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Traefik Migration Documentation

docs/content/migrate/v3.md

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Migration: Steps needed between the versions

This guide provides detailed migration steps for upgrading between different Traefik v3 versions. Each section covers breaking changes, deprecations, and configuration updates required for a smooth transition.

v3.0 to v3.1

Kubernetes Provider RBACs

Starting with v3.1, Traefik's Kubernetes Providers use the EndpointSlices API (requires Kubernetes >=v1.21) for service endpoint discovery. This change also introduces NodePort load-balancing capabilities.

The following RBAC updates are required for all Kubernetes providers:

  • Remove endpoints permissions and add endpointslices:
yaml
# Remove this section from your RBAC
# - apiGroups: [""]
#   resources: ["endpoints"]
#   verbs: ["get", "list", "watch"]

# Add this section instead
- apiGroups:
    - discovery.k8s.io
  resources:
    - endpointslices
  verbs:
    - list
    - watch
  • Add nodes permissions for NodePort support:
yaml
- apiGroups:
    - ""
  resources:
    - nodes
  verbs:
    - get
    - list
    - watch

!!! note "Affected Providers" These changes apply to:

- [KubernetesIngress](../reference/install-configuration/providers/kubernetes/kubernetes-ingress.md) provider
- [KubernetesCRD](../reference/install-configuration/providers/kubernetes/kubernetes-crd.md#requirements) provider
- [KubernetesGateway](../reference/install-configuration/providers/kubernetes/kubernetes-gateway.md#requirements) provider

Gateway API: KubernetesGateway Provider

The KubernetesGateway Provider is no longer experimental in v3.1 and can be enabled without the experimental.kubernetesgateway option.

Deprecated Configuration:

??? example "Experimental kubernetesgateway option (deprecated)"

```yaml tab="File (YAML)"
experimental:
  kubernetesgateway: true
```

```toml tab="File (TOML)"
[experimental]
    kubernetesgateway=true
```

```bash tab="CLI"
--experimental.kubernetesgateway=true
```

Migration Steps:

  1. Remove the kubernetesgateway option from the experimental section
  2. Configure the provider using the KubernetesGateway Provider documentation

v3.1.0 to v3.1.1

IngressClass Lookup

The disableIngressClassLookup option has been deprecated and will be removed in the next major version.

Migration Required:

  • Old: disableIngressClassLookup
  • New: disableClusterScopeResources

The new option provides broader control over cluster scope resources discovery, including both IngressClass and Nodes resources.

v3.1 to v3.2

Kubernetes CRD Provider

New optional fields have been added to several CRDs. These updates are backward compatible and only add new functionality.

Apply the latest CRDs:

shell
kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.3/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml

Updated Resources:

Kubernetes Gateway Provider Standard Channel

Starting with v3.2, the Kubernetes Gateway Provider now supports GRPCRoute resources.

Therefore, in the corresponding RBACs (see KubernetesGateway provider RBACs), the grcroutes and grpcroutes/status rights have to be added.

Required RBAC Updates:

yaml
...
- apiGroups:
    - gateway.networking.k8s.io
  resources:
    - grpcroutes
  verbs:
    - get
    - list
    - watch
- apiGroups:
    - gateway.networking.k8s.io
  resources:
    - grpcroutes/status
  verbs:
    - update
...

Kubernetes Gateway Provider Experimental Channel

Due to breaking changes in Kubernetes Gateway v1.2.0-rc1, Traefik v3.3 only supports Kubernetes Gateway v1.2.x when experimental features are enabled.

New Feature: BackendTLSPolicy Support

The provider now supports BackendTLSPolicy resources.

Therefore, in the corresponding RBACs (see KubernetesGateway provider RBACs), the backendtlspolicies and backendtlspolicies/status rights have to be added.

Required RBAC Updates:

yaml
  ...
  - apiGroups:
      - ""
    resources:
      - configmaps
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - gateway.networking.k8s.io
    resources:
      - backendtlspolicies
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - gateway.networking.k8s.io
    resources:
      - backendtlspolicies/status
    verbs:
      - update
  ...

v3.2.1

X-Forwarded-Prefix Header Changes

In v3.2.1, the X-Forwarded-Prefix header is now handled like other X-Forwarded-* headers - Traefik removes it when sent from untrusted sources.

This change improves security by preventing header spoofing from untrusted clients. Refer to the Forwarded headers documentation for configuration details.

v3.2.2

Swarm Provider Label Updates

In v3.2.2, Swarm-specific labels have been deprecated and will be removed in a future version.

Migration Required:

Deprecated LabelNew Label
traefik.docker.networktraefik.swarm.network
traefik.docker.lbswarmtraefik.swarm.lbswarm

v3.2 to v3.3

ACME DNS Certificate Resolver

In v3.3, DNS challenge configuration options have been reorganized for better clarity.

Migration Required:

Deprecated OptionNew Option
acme.dnsChallenge.delaybeforecheckacme.dnsChallenge.propagation.delayBeforeChecks
acme.dnsChallenge.disablepropagationcheckacme.dnsChallenge.propagation.disableChecks

Tracing Global Attributes

In v3.3, the tracing configuration has been clarified to better reflect its purpose.

Migration Required:

  • Old: tracing.globalAttributes
  • New: tracing.resourceAttributes

The old option name was misleading as it specifically adds resource attributes for the collector, not global span attributes.

v3.3.4

OpenTelemetry Request Duration Metric

In v3.3.4, the OpenTelemetry Request Duration metric unit has been standardized to match other providers and naming conventions.

Change Details:

  • Metric: traefik_(entrypoint|router|service)_request_duration_seconds
  • Old Unit: Milliseconds
  • New Unit: Seconds

This change ensures consistency across all metrics providers and follows standard naming conventions.

v3.3.5

Compress Middleware Default Encodings

In v3.3.5, the default compression algorithms have been reordered to favor gzip compression.

New Default: gzip, br, zstd

This change affects requests that either:

  • Don't specify preferred algorithms in the Accept-Encoding header
  • Have no order preference in their Accept-Encoding header

The reordering helps ensure better compatibility with older clients that may not support newer compression algorithms.

v3.3.6

Request Path Sanitization

Starting with v3.3.6, incoming request paths are now automatically cleaned before processing for security and consistency.

What's Changed:

The following path segments are now interpreted and collapsed:

  • /../ (parent directory references)
  • /./ (current directory references)
  • Duplicate slash segments (//)

Disabling Sanitization:

yaml
# EntryPoint HTTP configuration
entryPoints:
  web:
    address: ":80"
    http:
      sanitizePath: false  # Not recommended

!!! danger "Security Warning" Setting sanitizePath: false is not safe. This option should only be used with legacy clients that don't properly URL-encode data. Always ensure requests are properly URL-encoded instead of disabling this security feature.

Example Risk: Base64 data containing "/" characters can lead to unsafe routing when path sanitization is disabled and the data isn't URL-encoded.

v3.3 to v3.4

Kubernetes CRD Provider

Load-Balancing Strategy Updates

Starting with v3.4, HTTP service definitions now support additional load-balancing strategies for better traffic distribution.

Apply Updated CRDs:

shell
kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.4/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml

New Strategy Values:

  • wrr (Weighted Round Robin)
  • p2c (Power of Two Choices)

!!! warning "Deprecation" The RoundRobin strategy is deprecated but still supported (equivalent to wrr). It will be removed in the next major release.

Refer to the HTTP Services Load Balancing documentation for detailed information.

ServersTransport CA Certificate Configuration

A new rootCAs option has been added to the ServersTransport and ServersTransportTCP CRDs. It supports both ConfigMaps and Secrets for CA certificates and replaces the rootCAsSecrets option.

Apply Updates:

shell
# Update CRDs
kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.4/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml

# Update RBACs
kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.4/docs/content/reference/dynamic-configuration/kubernetes-crd-rbac.yml

New Configuration Format:

yaml
---
apiVersion: traefik.io/v1alpha1
kind: ServersTransport
metadata:
  name: foo
  namespace: bar
spec:
  rootCAs:
    - configMap: ca-config-map
    - secret: ca-secret
      
---      
apiVersion: traefik.io/v1alpha1
kind: ServersTransportTCP
metadata:
  name: foo
  namespace: bar
spec:
  rootCAs:
    - configMap: ca-config-map
    - secret: ca-secret

!!! warning "Deprecation" The rootCAsSecrets option (Secrets only) is still supported but deprecated. It will be removed in the next major release.

Rule Syntax Configuration

In v3.4, rule syntax configuration options will be removed in the next major version.

Deprecated Options:

  • core.defaultRuleSyntax (static configuration)
  • ruleSyntax (router option)

These options were transitional helpers for migrating from v2 to v3 syntax. Please ensure all router rules use v3 syntax before the next major release.

v3.4.1

Request Path Normalization

Starting with v3.4.1, request paths are now normalized according to RFC 3986 standards for better consistency and security.

Normalization Process:

  1. Unreserved Character Decoding: Characters like %2E (.) are decoded to their literal form
  2. Case Normalization: Percent-encoded characters are uppercased (%2e becomes %2E)

This follows RFC 3986 percent-encoding normalization and case normalization standards.

Processing Order:

  1. Path normalization (cannot be disabled)
  2. Path sanitization (if enabled)

Reserved Character Handling in Routing

Starting with v3.4.1, reserved characters (per RFC 3986) remain encoded during router rule matching to prevent routing ambiguity.

Why This Matters: Reserved characters change the meaning of request paths when decoded. Keeping them encoded during routing prevents security vulnerabilities and ensures predictable routing behavior.

Request Path Matching Examples

The following table illustrates how path matching behavior has changed:

Request PathRouter RuleTraefik v3.4.0Traefik v3.4.1Explanation
/foo%2FbarPathPrefix(`/foo/bar`)MatchNo match%2F (/) stays encoded, preventing false matches
/foo/../barPathPrefix(`/foo`)No matchNo matchPath traversal is sanitized away
/foo/../barPathPrefix(`/bar`)MatchMatchResolves to /bar after sanitization
/foo/%2E%2E/barPathPrefix(`/foo`)MatchNo matchEncoded dots normalized then sanitized
/foo/%2E%2E/barPathPrefix(`/bar`)No matchMatchResolves to /bar after normalization + sanitization

v3.4.5

MultiPath TCP

Since v3.4.5, the MultiPath TCP support introduced with v3.4.2 has been removed. It appears that enabling MPTCP on some platforms can cause Traefik to stop with the following error logs message:

  • set tcp X.X.X.X:X->X.X.X.X:X: setsockopt: operation not supported

However, it can be re-enabled by setting the multipathtcp variable in the GODEBUG environment variable, see the related go documentation.

v3.5.0

Observability

TraceVerbosity on Routers and Entrypoints

Starting with v3.5.0, a new traceVerbosity option is available for both entrypoints and routers. This option allows you to control the level of detail for tracing spans. Routers can override the value inherited from their entrypoint.

Impact:

  • If you rely on tracing, review your configuration to explicitly set the desired verbosity level.
  • Existing configurations will default to minimal unless overridden, which will result in fewer spans being generated than before.

Possible values are:

  • minimal: produces a single server span and one client span for each request processed by a router.
  • detailed: enables the creation of additional spans for each middleware executed for each request processed by a router.

See the updated documentation for entrypoints and dynamic routers.

K8s Resource Attributes

Since v3.5.0, the semconv attributes k8s.pod.name and k8s.pod.uid are injected automatically in OTel resource attributes when OTel tracing/logs/metrics are enabled.

For that purpose, the following right has to be added to the Traefik Kubernetes RBACs:

yaml
  ...
  - apiGroups:
      - ""
    resources:
      - pods
    verbs:
      - get
  ...

v3.5.2

Deprecation of ProxyProtocol option

Starting with v3.5.2, the proxyProtocol option for TCP LoadBalancer is deprecated. This option can now be configured at the TCPServersTransport level, please check out the documentation for more details.

Kubernetes CRD Provider

To use the new proxyprotocol option in the Kubernetes CRD provider, you need to update your CRDs.

Apply Updated CRDs:

shell
kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.5/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml

v3.5.4

Certificate Metric Renamed with OpenTelemetry

Starting with v3.5.4, and when using OpenTelemetry, the traefik_tls_certs_not_after_milliseconds metric is renamed to traefik_tls_certs_not_after_seconds. This change aligns the metric name with its real unit precision, which is in seconds.

v3.6.0

Kubernetes Gateway API Provider

Starting with v3.6.0, the Kubernetes Gateway API provider only supports version v1.4.0 of the specification, which requires the Gateway API CRDs to be updated.

Apply Updated CRDs:

shell
kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.4.0/standard-install.yaml

For the experimental channel:

shell
kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.4.0/experimental-install.yaml

Kubernetes CRD Provider

To use the new leasttime load-balancer algorithm with the Kubernetes CRD provider, you need to update your CRDs.

Apply Updated CRDs:

shell
kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.7/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml

v3.6.2

Ingress NGINX Provider

The KubernetesIngressNGINX Provider is no longer experimental in v3.6.2 and can be enabled without the experimental.kubernetesIngressNGINX option.

Deprecated Configuration:

??? example "Experimental kubernetesIngressNGINX option (deprecated)"

```yaml tab="File (YAML)"
experimental:
  kubernetesIngressNGINX: true
```

```toml tab="File (TOML)"
[experimental]
    kubernetesIngressNGINX=true
```

```bash tab="CLI"
--experimental.kubernetesIngressNGINX=true
```

Migration Steps:

  1. Remove the kubernetesIngressNGINX option from the experimental section
  2. Configure the provider using the kubernetesIngressNGINX Provider documentation

v3.6.4

Encoded Characters in Request Path

Starting with v3.6.4, for security reasons, Traefik now rejects requests with a path containing a specific set of encoded characters by default.

When such a request is received, Traefik responds with a 400 Bad Request status code.

Here is the list of the encoded characters that are rejected by default, along with the corresponding configuration option to allow them:

Encoded CharacterCharacterConfig option to allow the encoded character
%2f or %2F/ (slash)entryPoints.<name>
.http.encodedCharacters
.allowEncodedSlash
%5c or %5C\ (backslash)entryPoints.<name>
.http.encodedCharacters
.allowEncodedBackSlash
%00NULL (null character)entryPoints.<name>
.http.encodedCharacters
.allowEncodedNullCharacter
%3b or %3B; (semicolon)entryPoints.<name>
.http.encodedCharacters
.allowEncodedSemicolon
%25% (percent)entryPoints.<name>
.http.encodedCharacters
.allowEncodedPercent
%3f or %3F? (question mark)entryPoints.<name>
.http.encodedCharacters
.allowEncodedQuestionMark
%23# (hash)entryPoints.<name>
.http.encodedCharacters
.allowEncodedHash

Please check out the entrypoint encodedCharacters option documentation for more details.

v3.6.7

Encoded Characters Configuration Default Values

Since v3.6.7, the options for encoded characters now have a true default value. This means that Traefik will not reject requests with a path containing a specific set of encoded characters by default. It is now up to the users to configure the security hardening of encoded characters.

Here is the list of the encoded characters that can be configured to false to disallow them:

Encoded CharacterCharacterConfig optionsDefault value
%2f or %2F/ (slash)entryPoints.<name>
.http.encodedCharacters
.allowEncodedSlashtrue
%5c or %5C\ (backslash)entryPoints.<name>
.http.encodedCharacters
.allowEncodedBackSlashtrue
%00NULL (null character)entryPoints.<name>
.http.encodedCharacters
.allowEncodedNullCharactertrue
%3b or %3B; (semicolon)entryPoints.<name>
.http.encodedCharacters
.allowEncodedSemicolontrue
%25% (percent)entryPoints.<name>
.http.encodedCharacters
.allowEncodedPercenttrue
%3f or %3F? (question mark)entryPoints.<name>
.http.encodedCharacters
.allowEncodedQuestionMarktrue
%23# (hash)entryPoints.<name>
.http.encodedCharacters
.allowEncodedHashtrue

Note: This check is not done against query parameters, but only against the request path as defined in RFC3986 section-3.

Please check out the entrypoint encodedCharacters option documentation for more details.

v3.6.8

Health Check Request Path

Since v3.6.8, the configured path for the health check request is now verified to be a relative URL, and the health check will fail if it is not.

v3.6.9

maxResponseBodySize configuration on ForwardAuth middleware

In v3.6.9, a new maxResponseBodySize option has been added to the ForwardAuth middleware configuration. The default value for this option is -1, which means there is no limit to the response body size. However, it is strongly recommended to set this option to a suitable value to avoid performance and security issues, such as DoS attacks and memory exhaustion.

Please check out the ForwardAuth middleware documentation for more details.

Kubernetes CRD Provider

To use the new maxResponseBodySize option in the ForwardAuth middleware with the Kubernetes CRD provider, you need to update your CRDs.

Apply Updated CRDs:

shell
kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.7/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml

v3.7.0

Ingress NGINX Provider

Starting with v3.7.0, the Ingress NGINX provider now supports the nginx.ingress.kubernetes.io/custom-headers annotation to add custom headers to the response forwarded to the client.

Therefore, in the corresponding RBACs (see KubernetesIngressNGINX provider RBACs) the configmaps right has been added.

Required RBAC Updates:

yaml
  ...
  - apiGroups:
      - ""
    resources:
      - configmaps
    verbs:
      - list
      - watch  
  ...

Kubernetes Gateway API Provider

Starting with v3.7.0, the Kubernetes Gateway API provider supports version v1.5.1 of the specification, which requires the Gateway API CRDs to be updated.

TLSRoute has graduated to the Standard channel and no longer requires the experimentalChannel option. The experimentalChannel option is now only needed for TCPRoute.

Apply Updated CRDs:

shell
kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.5.1/standard-install.yaml

For the experimental channel:

shell
kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.5.1/experimental-install.yaml

Kubernetes CRD Provider

To use the new options of the retry middleware with the Kubernetes CRD provider, you need to update your CRDs.

Apply Updated CRDs:

shell
kubectl apply -f https://raw.githubusercontent.com/traefik/traefik/v3.7/docs/content/reference/dynamic-configuration/kubernetes-crd-definition-v1.yml