feat(source): add min-ttl support

[ivankatliarchuk]

What does it do ?

• Found an elegant way to modify TTL with source wrapper
• Added documentation

Motivation

Fixes #1829

More

• Yes, this PR title follows Conventional Commits
• Yes, I added unit tests
• Yes, I updated end user documentation accordingly

Tested on real cluster

Manifest

---
apiVersion: v1
kind: Namespace
metadata:
  name: extdns
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-v1
  namespace: extdns
  annotations:
    dns.company.com/label: controllertest-v1
    external-dns.alpha.kubernetes.io/internal-hostname: nginx-v1.local.tld
spec:
  type: ClusterIP
  ports:
    - port: 80
      name: http
      targetPort: 80
  selector:
    app: nginx
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-v2
  namespace: extdns
  annotations:
    dns.company.com/label: controllertest-v2
    dns.issue/type: issue-5634
    external-dns.alpha.kubernetes.io/ttl: "1m"
    external-dns.alpha.kubernetes.io/internal-hostname: nginx-v2i.local.tld
spec:
  type: ClusterIP
  ports:
    - port: 80
      name: http
      targetPort: 80
  selector:
    app: nginx
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-v3
  namespace: extdns
  annotations:
    dns.company.com/label: controllertest-v2
    dns.issue/type: issue-5634
    # external-dns.alpha.kubernetes.io/ttl: "180"
    external-dns.alpha.kubernetes.io/internal-hostname: nginx-v3.local.tld
spec:
  type: ClusterIP
  ports:
    - port: 80
      name: http
      targetPort: 80
  selector:
    app: nginx
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  namespace: extdns
spec:
  replicas: 2
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
        - image: nginx
          name: nginx
          ports:
            - containerPort: 80
              name: http
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-v4
  namespace: extdns
  annotations:
    dns.company.com/label: controllertest-v2
    dns.issue/type: issue-5634
    # external-dns.alpha.kubernetes.io/ttl: "180"
    external-dns.alpha.kubernetes.io/internal-hostname: nginx-v4.local.tld
spec:
  type: ClusterIP
  ports:
    - port: 80
      name: http
      targetPort: 80
  selector:
    app: nginx

arguments

go run main.go \
    --provider=aws \
    --registry=txt \
    --source=service \
    --log-level=debug \
    --zone-name-filter=local.tld

results (sets to provider deafult)

arguments

go run main.go \
    --provider=aws \
    --registry=txt \
    --source=service \
    --log-level=debug \
    --zone-name-filter=local.tld \
    --min-ttl=1m15s

results

[ivankatliarchuk]

Hi @jhemtjpr I'd appreciate it if you could review this and assess where the solution makes sense. If you familiar with Go, you could give it a try as well how to test a PR ?. This will require golang to be installed.

[jhemtjpr]

Hi @jhemtjpr I'd appreciate it if you could review this and assess where the solution makes sense. If you familiar with Go, you could give it a try as well how to test a PR ?. This will require golang to be installed.

I am not well versed into running or testing Go applications, but the detailed explanation and the code is clear and easy to read.

minTTL: [...] This value will be used if the TTL for a source is not set.

This definitely covers the use case I need, allowing the annotation to take precedence over minTTL. That's perfect.

Thank you for the effort!

[mloiseleur]

/lgtm
/assign @szuecs for final review

[ivankatliarchuk]

i'll put on hold to prevent accidental merge

/hold

[ivankatliarchuk]

To only merge after #5687

[ivankatliarchuk]

/hold cancel

[mloiseleur]

@ivankatliarchuk LGTM. Just left a last suggestion on CLI help message, to make it more aligned with documentation.

[mloiseleur]

/lgtm

[ivankatliarchuk]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ivankatliarchuk

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[ivankatliarchuk]

/test pull-external-dns-unit-test