dashboard and status API list a port's domains apart from its hostnames (closes #245)

A port entry in the state saves the apex domains that resolve to its
address with its hostnames. The dashboard's Ports table now has a
Domains column next to Hostnames, and a port entry in /api/v1/status
has a `domains` list, with `hostnames` no longer holding a domain. A
name is taken as a domain when it has a domain entry, as the dashboard
and API already tell a domain's own records from a hostname's. Both
read the split from one function, buildPorts. The state file is
unchanged; README says its port `hostnames` include domains.

Model: opus-5-5

README.md

@@ -239,7 +239,8 @@ dnswatcher includes an unauthenticated, read-only web dashboard at the root URL
   per nameserver and status, shown as a hostname's are.
 - **Hostnames** with per-nameserver DNS records and status. For a nameserver
   whose query failed, the reason is shown in place of the records.
-- **Ports** with open/closed state and associated hostnames.
+- **Ports** with open/closed state and the domains and hostnames that resolve to
+  each address, in separate columns.
 - **TLS certificates** with CN, issuer, expiry, and status. For a failed check,
   the reason is shown in place of CN, issuer and expiry.
 - **Recent alerts** (last 100 notifications sent since the process started),
@@ -272,7 +273,9 @@ In `/api/v1/status`, each nameserver entry and certificate entry whose `status`
 is `error` also has `error`, the reason, as in the state file (see State File
 Format). A domain's own records are in its entry in `domains`, under
 `recordsByNameserver`, in the form a hostname's entry in `hostnames` has them
-under `nameservers`; `hostnames` and `counts.hostnames` hold no domain.
+under `nameservers`; `hostnames` and `counts.hostnames` hold no domain. A port
+entry lists the domains that resolve to its address in `domains`, and the
+hostnames in `hostnames`.
 
 `/metrics` is served only when `DNSWATCHER_METRICS_USERNAME` is set, behind
 Basic Auth. It has the Prometheus Go client's default metrics only (Go runtime,
@@ -561,8 +564,9 @@ previous check's list is kept, or `null` when no earlier check saved one. A
 state file without it loads, and the first check after that saves it without a
 notification.
 
-A port entry in the older format, with one `hostname` instead of the `hostnames`
-list, loads as a list of that one name.
+A port entry's `hostnames` lists every name that resolves to its address,
+domains included. A port entry in the older format, with one `hostname` instead
+of the `hostnames` list, loads as a list of that one name.
 
 ---
 

TODO.md

@@ -19,6 +19,8 @@ trial run of the finished image: https://git.eeqj.de/sneak/dnswatcher/issues/149
 
 # Completed Steps
 
+- 2026-10-02: the dashboard's Ports table and `/api/v1/status` port entries list
+  a port's domains apart from its hostnames (closes #245).
 - 2026-10-02: nameservers a referral names without addresses are looked up,
   three deep at most; `pool.ntp.org`'s nameservers resolve (closes #221).
 - 2026-10-02: an apex domain is not counted or listed as a hostname; its records

internal/handlers/dashboard.go

@@ -45,11 +45,14 @@ func newDashboardTemplate() *template.Template {
 
 // dashboardData is the data passed to the dashboard template. Hostnames
 // and DomainRecords split the records in Snapshot.Hostnames, which also
-// holds the apex domains' own (see splitHostnames).
+// holds the apex domains' own (see splitHostnames). Ports holds
+// Snapshot.Ports with each port's names split into domains and
+// hostnames, as /api/v1/status gives them (see buildPorts).
 type dashboardData struct {
 	Snapshot      state.Snapshot
 	Hostnames     map[string]*state.HostnameState
 	DomainRecords map[string]*state.HostnameState
+	Ports         map[string]*statusPortInfo
 	Alerts        []notify.AlertEntry
 	StateAge      string
 	GeneratedAt   string
@@ -71,6 +74,7 @@ func (h *Handlers) HandleDashboard() http.HandlerFunc {
 			Snapshot:      snap,
 			Hostnames:     hostnames,
 			DomainRecords: domainRecords,
+			Ports:         buildPorts(snap),
 			Alerts:        alerts,
 			StateAge:      relTime(snap.LastUpdated),
 			GeneratedAt:   time.Now().UTC().Format("2006-01-02 15:04:05"),

internal/handlers/dashboard_test.go

@@ -205,3 +205,51 @@ func TestDashboardShowsDomainRecordsUnderDomains(t *testing.T) {
 		t.Errorf("summary bar does not say %q", summary)
 	}
 }
+
+// rowCells returns the text of each cell of a dashboard table row
+// whose cells start with tag, "<th" or "<td".
+func rowCells(row string, tag string) []string {
+	tags := regexp.MustCompile(`<[^>]*>`)
+	parts := strings.Split(row, tag)[1:]
+	cells := make([]string, 0, len(parts))
+
+	for _, cell := range parts {
+		text := tags.ReplaceAllString(tag+cell, " ")
+		cells = append(cells, strings.Join(strings.Fields(text), " "))
+	}
+
+	return cells
+}
+
+// TestDashboardPortsTellDomainsFromHostnames checks that the Ports
+// table lists an apex domain under Domains and a hostname under
+// Hostnames when both resolve to the port's address.
+func TestDashboardPortsTellDomainsFromHostnames(t *testing.T) {
+	t.Parallel()
+
+	page := get(t, newHandlersWithFailures(t).HandleDashboard())
+	ports := dashboardSection(t, page, "Ports")
+
+	headings := rowCells(dashboardRow(t, ports, "Address</th>"), "<th")
+	cells := rowCells(dashboardRow(t, ports, sharedPort), "<td")
+
+	if len(cells) != len(headings) {
+		t.Fatalf("row of %s has cells %q under headings %q",
+			sharedPort, cells, headings)
+	}
+
+	under := make(map[string]string)
+	for i, heading := range headings {
+		under[heading] = cells[i]
+	}
+
+	if under["Domains"] != testDomain {
+		t.Errorf("row of %s lists %q under Domains, want %q",
+			sharedPort, under["Domains"], testDomain)
+	}
+
+	if under["Hostnames"] != testHostname {
+		t.Errorf("row of %s lists %q under Hostnames, want %q",
+			sharedPort, under["Hostnames"], testHostname)
+	}
+}

internal/handlers/status.go

@@ -32,8 +32,11 @@ type statusHostnameInfo struct {
 }
 
 // statusPortInfo holds status information for a monitored port.
+// Domains and Hostnames list the apex domains and the hostnames that
+// resolve to its address.
 type statusPortInfo struct {
 	Open        bool      `json:"open"`
+	Domains     []string  `json:"domains"`
 	Hostnames   []string  `json:"hostnames"`
 	LastChecked time.Time `json:"lastChecked"`
 }
@@ -99,7 +102,6 @@ func buildStatusResponse(
 		LastUpdated:  snap.LastUpdated,
 		Domains:      make(map[string]*statusDomainInfo),
 		Hostnames:    make(map[string]*statusHostnameInfo),
-		Ports:        make(map[string]*statusPortInfo),
 		Certificates: make(map[string]*statusCertificateInfo),
 	}
 
@@ -107,7 +109,7 @@ func buildStatusResponse(
 
 	buildDomains(snap, domainRecords, resp)
 	buildHostnames(hostnames, resp)
-	buildPorts(snap, resp)
+	resp.Ports = buildPorts(snap)
 	buildCertificates(snap, resp)
 	buildCounts(resp)
 
@@ -195,21 +197,36 @@ func nameserverInfo(
 	return info
 }
 
-func buildPorts(
-	snap state.Snapshot,
-	resp *statusResponse,
-) {
+// buildPorts returns the port entries saved in snap. A port entry
+// saves apex domains with its hostnames; they are told apart as in
+// splitHostnames, by a domain entry in snap.Domains.
+func buildPorts(snap state.Snapshot) map[string]*statusPortInfo {
+	ports := make(map[string]*statusPortInfo, len(snap.Ports))
+
 	for key, ps := range snap.Ports {
-		hostnames := make([]string, len(ps.Hostnames))
-		copy(hostnames, ps.Hostnames)
+		domains := []string{}
+		hostnames := []string{}
+
+		for _, name := range ps.Hostnames {
+			if _, isDomain := snap.Domains[name]; isDomain {
+				domains = append(domains, name)
+			} else {
+				hostnames = append(hostnames, name)
+			}
+		}
+
+		sort.Strings(domains)
 		sort.Strings(hostnames)
 
-		resp.Ports[key] = &statusPortInfo{
+		ports[key] = &statusPortInfo{
 			Open:        ps.Open,
+			Domains:     domains,
 			Hostnames:   hostnames,
 			LastChecked: ps.LastChecked,
 		}
 	}
+
+	return ports
 }
 
 func buildCertificates(

internal/handlers/status_test.go

@@ -21,7 +21,8 @@ import (
 // The state the handler tests serve: www.example.com has one nameserver
 // that answered and one whose query failed, and its certificate check
 // failed. example.net is an apex domain, whose own records are saved
-// with the hostnames' records, as the watcher saves them.
+// with the hostnames' records, as the watcher saves them. Both names
+// resolve to domainAddress, whose port 443 entry lists them.
 const (
 	testHostname     = "www.example.com"
 	answeringNS      = "ns1.example.com."
@@ -32,6 +33,7 @@ const (
 	testDomain       = "example.net"
 	domainNS         = "a.iana-servers.net."
 	domainAddress    = "192.0.2.2"
+	sharedPort       = domainAddress + ":443"
 )
 
 // newHandlersWithFailures builds real Handlers whose state holds the
@@ -65,12 +67,31 @@ func newHandlersWithFailures(t *testing.T) *handlers.Handlers {
 		t.Fatalf("state.New: %v", err)
 	}
 
+	setTestState(st)
+
+	hnd, err := handlers.New(nil, handlers.Params{
+		Logger:  log,
+		Globals: glob,
+		State:   st,
+		Notify:  notifier,
+	})
+	if err != nil {
+		t.Fatalf("handlers.New: %v", err)
+	}
+
+	return hnd
+}
+
+// setTestState sets the entries described above in st.
+func setTestState(st *state.State) {
 	now := time.Now()
 
 	st.SetHostnameState(testHostname, &state.HostnameState{
 		RecordsByNameserver: map[string]*state.NameserverRecordState{
 			answeringNS: {
-				Records:     map[string][]string{"A": {"192.0.2.1"}},
+				Records: map[string][]string{
+					"A": {"192.0.2.1", domainAddress},
+				},
 				Status:      "ok",
 				LastChecked: now,
 			},
@@ -106,17 +127,11 @@ func newHandlersWithFailures(t *testing.T) *handlers.Handlers {
 		LastChecked: now,
 	})
 
-	hnd, err := handlers.New(nil, handlers.Params{
-		Logger:  log,
-		Globals: glob,
-		State:   st,
-		Notify:  notifier,
+	st.SetPortState(sharedPort, &state.PortState{
+		Open:        true,
+		Hostnames:   []string{testDomain, testHostname},
+		LastChecked: now,
 	})
-	if err != nil {
-		t.Fatalf("handlers.New: %v", err)
-	}
-
-	return hnd
 }
 
 // get serves one GET request to handler and returns the response body.
@@ -217,3 +232,36 @@ func TestStatusGivesDomainRecordsUnderTheDomain(t *testing.T) {
 			testDomain, domainNS, records, domainAddress)
 	}
 }
+
+// TestStatusPortsTellDomainsFromHostnames checks that a port entry in
+// /api/v1/status lists an apex domain in domains and a hostname in
+// hostnames when both resolve to its address.
+func TestStatusPortsTellDomainsFromHostnames(t *testing.T) {
+	t.Parallel()
+
+	body := get(t, newHandlersWithFailures(t).HandleStatus())
+
+	var resp struct {
+		Ports map[string]struct {
+			Domains   []string `json:"domains"`
+			Hostnames []string `json:"hostnames"`
+		} `json:"ports"`
+	}
+
+	err := json.Unmarshal([]byte(body), &resp)
+	if err != nil {
+		t.Fatalf("decoding response: %v", err)
+	}
+
+	port := resp.Ports[sharedPort]
+
+	if !slices.Equal(port.Domains, []string{testDomain}) {
+		t.Errorf("port %s domains = %v, want [%s]",
+			sharedPort, port.Domains, testDomain)
+	}
+
+	if !slices.Equal(port.Hostnames, []string{testHostname}) {
+		t.Errorf("port %s hostnames = %v, want [%s]",
+			sharedPort, port.Hostnames, testHostname)
+	}
+}

internal/handlers/templates/dashboard.html

@@ -157,19 +157,20 @@
         >
           Ports
         </h2>
-        {{ if .Snapshot.Ports }}
+        {{ if .Ports }}
         <div class="overflow-x-auto">
           <table class="w-full text-left text-xs">
             <thead>
               <tr class="text-slate-500 uppercase tracking-wider">
                 <th class="py-2 px-3">Address</th>
                 <th class="py-2 px-3">State</th>
+                <th class="py-2 px-3">Domains</th>
                 <th class="py-2 px-3">Hostnames</th>
                 <th class="py-2 px-3">Checked</th>
               </tr>
             </thead>
             <tbody class="divide-y divide-slate-800">
-              {{ range $key, $ps := .Snapshot.Ports }}
+              {{ range $key, $ps := .Ports }}
               <tr class="hover:bg-surface-800/50">
                 <td class="py-2 px-3 text-slate-200 font-medium">
                   {{ $key }}
@@ -187,6 +188,9 @@
                   >
                   {{ end }}
                 </td>
+                <td class="py-2 px-3 text-slate-400 break-all">
+                  {{ joinStrings $ps.Domains ", " }}
+                </td>
                 <td class="py-2 px-3 text-slate-400 break-all">
                   {{ joinStrings $ps.Hostnames ", " }}
                 </td>