Inherit proxy configuration

[imagejan]

Using appose (e.g. through installation of SAMJ-IJ) behind a proxy can fail, even if the proxy is correctly set in Fiji/ImageJ.

We should document how proxy settings should be set:

• having a proxy_servers entry in ~/.condarc works currently (for conda/micromamba-based environment creation)
• for a future pixi-based solver, the proxy configuration would probably need to go to the pixi configuration (see also Add info for proxy-config to docs prefix-dev/pixi#4150)

Alternatively, Fiji could propagate the setting from the Java side to the mamba/pixi invocation by setting the HTTPS_PROXY environment variable(s) appropriately.

[ctrueden]

@imagejan I like the idea of propagating the setting from Java to the environment builder (via env vars or whatever that build tool prefers). Do you think it's sufficient to look at the system properties https.proxyHost, https.proxyPort, http.proxyHost, and http.proxyPort? Do you do anything else to configure your Fiji to work with your proxy setup?

[imagejan]

@ctrueden for most Fiji plugins (i.e. everything Java), the setting in Edit > Options > Proxy Settings... is sufficient, yes. So I guess https.proxyHost etc. for looking up should be sufficient, right?

[ctrueden]

From the source code, yeah, it looks like the Proxy Settings plugin sets those system properties. But it also sets the ImageJ prefs proxy.server and proxy.port. Hopefully there isn't skew there, but if there is, we may need to add logic to ImageJ or ImageJ2 to set the system properties to match the ImageJ prefs at ImageJ startup. The Proxy Settings plugin also has the option to set java.net.useSystemProxies which maybe does something more magical behind the scenes.

Anyway, at the Appose level here, using https.proxyHost and https.proxyPort seems like a good start, and we can troubleshoot if it's still not good enough.