Handle string ports in docker compose v2 config yaml

internal/compose/compose.go

@@ -54,6 +54,20 @@ type portMapping struct {
 	Protocol     string
 }
 
+type intOrStringYaml int
+
+func (p *intOrStringYaml) UnmarshalYAML(node *yaml.Node) error {
+	var s string
+	err := node.Decode(&s)
+	if err == nil {
+		i, err := strconv.Atoi(s)
+		*p = intOrStringYaml(i)
+		return err
+	}
+
+	return node.Decode(p)
+}
+
 // UnmarshalYAML unmarshals a Docker Compose port mapping in YAML to
 // a portMapping.
 func (p *portMapping) UnmarshalYAML(node *yaml.Node) error {
@@ -67,18 +81,18 @@ func (p *portMapping) UnmarshalYAML(node *yaml.Node) error {
 		}
 
 		var s struct {
-			HostIP    string `yaml:"host_ip"`
-			Target    int
-			Published int
+			HostIP    string          `yaml:"host_ip"`
+			Target    intOrStringYaml // Docker compose v2 can define ports as strings.
+			Published intOrStringYaml // Docker compose v2 can define ports as strings.
 			Protocol  string
 		}
 
 		if err := yaml.Unmarshal(b, &s); err != nil {
 			return errors.Wrap(err, "could not unmarshal YAML map node")
 		}
 
-		p.InternalPort = s.Target
-		p.ExternalPort = s.Published
+		p.InternalPort = int(s.Target)
+		p.ExternalPort = int(s.Published)
 		p.Protocol = s.Protocol
 		p.ExternalIP = s.HostIP
 		return nil

internal/compose/compose_test.go

@@ -0,0 +1,33 @@
+// Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+// or more contributor license agreements. Licensed under the Elastic License;
+// you may not use this file except in compliance with the Elastic License.
+
+package compose
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gopkg.in/yaml.v3"
+)
+
+func TestIntOrStringYaml(t *testing.T) {
+	cases := []struct {
+		yaml     string
+		expected int
+	}{
+		{`"9200"`, 9200},
+		{`'9200'`, 9200},
+		{`9200`, 9200},
+	}
+
+	for _, c := range cases {
+		t.Run(c.yaml, func(t *testing.T) {
+			var n intOrStringYaml
+			err := yaml.Unmarshal([]byte(c.yaml), &n)
+			require.NoError(t, err)
+			assert.Equal(t, c.expected, int(n))
+		})
+	}
+}