chore: inheriting proxy env vars from host when building with docker

[AlseinX]

Modified the build script to pass HTTP_PROXY environment variables from the host machine to the build container, so that developers under GFW would use their custom proxy to build the project.

[Kailai-Wang]

It's great that you proactively submit PRs to tackle the problem you met 👍

Have you tried this?
https://docs.docker.com/network/proxy/

Like using a customised docker config for it - as it doesn't apply to everyone, maybe it's a good idea to keep the change local too

[Kailai-Wang]

It also seems that even without definition inside Dockerfile, the env HTTP_RPOXY can be recognised:

docker build --no-cache --progress=plain  --build-arg HTTP_PROXY="http://proxy.example.com:3128" -t tmp -<<EOF
FROM alpine
RUN env | grep -i _PROXY
EOF

#0 building with "desktop-linux" instance using docker driver

#1 [internal] load .dockerignore
#1 transferring context: 2B done
#1 DONE 0.0s

#2 [internal] load build definition from Dockerfile
#2 transferring dockerfile: 74B done
#2 DONE 0.0s

#3 [internal] load metadata for docker.io/library/alpine:latest
#3 DONE 0.7s

#4 [1/2] FROM docker.io/library/alpine@sha256:eece025e432126ce23f223450a0326fbebde39cdf496a85d8c016293fc851978
#4 CACHED

#5 [2/2] RUN env | grep -i _PROXY
#5 0.160 http_proxy=http://proxy.example.com:3128
#5 0.160 HTTP_PROXY=http://proxy.example.com:3128
#5 DONE 0.2s

#6 exporting to image
#6 exporting layers 0.0s done
#6 writing image sha256:61266719edeac635a4e8a606d67321e8484c20224296759db620c7f617e108c2 done
#6 naming to docker.io/library/tmp done
#6 DONE 0.0s

[AlseinX]

It also seems that even without definition inside Dockerfile, the env HTTP_RPOXY can be recognised:

I performed a test removing the definitions inside Dockerfile, within the server under GFW.
It fails to recognise the proxy settings and seems not to work exactly as documented.

[Kailai-Wang]

I performed a test removing the definitions inside Dockerfile, within the server under GFW.
It fails to recognise the proxy settings and seems not to work exactly as documented

This is utterly strange.
It should at least get those envs assigned inside your docker, what's output if you add RUN env | grep _PROXY in Dockerfile?

Whether it can actually access host proxy is another story.

[AlseinX]

I tried and found that --build-arg HTTP_PROXY="..." only sets exact HTTP_PROXY, and others are unset, therefore it does not recognise, which means I have to pass all of these env vars with --build-arg within the build script
I have recommitted to remove modification on dockerfile.

[Kailai-Wang]

Thanks!

[Kailai-Wang]

In my test --network=host is enough for the container to access services on the host via e.g. localhost:<port-number>, but anyway it's not that important