Overview
The .NET runtime is the software stack responsible for installing your
application code and its dependencies and running your application. The flexible
runtime is declared in your app.yaml
file:
runtime: aspnetcore
env: flex
Runtimes in the flexible environment are built using Docker.
Google Cloud Tools for Visual Studio
creates an app.yaml
file and a Dockerfile in the build output directory if
these files don't already exist in your project.
If you want to use GKE or other Docker hosts, you need to create a Dockerfile based on this image that copies your application code and installs dependencies. For example:
FROM gcr.io/google-appengine/aspnetcore:2.1
COPY . /app
WORKDIR /app
EXPOSE 8080
ENV ASPNETCORE_URLS=http://*:8080
ENTRYPOINT ["dotnet", "Metadata.dll"]
View a full list of base images that Google provides for building .NET containers.
HTTPS and forwarding proxies
App Engine terminates the HTTPS connection at the load balancer and forwards the
request to your application. Applications can examine the X-Forwarded-Proto
to
observe whether the original protocol was HTTP or HTTPS.
Some applications also need to ascertain the user's IP address. This is
available in the standard X-Forwarded-For
header.
Extending the runtime
The flexible environment .NET runtime can be used to create a custom runtime.
Custom runtimes are configured via a Dockerfile
.
You can customize the Dockerfile
and .dockerignore
as desired. Finally,
you will need to specify runtime: custom
instead of runtime: aspnetcore
in
app.yaml
. See
Customizing the .NET Runtime
for more information.
Environment variables
The following environment variables are set by the runtime environment:
Environment variable | Description |
---|---|
GAE_INSTANCE |
The name of the current instance. |
GAE_MEMORY_MB |
The amount of memory available to the application process. |
GAE_SERVICE |
The service name specified in your application's app.yaml
file, or if no service name is specified, it is set to default . |
GAE_VERSION |
The version label of the current application. |
GOOGLE_CLOUD_PROJECT |
The Project ID associated with your application, which is visible in the Google Cloud console |
PORT |
The port that will receive HTTP requests. |
You can set additional configuration variables with appsettings.json
.
Metadata server
Each instance of your application can use the Compute Engine metadata server to query information about the instance, including its host name, external IP address, instance ID, custom metadata, and service account information. App Engine does not allow you to set custom metadata for each instance, but you can set project-wide custom metadata and read it from your App Engine and Compute Engine instances.
This example function uses the metadata server to get the external IP address of the instance: