[Diaoul]

Closes #174.

Important

This brings a breaking change in dns resolution as we'll now resolve <service>.<namespace>.svc.<cluster-domain>. and not <service>.<namespace>.svc which will break if cluster-domain config is unset and different from default cluster.local.
👉 Let me know if this is OK or if you'd rather have the previous behavior preserved when cluster-domain config is unset.

Problem

Service.URL emitted <service>.<namespace>.svc, which is not a resolvable name on its own. It only ever worked because the pod's search list appended the cluster domain, so resolution landed on the third attempt.

Under ndots:1 — which the chart now exposes via dnsConfig (#169) so operators can avoid exactly that search-list walk — the absolute form is tried first, and .svc is not a delegated TLD, so every check sends an NXDOMAIN query to the root servers before falling back to the search list.

Change

Emit <service>.<namespace>.svc.<cluster-domain>. with a trailing dot, so the name is absolute regardless of the pod's ndots. Without the trailing dot this would only be half-fixed: …svc.cluster.local is 4 dots, still under the default ndots:5, so the search walk would continue (harmlessly, inside the cluster).

The cluster domain is configurable in Kubernetes, so this adds --cluster-domain (default cluster.local) rather than hardcoding a suffix.

URL now takes *config.Config, mirroring the existing Matches(obj, cfg) and Prefix(cfg) on the same interface. The three HTTP-based kinds ignore it via _.

Scope and safety

Only Service endpoints change. They are dialled by gatus as strings.TrimPrefix(e.URL, "tcp://") straight into CanCreateNetworkConnection, so there is no Host header or SNI that a trailing dot could disturb. Ingress/HTTPRoute/IngressRoute URLs are untouched.

Tests

TestService_URL gains cases for a custom cluster domain, an empty domain falling back to the default, and a configured domain that already carries a trailing dot not being doubled. --cluster-domain is covered in both TestLoad_Defaults and TestLoad_AllFlags. README's resource table and flag table updated.

go vet ./... and go test -race $(go list ./...) pass on Go 1.26.6, the version pinned in .mise/config.toml.

I could not get golangci-lint to run locally: my distro's Go is a patched build (go1.26.6-X:nodwarf5) and mise's vanilla 1.26.6 refuses to typecheck against it, producing compile: version "go1.26.6" does not match go tool version errors in files this PR does not touch. Leaving that to CI.

[greptile-apps]

Greptile Summary

This PR fully qualifies generated Kubernetes Service hostnames using a configurable cluster domain, avoiding DNS search-list resolution.

• Adds --cluster-domain with a cluster.local default.
• Passes runtime configuration into resource URL generation.
• Emits absolute Service hostnames with a trailing dot.
• Updates unit tests, end-to-end expectations, and documentation.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
internal/config/config.go	Adds the cluster-domain configuration field, default, and CLI flag.
internal/k8s/resource.go	Extends the Resource URL contract to receive runtime configuration.
internal/k8s/controller.go	Passes controller configuration into resource URL generation.
internal/resources/service.go	Generates absolute Service endpoint hostnames using the configured cluster domain.
internal/resources/service_test.go	Covers default, custom, empty, and trailing-dot cluster-domain behavior.
test/e2e/e2e_test.go	Updates end-to-end Service endpoint expectations to fully qualified hostnames.

_{Reviews (2): Last reviewed commit: "fix(resources): update remaining referen..." | Re-trigger Greptile}

[greptile-apps]

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[onedr0p]

Accepting the break as proposed. Preserving the old relative-name behavior when the flag is unset would keep the bug as the default forever, and cluster.local matches virtually every cluster; anyone on a custom domain sets --cluster-domain once. With bump-minor-pre-major this lands as a 0.x minor.

I pushed two small commits on top: the chart now exposes sidecar.clusterDomain (rendered only when non-empty, like the other structured flags), and the domain normalization trims before falling back so --cluster-domain=. can't produce svc... Thanks for the thorough writeup and the packet capture — merging once CI is green.