mapproxy-util is being executed as a python script

[CMCDragonkai]

Hi, we are packaging mapproxy for NixOS: NixOS/nixpkgs#68628. And we have hit some problems.

The main problem is that Nix will wrap executables as shell scripts in order to create an isolated environment. Once we execute mapproxy-util serve-develop mapproxy.yaml we get a syntax error.

»» ~/Projects/mapproxy/mymapproxy
 ♖ ../result/bin/mapproxy-util serve-develop mapproxy.yaml
[2019-10-02 13:22:18,621] mapproxy.config - INFO - reading: /home/cmcdragonkai/Projects/mapproxy/mymapproxy/mapproxy.yaml
[info]  * Running on http://127.0.0.1:8080/ (Press CTRL+C to quit)
[info]  * Restarting with reloader
  File "/nix/store/bfvw32p8c61jajjm7a8z98xbk1n6qiwz-python3.7-MapProxy-1.12.0/bin/mapproxy-util", line 2
    export PATH='/nix/store/kimimvhimclyfzlncpg36zjni3wn70nq-python3-3.7.3/bin:/nix/store/bfvw32p8c61jajjm7a8z98xbk1n6qiwz-python3.7-MapProxy-1.12.0/bin:/nix/store/rpayih9fb4ms2wjvmyn6kp7kmsizim49-python3.7-setuptools-40.8.0/bin:/nix/store/kp0g7z5h4kr6gx71jf9q0a9322p4jr5p-python3.7-numpy-1.16.2/bin:/nix/store/7vgnq00rxw9xh03920apdyj4ibgsmrix-gdal-2.4.0/bin'${PATH:+':'}$PATH
              ^
SyntaxError: invalid syntax

I suspect that this is occurring because mapproxy thinkgs that mapproxy-util is a python script. And from Nix's perspective these are arbitrary executables. So they should just be executed like any other executable without needing to call it again from python.

What we would do in Nixpkgs is to basically hotpatch the package so that it doesn't bother trying to call the script as a python script. This is similar to what we had to do for dvc: https://github.com/NixOS/nixpkgs/pull/54530/files#diff-551883c582fc9bc6f5388f662439af05

What I'd like to know is where your this patch is best applied? Where exactly in the program are you recalling mapproxy-util script like a Python script.

[Rakesh4G]

Hi all,
This issue seems to be fixed we add the following change in mapproxy/util/ext/serving.py.
replace "args = [sys.executable] + sys.argv" with
"args = sys.argv"

[olt]

This likely will break the reloading on other systems.

[CMCDragonkai]

That can be a Nixpkgs specific patch.

…

On 28 November 2019 13:53:55 GMT+08:00, Rakesh Gupta ***@***.***> wrote: Hi all, This issue seems to be fixed we add the following change in **mapproxy/util/ext/serving.py**. replace **"args = [sys.executable] + sys.argv"** with **"args = sys.argv"** -- You are receiving this because you authored the thread. Reply to this email directly or view it on GitHub: #424 (comment)

-- Sent from my Android device with K-9 Mail. Please excuse my brevity.

[CMCDragonkai]

Looks like this is done for Nixpkgs.