a6-plugin-redirect

Overview

The redirect plugin sends HTTP redirect responses (301, 302, etc.) to clients. It can redirect to a new URI, enforce HTTPS, or use regex patterns for complex path transformations. Unlike proxy-rewrite (which rewrites before forwarding to upstream), this plugin returns a redirect response directly to the client.

When to Use

• Enforce HTTPS by redirecting all HTTP requests
• Redirect old URLs to new locations (301 permanent redirect)
• Pattern-based URI rewrites using regex capture groups
• Redirect to external domains
• Append or preserve query strings during redirects

Plugin Configuration Reference (Route/Service)

Field	Type	Required	Default	Description
http_to_https	boolean	No	false	Redirect HTTP to HTTPS. Preserves URI and query string. Uses 301 status.
uri	string	No	—	Target redirect URI. Supports Nginx variables ($uri, $host, etc.). Can be absolute URL.
regex_uri	array[string]	No	—	Two-element array: ["regex_pattern", "replacement"]. PCRE regex with capture groups.
ret_code	integer	No	302	HTTP status code for the redirect response.
encode_uri	boolean	No	false	Encode the URI in the Location header per RFC 3986.
append_query_string	boolean	No	false	Append the original request query string to the redirect Location.

Mutual exclusion: Only ONE of http_to_https, uri, or regex_uri can be configured at a time.

Note: http_to_https and append_query_string cannot be used together (http_to_https already preserves query strings).

HTTPS Port Selection (for http_to_https)

When http_to_https is true, the HTTPS port is determined by priority:

1. plugin_attr.redirect.https_port in conf/config.yaml
2. Random port from apisix.ssl.listen (if SSL configured)
3. Default: 443

Step-by-Step: Enable redirect on a Route

1. HTTP to HTTPS redirect

a6 route create -f - <<'EOF'
{
  "id": "force-https",
  "uri": "/*",
  "plugins": {
    "redirect": {
      "http_to_https": true
    }
  }
}
EOF

Result: http://example.com/path?q=1 → https://example.com/path?q=1 (301)

2. Simple URI redirect (moved permanently)

a6 route create -f - <<'EOF'
{
  "id": "old-to-new",
  "uri": "/old-page",
  "plugins": {
    "redirect": {
      "uri": "/new-page",
      "ret_code": 301
    }
  }
}
EOF

3. Regex-based redirect with capture groups

a6 route create -f - <<'EOF'
{
  "id": "regex-redirect",
  "uri": "/blog/*",
  "plugins": {
    "redirect": {
      "regex_uri": ["^/blog/(\\d{4})/(\\d{2})/(.*)$", "/articles/$1-$2-$3"],
      "ret_code": 301
    }
  }
}
EOF

Result: /blog/2024/03/my-post → /articles/2024-03-my-post

Common Patterns

Redirect to external domain

{
  "plugins": {
    "redirect": {
      "uri": "https://new-domain.com/api/v2",
      "ret_code": 301
    }
  }
}

Redirect with Nginx variables

{
  "plugins": {
    "redirect": {
      "uri": "https://new-domain.com$request_uri",
      "ret_code": 301
    }
  }
}

Preserves the full original path and query string.

Append trailing slash

{
  "plugins": {
    "redirect": {
      "uri": "$uri/",
      "ret_code": 301
    }
  }
}

Redirect with query string preservation

{
  "plugins": {
    "redirect": {
      "uri": "/new-path",
      "append_query_string": true,
      "ret_code": 302
    }
  }
}

Request: /old-path?foo=bar&baz=1 → Location: /new-path?foo=bar&baz=1

Encode special characters in URI

{
  "plugins": {
    "redirect": {
      "uri": "/path with spaces/resource",
      "encode_uri": true,
      "ret_code": 302
    }
  }
}

Location header: /path%20with%20spaces/resource

Temporary redirect (302) for maintenance

{
  "plugins": {
    "redirect": {
      "uri": "/maintenance.html",
      "ret_code": 302
    }
  }
}

Use 302 (temporary) so browsers don't cache the redirect.

Troubleshooting

Symptom	Cause	Fix
Redirect loop	Route matches the redirect target	Ensure the target URI doesn't match the same route
Wrong HTTPS port	Default port selection	Set plugin_attr.redirect.https_port in config.yaml
Query string lost	Using uri without append_query_string	Add "append_query_string": true or use $request_uri
Duplicate query string	append_query_string with $request_uri	Don't combine both — $request_uri already includes query string
Nginx variable empty	Variable doesn't exist	Non-existent variables resolve to empty string (no error)
Regex not matching	Escaping or pattern issue	Escape backslashes in JSON: \\d+. Test regex with PCRE syntax.
Multiple redirect options set	http_to_https, uri, regex_uri are mutually exclusive	Use only ONE of the three options

Config Sync Example

version: "1"
routes:
  - id: force-https
    uri: /*
    plugins:
      redirect:
        http_to_https: true
  - id: old-blog-redirect
    uri: /blog/*
    plugins:
      redirect:
        regex_uri:
          - "^/blog/(\\d{4})/(\\d{2})/(.*)"
          - "/articles/$1-$2-$3"
        ret_code: 301