added redirect to pull non-existant local assets from live_endpoint url

[sjuerges]

This PR implements #69

It achieves that the nginx can serve local assets as before, but it will send HTTP 302 redirects to the standard live_endpoint url for files that are NOT found locally.

[antonym]

Seemed to work, but I notice it seems to have issues with the assets that contain a part2 file. It only downloads the first part if not found locally but fails on the second part.

[sjuerges]

Weird, wasnt an issue for me, specifically tested for it:
(local):

172.18.0.5 - - [03/Aug/2024:22:02:31 +0000] "GET /asset-mirror/releases/download/Galileo-11-2023-e0c48f1f/vmlinuz HTTP/1.1" 200 12881792 "-" "iPXE/1.21.1+ (g5a9f4)"                                                                            
172.18.0.5 - - [03/Aug/2024:22:02:32 +0000] "GET /asset-mirror/releases/download/Galileo-11-2023-e0c48f1f/initrd HTTP/1.1" 200 104039372 "-" "iPXE/1.21.1+ (g5a9f4)"                                                                            
172.18.0.5 - - [03/Aug/2024:22:02:34 +0000] "GET /asset-mirror/releases/download/Galileo-11-2023-e0c48f1f//airootfs.sfs HTTP/1.1" 206 1 "-" "curl/8.4.0"                                                                                        
172.18.0.5 - - [03/Aug/2024:22:02:52 +0000] "GET /asset-mirror/releases/download/Galileo-11-2023-e0c48f1f//airootfs.sfs HTTP/1.1" 200 2097151999 "-" "curl/8.4.0"                                                                               
172.18.0.5 - - [03/Aug/2024:22:02:53 +0000] "HEAD /asset-mirror/releases/download/Galileo-11-2023-e0c48f1f//airootfs.sfs.part2 HTTP/1.1" 200 0 "-" "curl/8.4.0"                                                                                 
172.18.0.5 - - [03/Aug/2024:22:02:55 +0000] "GET /asset-mirror/releases/download/Galileo-11-2023-e0c48f1f//airootfs.sfs.part2 HTTP/1.1" 200 258531329 "-" "curl/8.4.0"  

(remote):

172.18.0.5 - - [03/Aug/2024:21:55:07 +0000] "GET /ubuntu-squash/releases/download/1.2-e7db33e3/vmlinuz HTTP/1.1" 302 145 "-" "iPXE/1.21.1+ (g5a9f4)"                                                                                            
172.18.0.5 - - [03/Aug/2024:21:55:09 +0000] "GET /ubuntu-squash/releases/download/1.2-e7db33e3/initrd HTTP/1.1" 302 145 "-" "iPXE/1.21.1+ (g5a9f4)"                                                                                             
172.18.0.5 - - [03/Aug/2024:21:55:19 +0000] "HEAD /ubuntu-squash/releases/download/1.2-e7db33e3/filesystem.squashfs HTTP/1.1" 302 0 "-" "curl/7.67.0"                                                                                           
172.18.0.5 - - [03/Aug/2024:21:55:19 +0000] "GET /ubuntu-squash/releases/download/1.2-e7db33e3/filesystem.squashfs HTTP/1.1" 302 145 "-" "curl/7.67.0"                                                                                          
172.18.0.5 - - [03/Aug/2024:21:57:05 +0000] "HEAD /ubuntu-squash/releases/download/1.2-e7db33e3/filesystem.squashfs.part2 HTTP/1.1" 302 0 "-" "curl/7.67.0"                                                                                     
172.18.0.5 - - [03/Aug/2024:21:57:05 +0000] "GET /ubuntu-squash/releases/download/1.2-e7db33e3/filesystem.squashfs.part2 HTTP/1.1" 302 145 "-" "curl/7.67.0" 

@antonym Which image did you test with, maybe I can replicate/debug?

[nrvale0]

Related but tangential. Hope that's ok...

If I wanted to test this using netboot.xyz running in Docker Compose would it be sufficient to just pull the branch and then use the docker-compose.yml.example? I suspect I might also have to modify the image name also? Or just do a docker build of the default Dockerfile + tags but while this branch is selected in order to pull the modified default file?

EDIT: Yes, changing to the PR branch and rebuilding the image with the same tag/name worked.