title: serverless warm up plugin concurrent execution of warmup functions
body: <p>I got the serverless-plugin-warmup 4.2.0-rc.1 working fine with serverless version 1.36.2</p>
  
  <p>But it only executes with one single warmup call instead of the configured five.</p>
  
  <p>Is there any problem in my serverless.yml config?</p>
  
  <p>It is also strange that I have to add 'warmup: true' to the function section to get the function warmed up. According to the docs on <a href="https://github.com/FidelLimited/serverless-plugin-warmup" rel="nofollow noreferrer">https://github.com/FidelLimited/serverless-plugin-warmup</a> the config at custom section should be enough.</p>
  
  <pre><code>plugins:
    - serverless-prune-plugin
    - serverless-plugin-warmup
  custom:
    warmup:
      enabled: true
      concurrency: 5
      prewarm: true
      schedule: rate(2 minutes)
      source: { "type": "keepLambdaWarm" }
      timeout: 60
  
  functions:
    myFunction:
      name: ${self:service}-${opt:stage}-${opt:version}
      handler: myHandler
      environment:
        FUNCTION_NAME: myFunction
      warmup: true
  </code></pre>
  
  <p>in AWS Cloud Watch I only see one execution every 2 minutes. I would expect to see 5 executions every 2 minutes, or do I misunderstand something here?</p>
  
  <p><strong>EDIT:</strong>
  Now using the master branch concurrency works but now the context that is deliverd to the function which should be warmed is broken: Using Spring Cloud Functions => "Error parsing Client Context as JSON"</p>
  
  <p>Looking at the JS of the generated warmup function the delivered source looks not ok =></p>
  
  <pre><code>const functions = [{"name":"myFunction","config":{"enabled":true,"source":"\"\\\"{\\\\\\\"source\\\\\\\":\\\\\\\"serverless-plugin-warmup\\\\\\\"}\\\"\"","concurrency":3}}];
  </code></pre>
  
  <p>Config is:</p>
  
  <pre><code>custom:
    warmup:
      enabled: true
      concurrency: 3
      prewarm: true
      schedule: rate(5 minutes)
      timeout: 60
  </code></pre>