.Net Core INSTRUMENTATION_KEY is not set error

When you are debugging eShopOnContainers  on Visual Studio 2017 for the first time and when this build error throws INSTRUMENTATION_KEY  variable is not set.

goto   docker-compose.override.yml

Replace this line
- ApplicationInsights__InstrumentationKey=${INSTRUMENTATION_KEY}
to
- ApplicationInsights__InstrumentationKey=//${INSTRUMENTATION_KEY}

1. Make sure you set 4GB of Memory and  CPus -3 in Docker settings ->Advanced