Add new host to be used for container

[bording]

This PR makes the following changes:

• A new container host, based on Kestrel, has been introduced
  • For now, the new host is used only for the container and the PlatformSample.
  • The new host reads in the environment variables directly and uses the values to serve a dynamically constructed app.contants.js result, removing the need to write those out to disk before serving the website.
  • The new host also includes a reverse proxy so that all requests can go directly to the host's web application. API requests to ServiceControl and Monitoring APIs are forwarded by the revery proxy.
• A new MONITORING_URL setting has been added to the container. It accepts a single URI instead of an array of URIs. If this new setting and the old MONITORING_URLS are both set, the new setting takes precedence.
• The container now runs processes internally as non-root, so the default port has been changed to 9090.
• Some miscellaneous cleanup and improvements to other projects in the repo have also been included.

[ivanl-out]

Thanks @bording.

Just note that the change from port 90 to 9090 was a breaking change for us since our ingress in Azure Container Apps previously exposed port 90. We also had a startup probe hitting port 90. It might be good to include this in the release notes for others (I may have missed this).

Edit: I see the new port was noted in Container-README.md, so please disregard my comment, I just didn't read it since I was upgrading from a previous version.

[bording]

Thanks @bording.

Just note that the change from port 90 to 9090 was a breaking change for us since our ingress in Azure Container Apps previously exposed port 90. We also had a startup probe hitting port 90. It might be good to include this in the release notes for others (I may have missed this).

Edit: I see the new port was noted in Container-README.md, so please disregard my comment, I just didn't read it since I was upgrading from a previous version.

We have added a note to the release notes and the announcement regarding the change.

However, the only thing that really changed was the port inside the container. Externally, you can continue to map that to whatever port you desire.

For example using docker:

docker run -p 90:9090 particular/servicepulse:latest

Would let you keep using 90 as the public-facing port.