Local logging

By default, SDKs write info, warn, and error logs to the console.

To send logs elsewhere—for example, to your observability or monitoring system—define a custom logging callback using the logsHandler option when calling createSource.

The logsHandler callback receives all log output as well as analytics events, split exposures, and flag evaluations, so you can forward them to your own data warehouse or analytics system. For example, you can define a callback to forward all analytics events and split exposures to Segment.

Server

src/lib/getHypertune.ts

import { createSource } from "../generated/hypertune";

const hypertuneSource = createSource({
  token: process.env.HYPERTUNE_TOKEN!,
  logsHandler: (logs) => {
    logs.messageList.forEach(({ level, message, metadata }) => {
      if ([LogLevel.Warn, LogLevel.Error].includes(level)) {
        console.log(`[Hypertune] [${level}] ${message}`, metadata);
      }
    });
    logs.eventList.forEach((event) => {
      console.log("[Hypertune] [Event]", event);
    });
    logs.exposureList.forEach((exposure) => {
      console.log("[Hypertune] [Exposure]", exposure);
    });
    logs.evaluationList.forEach((evaluation) => {
      console.log("[Hypertune] [Evaluation]", evaluation);
    });
  },
});

export default async function getHypertune() {
  // Get flag updates in serverless environments
  // await hypertuneSource.initIfNeeded();

  return hypertuneSource.root({
    args: {
      context: {
        environment:
          process.env.NODE_ENV === "development"
            ? "development"
            : "production",
        user: { id: "1", name: "Test", email: "[email protected]" },
      },
    },
  });
}

Browser

src/components/AppHypertuneProvider.tsx

import { HypertuneProvider } from "../generated/hypertune.react";

export default function AppHypertuneProvider({
  children,
}: {
  children: React.ReactNode;
}) {
  return (
    <HypertuneProvider
      createSourceOptions={{
        token: import.meta.env.VITE_HYPERTUNE_TOKEN!,
        logsHandler: (logs) => {
          logs.messageList.forEach(({ level, message, metadata }) => {
            if ([LogLevel.Warn, LogLevel.Error].includes(level)) {
              console.log(`[Hypertune] [${level}] ${message}`, metadata);
            }
          });
          logs.eventList.forEach((event) => {
            console.log("[Hypertune] [Event]", event);
          });
          logs.exposureList.forEach((exposure) => {
            console.log("[Hypertune] [Exposure]", exposure);
          });
          logs.evaluationList.forEach((evaluation) => {
            console.log("[Hypertune] [Evaluation]", evaluation);
          });
        },
      }}
      rootArgs={{
        context: {
          environment:
            process.env.NODE_ENV === "development"
              ? "development"
              : "production",
          user: { id: "1", name: "Test", email: "[email protected]" },
        },
      }}
    >
      {children}
    </HypertuneProvider>
  );
}

---

logsHandler?: (logs: Logs) => void;

type Logs {
  messageList: Message[];
  eventList?: Event[];
  exposureList?: Exposure[];
  evaluationList?: Evaluation[];
}

export type Message = {
  level: LogLevel;
  message: string;
  metadata: object;
}

export type Event = {
  objectTypeName: string;
  payload: ObjectValue;
};

export type Exposure = {
  splitId: string;
  unitId: string;
  event: Event | null;
  assignment: SplitAssignment;
};

export type Evaluation = {
  path: string;
  value: Value;
  args: { [path: string]: ObjectValue };
  isFallback: boolean;
};

enum LogLevel {
  Debug = 'Debug',
  Error = 'Error',
  Info = 'Info',
  Warn = 'Warn'
}