Client Resolution

The Judge0 Python SDK supports two main client flavors: Community Edition (CE) and Extra Community Edition (Extra CE), which correspond to the Judge0 Cloud editions. When you use functions like judge0.run or judge0.execute without explicitly providing a client instance, the SDK automatically resolves and initializes a client for you. This process, handled by the internal _get_implicit_client function, follows a specific order of priority.

The SDK determines which client to use based on environment variables. Here’s the resolution order:

  1. Custom Client (Self-Hosted)

The SDK first checks for a self-hosted Judge0 instance. If you have your own deployment of Judge0, you can configure the SDK to use it by setting the following environment variables:

  • For CE flavor:

    • JUDGE0_CE_ENDPOINT: The URL of your self-hosted Judge0 CE instance.

    • JUDGE0_CE_AUTH_HEADERS: A JSON string representing the authentication headers.

  • For Extra CE flavor:

    • JUDGE0_EXTRA_CE_ENDPOINT: The URL of your self-hosted Judge0 Extra CE instance.

    • JUDGE0_EXTRA_CE_AUTH_HEADERS: A JSON string representing the authentication headers.

If these variables are set, the SDK will initialize a Client instance with your custom endpoint and headers.

  1. Hub Clients

If a custom client is not configured, the SDK will try to find API keys for one of the supported hub clients. The SDK checks for the following environment variables in order:

  • Judge0 Cloud:

    • JUDGE0_CLOUD_CE_AUTH_HEADERS for Judge0CloudCE

    • JUDGE0_CLOUD_EXTRA_CE_AUTH_HEADERS for Judge0CloudExtraCE

  • RapidAPI:

    • JUDGE0_RAPID_API_KEY for both RapidJudge0CE and RapidJudge0ExtraCE

  • AllThingsDev:

    • JUDGE0_ATD_API_KEY for both ATDJudge0CE and ATDJudge0ExtraCE

The first API key found determines the client that will be used.

  1. Preview Client

If none of the above environment variables are set, the SDK falls back to using a preview client. This is an unauthenticated client that connects to the official Judge0 Cloud service. It initializes Judge0CloudCE() and Judge0CloudExtraCE() for the CE and Extra CE flavors, respectively.

When the preview client is used, a warning message is logged to the console, as this option is not recommended for production use. To suppress this warning, you can set the JUDGE0_SUPPRESS_PREVIEW_WARNING environment variable.

Example Resolution Flow

When you call a function like judge0.run(..., flavor=judge0.CE), the SDK will:

  1. Check if JUDGE0_IMPLICIT_CE_CLIENT is already initialized. If so, use it.

  2. Check for JUDGE0_CE_ENDPOINT and JUDGE0_CE_AUTH_HEADERS to configure a Client.

  3. Check for JUDGE0_CLOUD_CE_AUTH_HEADERS to configure a Judge0CloudCE client.

  4. Check for JUDGE0_RAPID_API_KEY to configure a RapidJudge0CE client.

  5. Check for JUDGE0_ATD_API_KEY to configure an ATDJudge0CE client.

  6. If none of the above are found, initialize a preview Judge0CloudCE client and log a warning.

This implicit client resolution makes it easy to get started with the Judge0 Python SDK while providing the flexibility to configure it for different environments and services.