Refactor dockerswarm refresh for testing (#7541)

We were missing testing on the behaviour of the configuration
unmarshalling.

This PR adds a refresh command that can be used to test that we
use the correct refresh function.

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

discovery/dockerswarm/dockerswarm.go

@@ -82,6 +82,7 @@ func (c *SDConfig) UnmarshalYAML(unmarshal func(interface{}) error) error {
 type Discovery struct {
 	*refresh.Discovery
 	client *client.Client
+	role   string
 	port   int
 }
 
@@ -89,6 +90,7 @@ type Discovery struct {
 func NewDiscovery(conf *SDConfig, logger log.Logger) (*Discovery, error) {
 	d := &Discovery{
 		port: conf.Port,
+		role: conf.Role,
 	}
 
 	rt, err := config_util.NewRoundTripperFromConfig(conf.HTTPClientConfig, "dockerswarm_sd", false)
@@ -117,21 +119,24 @@ func NewDiscovery(conf *SDConfig, logger log.Logger) (*Discovery, error) {
 		return nil, fmt.Errorf("error setting up docker swarm client: %w", err)
 	}
 
-	var r func(context.Context) ([]*targetgroup.Group, error)
-	switch conf.Role {
-	case "services":
-		r = d.refreshServices
-	case "nodes":
-		r = d.refreshNodes
-	case "tasks":
-		r = d.refreshTasks
-	}
-
 	d.Discovery = refresh.NewDiscovery(
 		logger,
 		"dockerswarm",
 		time.Duration(conf.RefreshInterval),
-		r,
+		d.refresh,
 	)
 	return d, nil
 }
+
+func (d *Discovery) refresh(ctx context.Context) ([]*targetgroup.Group, error) {
+	switch d.role {
+	case "services":
+		return d.refreshServices(ctx)
+	case "nodes":
+		return d.refreshNodes(ctx)
+	case "tasks":
+		return d.refreshTasks(ctx)
+	default:
+		panic(fmt.Errorf("unexpected role %s", d.role))
+	}
+}

discovery/dockerswarm/nodes_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/go-kit/kit/log"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/util/testutil"
+	"gopkg.in/yaml.v2"
 )
 
 func TestDockerSwarmNodesSDRefresh(t *testing.T) {
@@ -28,14 +29,20 @@ func TestDockerSwarmNodesSDRefresh(t *testing.T) {
 	sdmock.Setup()
 
 	e := sdmock.Endpoint()
-	cfg := DefaultSDConfig
+	url := e[:len(e)-1]
-	cfg.Host = e[:len(e)-1]
+	cfgString := fmt.Sprintf(`
+---
+role: nodes
+host: %s
+`, url)
+	var cfg SDConfig
+	testutil.Ok(t, yaml.Unmarshal([]byte(cfgString), &cfg))
 
 	d, err := NewDiscovery(&cfg, log.NewNopLogger())
 	testutil.Ok(t, err)
 
 	ctx := context.Background()
-	tgs, err := d.refreshNodes(ctx)
+	tgs, err := d.refresh(ctx)
 	testutil.Ok(t, err)
 
 	testutil.Equals(t, 1, len(tgs))

discovery/dockerswarm/services_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/go-kit/kit/log"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/util/testutil"
+	"gopkg.in/yaml.v2"
 )
 
 func TestDockerSwarmSDServicesRefresh(t *testing.T) {
@@ -28,14 +29,20 @@ func TestDockerSwarmSDServicesRefresh(t *testing.T) {
 	sdmock.Setup()
 
 	e := sdmock.Endpoint()
-	cfg := DefaultSDConfig
+	url := e[:len(e)-1]
-	cfg.Host = e[:len(e)-1]
+	cfgString := fmt.Sprintf(`
+---
+role: services
+host: %s
+`, url)
+	var cfg SDConfig
+	testutil.Ok(t, yaml.Unmarshal([]byte(cfgString), &cfg))
 
 	d, err := NewDiscovery(&cfg, log.NewNopLogger())
 	testutil.Ok(t, err)
 
 	ctx := context.Background()
-	tgs, err := d.refreshServices(ctx)
+	tgs, err := d.refresh(ctx)
 	testutil.Ok(t, err)
 
 	testutil.Equals(t, 1, len(tgs))

discovery/dockerswarm/tasks_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/go-kit/kit/log"
 	"github.com/prometheus/common/model"
 	"github.com/prometheus/prometheus/util/testutil"
+	"gopkg.in/yaml.v2"
 )
 
 func TestDockerSwarmTasksSDRefresh(t *testing.T) {
@@ -28,14 +29,20 @@ func TestDockerSwarmTasksSDRefresh(t *testing.T) {
 	sdmock.Setup()
 
 	e := sdmock.Endpoint()
-	cfg := DefaultSDConfig
+	url := e[:len(e)-1]
-	cfg.Host = e[:len(e)-1]
+	cfgString := fmt.Sprintf(`
+---
+role: tasks
+host: %s
+`, url)
+	var cfg SDConfig
+	testutil.Ok(t, yaml.Unmarshal([]byte(cfgString), &cfg))
 
 	d, err := NewDiscovery(&cfg, log.NewNopLogger())
 	testutil.Ok(t, err)
 
 	ctx := context.Background()
-	tgs, err := d.refreshTasks(ctx)
+	tgs, err := d.refresh(ctx)
 	testutil.Ok(t, err)
 
 	testutil.Equals(t, 1, len(tgs))