Evaluation Proxy

The Evaluation Proxy is a Service to enable, enhance, and optimize local evaluation running within your infrastructure.

Enable local evaluation on unsupported platforms:
Use remote Evaluation APIs and SDKs to run local evaluation in your infrastructure.

Automatically track assignment events for local evaluations:
Identical assignment events are deduplicated for 24 hours.

Enhance local evaluation with large cohort targeting:
Targeted cohorts are synced hourly to the Evaluation Proxy and added to the user prior to evaluation.

Configuration¶

The evaluation proxy is either configured via a YAML file (recommended, more configuration options), or using environment variables.

The default location for the configuration YAML file is /etc/evaluation-proxy-config.yaml. You may also configure the file location using the PROXY_CONFIG_FILE_PATH environment variable.

The configuration YAML file base is an object with two primary sub objects:

• projects (required)
• configuration (optional).

projects:
  - id: "YOUR PROJECT ID"
    apiKey: "YOUR API KEY"
    secretKey: " YOUR SECRET KEY"
    deploymentKeys:
      - "YOUR DEPLOYMENT KEY 1"
      - "YOUR DEPLOYMENT KEY 2"

configuration:
  redis:
    uri: "YOUR REDIS URI" # e.g. "redis://localhost:6379"

projects¶

A required array of objects with the following fields, all which are required.

configuration¶

An optional object of extra configuration.

configuration:
  # Other configurations...
  serverUrl: "https://api.lab.eu.amplitude.com"
  cohortServerUrl: "https://cohort.lab.eu.amplitude.com"

redis¶

Configure the evaluation proxy to use Redis as a persistent storage. Highly recommended to enable the evaluation proxy to run efficiently.

Deployment¶

The evaluation proxy is stateless, and should be deployed with multiple instances behind a load balancer for high availability and scalability. For example, a kubernetes deployment with greater than one replica.

Kubernetes¶

Use the evaluation proxy Helm chart to install the proxy service on kubernetes or generate the files needed to deploy the service manually. The repository also contains an example of running the evaluation proxy on kubernetes locally using minikube.

Add helm repo¶

helm repo add \
    evaluation-proxy-helm https://amplitude.github.io/evaluation-proxy-helm

Configure values.yaml¶

Configure the chart values. The recommended approach to configuring and installing the helm chart is using a values.yaml configuration file.

The chart's evaluationProxy value contents exactly match the evaluation proxy's configuration file fields.

evaluationProxy:
  # At least one project is required.
  projects:
    - id: "TODO"
      apiKey: "TODO"
      secretKey: "TODO"
      deploymentKeys:
        - "TODO"
  configuration: {}
#    redis:
#      uri: "redis://redis-master.default.svc.cluster.local:6379"

Install helm chart¶

helm install -f values.yaml \
    evaluation-proxy evaluation-proxy-helm/evaluation-proxy

Docker¶

You may run the docker image directly. First, create a configuration file, then run the docker image mounting the file as a volume to the expected directory in the container.

docker run \
    -v CONFIG_FILE_PATH:/etc/evaluation-proxy-config.yaml \
    amplitudeinc/evaluation-proxy

Evaluation¶

The Evaluation Proxy exposes remote Evaluation API and SDK endpoints to run local evaluation within your cluster. This is useful to enable platforms and languages which aren't supported by local evaluation SDKs. As an added benefit, fetch requests made to the evaluation proxy can target cohorts of users, and have assignment events tracked automatically to Amplitude.

Requests must be sent to the service using http on port 3546.

SDK proxy mode¶

Certain local evaluation SDKs are configurable to run in proxy mode. In proxy mode, flag configurations, full cohorts, and cohort memberships are synced from the evaluation proxy rather than from Amplitude directly. This reduces SDK startup time and provides redundancy for flags and cohorts for local evaluation SDKs running within your infrastructure.