[GitHub] xingzhou commented on issue #77: Nginx can not forward the following requests to controller once the major controller is restarted.

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xingzhou commented on issue #77: Nginx can not forward the following requests to controller once the major controller is restarted.
URL: https://github.com/apache/incubator-openwhisk-deploy-kube/issues/77#issuecomment-344488691
 
 
   Took some investigation on how Nginx resolve domain name, and found out that Nginx will cache the resolved IP until next time restart or reload configurations.
   
   Here is a [blog](https://www.nadeau.tv/nginx-proxy_pass-dns-cache/) discussing this issue. 
   
   So for now, we have some solutions to try:
   1. For `proxy_pass` config, we can try to use a var instead of a url, but this only works for single url, not the groups in upstream directive. In our case, we are using multiple controllers for HA, so this is not a good choice for us.
   
   2. Use Nginx PLUS, which is a non-free commercial edition of Nginx.
   
   3. There is a free Nginx module [here](https://github.com/GUI/nginx-upstream-dynamic-servers), can resolve the dynamic DNS name resolve issue. But since it's not official modules, the license and compatibility can be problems.
   
   4. Periodically reload(not restart) the Nginx, this may force Nginx to re-resolve DNS names.
   
   For now, I'm thinking only #4 might be an option for us, @daisy-ycguo, @DanLavine and @dgrove-oss , your comments?

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