Support multiple namespaces for Consul and ConsulCatalog providers

Co-authored-by: Kevin Pollet <pollet.kevin@gmail.com>

pkg/provider/kv/consul/consul.go

@@ -4,30 +4,80 @@ import (
 	"errors"
 
 	"github.com/kvtools/valkeyrie/store"
+	"github.com/traefik/traefik/v2/pkg/log"
 	"github.com/traefik/traefik/v2/pkg/provider"
 	"github.com/traefik/traefik/v2/pkg/provider/kv"
 )
 
+// providerName is the Consul provider name.
+const providerName = "consul"
+
 var _ provider.Provider = (*Provider)(nil)
 
-// Provider holds configurations of the provider.
-type Provider struct {
+// ProviderBuilder is responsible for constructing namespaced instances of the Consul provider.
+type ProviderBuilder struct {
 	kv.Provider `export:"true"`
+
+	// Deprecated: use Namespaces instead.
+	Namespace  string   `description:"Sets the namespace used to discover the configuration (Consul Enterprise only)." json:"namespace,omitempty" toml:"namespace,omitempty" yaml:"namespace,omitempty"`
+	Namespaces []string `description:"Sets the namespaces used to discover the configuration (Consul Enterprise only)." json:"namespaces,omitempty" toml:"namespaces,omitempty" yaml:"namespaces,omitempty"`
 }
 
 // SetDefaults sets the default values.
-func (p *Provider) SetDefaults() {
+func (p *ProviderBuilder) SetDefaults() {
 	p.Provider.SetDefaults()
 	p.Endpoints = []string{"127.0.0.1:8500"}
 }
 
+// BuildProviders builds Consul provider instances for the given namespaces configuration.
+func (p *ProviderBuilder) BuildProviders() []*Provider {
+	// We can warn about that, because we've already made sure before that
+	// Namespace and Namespaces are mutually exclusive.
+	if p.Namespace != "" {
+		log.WithoutContext().Warnf("Namespace option is deprecated, please use the Namespaces option instead.")
+	}
+
+	if len(p.Namespaces) == 0 {
+		return []*Provider{{
+			Provider: p.Provider,
+			name:     providerName,
+			// p.Namespace could very well be empty.
+			namespace: p.Namespace,
+		}}
+	}
+
+	var providers []*Provider
+	for _, namespace := range p.Namespaces {
+		providers = append(providers, &Provider{
+			Provider:  p.Provider,
+			name:      providerName + "-" + namespace,
+			namespace: namespace,
+		})
+	}
+
+	return providers
+}
+
+// Provider holds configurations of the provider.
+type Provider struct {
+	kv.Provider
+
+	name      string
+	namespace string
+}
+
 // Init the provider.
 func (p *Provider) Init() error {
 	// Wildcard namespace allows fetching KV values from any namespace for recursive requests (see https://www.consul.io/api/kv#ns).
 	// As we are not supporting multiple namespaces at the same time, wildcard namespace is not allowed.
-	if p.Namespace == "*" {
+	if p.namespace == "*" {
 		return errors.New("wildcard namespace is not supported")
 	}
 
-	return p.Provider.Init(store.CONSUL, "consul")
+	// In case they didn't initialize with BuildProviders.
+	if p.name == "" {
+		p.name = providerName
+	}
+
+	return p.Provider.Init(store.CONSUL, p.name, p.namespace)
 }

pkg/provider/kv/consul/consul_test.go

@@ -0,0 +1,59 @@
+package consul
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestNamespaces(t *testing.T) {
+	testCases := []struct {
+		desc               string
+		namespace          string
+		namespaces         []string
+		expectedNamespaces []string
+	}{
+		{
+			desc:               "no defined namespaces",
+			expectedNamespaces: []string{""},
+		},
+		{
+			desc:               "deprecated: use of defined namespace",
+			namespace:          "test-ns",
+			expectedNamespaces: []string{"test-ns"},
+		},
+		{
+			desc:               "use of 1 defined namespaces",
+			namespaces:         []string{"test-ns"},
+			expectedNamespaces: []string{"test-ns"},
+		},
+		{
+			desc:               "use of multiple defined namespaces",
+			namespaces:         []string{"test-ns1", "test-ns2", "test-ns3", "test-ns4"},
+			expectedNamespaces: []string{"test-ns1", "test-ns2", "test-ns3", "test-ns4"},
+		},
+	}
+
+	for _, test := range testCases {
+		test := test
+
+		t.Run(test.desc, func(t *testing.T) {
+			t.Parallel()
+
+			pb := &ProviderBuilder{
+				Namespace:  test.namespace,
+				Namespaces: test.namespaces,
+			}
+
+			assert.Equal(t, test.expectedNamespaces, extractNSFromProvider(pb.BuildProviders()))
+		})
+	}
+}
+
+func extractNSFromProvider(providers []*Provider) []string {
+	res := make([]string, len(providers))
+	for i, p := range providers {
+		res[i] = p.namespace
+	}
+	return res
+}

pkg/provider/kv/etcd/etcd.go

@@ -21,5 +21,5 @@ func (p *Provider) SetDefaults() {
 
 // Init the provider.
 func (p *Provider) Init() error {
-	return p.Provider.Init(store.ETCDV3, "etcd")
+	return p.Provider.Init(store.ETCDV3, "etcd", "")
 }

pkg/provider/kv/kv.go

@@ -30,12 +30,12 @@ type Provider struct {
 	Username  string           `description:"KV Username" json:"username,omitempty" toml:"username,omitempty" yaml:"username,omitempty" loggable:"false"`
 	Password  string           `description:"KV Password" json:"password,omitempty" toml:"password,omitempty" yaml:"password,omitempty" loggable:"false"`
 	Token     string           `description:"KV Token" json:"token,omitempty" toml:"token,omitempty" yaml:"token,omitempty" loggable:"false"`
-	Namespace string           `description:"KV Namespace" json:"namespace,omitempty" toml:"namespace,omitempty" yaml:"namespace,omitempty"`
 	TLS       *types.ClientTLS `description:"Enable TLS support" json:"tls,omitempty" toml:"tls,omitempty" yaml:"tls,omitempty" export:"true" `
 
+	name      string
+	namespace string
 	storeType store.Backend
 	kvClient  store.Store
-	name      string
 }
 
 // SetDefaults sets the default values.
@@ -44,11 +44,12 @@ func (p *Provider) SetDefaults() {
 }
 
 // Init the provider.
-func (p *Provider) Init(storeType store.Backend, name string) error {
+func (p *Provider) Init(storeType store.Backend, name, namespace string) error {
 	ctx := log.With(context.Background(), log.Str(log.ProviderName, name))
 
-	p.storeType = storeType
 	p.name = name
+	p.namespace = namespace
+	p.storeType = storeType
 
 	kvClient, err := p.createKVClient(ctx)
 	if err != nil {
@@ -167,7 +168,7 @@ func (p *Provider) createKVClient(ctx context.Context) (store.Store, error) {
 		Username:          p.Username,
 		Password:          p.Password,
 		Token:             p.Token,
-		Namespace:         p.Namespace,
+		Namespace:         p.namespace,
 	}
 
 	if p.TLS != nil {

pkg/provider/kv/redis/redis.go

@@ -21,5 +21,5 @@ func (p *Provider) SetDefaults() {
 
 // Init the provider.
 func (p *Provider) Init() error {
-	return p.Provider.Init(store.REDIS, "redis")
+	return p.Provider.Init(store.REDIS, "redis", "")
 }

pkg/provider/kv/zk/zk.go

@@ -21,5 +21,5 @@ func (p *Provider) SetDefaults() {
 
 // Init the provider.
 func (p *Provider) Init() error {
-	return p.Provider.Init(store.ZK, "zookeeper")
+	return p.Provider.Init(store.ZK, "zookeeper", "")
 }