly provide the --data-center flag, otherwise; these values are pulled from the backend cluster and would need to be pulled from the system.local and system.peers table to properly setup the peers data-center: values. Here's an example proxy.yaml:

peers:
  - rpc-address: 127.0.0.1
    data-center: dc-1
  - rpc-address: 127.0.0.2
    data-center: dc-2

Note: It's okay for the peers: to contain entries for the current proxy itself because they'll just be omitted.

Getting started

There are three methods for using cql-proxy:

• Locally build and run cql-proxy
• Run a docker image that has cql-proxy installed
• Use a Kubernetes container to run cql-proxy

Locally build and run

1. Build cql-proxy.

   go build

2. Run with your desired database.

   • DataStax Astra cluster:

     ./cql-proxy --astra-token <astra-token> --astra-database-id <astra-database-id>

     The <astra-token> can be generated using these instructions. The proxy also supports using the Astra Secure Connect Bundle along with a client ID and secret generated using these instructions:

     ./cql-proxy --astra-bundle <your-secure-connect-zip> \
     --username <astra-client-id> --password <astra-client-secret>
     

   • Apache Cassandra cluster:

     ./cql-proxy --contact-points <cluster node IPs or DNS names> [--username <username>] [--password <password>]

Run a cql-proxy docker image

1. Run with your desired database.

   • DataStax Astra cluster:

     docker run -p 9042:9042 \
       datastax/cql-proxy:v0.1.3 \
       --astra-token <astra-token> --astra-database-id <astra-database-id>

     The <astra-token> can be generated using these instructions. The proxy also supports using the Astra Secure Connect Bundle, but it requires mounting the bundle to a volume in the container:

     docker run -v <your-secure-connect-bundle.zip>:/tmp/scb.zip -p 9042:9042 \
     --rm datastax/cql-proxy:v0.1.3 \
     --astra-bundle /tmp/scb.zip --username <astra-client-id> --password <astra-client-secret>

   • Apache Cassandra cluster:

     docker run -p 9042:9042 \
       datastax/cql-proxy:v0.1.3 \
       --contact-points <cluster node IPs or DNS names> [--username <username>] [--password <password>]

If you wish to have the docker image removed after you are done with it, add --rm before the image name datastax/cql-proxy:v0.1.3.

Use Kubernetes

Using Kubernetes with cql-proxy requires a number of steps:

1. Generate a token following the Astra instructions. This step will display your Client ID, Client Secret, and Token; make sure you download the information for the next steps. Store the secure bundle in /tmp/scb.zip to match the example below.

2. Create cql-proxy.yaml. You'll need to add three sets of information: arguments, volume mounts, and volumes.

• Argument: Modify the local bundle location, username and password, using the client ID and client secret obtained in the last step to the container argument.

  command: ["./cql-proxy"]
  args: ["--astra-bundle=/tmp/scb.zip","--username=Client ID","--password=Client Secret"]
  

• Volume mounts: Modify /tmp/ as a volume mount as required.

  volumeMounts:
    - name: my-cm-vol
    mountPath: /tmp/
  

• Volume: Modify the configMap filename as required. In this example, it is named cql-proxy-configmap. Use the same name for the volumes that you used for the volumeMounts.

  volumes:
    - name: my-cm-vol
      configMap:
        name: cql-proxy-configmap        
  

3. Create a configmap. Use the same secure bundle that was specified in the cql-proxy.yaml.

   kubectl create configmap cql-proxy-configmap --from-file /tmp/scb.zip 

4. Check the configmap that was created.

   kubectl describe configmap config
     
     Name:         config
     Namespace:    default
     Labels:       <none>
     Annotations:  <none>
   
     Data
     ====
   
     BinaryData
     ====
     scb.zip: 12311 bytes

5. Create a Kubernetes deployment with the YAML file you created:

   kubectl create -f cql-proxy.yaml

6. Check the logs:

   kubectl logs <deployment-name>

Known issues

Token-aware load balancing

Drivers that use token-aware load balancing may print a warning or may not work when using cql-proxy. Because cql-proxy abstracts the backend cluster as a single endpoint this doesn't always work well with token-aware drivers that expect there to be at least "replication factor" number of nodes in the cluster. Many drivers print a warning (which can be ignored) and fallback to something like round-robin, but other drivers might fail with an error. For the drivers that fail with an error it is required that they disable token-aware or configure the round-robin load balancing policy.