[Bug] Kobo Sync API not available via reverse proxy

[Matthias-vdE]

What Went Wrong?

I have my instance of Booklore behind a npm-plus reverse proxy. This is reachable via https://booklore.mydomain.com. I can login, edit books, everything works just fine.

However, trying to reach the API endpoint:

https://booklore.mydomain.com/api/kobo/{api-key} always redirects me to the homepage.

Using the IP address

http://{ip}:{port}/api/kobo/{api-key}

Gives me a JSON web page.

My Kobo Ereader conf file contains the required "api_endpoint" for syncing.

Using my domain name does not work. Using the IP and Port does work.

However, this did work in the previous version. Nothing has changed about my proxy configuration. I am still using the advanced config as described in https://booklore.org/docs/integration/kobo?_highlight=reverse&_highlight=proxy#%EF%B8%8F-nginx-proxy-configuration

Neither the Booklore container, nor the npm-plus container are showing errors. My Kobo gives the error "Sync Failed. No Internet Access" when using the domain name instead of the ip:port.

How Can We Reproduce This?

1. Use booklore behind an npm-plus reverse proxy: Sync Failed.
2. Use booklore directly via ip:port: Sync works.

What Should Have Happened?

Sync should also work via reverse proxy when configured as described in the documentation.

Screenshots or Error Messages (Optional)

No response

Any Ideas on How to Fix This? (Optional)

No response

Your Setup

• Booklore v1.18.5
• Installation: Docker
• Reverse proxy: npm-plus

Before Submitting

• I've searched existing issues and confirmed this bug hasn't been reported yet

[ja-m]

Same here. I'm behind Cloudflare.
With the local URL, everything is ok:
http://local.lan:6060/api/kobo/<token>

If I use the external address
https://cloudflare.tunnel/api/kobo/<token>
it redirects me to the Login-Page.

[Toastienergy]

I´m trying to find out what I did wrong for over 1 hour. I have the same problem

[balazs-szucs]

Did you try some of the suggestions here: janeczku/calibre-web#1891 (comment) or here: https://www.reddit.com/r/Calibre/comments/ybmn1n/calibre_web_kobo_sync_issue_docker_reverse_proxy/

Or existing Booklore tickets?

[ja-m]

I have no problems with calibre-web.
My settings there:
External port in calibre-web: 80
Calibre-web-Docker-Port: 8083:8083
Cloudflare URL: https://cloudflare.tunnel

[Pinewood538]

Just ran into this issue today. Maybe this function in KoboUrlBuilder.java is the culprit:

if (IP_ADDRESS_PATTERN.matcher(host).matches() || "localhost".equals(host)) {
	builder.port(port);
}

which is why it works when given an IP address, but not when given a domain

EDIT: my problem actually looks to be different than yours. I can sync, but the actual download links generated by Booklore for my kobo device have the port removed due to the above function.

[Matthias-vdE]

Did you try some of the suggestions here: janeczku/calibre-web#1891 (comment) or here: https://www.reddit.com/r/Calibre/comments/ybmn1n/calibre_web_kobo_sync_issue_docker_reverse_proxy/

Or existing Booklore tickets?

Both of these links refer to the API endpoint as

api_endpoint=https://books.<domain>/kobo/<token>

But Booklore documentation mentions

api_endpoint=https://<your-domain>/api/kobo/<your-token>

Notice the /api/ difference in the URL. And this appears to be correct, as it works fine with ip:port.

I don't think there's an issue with proxy buffers either, as those are changed via the npm advanced config as described in the documentation.

Furthermore, it worked with the previous version. Which is to say I'm definitely not ruling out an issue with my environment, but nothing has changed there between Booklore versions.

[perrottg]

It may be how your reverse proxy is configured as it is working for me on 1.18.5. I am using traefik as the reverse proxy.

[Toastienergy]

It may be how your reverse proxy is configured as it is working for me on 1.18.5. I am using traefik as the reverse proxy.

What is your setup? Also using traefik myself and it's not working

[Matthias-vdE]

Would also be interested what it looks like in Traefik. Here is my currently non-functioning npm-plus configuration:

(The LANOnly ACL is not the issue here. Using any of the other options makes no difference. Yes I am using a different port as the default was already in use.)

Changing any of the TLS options doesn´t seem to make a difference for this issue.

I don´t have any custom locations. This is my advanced config, as per the documentation:

[Toastienergy]

I don't know how this happened but my API endpoint wasn't /Kobo but /koreader. So at least for me everything works perfectly.

[rogueai]

I'm not sure if this is related, but I've found that KoboUrlBuilder only considers an ip address when building X-Forwarded-Port, that doesn't work on my traefik setup as I have booklore under https://my-domain:1234

[hot22shot]

Hello, it works for me using traefik, here's my complete traefik configuration for booklore :

labels:
      traefik.enable: true
      traefik.docker.network: mytraefiknetwork
      traefik.http.routers.booklore.tls: true
      traefik.http.routers.booklore.tls.certresolver: mytlsprovider
      traefik.http.routers.booklore.rule: Host(`booklore.mydomain.ext`)
      traefik.http.routers.booklore.entryPoints: websecure
      traefik.http.services.booklore.loadbalancer.server.port: 6060
      # --- Settings for kobo sync with booklore
      # --- 1. Headers (Optional but recommended for sync reliability) ---
      # Forces the "X-Forwarded-Proto: https" to ensure the app generates https:// links
      traefik.http.middlewares.booklore-headers.headers.sslredirect: true
      traefik.http.middlewares.booklore-headers.headers.stsseconds: "31536000"
      traefik.http.middlewares.booklore-headers.headers.browserxssfilter: true
      # --- 2. Buffering (Equivalent to Nginx proxy_buffers) ---
      # Retries request if network error occurs (helps with fragile syncs)
      traefik.http.middlewares.booklore-buffer.buffering.retryExpression: "IsNetworkError() && Attempts() <= 2"
      # Max Request Body: ~2GB (Allows large book uploads)
      traefik.http.middlewares.booklore-buffer.buffering.maxRequestBodyBytes: "2000000000"
      # Max Response Body: ~2GB (Allows large book downloads during sync)
      traefik.http.middlewares.booklore-buffer.buffering.maxResponseBodyBytes: "2000000000"
      # Memory Limit: 1MB (Equivalent to 'proxy_buffer_size', flushes to disk after this)
      traefik.http.middlewares.booklore-buffer.buffering.memRequestBodyBytes: "1048576"
      traefik.http.middlewares.booklore-buffer.buffering.memResponseBodyBytes: "1048576"
      # --- Apply the Middlewares ---
      traefik.http.routers.booklore.middlewares: "booklore-headers,booklore-buffer"

And for reference my kobo configuration api endpoint is :

api_endpoint=https://booklore.mydomain.ext/api/kobo/mytoken

[FileGo]

Has anybody got this working with Caddy as reverse proxy?