v0.33.7_docker_hostnames

docker-agent/docker.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"context"
+	"crypto/sha256"
 	"encoding/json"
 	"fmt"
 	"io"
@@ -92,20 +93,18 @@ func serviceIdentity(c dockerContainer, p dockerPort) (key, technical string) {
 	project := c.Labels["com.docker.compose.project"]
 	composeService := c.Labels["com.docker.compose.service"]
 	replica := c.Labels["com.docker.compose.container-number"]
-	suffix := strconv.Itoa(int(p.PrivatePort))
 	if project != "" && composeService != "" {
 		if replica == "" {
 			replica = name
 		}
 		key = fmt.Sprintf("compose:%s/%s/%s:%d/%s", project, composeService, replica, p.PrivatePort, p.Type)
-		technicalBase := project + "-" + composeService
-		if replica != "1" {
-			technicalBase += "-" + replica
+		technical = dnsLabel(name)
+		if name == "container" {
+			technical = dnsLabel(composeService)
 		}
-		technical = dnsLabel(technicalBase + "-" + suffix)
 	} else {
 		key = fmt.Sprintf("container:%s:%d/%s", name, p.PrivatePort, p.Type)
-		technical = dnsLabel(name + "-" + suffix)
+		technical = dnsLabel(name)
 	}
 	return key, technical
 }
@@ -163,5 +162,43 @@ func servicesFrom(containers []dockerContainer) []service {
 		out = append(out, *item)
 	}
 	sort.Slice(out, func(i, j int) bool { return out[i].Key < out[j].Key })
+	// Prefer the Docker container name. Add the internal port only when names
+	// collide; retain stable service keys and prevent any duplicate hostnames.
+	counts := make(map[string]int, len(out))
+	for _, item := range out {
+		counts[item.TechnicalName]++
+	}
+	for i := range out {
+		if counts[out[i].TechnicalName] > 1 {
+			out[i].TechnicalName = dnsLabel(out[i].TechnicalName + "-" + strconv.Itoa(int(out[i].PrivatePort)))
+		}
+	}
+	// Port suffixes can still collide after normalization/truncation.
+	// Resolve these deterministically using a short hash of the stable key.
+	counts = make(map[string]int, len(out))
+	for _, item := range out {
+		counts[item.TechnicalName]++
+	}
+	used := make(map[string]struct{}, len(out))
+	for i := range out {
+		name := out[i].TechnicalName
+		if counts[name] > 1 {
+			digest := sha256.Sum256([]byte(out[i].Key))
+			name = fmt.Sprintf("%s-%x", strings.TrimRight(name[:min(len(name), 48)], "-"), digest[:6])
+		}
+		// Extremely unlikely hash collisions are still resolved without
+		// changing the stable key or depending on Docker listing order.
+		for attempt := 0; ; attempt++ {
+			candidate := name
+			if attempt > 0 {
+				candidate = fmt.Sprintf("%s-%d", name[:min(len(name), 56)], attempt)
+			}
+			if _, exists := used[candidate]; !exists {
+				out[i].TechnicalName = candidate
+				used[candidate] = struct{}{}
+				break
+			}
+		}
+	}
 	return out
 }