Support multiple namespaces for Consul and ConsulCatalog providers

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

.golangci.toml

@@ -174,6 +174,8 @@
     "SA1019: cfg.SSLHost is deprecated",
     "SA1019: cfg.SSLForceHost is deprecated",
     "SA1019: cfg.FeaturePolicy is deprecated",
+    "SA1019: c.Providers.ConsulCatalog.Namespace is deprecated",
+    "SA1019: c.Providers.Consul.Namespace is deprecated",
   ]
  [[issues.exclude-rules]]
     path = "(.+)_test.go"

docs/content/deprecation/features.md

@@ -3,9 +3,10 @@
 This page is maintained and updated periodically to reflect our roadmap and any decisions around feature deprecation.
 
 | Feature                                                       | Deprecated | End of Support | Removal |
-|-------------------------------------------------------|------------|----------------|---------|
+|---------------------------------------------------------------|------------|----------------|---------|
 | [Pilot Dashboard (Metrics)](#pilot-dashboard-metrics)         | 2.7        | 2.8            | 2.9     |
 | [Pilot Plugins](#pilot-plugins)                               | 2.7        | 2.8            | 2.9     |
+| [Consul Enterprise Namespaces](#consul-enterprise-namespaces) | 2.8        | TBD            | TBD     |
 
 ## Impact
 
@@ -18,3 +19,8 @@ In 2.9, the Pilot platform and all Traefik integration code will be permanently
 
 Starting on 2.7 the pilot token will not be a requirement anymore.  
 At 2.9, a new plugin catalog home should be available, decoupled from pilot.
+
+### Consul Enterprise Namespaces
+
+Starting on 2.8 the `namespace` option of Consul and Consul Catalog providers is deprecated, 
+please use the `namespaces` options instead.  

docs/content/migration/v2.md

@@ -464,3 +464,7 @@ In `v2.6.1`, the Datadog tags added to a span changed from `service.name` to `tr
 
 In `v2.8`, the `caOptional` option is deprecated as TLS client authentication is a server side option.
 This option available in the ForwardAuth middleware, as well as in the HTTP, Consul, Etcd, Redis, ZooKeeper, Marathon, Consul Catalog, and Docker providers has no effect and must not be used anymore.
+
+### Consul Enterprise Namespaces
+
+In `v2.8`, the `namespace` option of Consul and Consul Catalog providers is deprecated, please use the `namespaces` options instead.

docs/content/providers/consul-catalog.md

@@ -525,7 +525,7 @@ providers:
 ```
 
 ```bash tab="CLI"
---providers.consulcatalog.defaultRule="Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)"
+--providers.consulcatalog.defaultRule=Host(`{{ .Name }}.{{ index .Labels \"customLabel\"}}`)
 # ...
 ```
 
@@ -669,6 +669,8 @@ For additional information, refer to [Restrict the Scope of Service Discovery](.
 
 ### `namespace`
 
+??? warning "Deprecated in favor of the [`namespaces`](#namespaces) option."
+
     _Optional, Default=""_
     
     The `namespace` option defines the namespace in which the consul catalog services will be discovered.
@@ -678,6 +680,10 @@ The `namespace` option defines the namespace in which the consul catalog service
         The namespace option only works with [Consul Enterprise](https://www.consul.io/docs/enterprise),
         which provides the [Namespaces](https://www.consul.io/docs/enterprise/namespaces) feature.
     
+    !!! warning
+    
+        One should only define either the `namespaces` option or the `namespace` option.
+    
     ```yaml tab="File (YAML)"
     providers:
       consulCatalog:
@@ -696,6 +702,46 @@ providers:
     # ...
     ```
 
+### `namespaces`
+
+_Optional, Default=""_
+
+The `namespaces` option defines the namespaces in which the consul catalog services will be discovered.
+When using the `namespaces` option, the discovered configuration object names will be suffixed as shown below:
+
+```text
+<resource-name>@consulcatalog-<namespace>
+```
+
+!!! warning
+
+    The namespaces option only works with [Consul Enterprise](https://www.consul.io/docs/enterprise),
+    which provides the [Namespaces](https://www.consul.io/docs/enterprise/namespaces) feature.
+
+!!! warning
+
+    One should only define either the `namespaces` option or the `namespace` option.
+
+```yaml tab="File (YAML)"
+providers:
+  consulCatalog:
+    namespaces: 
+      - "ns1"
+      - "ns2"
+    # ...
+```
+
+```toml tab="File (TOML)"
+[providers.consulCatalog]
+  namespaces = ["ns1", "ns2"]
+  # ...
+```
+
+```bash tab="CLI"
+--providers.consulcatalog.namespaces=ns1,ns2
+# ...
+```
+
 ### `watch`
 
 _Optional, Default=false_

docs/content/providers/consul.md

@@ -61,6 +61,8 @@ providers:
 
 ### `namespace`
 
+??? warning "Deprecated in favor of the [`namespaces`](#namespaces) option."
+
     _Optional, Default=""_
     
     The `namespace` option defines the namespace to query.
@@ -70,6 +72,10 @@ The `namespace` option defines the namespace to query.
         The namespace option only works with [Consul Enterprise](https://www.consul.io/docs/enterprise),
         which provides the [Namespaces](https://www.consul.io/docs/enterprise/namespaces) feature.
     
+    !!! warning
+    
+        One should only define either the `namespaces` option or the `namespace` option.
+    
     ```yaml tab="File (YAML)"
     providers:
       consul:
@@ -87,6 +93,46 @@ providers:
     --providers.consul.namespace=production
     ```
 
+### `namespaces`
+
+_Optional, Default=""_
+
+The `namespaces` option defines the namespaces to query.
+When using the `namespaces` option, the discovered configuration object names will be suffixed as shown below:
+
+```text
+<resource-name>@consul-<namespace>
+```
+
+!!! warning
+
+    The namespaces option only works with [Consul Enterprise](https://www.consul.io/docs/enterprise),
+    which provides the [Namespaces](https://www.consul.io/docs/enterprise/namespaces) feature.
+
+!!! warning
+
+    One should only define either the `namespaces` option or the `namespace` option.
+
+```yaml tab="File (YAML)"
+providers:
+  consul:
+    namespaces: 
+      - "ns1"
+      - "ns2"
+    # ...
+```
+
+```toml tab="File (TOML)"
+[providers.consul]
+  namespaces = ["ns1", "ns2"]
+  # ...
+```
+
+```bash tab="CLI"
+--providers.consul.namespaces=ns1,ns2
+# ...
+```
+
 ### `username`
 
 _Optional, Default=""_

docs/content/reference/static-configuration/cli-ref.md

@@ -403,7 +403,10 @@ Enable Consul backend with default settings. (Default: ```false```)
 KV store endpoints (Default: ```127.0.0.1:8500```)
 
 `--providers.consul.namespace`:  
-KV Namespace
+Sets the namespace used to discover the configuration (Consul Enterprise only).
+
+`--providers.consul.namespaces`:  
+Sets the namespaces used to discover the configuration (Consul Enterprise only).
 
 `--providers.consul.password`:  
 KV Password
@@ -492,11 +495,14 @@ Expose containers by default. (Default: ```true```)
 `--providers.consulcatalog.namespace`:  
 Sets the namespace used to discover services (Consul Enterprise only).
 
+`--providers.consulcatalog.namespaces`:  
+Sets the namespaces used to discover services (Consul Enterprise only).
+
 `--providers.consulcatalog.prefix`:  
-Prefix for consul service tags. Default 'traefik' (Default: ```traefik```)
+Prefix for consul service tags. (Default: ```traefik```)
 
 `--providers.consulcatalog.refreshinterval`:  
-Interval for check Consul API. Default 15s (Default: ```15```)
+Interval for check Consul API. (Default: ```15```)
 
 `--providers.consulcatalog.requireconsistent`:  
 Forces the read to be fully consistent. (Default: ```false```)
@@ -594,9 +600,6 @@ Enable Etcd backend with default settings. (Default: ```false```)
 `--providers.etcd.endpoints`:  
 KV store endpoints (Default: ```127.0.0.1:2379```)
 
-`--providers.etcd.namespace`:  
-KV Namespace
-
 `--providers.etcd.password`:  
 KV Password
 
@@ -858,9 +861,6 @@ Enable Redis backend with default settings. (Default: ```false```)
 `--providers.redis.endpoints`:  
 KV store endpoints (Default: ```127.0.0.1:6379```)
 
-`--providers.redis.namespace`:  
-KV Namespace
-
 `--providers.redis.password`:  
 KV Password
 
@@ -900,9 +900,6 @@ Enable ZooKeeper backend with default settings. (Default: ```false```)
 `--providers.zookeeper.endpoints`:  
 KV store endpoints (Default: ```127.0.0.1:2181```)
 
-`--providers.zookeeper.namespace`:  
-KV Namespace
-
 `--providers.zookeeper.password`:  
 KV Password
 

docs/content/reference/static-configuration/env-ref.md

@@ -459,11 +459,14 @@ Expose containers by default. (Default: ```true```)
 `TRAEFIK_PROVIDERS_CONSULCATALOG_NAMESPACE`:  
 Sets the namespace used to discover services (Consul Enterprise only).
 
+`TRAEFIK_PROVIDERS_CONSULCATALOG_NAMESPACES`:  
+Sets the namespaces used to discover services (Consul Enterprise only).
+
 `TRAEFIK_PROVIDERS_CONSULCATALOG_PREFIX`:  
-Prefix for consul service tags. Default 'traefik' (Default: ```traefik```)
+Prefix for consul service tags. (Default: ```traefik```)
 
 `TRAEFIK_PROVIDERS_CONSULCATALOG_REFRESHINTERVAL`:  
-Interval for check Consul API. Default 15s (Default: ```15```)
+Interval for check Consul API. (Default: ```15```)
 
 `TRAEFIK_PROVIDERS_CONSULCATALOG_REQUIRECONSISTENT`:  
 Forces the read to be fully consistent. (Default: ```false```)
@@ -481,7 +484,10 @@ Watch Consul API events. (Default: ```false```)
 KV store endpoints (Default: ```127.0.0.1:8500```)
 
 `TRAEFIK_PROVIDERS_CONSUL_NAMESPACE`:  
-KV Namespace
+Sets the namespace used to discover the configuration (Consul Enterprise only).
+
+`TRAEFIK_PROVIDERS_CONSUL_NAMESPACES`:  
+Sets the namespaces used to discover the configuration (Consul Enterprise only).
 
 `TRAEFIK_PROVIDERS_CONSUL_PASSWORD`:  
 KV Password
@@ -594,9 +600,6 @@ Enable Etcd backend with default settings. (Default: ```false```)
 `TRAEFIK_PROVIDERS_ETCD_ENDPOINTS`:  
 KV store endpoints (Default: ```127.0.0.1:2379```)
 
-`TRAEFIK_PROVIDERS_ETCD_NAMESPACE`:  
-KV Namespace
-
 `TRAEFIK_PROVIDERS_ETCD_PASSWORD`:  
 KV Password
 
@@ -858,9 +861,6 @@ Enable Redis backend with default settings. (Default: ```false```)
 `TRAEFIK_PROVIDERS_REDIS_ENDPOINTS`:  
 KV store endpoints (Default: ```127.0.0.1:6379```)
 
-`TRAEFIK_PROVIDERS_REDIS_NAMESPACE`:  
-KV Namespace
-
 `TRAEFIK_PROVIDERS_REDIS_PASSWORD`:  
 KV Password
 
@@ -900,9 +900,6 @@ Enable ZooKeeper backend with default settings. (Default: ```false```)
 `TRAEFIK_PROVIDERS_ZOOKEEPER_ENDPOINTS`:  
 KV store endpoints (Default: ```127.0.0.1:2181```)
 
-`TRAEFIK_PROVIDERS_ZOOKEEPER_NAMESPACE`:  
-KV Namespace
-
 `TRAEFIK_PROVIDERS_ZOOKEEPER_PASSWORD`:  
 KV Password
 

docs/content/reference/static-configuration/file.toml

@@ -28,12 +28,6 @@
     [entryPoints.EntryPoint0.forwardedHeaders]
       insecure = true
       trustedIPs = ["foobar", "foobar"]
-    [entryPoints.EntryPoint0.udp]
-      timeout = 42
-    [entryPoints.EntryPoint0.http2]
-      maxConcurrentStreams = 42
-    [entryPoints.EntryPoint0.http3]
-      advertisedPort = 42
     [entryPoints.EntryPoint0.http]
       middlewares = ["foobar", "foobar"]
       [entryPoints.EntryPoint0.http.redirections]
@@ -53,6 +47,8 @@
         [[entryPoints.EntryPoint0.http.tls.domains]]
           main = "foobar"
           sans = ["foobar", "foobar"]
+    [entryPoints.EntryPoint0.http2]
+      maxConcurrentStreams = 42
     [entryPoints.EntryPoint0.http3]
       advertisedPort = 42
     [entryPoints.EntryPoint0.udp]
@@ -161,6 +157,7 @@
     connectByDefault = true
     serviceName = "foobar"
     namespace = "foobar"
+    namespaces = ["foobar", "foobar"]
     watch = true
     [providers.consulCatalog.endpoint]
       address = "foobar"
@@ -194,6 +191,7 @@
     password = "foobar"
     token = "foobar"
     namespace = "foobar"
+    namespaces = ["foobar", "foobar"]
     [providers.consul.tls]
       ca = "foobar"
       caOptional = true
@@ -206,7 +204,6 @@
     username = "foobar"
     password = "foobar"
     token = "foobar"
-    namespace = "foobar"
     [providers.etcd.tls]
       ca = "foobar"
       caOptional = true
@@ -219,7 +216,6 @@
     username = "foobar"
     password = "foobar"
     token = "foobar"
-    namespace = "foobar"
     [providers.zooKeeper.tls]
       ca = "foobar"
       caOptional = true
@@ -232,7 +228,6 @@
     username = "foobar"
     password = "foobar"
     token = "foobar"
-    namespace = "foobar"
     [providers.redis.tls]
       ca = "foobar"
       caOptional = true

docs/content/reference/static-configuration/file.yaml

@@ -32,12 +32,6 @@ entryPoints:
       trustedIPs:
       - foobar
       - foobar
-    http2:
-      maxConcurrentStreams: 42
-    http3:
-      advertisedPort: 42
-    udp:
-      timeout: 42
     http:
       redirections:
         entryPoint:
@@ -60,6 +54,8 @@ entryPoints:
             sans:
               - foobar
               - foobar
+    http2:
+      maxConcurrentStreams: 42
     http3:
       advertisedPort: 42
     udp:
@@ -173,6 +169,9 @@ providers:
     connectByDefault: true
     serviceName: foobar
     namespace: foobar
+    namespaces:
+      - foobar
+      - foobar
     watch: true
     endpoint:
       address: foobar
@@ -210,6 +209,9 @@ providers:
     password: foobar
     token: foobar
     namespace: foobar
+    namespaces:
+      - foobar
+      - foobar
     tls:
       ca: foobar
       caOptional: true
@@ -224,7 +226,6 @@ providers:
     username: foobar
     password: foobar
     token: foobar
-    namespace: foobar
     tls:
       ca: foobar
       caOptional: true
@@ -239,7 +240,6 @@ providers:
     username: foobar
     password: foobar
     token: foobar
-    namespace: foobar
     tls:
       ca: foobar
       caOptional: true
@@ -254,7 +254,6 @@ providers:
     username: foobar
     password: foobar
     token: foobar
-    namespace: foobar
     tls:
       ca: foobar
       caOptional: true

pkg/config/static/static_config.go

@@ -183,10 +183,10 @@ type Providers struct {
 	KubernetesGateway *gateway.Provider              `description:"Enable Kubernetes gateway api provider with default settings." json:"kubernetesGateway,omitempty" toml:"kubernetesGateway,omitempty" yaml:"kubernetesGateway,omitempty" export:"true" label:"allowEmpty" file:"allowEmpty"`
 	Rest              *rest.Provider                 `description:"Enable Rest backend with default settings." json:"rest,omitempty" toml:"rest,omitempty" yaml:"rest,omitempty" export:"true" label:"allowEmpty" file:"allowEmpty"`
 	Rancher           *rancher.Provider              `description:"Enable Rancher backend with default settings." json:"rancher,omitempty" toml:"rancher,omitempty" yaml:"rancher,omitempty" export:"true" label:"allowEmpty" file:"allowEmpty"`
-	ConsulCatalog     *consulcatalog.Provider `description:"Enable ConsulCatalog backend with default settings." json:"consulCatalog,omitempty" toml:"consulCatalog,omitempty" yaml:"consulCatalog,omitempty" label:"allowEmpty" file:"allowEmpty" export:"true"`
+	ConsulCatalog     *consulcatalog.ProviderBuilder `description:"Enable ConsulCatalog backend with default settings." json:"consulCatalog,omitempty" toml:"consulCatalog,omitempty" yaml:"consulCatalog,omitempty" label:"allowEmpty" file:"allowEmpty" export:"true"`
 	Ecs               *ecs.Provider                  `description:"Enable AWS ECS backend with default settings." json:"ecs,omitempty" toml:"ecs,omitempty" yaml:"ecs,omitempty" label:"allowEmpty" file:"allowEmpty" export:"true"`
 
-	Consul    *consul.Provider `description:"Enable Consul backend with default settings." json:"consul,omitempty" toml:"consul,omitempty" yaml:"consul,omitempty" label:"allowEmpty" file:"allowEmpty"  export:"true"`
+	Consul    *consul.ProviderBuilder `description:"Enable Consul backend with default settings." json:"consul,omitempty" toml:"consul,omitempty" yaml:"consul,omitempty" label:"allowEmpty" file:"allowEmpty"  export:"true"`
 	Etcd      *etcd.Provider          `description:"Enable Etcd backend with default settings." json:"etcd,omitempty" toml:"etcd,omitempty" yaml:"etcd,omitempty" label:"allowEmpty" file:"allowEmpty" export:"true"`
 	ZooKeeper *zk.Provider            `description:"Enable ZooKeeper backend with default settings." json:"zooKeeper,omitempty" toml:"zooKeeper,omitempty" yaml:"zooKeeper,omitempty" label:"allowEmpty" file:"allowEmpty" export:"true"`
 	Redis     *redis.Provider         `description:"Enable Redis backend with default settings." json:"redis,omitempty" toml:"redis,omitempty" yaml:"redis,omitempty" label:"allowEmpty" file:"allowEmpty" export:"true"`
@@ -257,7 +257,7 @@ func (c *Configuration) SetEffectiveConfiguration() {
 		c.Pilot.SetDefaults()
 	}
 
-	// Disable Gateway API provider if not enabled in experimental
+	// Disable Gateway API provider if not enabled in experimental.
 	if c.Experimental == nil || !c.Experimental.KubernetesGateway {
 		c.Providers.KubernetesGateway = nil
 	}
@@ -328,6 +328,14 @@ func (c *Configuration) ValidateConfiguration() error {
 		acmeEmail = resolver.ACME.Email
 	}
 
+	if c.Providers.ConsulCatalog != nil && c.Providers.ConsulCatalog.Namespace != "" && len(c.Providers.ConsulCatalog.Namespaces) > 0 {
+		return fmt.Errorf("consul catalog provider cannot have both namespace and namespaces options configured")
+	}
+
+	if c.Providers.Consul != nil && c.Providers.Consul.Namespace != "" && len(c.Providers.Consul.Namespaces) > 0 {
+		return fmt.Errorf("consul provider cannot have both namespace and namespaces options configured")
+	}
+
 	return nil
 }
 

pkg/provider/aggregator/aggregator.go

@@ -109,11 +109,15 @@ func NewProviderAggregator(conf static.Providers) ProviderAggregator {
 	}
 
 	if conf.ConsulCatalog != nil {
-		p.quietAddProvider(conf.ConsulCatalog)
+		for _, pvd := range conf.ConsulCatalog.BuildProviders() {
+			p.quietAddProvider(pvd)
+		}
 	}
 
 	if conf.Consul != nil {
-		p.quietAddProvider(conf.Consul)
+		for _, pvd := range conf.Consul.BuildProviders() {
+			p.quietAddProvider(pvd)
+		}
 	}
 
 	if conf.Etcd != nil {

pkg/provider/consulcatalog/config_test.go

@@ -219,7 +219,7 @@ func TestDefaultRule(t *testing.T) {
 					Status:  api.HealthPassing,
 				},
 			},
-			defaultRule: DefaultTemplateRule,
+			defaultRule: defaultTemplateRule,
 			expected: &dynamic.Configuration{
 				TCP: &dynamic.TCPConfiguration{
 					Routers:     map[string]*dynamic.TCPRouter{},
@@ -262,8 +262,10 @@ func TestDefaultRule(t *testing.T) {
 			t.Parallel()
 
 			p := Provider{
+				Configuration: Configuration{
 					ExposedByDefault: true,
 					DefaultRule:      test.defaultRule,
+				},
 			}
 
 			err := p.Init()
@@ -2618,10 +2620,12 @@ func Test_buildConfiguration(t *testing.T) {
 			t.Parallel()
 
 			p := Provider{
+				Configuration: Configuration{
 					ExposedByDefault: true,
 					DefaultRule:      "Host(`{{ normalize .Name }}.traefik.wtf`)",
 					ConnectAware:     test.ConnectAware,
 					Constraints:      test.constraints,
+				},
 			}
 
 			err := p.Init()
@@ -2651,3 +2655,55 @@ func Test_buildConfiguration(t *testing.T) {
 		})
 	}
 }
+
+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/consulcatalog/consul_catalog.go

@@ -22,8 +22,11 @@ import (
 	"github.com/traefik/traefik/v2/pkg/types"
 )
 
-// DefaultTemplateRule The default template for the default rule.
+// defaultTemplateRule is the default template for the default rule.
-const DefaultTemplateRule = "Host(`{{ normalize .Name }}`)"
+const defaultTemplateRule = "Host(`{{ normalize .Name }}`)"
+
+// providerName is the Consul Catalog provider name.
+const providerName = "consulcatalog"
 
 var _ provider.Provider = (*Provider)(nil)
 
@@ -41,12 +44,50 @@ type itemData struct {
 	ExtraConf  configuration
 }
 
-// Provider holds configurations of the provider.
+// ProviderBuilder is responsible for constructing namespaced instances of the Consul Catalog provider.
-type Provider struct {
+type ProviderBuilder struct {
+	Configuration `export:"true"`
+
+	// Deprecated: use Namespaces option instead.
+	Namespace  string   `description:"Sets the namespace used to discover services (Consul Enterprise only)." json:"namespace,omitempty" toml:"namespace,omitempty" yaml:"namespace,omitempty"`
+	Namespaces []string `description:"Sets the namespaces used to discover services (Consul Enterprise only)." json:"namespaces,omitempty" toml:"namespaces,omitempty" yaml:"namespaces,omitempty"`
+}
+
+// BuildProviders builds Consul Catalog 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{{
+			Configuration: p.Configuration,
+			name:          providerName,
+			// p.Namespace could very well be empty.
+			namespace: p.Namespace,
+		}}
+	}
+
+	var providers []*Provider
+	for _, namespace := range p.Namespaces {
+		providers = append(providers, &Provider{
+			Configuration: p.Configuration,
+			name:          providerName + "-" + namespace,
+			namespace:     namespace,
+		})
+	}
+
+	return providers
+}
+
+// Configuration represents the Consul Catalog provider configuration.
+type Configuration struct {
 	Constraints       string          `description:"Constraints is an expression that Traefik matches against the container's labels to determine whether to create any route for that container." json:"constraints,omitempty" toml:"constraints,omitempty" yaml:"constraints,omitempty" export:"true"`
 	Endpoint          *EndpointConfig `description:"Consul endpoint settings" json:"endpoint,omitempty" toml:"endpoint,omitempty" yaml:"endpoint,omitempty" export:"true"`
-	Prefix            string          `description:"Prefix for consul service tags. Default 'traefik'" json:"prefix,omitempty" toml:"prefix,omitempty" yaml:"prefix,omitempty" export:"true"`
+	Prefix            string          `description:"Prefix for consul service tags." json:"prefix,omitempty" toml:"prefix,omitempty" yaml:"prefix,omitempty" export:"true"`
-	RefreshInterval   ptypes.Duration `description:"Interval for check Consul API. Default 15s" json:"refreshInterval,omitempty" toml:"refreshInterval,omitempty" yaml:"refreshInterval,omitempty" export:"true"`
+	RefreshInterval   ptypes.Duration `description:"Interval for check Consul API." json:"refreshInterval,omitempty" toml:"refreshInterval,omitempty" yaml:"refreshInterval,omitempty" export:"true"`
 	RequireConsistent bool            `description:"Forces the read to be fully consistent." json:"requireConsistent,omitempty" toml:"requireConsistent,omitempty" yaml:"requireConsistent,omitempty" export:"true"`
 	Stale             bool            `description:"Use stale consistency for catalog reads." json:"stale,omitempty" toml:"stale,omitempty" yaml:"stale,omitempty" export:"true"`
 	Cache             bool            `description:"Use local agent caching for catalog reads." json:"cache,omitempty" toml:"cache,omitempty" yaml:"cache,omitempty" export:"true"`
@@ -55,9 +96,25 @@ type Provider struct {
 	ConnectAware      bool            `description:"Enable Consul Connect support." json:"connectAware,omitempty" toml:"connectAware,omitempty" yaml:"connectAware,omitempty" export:"true"`
 	ConnectByDefault  bool            `description:"Consider every service as Connect capable by default." json:"connectByDefault,omitempty" toml:"connectByDefault,omitempty" yaml:"connectByDefault,omitempty" export:"true"`
 	ServiceName       string          `description:"Name of the Traefik service in Consul Catalog (needs to be registered via the orchestrator or manually)." json:"serviceName,omitempty" toml:"serviceName,omitempty" yaml:"serviceName,omitempty" export:"true"`
-	Namespace         string          `description:"Sets the namespace used to discover services (Consul Enterprise only)." json:"namespace,omitempty" toml:"namespace,omitempty" yaml:"namespace,omitempty" export:"true"`
 	Watch             bool            `description:"Watch Consul API events." json:"watch,omitempty" toml:"watch,omitempty" yaml:"watch,omitempty" export:"true"`
+}
 
+// SetDefaults sets the default values.
+func (c *Configuration) SetDefaults() {
+	c.Endpoint = &EndpointConfig{}
+	c.RefreshInterval = ptypes.Duration(15 * time.Second)
+	c.Prefix = "traefik"
+	c.ExposedByDefault = true
+	c.DefaultRule = defaultTemplateRule
+	c.ServiceName = "traefik"
+}
+
+// Provider is the Consul Catalog provider implementation.
+type Provider struct {
+	Configuration
+
+	name              string
+	namespace         string
 	client            *api.Client
 	defaultRuleTpl    *template.Template
 	certChan          chan *connectCert
@@ -81,17 +138,6 @@ type EndpointHTTPAuthConfig struct {
 	Password string `description:"Basic Auth password" json:"password,omitempty" toml:"password,omitempty" yaml:"password,omitempty" loggable:"false"`
 }
 
-// SetDefaults sets the default values.
-func (p *Provider) SetDefaults() {
-	endpoint := &EndpointConfig{}
-	p.Endpoint = endpoint
-	p.RefreshInterval = ptypes.Duration(15 * time.Second)
-	p.Prefix = "traefik"
-	p.ExposedByDefault = true
-	p.DefaultRule = DefaultTemplateRule
-	p.ServiceName = "traefik"
-}
-
 // Init the provider.
 func (p *Provider) Init() error {
 	defaultRuleTpl, err := provider.MakeDefaultRuleTemplate(p.DefaultRule, nil)
@@ -103,19 +149,24 @@ func (p *Provider) Init() error {
 	p.certChan = make(chan *connectCert, 1)
 	p.watchServicesChan = make(chan struct{}, 1)
 
+	// In case they didn't initialize Provider with BuildProviders.
+	if p.name == "" {
+		p.name = providerName
+	}
+
 	return nil
 }
 
 // Provide allows the consul catalog provider to provide configurations to traefik using the given configuration channel.
 func (p *Provider) Provide(configurationChan chan<- dynamic.Message, pool *safe.Pool) error {
 	var err error
-	p.client, err = createClient(p.Namespace, p.Endpoint)
+	p.client, err = createClient(p.namespace, p.Endpoint)
 	if err != nil {
 		return fmt.Errorf("failed to create consul client: %w", err)
 	}
 
 	pool.GoCtx(func(routineCtx context.Context) {
-		ctxLog := log.With(routineCtx, log.Str(log.ProviderName, "consulcatalog"))
+		ctxLog := log.With(routineCtx, log.Str(log.ProviderName, p.name))
 		logger := log.FromContext(ctxLog)
 
 		operation := func() error {
@@ -210,7 +261,7 @@ func (p *Provider) loadConfiguration(ctx context.Context, certInfo *connectCert,
 	}
 
 	configurationChan <- dynamic.Message{
-		ProviderName:  "consulcatalog",
+		ProviderName:  p.name,
 		Configuration: p.buildConfiguration(ctx, data, certInfo),
 	}
 

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.
+// ProviderBuilder is responsible for constructing namespaced instances of the Consul provider.
-type Provider struct {
+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", "")
 }

pkg/redactor/redactor_config_test.go

@@ -682,7 +682,8 @@ func TestDo_staticConfiguration(t *testing.T) {
 		Prefix:                    "MyPrefix",
 	}
 
-	config.Providers.ConsulCatalog = &consulcatalog.Provider{
+	config.Providers.ConsulCatalog = &consulcatalog.ProviderBuilder{
+		Configuration: consulcatalog.Configuration{
 			Constraints: `Label("foo", "bar")`,
 			Endpoint: &consulcatalog.EndpointConfig{
 				Address:    "MyAddress",
@@ -709,6 +710,9 @@ func TestDo_staticConfiguration(t *testing.T) {
 			Cache:             true,
 			ExposedByDefault:  true,
 			DefaultRule:       "PathPrefix(`/`)",
+		},
+		Namespace:  "ns",
+		Namespaces: []string{"ns1", "ns2"},
 	}
 
 	config.Providers.Ecs = &ecs.Provider{
@@ -723,7 +727,7 @@ func TestDo_staticConfiguration(t *testing.T) {
 		SecretAccessKey:      "AwsSecretAccessKey",
 	}
 
-	config.Providers.Consul = &consul.Provider{
+	config.Providers.Consul = &consul.ProviderBuilder{
 		Provider: kv.Provider{
 			RootKey:   "RootKey",
 			Endpoints: nil,
@@ -737,6 +741,8 @@ func TestDo_staticConfiguration(t *testing.T) {
 				InsecureSkipVerify: true,
 			},
 		},
+		Namespace:  "ns",
+		Namespaces: []string{"ns1", "ns2"},
 	}
 
 	config.Providers.Etcd = &etcd.Provider{

pkg/redactor/testdata/anonymized-static-config.json

@@ -206,7 +206,12 @@
       "stale": true,
       "cache": true,
       "exposedByDefault": true,
-      "defaultRule": "xxxx"
+      "defaultRule": "xxxx",
+      "namespace": "xxxx",
+      "namespaces": [
+        "xxxx",
+        "xxxx"
+      ]
     },
     "ecs": {
       "constraints": "Label(\"foo\", \"bar\")",
@@ -232,7 +237,12 @@
         "cert": "xxxx",
         "key": "xxxx",
         "insecureSkipVerify": true
-      }
+      },
+      "namespace": "xxxx",
+      "namespaces": [
+        "xxxx",
+        "xxxx"
+      ]
     },
     "etcd": {
       "rootKey": "xxxx",

webui/src/components/_commons/PanelMiddlewares.vue

@@ -1142,9 +1142,15 @@ export default {
     getProviderLogoPath (provider) {
       const name = provider.toLowerCase()
 
-      if (name.includes('plugin-')) {
+      if (name.startsWith('plugin-')) {
         return 'statics/providers/plugin.svg'
       }
+      if (name.startsWith('consul-')) {
+        return `statics/providers/consul.svg`
+      }
+      if (name.startsWith('consulcatalog-')) {
+        return `statics/providers/consulcatalog.svg`
+      }
 
       return `statics/providers/${name}.svg`
     }

webui/src/components/_commons/PanelMirroringServices.vue

@@ -66,9 +66,15 @@ export default {
       const provider = this.getProvider(service)
       const name = provider.toLowerCase()
 
-      if (name.includes('plugin-')) {
+      if (name.startsWith('plugin-')) {
         return 'statics/providers/plugin.svg'
       }
+      if (name.startsWith('consul-')) {
+        return `statics/providers/consul.svg`
+      }
+      if (name.startsWith('consulcatalog-')) {
+        return `statics/providers/consulcatalog.svg`
+      }
 
       return `statics/providers/${name}.svg`
     }

webui/src/components/_commons/PanelRouterDetails.vue

@@ -132,9 +132,15 @@ export default {
     getProviderLogoPath () {
       const name = this.data.provider.toLowerCase()
 
-      if (name.includes('plugin-')) {
+      if (name.startsWith('plugin-')) {
         return 'statics/providers/plugin.svg'
       }
+      if (name.startsWith('consul-')) {
+        return `statics/providers/consul.svg`
+      }
+      if (name.startsWith('consulcatalog-')) {
+        return `statics/providers/consulcatalog.svg`
+      }
 
       return `statics/providers/${name}.svg`
     }

webui/src/components/_commons/PanelServiceDetails.vue

@@ -146,9 +146,15 @@ export default {
     getProviderLogoPath () {
       const name = this.data.provider.toLowerCase()
 
-      if (name.includes('plugin-')) {
+      if (name.startsWith('plugin-')) {
         return 'statics/providers/plugin.svg'
       }
+      if (name.startsWith('consul-')) {
+        return `statics/providers/consul.svg`
+      }
+      if (name.startsWith('consulcatalog-')) {
+        return `statics/providers/consulcatalog.svg`
+      }
 
       return `statics/providers/${name}.svg`
     }

webui/src/components/_commons/PanelWeightedServices.vue

@@ -66,9 +66,15 @@ export default {
       const provider = this.getProvider(service)
       const name = provider.toLowerCase()
 
-      if (name.includes('plugin-')) {
+      if (name.startsWith('plugin-')) {
         return 'statics/providers/plugin.svg'
       }
+      if (name.startsWith('consul-')) {
+        return `statics/providers/consul.svg`
+      }
+      if (name.startsWith('consulcatalog-')) {
+        return `statics/providers/consulcatalog.svg`
+      }
 
       return `statics/providers/${name}.svg`
     }

webui/src/components/_commons/ProviderIcon.vue

@@ -11,9 +11,15 @@ export default {
     getLogoPath () {
       const name = this.name.toLowerCase()
 
-      if (name.includes('plugin-')) {
+      if (name.startsWith('plugin-')) {
         return 'statics/providers/plugin.svg'
       }
+      if (name.startsWith('consul-')) {
+        return `statics/providers/consul.svg`
+      }
+      if (name.startsWith('consulcatalog-')) {
+        return `statics/providers/consulcatalog.svg`
+      }
 
       return `statics/providers/${name}.svg`
     }

webui/src/components/dashboard/PanelProvider.vue

@@ -28,9 +28,15 @@ export default {
     getLogoPath () {
       const name = this.getName.toLowerCase()
 
-      if (name.includes('plugin-')) {
+      if (name.startsWith('plugin-')) {
         return 'statics/providers/plugin.svg'
       }
+      if (name.startsWith('consul-')) {
+        return `statics/providers/consul.svg`
+      }
+      if (name.startsWith('consulcatalog-')) {
+        return `statics/providers/consulcatalog.svg`
+      }
 
       return `statics/providers/${name}.svg`
     }