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fix: new ca-filter causing expontentially more api-calls #3608

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Merged
merged 1 commit into from
Mar 13, 2024
+11 −11
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fix: new ca-filter causing expontentially more api-calls #3608

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22 changes: 11 additions & 11 deletions pkg/ingress/cert_discovery.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@ package ingress

import (
"context"
"slices"
"strings"
"sync"
"time"
Expand All @@ -16,6 +15,7 @@ import (
"github.com/pkg/errors"
"k8s.io/apimachinery/pkg/util/cache"
"k8s.io/apimachinery/pkg/util/sets"
"k8s.io/utils/strings/slices"
"sigs.k8s.io/aws-load-balancer-controller/pkg/aws/services"
)

Expand Down Expand Up @@ -153,18 +153,18 @@ func (d *acmCertDiscovery) loadDomainsForCertificate(ctx context.Context, certAR
certDetail := resp.Certificate

// check if cert is issued from an allowed CA
// otherwise empty-out the list of domains
domains := sets.String{}
if len(d.allowedCAARNs) == 0 || slices.Contains(d.allowedCAARNs, awssdk.StringValue(certDetail.CertificateAuthorityArn)) {
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just for my understanding, the originally PR didn't introduce any regression right?
And you faced this issue due to you used the new "allowedCAARNs" feature?
If so, this fix looks good to me. However, i'd like to change this code to be like

domains := sets.NewString(aws.StringValueSlice(certDetail.SubjectAlternativeNames)...)
switch aws.StringValue(certDetail.Type) {
case acm.CertificateTypeImported:
	d.certDomainsCache.Set(certARN, domains, d.importedCertDomainsCacheTTL)
case acm.CertificateTypeAmazonIssued, acm.CertificateTypePrivate:
	d.certDomainsCache.Set(certARN, domains, d.privateCertDomainsCacheTTL)
}
if len(d.allowedCAARNs) == 0 || slices.Contains(d.allowedCAARNs, awssdk.StringValue(certDetail.CertificateAuthorityArn)) {
   return domains, nil
}
return sets.String{}, nil

technically there is no functional difference since allowedCAARNs is a controller-level flag which is immutable given the controller's lifetime. However, from coding perspective, the cache shall be for the "domains" before the "CA filter logic" and this make the code more robust(e.g. works even allowedCAARNs can be dynamically updated somehow).

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Our PR introduce this behavior only if both conditions are met:

  1. use the --allowed-certificate-authority-arns=... parameter
  2. there exists certificates inside AWS ACM which are not issued from a authority in the allowed list.

I/we can test your proposal tomorrow in our staging environment. But I assume that your proposed code change does not work properly as we then also cache the domain(s) of a certificate which is not issued from an allowed CA.

And the function first tries to load the domains from the cache before it reaches this filtering code block:

func (d *acmCertDiscovery) loadDomainsForCertificate(ctx context.Context, certARN string) (sets.String, error) {
	if rawCacheItem, ok := d.certDomainsCache.Get(certARN); ok {
		return rawCacheItem.(sets.String), nil
	}
	// only continues in case we didn't find it inside the cache

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@mkilchhofer
You are right, the cache shall be the domains after the filter.
ideally we should refactor the code such that the cache stores certificate details from AWS. (but for now it only caches domains and your filter logic is on cert CA), thus filter logic has to be run before the cache.

I'll approve this, and maybe refactor this in the future if we ever need to make the ca list mutable.

domains := sets.NewString(aws.StringValueSlice(certDetail.SubjectAlternativeNames)...)
switch aws.StringValue(certDetail.Type) {
case acm.CertificateTypeImported:
d.certDomainsCache.Set(certARN, domains, d.importedCertDomainsCacheTTL)
case acm.CertificateTypeAmazonIssued, acm.CertificateTypePrivate:
d.certDomainsCache.Set(certARN, domains, d.privateCertDomainsCacheTTL)
}
return domains, nil
domains = sets.NewString(aws.StringValueSlice(certDetail.SubjectAlternativeNames)...)
}
return sets.String{}, nil

switch aws.StringValue(certDetail.Type) {
case acm.CertificateTypeImported:
d.certDomainsCache.Set(certARN, domains, d.importedCertDomainsCacheTTL)
case acm.CertificateTypeAmazonIssued, acm.CertificateTypePrivate:
d.certDomainsCache.Set(certARN, domains, d.privateCertDomainsCacheTTL)
}
return domains, nil
}
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@mkilchhofer mkilchhofer Mar 11, 2024 •
edited
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Real resp. resulting diff for this feature (#3565) can be viewed here:
v2.7.1...the-technat:aws-load-balancer-controller:main

Or on this screenshot:

image


func (d *acmCertDiscovery) domainMatchesHost(domainName string, tlsHost string) bool {
Expand Down