start-sdk/lib/health/util.ts

import { Effects } from "../types";
import { isKnownError } from "../util";
import { HealthResult } from "./healthRunner";

/**
 * This is a helper function to check if a web url is reachable.
 * @param url
 * @param createSuccess
 * @returns
 */
export const checkWebUrl: (
  url: string,
  createSuccess?: null | ((response?: string | null) => string)
) => (effects: Effects, duration: number) => Promise<HealthResult> = (
  url,
  createSuccess = null
) => {
  return async (effects, duration) => {
    const errorValue = guardDurationAboveMinimum({
      duration,
      minimumTime: 5000,
    });
    if (!!errorValue) {
      return errorValue;
    }

    return await effects
      .fetch(url)
      .then((x) => ({
        success: createSuccess?.(x.body) ?? `Successfully fetched URL: ${url}`,
      }))
      .catch((e) => {
        effects.warn(`Error while fetching URL: ${url}`);
        effects.error(JSON.stringify(e));
        effects.error(e.toString());
        return { failure: `Error while fetching URL: ${url}` };
      });
  };
};

/**
 * Running a health script, is used when we want to have a simple
 * script in bash or something like that. It should return something that is useful
 * in {result: string} else it is considered an error
 * @param param0
 * @returns
 */
export const runHealthScript =
  ({
    command,
    args,
    message,
  }: {
    command: string;
    args: string[];
    message: ((result: unknown) => string) | null;
  }) =>
  async (effects: Effects, _duration: number): Promise<HealthResult> => {
    const res = await effects.runCommand({ command, args });
    return {
      success:
        message?.(res) ?? `Have ran script ${command} and the result: ${res}`,
    };
  };

// Ensure the starting duration is pass a minimum
export const guardDurationAboveMinimum = (input: {
  duration: number;
  minimumTime: number;
}): null | HealthResult =>
  input.duration <= input.minimumTime ? { starting: null } : null;

export const catchError = (effects: Effects) => (e: unknown) => {
  if (isKnownError(e)) return e;
  effects.error(`Health check failed: ${e}`);
  return { failure: "Error while running health check" };
};