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Sauce Connect Proxy Tunnel Pool Setup

Tunnel Pool enables you to run parallel tests through multiple Sauce Connect Proxy tunnels, improving test reliability and scalability. It is ideal for high-concurrency environments, allowing for automatic load balancing and increased fault tolerance.

Benefits of Tunnel Pools

  • Load balancing: Jobs are evenly distributed across available tunnels.
  • Failover: If a tunnel fails, new tests will be rerouted through another active tunnel.
  • Rolling restarts: You can restart individual tunnels without interrupting ongoing tests.

Limitations

  • If a Sauce Connect client on your side or a tunnel VM on Sauce Labs' side goes down during a test, the test may fail.
  • Tunnel pools are not self-healing or automatically restarted. If a tunnel stops, you'll need to restart it manually. This can be automated using a service manager like systemd.

Prerequisites​

Before setting up a tunnel pool, ensure your environment is compatible with Sauce Connect Proxy by following the Quickstart guide.

Consider your needs:

Concurrency

Each tunnel in a pool counts toward your tunnel concurrency limit.

Architecture​

The following diagram illustrates the basic architecture of a Sauce Connect Proxy setup using a tunnel pool:

Basic setup using tunnel pool

Flow:

  • A test framework requests a new Sauce Test VM, referencing a tunnel name.
  • Sauce Labs selects an available tunnel from the pool.
  • The chosen tunnel is used for proxying traffic between Sauce Test VM and your site under test.

Setup Instructions​

Launching Tunnels for a Tunnel Pool​

You must start multiple tunnels with the same [tunnel-name] and the --tunnel-pool flag. Each tunnel should be started from a separate VM for maximum fault tolerance.

sc run --username $SAUCE_USERNAME --access-key $SAUCE_ACCESS_KEY \
  --tunnel-name tunnel_name_here \
  --tunnel-pool

Avoiding Colliding Tunnels​

Without --tunnel-pool, launching multiple tunnels with the same --tunnel-name will cause older instances to shut down. Always use the --tunnel-pool flag to allow multiple tunnels with the same name to coexist as a pool.

Running Tests using Tunnel Pool​

In your test script, specify the tunnel pool name using the tunnelName capability:

"tunnelName": "tunnel_pool_name_here"

Tips for Production Use​

Load Balancing and Failover​

Tunnel pools use a round-robin algorithm to distribute test traffic evenly. If a tunnel fails, traffic is routed to another in the pool. For optimal resilience run Sauce Connect Proxy on separate machines.

Monitoring and Maintenance​

Summary​

Tunnel pools increase test capacity, reliability, and performance by enabling multiple tunnels to operate under the same name. With proper configuration and monitoring, tunnel pools provide a powerful solution for high-concurrency test environments.