[GitHub] ningyougang commented on issue #4225: Change prewarm container

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ningyougang commented on issue #4225: Change prewarm container
URL: https://github.com/apache/incubator-openwhisk/pull/4225#issuecomment-456245349
 
 
   @markusthoemmes @rabbah 
   ### Background
   I think openwhisk needs some operation tools(page or API) to admin, for example:
   * real-time status of Action, Controller, Invoker, etc.
   * Change prewarm runtime container for invokers
   
   here, we just discuss `Change prewarm container for invokers`
   
   ### Requirements
   
   * Admin can add/delete extra prewarm container via controller.
     The flow may like this, admin sends a HTTP request to the controller, controller sends that request info to all invokers through kafka,
     invoker gets the request info, parse the prewarm runtime info, and do `add/delete prewarm container`
     
     Note, the prewarm runtime request info's image should be included in `${OPENWHISK_HOME}/ansible/files/runtimes.json` ,
     if `unknow prewarm runtime image` is sent to invoker, invoker should reject the request.
   
   
   * Need to support `different prewarm runtime` for different invokers?
   In future, invokers may support `group concept`, which means, some invokers's cpu, memory is very good, these invokers can execute some height works.
   but some invokers may execute some light works.
   In this situation, we may consider `heterogeneous invoker cluster support`, so invokers needs to support  `different prewarm runtime` also.
   So admin can send the http request to invoker to add/delete prewarm container.
   
   ### Question?
   ```
    Manipulating a single invoker in this case results in a divergence to the global configuration. If that invoker restarts, what happens?
   ```
   If invoker restarts,  the invoker will read the global runtime.json to create prewarm container( the extra adding prewarm container will be gone, because the invoker can't remember its previous state)
     

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