Environment variable replacement using tokens like VSTS\Powershell

[guibirow]

I've mentioned it on this issue microsoft/service-fabric-issues#776, but I am opening it as a formal feature request.

I have faced some challenges where I needed to pass environment variables to guest executable or containers, and in most cases, these values were already defined in the host machine.

An example I can give is a Guest Executable, with closed source, that expect a Environment Variable called PORT to be set, so it knows which port to open at startup.

Would not be a problem for fixed ports, like 80, 8080, and so on, but in cases we use dynamic ports provided by service fabric, we would have to create a custom startup script to set these variables.

Instead of executing from a batch file, a rough example is something like this:

In your ServiceManifest.xml:

  <CodePackage Name="Code" Version="1.0.0">
    <EntryPoint>
      <ExeHost>
        <Program>start.bat</Program>
        <WorkingFolder>CodePackage</WorkingFolder>
      </ExeHost>
    </EntryPoint>
  </CodePackage>

On the same folder (code) of your node.exe, you create the start.bat file with following contents:

set PORT=%Fabric_Endpoint_GuestEndpoint%
node start.js

Would be very easy if we could do just this from the manifest:

<EnvironmentOverrides CodePackageRef="Code">
  <EnvironmentVariable Name="PORT" Value="$Env:Fabric_Endpoint_GuestEndpoint" />
</EnvironmentOverrides>

[guibirow]

Common examples I can give is passing connection strings, passwords and other settings already set on environment variables defined in the host, instead of requesting these parameters at deployment or configuration files.