grpc unikernel#

A gRPC service as a Solo5 unikernel, on the nox-mirage.eio backend. It is the minimal use of the Mirage_eio.Grpc device: the device owns the listener and the HTTP/2 connection handling (it is Grpc_eio.Server.run bound to a declared net device), so the unikernel supplies only the method implementations.

The service, echo.Echo, is defined once in rpc/ and shared between the unikernel and the host client that drives it -- what a .proto would otherwise generate. Its methods carry raw bytes (application/grpc+raw) rather than protobuf, so the demo needs no schema compiler.

For a gRPC appliance that a stock client speaks to, see etcd: the same device, serving the real etcd v3 API to etcdctl.

Run on the host (native dev backend)#

A plain dune build links the native backend, which runs the same portable Eio over an in-process ocaml-slirp gateway. Publish the guest's port with -p and call through it:

dune exec -- unikernel-grpc -p 50051:50051
dune exec -- unikernel-grpc-client reverse "hello unikernel"
dune exec -- unikernel-grpc-client upper "hello unikernel"

The client ships with the example because there is no stock CLI for a raw-codec service: grpcurl needs protobuf reflection or a .proto.

Build and run under Solo5#

mrg up
mrg build -t solo5 unikernels/bin/apps/grpc
mrg run -p 50051:50051 unikernels/bin/apps/grpc

The unikernel binds 10.0.0.2:50051 in the guest; the published port reaches it from the host.