Octoprint: Download GCode Link Error with forwarded port

[RandomArker]

---

What were you doing?

Trying to download GCode from the http web interface on a port other than 80

1. Set up proxy to forward any port other than 80 to the plain http interface (not tried with SSL).. i.e. port 8000 to octoprint
2. go to octoprint at port 8000
3. try and download a gcode file

What did you expect to happen?

For the gcode file to download.

What happened instead?

404 - File Not Found (because the link contains no port information)

Did the same happen when running OctoPrint in safe mode?

Yes

Branch & Commit or Version of OctoPrint

OctoPrint 1.3.5 (master branch)

Operating System running OctoPrint

OctoPi 0.14

Printer model & used firmware incl. version

Creality CR-10 Stock

Browser and Version of Browser, Operating System running Browser

Edge, Windows 10
Chrome, Windows 10
Firefox, CentOS 7
Internet Explorer, Windows 7

Link to octoprint.log

Not applicable

Link to contents of terminal tab or serial.log

Not applicable

Link to contents of Javascript console in the browser

https://pastebin.com/7w9aKxkp

Screenshot(s)/video(s) showing the problem:

Screenshot attached

I have read the FAQ.

[GitIssueBot]

Hi @BinoX,

It looks like there is some information missing from your bug report that will be needed in order to solve the problem. Read the Contribution Guidelines which will provide you with a template to fill out here so that your bug report is ready to be investigated (I promise I'll go away then too!).

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I'm marking this one now as needing some more information. Please understand that if you do not provide that information within the next two weeks (until 2017-11-27 13:20 UTC) I'll close this ticket so it doesn't clutter the bug tracker. This is nothing personal, so please just be considerate and help the maintainers solve this problem quickly by following the guidelines linked above. Remember, the less time the devs have to spend running after information on tickets, the more time they have to actually solve problems and add awesome new features. Thank you!

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[kantlivelong]

Hmm... I'm not able to replicate this behavior. How is the proxy configured?

[RandomArker]

I'll post up my config in about a hour. It's an NGINX reverse proxy set up, which I use quite a lot for this kind of task...

I've also noticed that it happens for downloading log files as well, but downloading timelapses is fine

[foosel]

That sure is one long hour ;)

Any updates on the config?

[RandomArker]

Whoops! Terribly sorry, I completely forgot I posted this... Remembered when I tried to use it again earlier.
I use a similar config for other sites and services and they all work fine... Maybe Octoprint requires some extra settings...

Anyway here is my nginx config:

server {
    listen 8000;
    server_name _;

    location / {
        proxy_pass http://192.168.0.34:80;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

[kantlivelong]

Change proxy_set_header Host $host; to proxy_set_header Host $http_host;

[foosel]

OctoPrint needs to know what port a request is coming in on or it will assume the default port for the URL scheme. For that it will evaluate - in that order - the X-Forwarded-Hostheader, the Host header and the X-Forwarded-Server and X-Forwarded-Port headers.

Nginx' $host variable does never contain the port number (see also here). So if you do something like proxy_set_header Host $host;, if you connect then via http://example.com:8080 your nginx will only forward Host: example.com and quietly throw away the port number. So for lack of alternative information OctoPrint will default to the scheme default port 80 in such a case.

$http_host on the other hand is the actual Host header sent with the request, including the port number (so example.com:8080) - so use that and all will work just fine. Alternatively you can also use $host:$server_port - see the examples.

OctoPrint does generate some absolute URLs server side based on the incoming request on API responses that are used for downloads and such in the frontend - that's why it also needs the full port information. Other services might only generate relative URLs which then magically work even though the server only gets half of the facts.

[RandomArker]

Whoops, feeling a little embarrassed now. I've been administering Nginx (and various other systems) servers for years and I totally didn't see that I had only put $host instead of $http_host

I should know better than that! Fallen into the "blame everyone except myself" trap. I think I must have used one of my "trick" configs as a template (I have a few services that do not like anything other than the standard port being used... I did not write them!!!!)

Anyway,
Many thanks for showing me my mistake. Donation en route