Question: How to use environments in IIS websites / web apps?

[StefanScherer]

One question that some of the Docker Captains are discussing at the moment is how to set some environment variables eg. from the ENV or from docker run -e VAR=val to be used in IIS web apps.

As IIS is running as a Windows service it does not catch up these environments. What about using such ServiceMonitor.exe as ENTRYPOINT (or CMD) and set these envs as system environments before starting the Windows Service (IIS must be set to manual before I think).

[shirhatti]

While surfacing environment variables to be used by IIS apps is a reasonable ask that we NEED to address, I'm not convinced that ServiceMonitor.exe is the best place to surface it.

Including a few folks who might have an opinion on this @glennc @staceyhaffner @richlander @pan-wang

[friism]

An alternative would be for the image to run a web.config transform on start that transports Docker environment variables into web.config App Settings and connectionstrings. I suggested that here: https://github.com/Microsoft/Virtualization-Documentation/issues/401#issuecomment-251293311

[shirhatti]

@friism I want to make sure you are not conflating IIS configuration with ASP.NET configuration. We still need a way to say, set up environment variables for use in your PHP application. While what you bring up is important, it is a slightly different problem and I think the solution to that problem will live in the ASP.NET base image.

@StefanScherer you should just be able to run appcmd.exe to set an environment variable in your Dockerfile. However, we still need a way to flow settings from docker run -e VAR=val to IIS.

RUN appcmd.exe set config -section:system.applicationHost/applicationPools /+"[name='DefaultAppPool'].environmentVariables.[name='foo',value='bar']" /commit:apphost

[glennc]

Why the desire for this not to be something that ServiceMonitor.exe does? Is it not the job of ServiceMonitor to smooth exactly this sort of problem?

[shirhatti]

I'm afraid that auto-magically flowing environment variables would make this rather fragile. A few questions that pop up just off the top of my head

• Should the environment variables only be set for the DefaultAppPool?
• What would happen if I'm running my AppPool under a Group Managed Service Account as opposed to an AppPool identity?

In my opinion, ServiceMonitor.exe should remain a lightweight shim process. I'd be happy to try and build this as a standalone .exe let people try it out and then look at merging this into ServiceMonitor.exe.

However, this is just me thinking out loud at this point and I'm definitely open to suggestions.

[glennc]

I have never thought of ServiceMonitor as a lightweight shim. I have thought of it as the way to use IIS inside a container in the way I would expect/want an entrypoint to work. Is that just me?

[pan-wang]

as dock command will set the environment variable, we only need to restart the WAS service to adopt the variable. One simple solution is to disable WAS server from default iis container image.

[glennc]

@pan-wang Sounds like an easy solution, I like it :).

[rfeltis-alaska]

Any update on this? We are attempting to carry the same Docker image through multiple environments, but send in configuration changes as environment variables. If we have to modify our Dockerfile, then we have to build separate images for each environment. Not ideal.

[richlander]

A little off-topic ...

@rfeltis-alaska I'm curious ... are you using the microsoft/iis image directly? What type of application are you deploying (ASP.NET, PHP, ...)?

[ralphflywheel]

@richlander our image is based off of the microsoft/iis:windowsservercore family. We are deploying an ASP.NET WebAPI project.

[richlander]

Any reason to not use the aspnet image? We believe that many people are following your pattern and are wondering why. It's not a problem, just wondering why the aspnet image isn't a compelling option for you.

[ralphflywheel]

I think discoverability is a bit of a problem. I didn't know that there was an aspnet image. Most tutorials out there start you off with microsoft/iis. That being said, there isn't a ton of value being added from the aspnet Dockerfile. We already need to add more IIS features than the aspnet image brings (such as App Initialization) so we're going to be making an intermediate container anyway. I think we could go either way.

Here are the first two relevant Google searches for "docker iis":

http://blog.alexellis.io/run-iis-asp-net-on-windows-10-with-docker/

https://docs.microsoft.com/en-us/virtualization/windowscontainers/quick-start/quick-start-images

[richlander]

Thanks for the feedback! I suspect you nailed it.