feat(ovh): add cache based on DNS zone SOA value

[rbeuque74]

trafficstars

Hello external-dns maintainers, OVHcloud API team here :wave:

Description This pull-request patches the 'ovh' provider to add a small local cache of the fetched DNS records.

Context: we detected that numerous of our customers use your external-dns software to manage their DNS records, sending waves of API queries to our APIs. As these records are retrieved one by one, it generates a high amount of requests on our backend.

As we would like to keep allowing our customers using external-dns with the best experience, we leveraged the usage of the DNS zone SOA Serial to detect if the zone records might have changed since the last time we generated the cache. This way, we spare all the calls to retrieve the records that have been kept in cache, and serve them directly, since the SOA Serial haven't changed, guaranteeing that the DNS zone hasn't changed on our side.

This will also add a speed-up once the cache is warm, as long as the zone doesn't change.

This should also prevent users of external-dns from being targeted by potential rate-limiting in case of high activity on our backend.

Thanks in advance for your review. Romain

Checklist

• [x] Unit tests updated
• [x] End user documentation updated

[linux-foundation-easycla[bot]]

The committers listed above are authorized under a signed CLA.

• :white_check_mark: login: rbeuque74 / name: Romain Beuque (1a48cb8e165232ee16a465afb5bc51d26d64b549)

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[k8s-ci-robot]

Welcome @rbeuque74!

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[rbeuque74]

Hello, Kind reminder about this pull-request. Feel free to tell me if you want me to do some modification !

Best, Romain

[rbeuque74]

/auto-cc /cc @szuecs

[scraly]

Hi, any news aboutt his PR? :) Thanks

[rbeuque74]

/assign @njuettner /assign @szuecs

[rbeuque74]

/assign @seanmalloy

[szuecs]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rbeuque74, szuecs

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• ~~OWNERS~~ [szuecs]

Approvers can indicate their approval by writing /approve in a comment Approvers can cancel approval by writing /approve cancel in a comment

[szuecs]

/assign @njuettner

[szuecs]

I don't have the button to run the tests, so assigned @njuettner

[Raffo]

@rbeuque74 can you rebase so that I can let the test run and review the PR? Thanks!

[rbeuque74]

Hello @Raffo, PR is rebased !

Thanks Romain

[rbeuque74]

@rbeuque74: PR needs rebase.

and rebased :D

[rbeuque74]

Hello, Any news regarding this PR ?

Thanks, Romain

[k8s-triage-robot]

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/lifecycle stale

[rbeuque74]

Hello,

PR is rebased. Thanks, Romain

/remove-lifecycle stale

[szuecs]

/ok-to-test

[szuecs]

Please rebase

[rbeuque74]

Hello, pull-request is now rebased, thanks for approving the test run :)

/assign @szuecs

Romain

[johngmyers]

/lgtm

[johngmyers]

/test pull-external-dns-lint /test pull-external-dns-unit-test

[johngmyers]

/retest