Preview image on the Allsky Map does not work with http images

[RudyUitDordt]

The worldmap overview at [https://www.thomasjacquin.com/allsky-map/] shows a preview image of your allsky cam. Mine just shows blank. I tried the "image url" at the "remote website settings" but it does not seem to work. The link has no portnumber in it. What is it that I seem to do wrong?

My support file:
support-none-20250503074656.zip

[Oxize]

Ye, someone from allskyteam would look into that. Had something to do with secure site with unsecure link. Asked that last year. Never knew who this gonna pick up to fix it.

[EricClaeys]

@RudyUitDordt,
Try it now. You should see your image.

[RudyUitDordt]

And indeed I do, thanks!
What was the issue?

[EricClaeys]

@RudyUitDordt, as you may know, when a browser requests a web page from a server, the server returns a numeric HTML code and when successful, the page as well. When the server can't find the page, it returns code 404, "Not Found".

When the server DOES find the page, it usually returns HTML code 200 as well as the page. The browser then displays the page.

Your server, for whatever reason, returns code 304 when a browser requests your image. I had to look up what 304 was - it means "not modified". The server was telling your browser that your image hasn't been modified since the last time the image was requested. The server only sends 304, it does not also send the page.

All browsers understand what 304 means, and if they have a cached copy of the image, they display it, otherwise they ask the server for the page again, but in a different way that tells the server "Give me the page; I don't have it".

This is totally transparent to the user.

When you click on your pin on the Allsky Map, the map software requests the image from your Website. That's why there's often a short delay. The Allsky Map, however, isn't a web browser so doesn't understand all the HTML codes like 304. The Map server only knows if it got the image or it didn't. In your case, it didn't (it just got the 304 code), so your browser displayed the tiny generic "image not found" thumbnail.

It took me a couple hours to find out how to have the Allsky Map tell your server "Give me the page; I don't have it".
FYI, I suspect there are other users' servers that also return 304, so this fix will help them as well. This won't help @Oxize since it's a totally different problem.

Click for the actual fix.

When a browser requests a page from a server, the browser tells the server what page to get (i.e., the URL) as well as other stuff like what kind of file it expects back. In the case above, your browser told the server it expected to receive a .jpg file when it requested your image, so the browser sent a string to the server that looks like `Accept: image/jpg`.

Here's where my limited understanding of this handshake fails me. Sending Accept: image/jpg somehow told the server it was ok to send code 304 back without sending the image. The fix is to change what the browser sends to Accept: */* which means "I'll accept anything. This somehow tells the server to send the image back, not a code 304.

[RudyUitDordt]

Thanks for the clear answer, much appreciated!

[Oxize]

Why not mine? :(

[Oxize]

@EricClaeys ok thanks!

[Oxize]

Any luck?

[EricClaeys]

@Oxize,
I spent a couple hours testing on my server and thought I had it working, then it wasn't working and I don't know if I changed/broke something or it was never working and I thought it was.
Anyhow, I haven't testing it in a month.
Thanks for the reminder.

[Oxize]

Ye really looking forward if you can fix this.

[Oxize]

Any luck? @thomasjacquin or @EricClaeys his home setup?

[VReisOAR]

Currently experiencing this issue! Any suggestions to solve it?
http://85.245.200.98/allsky/

[EricClaeys]

@VReisOAR,
Your Image URL in the WebUI is set to http://85.245.200.98/images/20250621/image-20250621220448.jpg which does not exist, that's why your image doesn't appear on the Allsky Map until you click on the link, which takes you to your Pi, and displays the correct image, which is http://85.245.200.98/current/tmp/image.jpg.
So, update your Image URL.

Also, and more important:
You are asking to be hacked by using http on your Pi and not https.

[VReisOAR]

@VReisOAR, Your Image URL in the WebUI is set to http://85.245.200.98/images/20250621/image-20250621220448.jpg which does not exist, that's why your image doesn't appear on the Allsky Map until you click on the link, which takes you to your Pi, and displays the correct image, which is http://85.245.200.98/current/tmp/image.jpg. So, update your Image URL.

Also, and more important: You are asking to be hacked by using http on your Pi and not https.

So, i´m kind of noob with that. Can you help me setting to https? Please!

[EricClaeys]

@VReisOAR,
You can try these instructions, but I always tell people, "if you have to ask how to do it, then don't do it." It's very easy to screw something up and open a big door for hackers to get into. And people like you and I that don't know what we're doing tend to make mistakes.

Do at your own risk.