V2: Reverse proxy strip part of path

[vari (Varun Gupta)]

1. My Caddy version (caddy version):

v2.0.0-rc.3 h1:z2H/QnaRscip6aZJxwTbghu3zhC88Vo8l/K57WUce4Q=

2. How I run Caddy:

a. System environment:

Ubuntu18.04

Caddy is run via systemd service unit.

d. My complete Caddyfile or JSON config:

{
    "apps": {
        "http": {
            "servers": {
                "srv0": {
                    "listen": [":443"],
                    "routes": [
                        {
                            "match": [
                                {
                                    "host": ["localhost", "10.0.2.15"]
                                }
                            ],
                            "handle": [
								{
									"handler": "subroute",
									"routes": [
										{
											"handle": [
												{
													"encodings": {
														"gzip": {}
													},
													"handler": "encode"
												}
											]
										},
										{
											"handle": [
												{
													"handler": "rewrite",
													"uri_substring": [
                                                        {
                                                            "find": "/test",
                                                            "replace": "",
                                                            "limit": 0
                                                        }
                                                    ]
												},
												{
													"handler": "reverse_proxy",
													"upstreams": [
														{
															"dial": "localhost:4325"
														}
													]
												}
											],
											"match": [
												{
													"path": [
														"/test*"
													]
												}
											]
										},
										{
											"handle": [
												{
													"handler": "reverse_proxy",
													"upstreams": [
														{
															"dial": "localhost:4321"
														}
													]
												}
											]
										}
									]
								}
							],
                            "terminal": true
                        }
                    ]
                }
            }
        }
    }
}

3. The problem I’m having:

I’d like to have two reverse proxies set up - one which forwards requests made without any path (i.e. requests to /) to localhost:4321 and one which forwards requests to /test* to localhost:4325. For the second proxy, I’d like to strip the /test prefix from the URI when it is sent to the backend. I tried to use the rewrite handler for this, but it does not work - the /test prefix is being sent to the backend when the request is forwarded.

I’m probably making a mistake somewhere in the JSON config when setting this up so I would appreciate any guidance on how to do this correctly.

4. Error messages and/or full log output:

N/A

5. What I already tried:

Read relevant docs - as far as I can tell the config file should be correct.

[vari (Varun Gupta)]

Update: I enabled debug logging and it seems like the rewrite handler is not running / making changes - the debug output only shows that the http.handlers.reverse_proxy ran and proxied the request. Looking at the relevant code in rewrite.go I should see some output from the rewrite module if a rewrite actually happened. As far as I can tell, the rewrite should be occurring…

I’ve also tried using “strip_path_prefix” but that did not help either. Any suggestions would really be appreciated!

[calisro (Rob)]

I’m not sure if this helps. But this is what I use in the caddyfile (not json). Perhaps you can adapt it?

route /rct/* {
      uri strip_prefix rct
      reverse_proxy  localhost:6439 {
          header_up X-Real-IP {remote}
      }
}

[matt (Matt Holt)]

@vari You skipped some of the questions in the template How can we reproduce the problem you’re seeing?

[vari (Varun Gupta)]

The problem was that the output wasn’t giving my anything apart from the reverse proxy handler attempting to handle the non-stripped path so I figured that output wouldn’t be useful. In hindsight that was probably not a great decision on my part

I tested my config again and it seems to be working fine now. The only thing I modified was changing the matcher path to "/test" instead of "/test*". Not sure why that fixes the issue, but things work now so I’ll be leaving the config alone.

[matt (Matt Holt)]

No worries, thanks for clarifying!

@vari

I tested my config again and it seems to be working fine now. The only thing I modified was changing the matcher path to "/test" instead of "/test*" .

Huh, but your config posted above already has a matcher of /test* (with the asterisk). And indeed that should work.

Path matching is exact, unless you suffix with a * and then it is a prefix match: Request matchers (Caddyfile) — Caddy Documentation

PS. You can replace your whole uri_substring rewrite with "strip_path_prefix": "/test" since what you currently have doesn’t guarantee it will replace only the prefix. And it’s simpler.