Oracle DNS: ExternalDNS may hit API Rate limit

[anders-swanson]

What happened:

When using Oracle provider, ExternalDNS may hit the OCI DNS rate limit, especially if multiple clusters in the same tenancy are using ExternalDNS, or if you manage a large amount of records.

When the rate limit is consistently hit, users experience a delay in DNS propagation.

What you expected to happen:

ExternalDNS works seamlessly without errors creating/listing records.

How to reproduce it (as minimally and precisely as possible):

1. Install ExternalDNS using the oracle provider on multiple clusters (5+).
2. Create several records (10+) on each cluster using ExternalDNS.
3. See rate limiting errors and delays in DNS propagation.

Anything else we need to know?:

Some providers, e.g., AWs, implement DNS zone caching. A similar implementation in the Oracle provider will help with rate limiting by reducing the amount of outbound calls.

Environment:

• External-DNS version (use external-dns --version): v0.13.1
• DNS provider: oracle
• Others:

[anders-swanson]

I am happy to work on this issue.