Hi, Been trying to wrap my head around how DNS is used in Clearwater with multiple instances. This is purely for purposes of understanding the concept. I have not looked at the chef installation and operation procedures, but I assume the concept will be the same?
Here is what I understand so far and please correct me if I am missing something here: 1. Each server will have it's own clearwater/config configuration referencing the server function as a FQDN, e.g. sprout.tld, homer.tld, etc. This will be the exact same config across all servers and instances of servers except for the TLD, private and public IP. 2. The reason DNS is used is because multiple answers will be returned for each server type and "/etc/hosts" cannot be used to load balance responses. 3. Each server instance will have it's own public and private EC2 IP when created. 4. The private IP address changes each time the server is restarted, but the public IP remains across restarts. 5. Each server instance public or private IP has to be in a central DNS server. 6. Each time a new server is added or removed, the DNS entries have to be updated. Cache will be an issue here. >From this it seems that there is a lot of adding and removing of servers from >the central DNS and that cache would become an issue? As an alternative I have >seem some ideas around assigning Elastic IPs to instances and keeping the >elastic IPs in the DNS entries. This way there is no caching issue when >assigning the same elastic IP to to a new instance that has failed. So some of my questions are: 1. Can the clearwater config file not somehow be simplified and the private and public IP be gleamed from the instance itself? Simple ifconfig and hostname would return all three values. 2. If the private IP address changes each time an instance is restarted, this requires reconfiguration of the config file and the DNS entry? Will caching be an issue? 3. What is best to use for DNS? Route 53 or a separate DNS server? Route 53 does not seem to support private IP DNS entries (can be publicly accessed) and requires a public TLD. 4. Can /etc/hosts be used for simple single instance demo systems instead of DNS? Lots of questions I know, but important to understand ;-) Thanks Des Hartman
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