Reuse existing identical certificates

[gmintoco]

Is your feature request related to a problem? Please describe.

With multiple ingresses using the same hostname and in different namespaces (this is because each ingress is managed by another team along with their site)

Cert Manager will request a certificate for every ingress - quickly eating the rate limits up

Describe the solution you'd like

Cert Manager could just reuse identical certificates. IE if a 'Certificate' is created which will result in an identical cert (from another 'Certificate' then it should just use the current one and not create a Certificate Request/Order/Challenge

Describe alternatives you've considered

• Use a wildcard and default certificate on ingress controller - This is not ideal because it only works for one domain
• Use something like kubed to sync certs between namespaces - This is not ideal because it requires certificates to be premade (you can't sync certs that are created by the cert manager annotation on certificates)

Additional context

Environment details (remove if not applicable):

• Kubernetes version: 1.17
• cert-manager version: 1.4
• Install method: static

/kind feature

[jetstack-bot]

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[jetstack-bot]

@jetstack-bot: Closing this issue.

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