John Siu Blog

Hugo - Caddy Redirect

☰ Table of Content

If you migrate from wordpress or ghost.

What Is Needed

Redirections For WordPress Migration

#	From	To
1	`/index.php/`	`/`
2	`/index.php/*`	`/post/*`
3	`/index.php/category/*`	`/tags/*`
4	`/index.php/tag/*`	`/tags/*`
5	`/wp-login.php`	`/`

Redirections For Ghost Migration

#	From	To
6	`/*`	`/post/*`
7	`/category/*`	`/tags/*`
8	`/tag/*`	`/tags/*`

Details

Take #4 /index.php/tag/* to /tags/* as example, caddyfile will look like follow:

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example.com {
  file_server
  root * /www/site/example.com

  # Redirect #4
  @index2root path_regexp ^/index.php/tag/?(.*)
  redir @index2root /tags/{http.regexp.1}
}

Repeat the same for the remaining 7 and start looking ugly.

Factorize

When looking at the requirements, all redirects can be summarized into 2 rules:

Rule #	From	To	Comment
1	`<some path\>`	`<some path>/*`	Change path
2	`/<file/dir>`	`<some path>/*`	Move root level items to another path

Take /index.php/tag/* to /tags/* as example, it can be break into 2 steps:

/index.php/tag/* to /tag/*
/tag/* to /tags/*

Rule #1 applies to both steps. Creating common rule block in Caddy for Rule #1 and Rule #2 will cover all migration needs.

Caddy Snippets

Caddy v2 support snippet, a parameterized block that works like function call in programming.

Rule #1 Snippets

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(my_redir) {
	@{args.0} {
		path_regexp r ^{args.0}/?(.*)
		not path_regexp ^/tags/?.*
	}
	redir @{args.0} {args.1}{re.r.1}
}

This snippet will redirect {args.0}*, the request url, to {args.1}*.

It will not execute if request url is /tags*. This is to prevent redirect loop between /tag and /tags.

Again take /index.php/tag/* to /tags/* as example:

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import my_redir /index.php /
import my_redir /tag /tags/

Rule #2 Snippets

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(my_tryfile) {
	@{args.0} {
		file /{args.0}/{path}index.html /{args.0}/{path}/index.html
		path_regexp {args.0} ^/([^/]+)/?$
	}
	redir @{args.0} /{args.0}/{re.{args.0}.1}/
}

This snippet will redirect root level item request, to {args.0}/<item>, only if {args.0}/<item>/index.html exist.

Each site can only have one my_tryfile.

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import my_tryfile post

Final Solution

Following is caddyfile that covers all 8 redirections mentioned at the beginning:

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(my_redir) {
	@{args.0} {
		path_regexp r ^{args.0}/?(.*)
		not path_regexp ^/tags/?.*
	}
	redir @{args.0} {args.1}{re.r.1}
}

(my_tryfile) {
	@{args.0} {
		file /{args.0}/{path}index.html /{args.0}/{path}/index.html
		path_regexp {args.0} ^/([^/]+)/?$
	}
	redir @{args.0} /{args.0}/{re.{args.0}.1}/
}

example.com {
	file_server
	root * /www/site/example.com

  # Redirect
	import my_redir /category /tags/
	import my_redir /cheatsheet /blog/
	import my_redir /index.php /
	import my_redir /tag /tags/
	import my_redir /wp-login.php /
	import my_tryfile blog
}