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google-app-engineamazon-ec2appscale

Outage protection: How to control if requests are routed to ec2 or appengine app instance

I have an application running on Google AppEngine. To minimise the risk of outages I would like to have 2 copies of the application running, one on Google Cloud and the other on EC2 (via appscale). Clearly if I have 2 applications running they will need access to the same data, meaning that I should write each transaction and change to S3 and datastore. If there is an outage I'll need to figure out how to ensure the database that was down catches up.

My question is: how can I route http requests such that if both services are up, they are sent to appengine but if appengine is down, the request is routed to EC2?

Solution

  • In order to route requests, you can

    • set your rules via Amazon's Route 53 DNS service, or
    • use a load balancing tool/service as mentioned above.

    For data replication, you can use Remote API from GAE to AppScale to make sure your data is consistent on both sites.

    You can also reach out to the AppScale community mailing list if you need help with this.