serverless-config-transformer

A simple package for transforming the Serverless config at build time. This was used for a gulpfile initially, but should be applicable otherwise. The original idea was to allow local development plugins to be different from those used for the production deployment.

How to use

This file is a reduced example based on a production gulpfile.

import { dest, series, src, task } from "gulp";
import ts from "gulp-typescript";
import merge from "merge2";
import {
  Serverless,
  ServerlessConfigTransformer,
} from "@0xc/serverless-config-transformer";
/* eslint-disable @typescript-eslint/no-var-requires */
const del = require("del");
const serverlessGulp = require("serverless-gulp");

const currentFolder = ".";
const backupFolder = ".backup";
const slsFile = "serverless.yml";

const slsFilePath = `${currentFolder}/${slsFile}`;
const backupSlsFilePath = `${backupFolder}/${slsFile}`;
const overwrite = { overwrite: true };

const serverlessConfigTransformer = new ServerlessConfigTransformer({
  converter: config => {
    config.plugins = ["serverless-webpack"];
    config.provider.package.include = ["dist/**"];
    config.custom = { webpack: config.custom!.webpack };
    config.functions = Object.keys(config.functions).reduce(
      (functions, key) => ({
        ...functions,
        [key]: {
          ...config.functions[key],
          handler: config.functions[key].handler.replace(/^src\//, "dist/"),
        },
      }),
      {} as Serverless.Functions,
    );

    return config;
  },
});

function backupConfig() {
  return src(slsFilePath).pipe(dest(backupFolder));
}

function updateConfig() {
  return src(slsFilePath, { read: true }).pipe(serverlessConfigTransformer);
}

function restoreConfig() {
  return src(backupSlsFilePath).pipe(dest(currentFolder, overwrite));
}

const tsProject = ts.createProject("tsconfig.build.json");
const outDir = "dist";

function compile(includeSourceMaps = false) {
  return () => {
    const srcs = tsProject.src().pipe(tsProject());

    if (includeSourceMaps) {
      return merge(srcs.js.pipe(dest(outDir)), srcs.dts.pipe(dest(outDir)));
    }

    return srcs.js.pipe(dest(outDir));
  };
}

function clean() {
  return del([outDir]);
}

task("clean", clean);
task("build", series("clean", compile(false)));

task("config:backup", backupConfig);
task("config:update", updateConfig);
task("config:restore", restoreConfig);

task("predeploy", series("config:backup", "config:update", "build"));
task("postdeploy", series("config:restore"));

This package only handles transformation of the Serverless config, which is a literal file transformation. You should backup and restore the original config yourself. Or at the very least, don't commit the changes made.