Caddy as reverse proxy and with subfolder

[beedaddy]

I managed to get KoInsight up and running as rootless Podman Quadlet on my Raspi5. But I have to use a subfolder like http://myhost.fritz.box/koinsight in order to access the KoInsight instance. But a simple

myhost.fritz.box hornet.fritz.box:80 {
	tls internal
	
        [...]

	redir /koinsight /koinsight/
	handle /koinsight/* {
		reverse_proxy 127.0.0.1:8081
	}

	[...]
}

does not work, because /assets and /books etc is then not accessible, and I get a blank page. Has anyone managed to get this work with a subfolder?

[gab-dev-7]

Hi! This is a classic issue

When you reverse proxy to a subfolder like /koinsight, Caddy handles the request just fine, but the HTML returned by the application is unaware of that subfolder.

1. You request myhost.fritz.box/koinsight.
2. Caddy proxies it. The app returns index.html.
3. Inside index.html, the app likely refers to its assets using "absolute" paths, like <script src="/app.js"> or <link href="/styles.css">.
4. The Error: Your browser sees /app.js and requests myhost.fritz.box/app.js (at the root), not myhost.fritz.box/koinsight/app.js.
5. Caddy sees the request for /app.js, sees it doesn't start with /koinsight, and returns a 404 (or your main dashboard).

Use a Subdomain

This is by far the easiest and most robust fix. If you can use koinsight.myhost.fritz.box, the application acts as if it's at the "root" /, and all those asset links (/app.js) work perfectly without any configuration changes.

koinsight.myhost.fritz.box {
    reverse_proxy 127.0.0.1:8081
}

Or Configure Application

For a subfolder to work, the application itself must be configured to know it is running under /koinsight so it can generate links like <script src="/koinsight/app.js">.

You can check if the container supports an environment variable for this (common ones are BASE_URL, PUBLIC_URL, or APP_URL). If the developer hasn't exposed a setting to change the "base path" or "public path" at runtime, Solution 1 is your only easy option.

Hope that clears up why the page is blank!