Lambda PowertoolsのParameters utilityで独自Providerを実装してGoogle Cloudからシークレット値を取得してみた

import { BaseProvider } from "@aws-lambda-powertools/parameters/base";
import { SecretManagerServiceClient } from "@google-cloud/secret-manager";
import type * as gax from "google-gax";
import type { ClientOptions } from "google-gax";

class GcloudSecretManagerServiceClient extends SecretManagerServiceClient {
  // SecretManagerServiceClientをそのまま使うと
  // `Failed to add user agent middleware Error: The client provided does not match the expected interface`
  // のwarnログが出力される
  // warnログ抑制のため期待されるinterfaceのダミー実装を組み込む

  public middlewareStack: object;
  public config: object;

  constructor(
    opts?: ClientOptions,
    gaxInstance?: typeof gax | typeof gax.fallback,
  ) {
    super(opts, gaxInstance);
    this.config = {};
    this.middlewareStack = {
      identify: () => [],
      addRelativeTo: () => {},
    };
  }

  send(): void {}
}

export class GcloudSecretManagerProvider extends BaseProvider {
  public declare client: GcloudSecretManagerServiceClient;

public constructor() {
    super({
      proto:
        GcloudSecretManagerServiceClient as new () => GcloudSecretManagerServiceClient,
    });
  }

  protected async _get(name: string): Promise<string> {
    const [res] = await this.client.accessSecretVersion({ name });

    return res.payload?.data?.toString() ?? "";
  }

  protected async _getMultiple(
    _path: string,
    _options?: unknown,
  ): Promise<Record<string, unknown> | undefined> {
    throw new Error("Method not implemented.");
  }
}

class GcloudSecretManagerServiceClient extends SecretManagerServiceClient {
  // SecretManagerServiceClientをそのまま使うと
  // `Failed to add user agent middleware Error: The client provided does not match the expected interface`
  // のwarnログが出力される
  // warnログ抑制のため期待されるinterfaceのダミー実装を組み込む

  public middlewareStack: object;
  public config: object;

  constructor(
    opts?: ClientOptions,
    gaxInstance?: typeof gax | typeof gax.fallback,
  ) {
    super(opts, gaxInstance);
    this.config = {};
    this.middlewareStack = {
      identify: () => [],
      addRelativeTo: () => {},
    };
  }

  send(): void {}
}

export class GcloudSecretManagerProvider extends BaseProvider {
  public declare client: GcloudSecretManagerServiceClient;

public constructor() {
    super({
      proto:
        GcloudSecretManagerServiceClient as new () => GcloudSecretManagerServiceClient,
    });
  }

  public async get(name: string): Promise<Record<string, unknown> | undefined> {
    return super.get(name) as Promise<Record<string, unknown> | undefined>;
  }

  public async getMultiple(path: string, _options?: unknown): Promise<void> {
    await super.getMultiple(path);
  }

  protected async _get(name: string): Promise<string> {
    const [res] = await this.client.accessSecretVersion({ name });

    return res.payload?.data?.toString() ?? "";
  }

  protected async _getMultiple(
    _path: string,
    _options?: unknown,
  ): Promise<Record<string, unknown> | undefined> {
    throw new Error("Method not implemented.");
  }
}

import { GcloudSecretManagerProvider } from "./gcloud-secret-manager-provider";

const main = async () => {
  const secretName =
    "projects/<プロジェクトNo>/secrets/<シークレット名>/versions/latest";

  const secretsProvider = new GcloudSecretManagerProvider();

  const secret = await secretsProvider.get(secretName);
  console.log(`secret: ${secret}`);
};

main();

$npx ts-node index.ts
secret: <Google Cloudから取得したシークレット値>