Support schema registry in kafka preset

Schema registry startup time is a bit longer than the broker, so
registry usage is hidden behind a flag to not make existing tests
slower.

preset/kafka/options.go

@@ -34,3 +34,13 @@ func WithMessagesFile(files string) Option {
 		o.MessagesFiles = append(o.MessagesFiles, files)
 	}
 }
+
+// WithSchemaRegistry makes the container wait for the schema registry port to
+// become available. Note that it takes longer to setup schema registry than
+// the broker itself. Gnomock will not wait for the registry by default, but it
+// may become available eventually.
+func WithSchemaRegistry() Option {
+	return func(o *P) {
+		o.UseSchemaRegistry = true
+	}
+}

preset/kafka/preset.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net/http"
 	"os"
 	"time"
 
@@ -17,16 +18,18 @@ import (
 
 // The following ports are exposed by this preset:.
 const (
-	BrokerPort    = "broker"
-	ZooKeeperPort = "zookeeper"
-	WebPort       = "web"
+	BrokerPort         = "broker"
+	ZooKeeperPort      = "zookeeper"
+	WebPort            = "web"
+	SchemaRegistryPort = "registry"
 )
 
 const (
-	defaultVersion = "2.5.1-L0"
-	brokerPort     = 49092
-	zookeeperPort  = 2181
-	webPort        = 3030
+	defaultVersion     = "2.5.1-L0"
+	brokerPort         = 49092
+	zookeeperPort      = 2181
+	webPort            = 3030
+	schemaRegistryPort = 8081
 )
 
 // Message is a single message sent to Kafka.
@@ -62,10 +65,11 @@ func Preset(opts ...Option) gnomock.Preset {
 
 // P is a Gnomock Preset implementation of Kafka.
 type P struct {
-	Version       string    `json:"version"`
-	Topics        []string  `json:"topics"`
-	Messages      []Message `json:"messages"`
-	MessagesFiles []string  `json:"messages_files"`
+	Version           string    `json:"version"`
+	Topics            []string  `json:"topics"`
+	Messages          []Message `json:"messages"`
+	MessagesFiles     []string  `json:"messages_files"`
+	UseSchemaRegistry bool      `json:"use_schema_registry"`
 }
 
 // Image returns an image that should be pulled to create this container.
@@ -83,6 +87,7 @@ func (p *P) Ports() gnomock.NamedPorts {
 
 	namedPorts[ZooKeeperPort] = gnomock.TCP(zookeeperPort)
 	namedPorts[WebPort] = gnomock.TCP(webPort)
+	namedPorts[SchemaRegistryPort] = gnomock.TCP(schemaRegistryPort)
 
 	return namedPorts
 }
@@ -133,6 +138,24 @@ func (p *P) healthcheck(ctx context.Context, c *gnomock.Container) (err error) {
 		return fmt.Errorf("can't create topic: %w", err)
 	}
 
+	if p.UseSchemaRegistry {
+		url := "http://" + c.Address(SchemaRegistryPort)
+
+		req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+		if err != nil {
+			return fmt.Errorf("invalid request: %w", err)
+		}
+
+		res, err := http.DefaultClient.Do(req)
+		if err != nil {
+			return fmt.Errorf("schema registry is not available: %w", err)
+		}
+
+		if err := res.Body.Close(); err != nil {
+			return fmt.Errorf("error closing schema registry response body: %w", err)
+		}
+	}
+
 	return nil
 }
 

preset/kafka/preset_test.go

@@ -2,6 +2,7 @@ package kafka_test
 
 import (
 	"context"
+	"net/http"
 	"testing"
 	"time"
 
@@ -94,3 +95,24 @@ func TestPreset_withDefaults(t *testing.T) {
 	require.NoError(t, err)
 	require.NoError(t, c.Close())
 }
+
+func TestPreset_withSchemaRegistry(t *testing.T) {
+	p := kafka.Preset(kafka.WithSchemaRegistry())
+	container, err := gnomock.Start(
+		p,
+		gnomock.WithContainerName("kafka-with-registry"),
+		gnomock.WithTimeout(time.Minute*10),
+	)
+	require.NoError(t, err)
+
+	defer func() { require.NoError(t, gnomock.Stop(container)) }()
+
+	c, err := kafkaclient.Dial("tcp", container.Address(kafka.BrokerPort))
+	require.NoError(t, err)
+	require.NoError(t, c.Close())
+
+	out, err := http.Get("http://" + container.Address(kafka.SchemaRegistryPort))
+	require.NoError(t, err)
+	require.Equal(t, http.StatusOK, out.StatusCode)
+	require.NoError(t, out.Body.Close())
+}

swagger/swagger.yaml

@@ -1038,6 +1038,10 @@ components:
           description: Kafka version.
           default: 2.5.1-L0
           example: latest
+        use_schema_registry:
+          type: boolean
+          description: Set to true to wait for schema registry on startup
+          default: false
       description: >
         This object describes a Kafka container.