async function updateLambdaCode()

in src/cfn-custom-resources/lambda-code-update/index.ts [16:71]

• 52 lines of code
• 2 McCabe index (conditional complexity)

async function updateLambdaCode(
  action: "Create" | "Update" | "Delete",
  lambdaFunction: string,
  stringifiedConfig: string,
  physicalResourceId?: string
) {
  if (action === "Delete") {
    // Deletes aren't executed; the Lambda Resource should just be deleted
    return { physicalResourceId: physicalResourceId!, Data: {} };
  }
  console.log(
    `Adding configuration to Lambda function ${lambdaFunction}:\n${stringifiedConfig}`
  );
  const region = lambdaFunction.split(":")[3];
  const lambdaClient = new Lambda({ region });
  // Parse the JSON to ensure it's validity (and avoid ugly errors at runtime)
  const config = JSON.parse(stringifiedConfig);
  // Fetch and extract Lambda zip contents to temporary folder, add configuration.json, and rezip
  const { Code } = await lambdaClient
    .getFunction({
      FunctionName: lambdaFunction,
    })
    .promise();
  const data = await fetch(Code!.Location!);
  const lambdaZip = new Zip(data);
  console.log(
    "Lambda zip contents:",
    lambdaZip.getEntries().map((entry) => entry.name)
  );
  console.log("Adding (fresh) configuration.json ...");
  const tempDir = mkdtempSync("/tmp/lambda-package");
  lambdaZip.extractAllTo(tempDir, true);
  writeFileSync(
    resolve(tempDir, "configuration.json"),
    Buffer.from(JSON.stringify(config, null, 2))
  );
  const newLambdaZip = new Zip();
  newLambdaZip.addLocalFolder(tempDir);
  console.log(
    "New Lambda zip contents:",
    newLambdaZip.getEntries().map((entry) => entry.name)
  );

  const { CodeSha256, Version, FunctionArn } = await lambdaClient
    .updateFunctionCode({
      FunctionName: lambdaFunction,
      ZipFile: newLambdaZip.toBuffer(),
      Publish: true,
    })
    .promise();
  console.log({ CodeSha256, Version, FunctionArn });
  return {
    physicalResourceId: lambdaFunction,
    Data: { CodeSha256, Version, FunctionArn },
  };
}