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Documentation

Request Matchers

Request matchers can be used to filter (or classify) requests by specific criteria.

Syntax

In the Caddyfile, a matcher token immediately following the directive can limit that directive's scope. The matcher token can be one of these forms:

  1. * to match all requests (wildcard; default).
  2. /path start with a forward slash to match a request path.
  3. @name to specify a named matcher.

Matcher tokens are usually optional. If a matcher token is omitted, it is the same as a wildcard matcher (*).

Examples

This directive applies to all HTTP requests:

reverse_proxy localhost:9000

And this is the same:

reverse_proxy * localhost:9000

But this directive applies only to requests having a path starting with /api/:

reverse_proxy /api/* localhost:9000

To match on anything other than a path, define a named matcher and refer to it using @name:

@post {
	method POST
}
reverse_proxy @post localhost:9000

Wildcard matchers

The wildcard matcher * matches all requests, and is only needed if a matcher token is required. For example, if the first argument you want to give a directive also happens to be a path, it would look exactly like a path matcher! So you can use a wildcard matcher to disambiguate, for example:

root * /home/www/mysite

Otherwise, this matcher is not often used. It is convenient to omit it when possible; just a matter of preference.

Path matchers

Because matching by path is so common, a single path matcher can be inlined, like so:

redir /old.html /new.html

Path matcher tokens must start with a forward slash /.

Path matching is an exact match by default; you must append a * for a fast prefix match. Note that /foo* will match /foo and /foo/ as well as /foobar; you might actually want /foo/* instead.

Named matchers

Defining a matcher with a unique name gives you more flexibility, allowing you to combine any available matchers into a set:

@name {
	...
}

Then you can use the matcher like so: @name

For example:

@websockets {
	header Connection *Upgrade*
	header Upgrade    websocket
}
reverse_proxy @websockets localhost:6001

This proxies only the requests that have a header field named "Connection" containing the word "Upgrade", and another field named "Upgrade" with a value of "websocket".

Like directives, named matcher definitions must go inside the site blocks that use them.

A named matcher definition constitutes a matcher set. Matchers in a set are AND'ed together; i.e. all must match. For example, if you have both a header and path matcher in the set, both must match.

For most matchers that accept multiple values, those values are OR'ed; i.e. one must match in order for the matcher to match.

Standard matchers

Full matcher documentation can be found in each respective matcher module's docs.

expression

⚠️ This module is still experimental and, as such, may experience breaking changes.

expression <cel...>

By any CEL (Common Expression Language) expression that returns true or false.

As a special case, Caddy placeholders (or Caddyfile shorthands) may be used in these CEL expressions, as they are preprocessed and converted to regular CEL function calls before being interpreted by the CEL environment.

Examples:

expression {method}.startsWith("P")

file

file {
	root      <paths>
	try_files <files...>
	try_policy first_exist|smallest_size|largest_size|most_recent_modified
}

By files.

  • root defines the directory in which to look for files. Default is the current working directory, or the root variable ({http.vars.root}) if set (can be set via the root directive).
  • try_files checks files in its list that match the try_policy.
  • try_policy specifies how to choose a file. Default is first_exist.
    • first_exist checks for file existence. The first file that exists is selected.
    • smallest_size chooses the file with the smallest size.
    • largest_size chooses the file with the largest size.
    • most_recent_modified chooses the file that was most recently modified.

An empty file matcher will see if the requested file (verbatim from the URI, relative to the site root) exists.

header <field> <value>

By request header fields.

  • <field> is the name of the HTTP header field to check.
  • <value> is the value the field must have to match.
    • If prefixed with *, it performs a fast suffix match.
    • If suffixed with *, it performs a fast prefix match.
    • If enclosed by *, it performs a fast substring match.
    • Otherwise, it is a fast exact match.

header_regexp

header_regexp [<name>] <field> <regexp>

Like header, but supports regular expressions. Capture groups can be accessed via placeholder like {http.regexp.name.capture_group} where name is the name of the regular expression (optional, but recommended) and capture_group is either the name or number of the capture group in the expression.

host

host <hosts...>

Matches request by the Host header field of the request. It is not common to use this in the Caddyfile, since most site blocks already indicate hosts in the address of the site. This matcher is mostly used in site blocks that don't define specific hostnames.

method

method <verbs...>

By the method (verb) of the HTTP request. Verbs should be uppercase, like POST.

not

not {
	<any other matchers...>
}

Encloses other matchers and negates their result.

path

path <paths...>

By request path, meaning the path component of the request's URI. Path matches are exact, but wildcards * may be used:

  • At the end, for a prefix match (/prefix/*)
  • At the beginning, for a suffix match (*.suffix)
  • On both sides, for a substring match (*/contains/*)
  • In the middle, for a globular match (/accounts/*/info)

path_regexp

path_regexp [<name>] <regexp>

Like path, but supports regular expressions. Capture groups can be accessed via placeholder like {http.regexp.name.capture_group} where name is the name of the regular expression (optional, but recommended) and capture_group is either the name or number of the capture group in the expression.

protocol

protocol http|https|grpc

By request protocol.

query

query <key>=<val>...

By query string parameters. Should be a sequence of key=value pairs.

remote_ip

remote_ip <ranges...>

By remote (client) IP address. Accepts exact IPs or CIDR ranges.