Example configuration file

config.ts

const stages = ['production', 'staging', 'development', 'test'] as const;

type Stage = typeof stages[number];

function getStage(stages: Stage[]) {
  if (!stages.length) return 'production';

  for (const stage of stages) {
    // if any of the provided stages is production, assume we are in production
    if (stage === 'production') {
      return stage;
    }
  }

  return stages[0];
}

function notEmpty<TValue>(value: TValue | null | undefined): value is TValue {
  return value !== null && value !== undefined;
}

function isStage(potentialStage: string): potentialStage is Stage {
  return stages.includes(potentialStage as Stage);
}

const stage = getStage(
  [process.env.NODE_ENV, process.env.APP_ENV].filter(notEmpty).filter(isStage)
);

function envToBool(value: string | undefined) {
  if (!value) {
    return false;
  }

  return ['true', 'TRUE', '1'].includes(value);
}

function envToStr(value: string | undefined, defaultValue = '') {
  return value === undefined ? defaultValue : value;
}

function envToNumber(value: string | undefined, defaultValue: number): number {
  const numValue = value === undefined || value === "" ? defaultValue : Number(value);
  
  return isNaN(numValue) ? defaultValue : numValue;
}

const configSchema = z.object({
  stage: z.enum(stages),
  ci: z.object({
    isPullRequest: z.boolean(),
  }),
  api: {
    tokenLifetimeMs: z.number().min(1),
  },
  database: {
    url: z.string().min(1),
    shouldMigrate: z.boolean(),
  },
  sentry: {
    enabled: z.boolean(),
    dsn: z.string().optional(),
  },
  git: {
    commit: z.string().optional(),
  },
});

export const config = configSchema.parse({
  stage,
  ci: {
    isPullRequest: envToBool(process.env.IS_PULL_REQUEST),
  },
  api: {
    tokenLifetimeMs: envToNumber(process.env.API_TOKEN_LIFETIME_MS, 3600000), // 3600000ms = 1h
  },
  database: {
    url: envToStr(process.env.DATABASE_URL),
    shouldMigrate: envToBool(process.env.SHOULD_MIGRATE),
  },
  sentry: {
    enabled: envToBool(process.env.SENTRY_ENABLED),
    dsn: envToStr(process.env.NEXT_PUBLIC_SENTRY_DSN),
  },
  git: {
    commit: envToStr(process.env.FC_GIT_COMMIT_SHA || process.env.RENDER_GIT_COMMIT),
  },
});