serverless/lib/plugins/aws/info/get-resource-count.js

import BbPromise from 'bluebird'

export default {
  async getResourceCount(nextToken, resourceCount = 0) {
    const params = {
      StackName: this.provider.naming.getStackName(),
      NextToken: nextToken,
    }
    return this.provider
      .request('CloudFormation', 'listStackResources', params)
      .then((result) => {
        if (Object.keys(result).length) {
          this.gatheredData.info.resourceCount =
            resourceCount + result.StackResourceSummaries.length
          if (result.NextToken) {
            return this.getResourceCount(
              result.NextToken,
              this.gatheredData.info.resourceCount,
            )
          }
        }
        return BbPromise.resolve()
      })
  },
}