Strip leading slash from container names in template data

The Docker API returns container names prefixed with "/" (e.g.
"/mycontainer"), so {{index .Names 0}} produced "/mycontainer"
instead of "mycontainer" as documented in the README.

Fixes #648

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: lucaslorentz

generator/containers.go

@@ -1,6 +1,8 @@
 package generator
 
 import (
+	"strings"
+
 	"github.com/docker/docker/api/types"
 	"github.com/lucaslorentz/caddy-docker-proxy/v2/caddyfile"
 	"go.uber.org/zap"
@@ -9,11 +11,21 @@ import (
 func (g *CaddyfileGenerator) getContainerCaddyfile(container *types.Container, logger *zap.Logger) (*caddyfile.Container, error) {
 	caddyLabels := g.filterLabels(container.Labels)
 
+	trimContainerNames(container)
+
 	return labelsToCaddyfile(caddyLabels, container, func() ([]string, error) {
 		return g.getContainerIPAddresses(container, logger, true)
 	})
 }
 
+// trimContainerNames removes the leading slash from container names.
+// The Docker API returns names prefixed with "/" (e.g. "/mycontainer").
+func trimContainerNames(container *types.Container) {
+	for i, name := range container.Names {
+		container.Names[i] = strings.TrimPrefix(name, "/")
+	}
+}
+
 func (g *CaddyfileGenerator) getContainerIPAddresses(container *types.Container, logger *zap.Logger, onlyIngressIps bool) ([]string, error) {
 	ips := []string{}
 

generator/containers_test.go

@@ -13,7 +13,7 @@ func TestContainers_TemplateData(t *testing.T) {
 	dockerClient.ContainersData = []types.Container{
 		{
 			Names: []string{
-				"container-name",
+				"/container-name",
 			},
 			NetworkSettings: &types.SummaryNetworkSettings{
 				Networks: map[string]*network.EndpointSettings{