traefik/docs/content/middlewares/http/replacepathregex.md
2023-03-21 16:45:33 +01:00

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---
title: "Traefik ReplacePathRegex Documentation"
description: "In Traefik Proxy's HTTP middleware, ReplacePathRegex updates paths before forwarding requests, using a regex. Read the technical documentation."
---
# ReplacePathRegex
Updating the Path Before Forwarding the Request (Using a Regex)
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The ReplaceRegex replaces the path of a URL using regex matching and replacement.
## Configuration Examples
```yaml tab="Docker"
# Replace path with regex
labels:
- "traefik.http.middlewares.test-replacepathregex.replacepathregex.regex=^/foo/(.*)"
- "traefik.http.middlewares.test-replacepathregex.replacepathregex.replacement=/bar/$$1"
```
```yaml tab="Kubernetes"
# Replace path with regex
apiVersion: traefik.io/v1alpha1
kind: Middleware
metadata:
name: test-replacepathregex
spec:
replacePathRegex:
regex: ^/foo/(.*)
replacement: /bar/$1
```
```yaml tab="Consul Catalog"
# Replace path with regex
- "traefik.http.middlewares.test-replacepathregex.replacepathregex.regex=^/foo/(.*)"
- "traefik.http.middlewares.test-replacepathregex.replacepathregex.replacement=/bar/$1"
```
```yaml tab="File (YAML)"
# Replace path with regex
http:
middlewares:
test-replacepathregex:
replacePathRegex:
regex: "^/foo/(.*)"
replacement: "/bar/$1"
```
```toml tab="File (TOML)"
# Replace path with regex
[http.middlewares]
[http.middlewares.test-replacepathregex.replacePathRegex]
regex = "^/foo/(.*)"
replacement = "/bar/$1"
```
## Configuration Options
### General
The ReplacePathRegex middleware will:
- replace the matching path with the specified one.
- store the original path in a `X-Replaced-Path` header.
!!! tip
Regular expressions and replacements can be tested using online tools such as [Go Playground](https://play.golang.org/p/mWU9p-wk2ru) or the [Regex101](https://regex101.com/r/58sIgx/2).
When defining a regular expression within YAML, any escaped character needs to be escaped twice: `example\.com` needs to be written as `example\\.com`.
### `regex`
The `regex` option is the regular expression to match and capture the path from the request URL.
### `replacement`
The `replacement` option defines the replacement path format, which can include captured variables.
!!! warning
Care should be taken when defining replacement expand variables: `$1x` is equivalent to `${1x}`, not `${1}x` (see [Regexp.Expand](https://golang.org/pkg/regexp/#Regexp.Expand)), so use `${1}` syntax.