Rewrite or redirect Firebase Function

Help
1

1. Caddy version (caddy version): v2.2.1

2. How I run Caddy: As a systemd service on Ubuntu server 20.04. Default Caddyfile on /etc/caddy/Caddyfile

a. System environment: Ubuntu server 20.04

b. Command:

service caddy restart

c. Service/unit/compose file:

[Unit]
Description=Caddy
Documentation=https://caddyserver.com/docs/
After=network.target network-online.target
Requires=network-online.target

[Service]
User=caddy
Group=caddy
ExecStart=/usr/bin/caddy run --environ --config /etc/caddy/Caddyfile
ExecReload=/usr/bin/caddy reload --config /etc/caddy/Caddyfile
TimeoutStopSec=5s
LimitNOFILE=1048576
LimitNPROC=512
PrivateTmp=true
ProtectSystem=full
AmbientCapabilities=CAP_NET_BIND_SERVICE

[Install]
WantedBy=multi-user.target

d. My complete Caddyfile or JSON config:

{
    email myemail@example.com
}

subdomain.domain.com, www.subdomain.domain.com {
    root * /usr/share/caddy
    file_server
    import webconf

    uri replace /api/ /test_api/
    reverse_proxy /test_api/* https://region-project.cloudfunctions.net
}

3. The problem I’m having:

Hello there.
I’m using Firebase Cloud functions and I’m trying to give them pretty urls. I want to point specific URLs from Caddy to another specific URL (firebase function url).

In the example Caddyfile I’m trying to redirect any request received at subdomain.domain.com/api to be redirected to https://region-project.cloudfunctions.net/test_api without the client noticing they’re actually calling Firebase.
I’m trying to make this work to every subsequent resource, i.e. subdomain.domain.com/api/resource to https://region-project.cloudfunctions.net/test_api/resource

I would like to understand what I need to do to achieve that. All help is appreciated!

4. Error messages and/or full log output:

I receive a 404 http error page issued by Google for this endpoint.

5. What I already tried:

I’ve tried to use uri replace and also rewrite for the /api path and reverse proxy after that.

6. Links to relevant resources:

2

That should work okay…

What’s import webconf pulling in? That’s not included in what you posted.

Another approach would be to use handle_path instead (which implicitly strips a prefix from a URL), give this a shot:

handle_path /api* {
	rewrite * /test_api{path}
	reverse_proxy https://region-project.cloudfunctions.net
}

Oh come to think of it, I think it’s likely because the upstream expects the Host to be set to your cloudfunctions domain:

reverse_proxy https://region-project.cloudfunctions.net {
	header_up Host region-project.cloudfunctions.net
}

By default, Caddy will pass through the domain from the original request (i.e. subdomain.domain.com or whatever) for the Host, and this likely breaks what Google wanted.

3

Thank you so much for your quick help!

Sorry, I missed that. Is just this:

    (webconf) {
      encode gzip
    }

As for using handle_path as you suggested, it works the same, getting the same error from Google. When I try adding the Host header inside the reverse_proxy directive, like this:

subdomain.domain.com, www.subdomain.domain.com {
    root * /usr/share/caddy
    file_server
    #import webconf

    handle_path /api* {
        rewrite * /test_api{path}
        reverse_proxy https://region-project.cloudfunctions.net{
            header_up Host region-project.cloudfunctions.net
        }
    }
}

I got the error Error during parsing: due to parsing difficulties, placeholders are not allowed when an upstream address contains a scheme.

Is there anyway to add such header to that reverse_proxy?

Thank you so much.

4

You missed the space before the {. Spaces are important in the Caddyfile. The lexer tokenizes the config by using whitespace as the delimiter. Here, Caddy thinks your upstream is a placeholder because it contains { which isn’t allowed here (when using https:// as well).

1 Like
5

I get it. Thank you so much for your help, it works perfectly now.

1 Like
6

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