[Mono-dev] Environment.GetEnvironmentVariable() not working in Linux ASP.NET app

[Oskar Berggren]

2011/11/9 H . <test051102 at hotmail.com>:
> Hi Robert,
>
> I didn't know that Linux hides certain environment variables from a process
> depending on the identity it is running in. I guess that the only choice for

It doesn't, not as such. Environment variables are inherently per
process, and this is the same in Windows. When a process is launched
it generally inherits the environment variables from its parent, with
any requested modifications.

Then it boils down to how are environment variables configured
administratively for a particular system? The concept of system-wide
and per-user environment variables is an abstraction built on the
above facility, and there is no fundamental requirement for that (e.g.
it would be possibly to build a system where they are set and applied
per executable name, or something entirely different).

In Windows there is a control panel app to set them per user or
system-wide. In Linux each distro may have different methods, but
basically any "system-wide" environment settings will be stored in
e.g. /etc/environment, and it then becomes the responsibility of a few
"core" processes to read and apply these settings to themselves during
e.g. login. "Regular" applications launched by the user will then
inherit them.

Concerning proxy settings with Ubuntu 10.04 as example: These are in
System->Preferences->Network Proxy. These are by default per user
(since it's under Preferences, not Administration). However, the
button "Apply System-Wide" is provided. Clicking that then gives me:

oskar$ cat /etc/environment
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games"
LANG="en_US.UTF-8"
http_proxy="http://ff:8080/"


oskar$ sudo su - www-data
www-data$ printenv|grep -i prox
http_proxy=http://ff:8080/


Notice how the proxy is applied also for the www-data user. However,
to make the web server see the change it would have to be restarted.
Possibly a reboot is the easiest way to ensure they are re-read.


/Oskar



> platform indepent ASP.NET apps is then to configure proxy settings via
> web.config. Alternatively, it is possible to set the WebClient object's
> Proxy property to null in case no proxies should be used. This is most
> likely valid in intranet environments. The current Mono/master supports both
> of these methods.
>
>
> Best regards,
> Martin
>
>
>
>> To: mono-devel-list at lists.ximian.com
>> From: robertj at gmx.net
>> Date: Sat, 5 Nov 2011 11:47:51 +0100
>> Subject: Re: [Mono-dev] Environment.GetEnvironmentVariable() not working
>> in Linux ASP.NET app
>>
>> Hi Martin,
>>
>> On 05.11.2011 09:48, H . wrote:
>> >
>> > Hi Robert,
>> >
>> > I am using XSP2& MonoDevelop to debug.
>>
>> You have to restart your user session if you've changed
>> the proxy settings. Being environment-based, these settings
>> won't propagate to running processes.
>>
>> >
>> > Based on the answers I think that it might be a Linux related issue.
>> >
>> > I have implemented extensive proxy support for WebClient and it's
>> > underlying classes in Mono/master. This code is based on the no_proxy
>> > environment variable in Linux. The question is, how can we obtain the
>> > list of proxies to bypass in Linux? Is there a consistend way to do
>> > this for standard Linux apps AND Linux ASP.NET apps?
>>
>> There is no standard regarding proxy configuration besides
>> those two environment variables "http_proxy" and "no_proxy".
>>
>> Tools that make use of proxies (wget, curl, browsers) may
>> have other proprietary configurations, but at the and they
>> all support these environment variables.
>>
>> Robert
>>
>> >
>> >
>> > Best regards, Martin
>> >
>> >
>> >
>> >> To: mono-devel-list at lists.ximian.com From: robertj at gmx.net Date:
>> >> Thu, 3 Nov 2011 15:47:37 +0100 Subject: Re: [Mono-dev]
>> >> Environment.GetEnvironmentVariable() not working in Linux ASP.NET
>> >> app
>> >>
>> >> On 03.11.2011 14:12, H . wrote:
>> >>>
>> >>> Hi Robert,
>> >>
>> >>> thanks for your hints.
>> >>>
>> >>> The link sent describes how environment variables can be set up
>> >>> in Ubuntu. Of course, nobody would try to manually set up
>> >>> environment variables when trying to configure proxies. This is
>> >>> done by using System>Settings>Network Proxy. After that, Ubuntu
>> >>> sets up the necessary environment variables. In case of the
>> >>> no_proxy environment variable this can be tested by issuing "echo
>> >>> $no_proxy" on the command line.
>> >>
>> >> Yes, you may see it on *your* own command line, as a normal user,
>> >> but the web server (you didn't specify which one, so we can't
>> >> help) may have its own environment default settings.
>> >>
>> >> A common way to solve that (if Ubuntu's config tools don't provide
>> >> a facility to set either global or web server specific vars) is to
>> >> set this env var globally and manually.
>> >>
>> >> Robert
>> >>
>> >> _______________________________________________ Mono-devel-list
>> >> mailing list Mono-devel-list at lists.ximian.com
>> >> http://lists.ximian.com/mailman/listinfo/mono-devel-list
>> >
>> >
>> >
>> >
>> > _______________________________________________ Mono-devel-list
>> > mailing list Mono-devel-list at lists.ximian.com
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>>
>>
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