Update docs for object store metadata for go plugins
@@ -283,3 +283,22 @@ This pod has both a Configuration and Status.
### Items
A plugin with support for `PrinterItems` allow adding a `FlexLayoutItem` consisting of a width and a view component.
+
+## Custom Runtime
+
+### Custom object store
+
+For runtimes with custom object store implementations, Go plugins can pass arbitrary key/values when issuing calls to the object store.
+A plugin can set a grpc header with prefix `x-octant-` which will be consumed by the grpc server to set up random properties for the object store context.
+For example: To set a property named `foo` on the object store context, a plugin can set a grpc header named `x-octant-foo`.
+
+```go
+func handlePrint(request *service.PrintRequest) (plugin.PrintResponse, error) {
+ ...
+ key, err := store.KeyFromObject(request.Object)
+ if err != nil {
+ return plugin.PrintResponse{}, err
+ }
+ ctx = metadata.AppendToOutgoingContext(request.Context(), "x-octant-foo", "bar")
+ u, err := request.DashboardClient.Get(ctx, key)
+```
