deployasync.js

// Given a stack object of microservices to deploy,
// implement a deploy function that takes this object
// with a provided variable syntax, and runs the
// referenced microservice functions in order
// according to microservice dependencies.

const sleep = async (wait) => new Promise((resolve) => setTimeout(() => resolve(), wait))

const supportedServices = {
  database: async (inputs) => {
    console.log(`deploying database "${inputs.name}"`)

    await sleep(2000)

    return {
      url: 'https://database.com/url'
    }
  },
  backend: async (inputs) => {
    console.log(
      `deploying backend "${inputs.name}" and connecting with database "${inputs.databaseUrl.url}"`
    )

    await sleep(3000)

    return {
      url: 'https://backend.com/url'
    }
  },
  frontend: async (inputs) => {
    console.log(
      `deploying frontend "${inputs.name}" and connecting with backend "${inputs.backendUrl.url}"`
    )

    await sleep(3000)

    return {
      url: 'https://frontend.com/url'
    }
  }
}

const hash = {};

const deploy = (stack) => {


  const fillIn = (item) => {
    Object.keys(item).forEach((key) => {
      const val = item[key];
      let result = val.match(/\${(\w+)\.\w+}/)
      if (result !== null) {
        const service = result[1];
        item[key] = hash[service];
      }
    })
  }

  Object.keys(stack).forEach((key) => {
    const item = stack[key];
    const dependencies = []
    Object.keys(item).forEach((key) => {
      const val = item[key];
      let result = val.match(/\${(\w+)\.\w+}/)
      if (result !== null) {
        const service = result[1];
        dependencies.push(service);
      }
    })
    hash[key] = dependencies.reduce((p, c) => {
      return p.then(() => hash[c])

    }, Promise.resolve(0))
    .then(() => {
      fillIn(item);
      return supportedServices[key](item)
    })
    .then((val) => {
      hash[key] = val;
      return val
    })
  })
  return Promise.all(Object.keys(hash).map((key) => hash[key]))
}

deploy({
  database: {
    name: 'users'
  },
  backend: {
    name: 'users',
    databaseUrl: '${database.url}'
  },
  frontend: {
    name: 'users',
    backendUrl: '${backend.url}'
  }
})
.then(() => {
  console.log("All done!!")
  console.log("Final hash:", hash);
})

/*
output

deploying database "users"
deploying backend "users" and connecting with database "https://database.com/url"
deploying frontend "users" and connecting with backend "https://backend.com/url"
All done!!
Final hash: { database: { url: 'https://database.com/url' },
  backend: { url: 'https://backend.com/url' },
  frontend: { url: 'https://frontend.com/url' } }

*/