Orchard Controller: implement an SSH server that acts as a jump host (#179)

* proxy.Connections(): require io.ReadWriteCloser instead of net.Conn

* Orchard Controller: implement an SSH server that acts as a jump host

* Issue a warning if the name used will be invalid in the future

* Further restrict uppercase characters in names in the future

The rationale is similar to https://github.com/kubernetes/kubernetes/issues/71140.

We won't want to munge the user's input and introduce subtle bugs doing
lowercase comparisons.

internal/tests/devcontroller/devcontroller.go

@@ -0,0 +1,57 @@
+package devcontroller
+
+import (
+	"context"
+	"errors"
+	"github.com/cirruslabs/orchard/internal/command/dev"
+	"github.com/cirruslabs/orchard/internal/controller"
+	"github.com/cirruslabs/orchard/internal/worker"
+	"github.com/cirruslabs/orchard/pkg/client"
+	"github.com/stretchr/testify/require"
+	"net/http"
+	"testing"
+	"time"
+)
+
+func StartIntegrationTestEnvironment(t *testing.T) (*client.Client, *controller.Controller, *worker.Worker) {
+	return StartIntegrationTestEnvironmentWithAdditionalOpts(t, nil, nil)
+}
+
+func StartIntegrationTestEnvironmentWithAdditionalOpts(
+	t *testing.T,
+	additionalControllerOpts []controller.Option,
+	additionalWorkerOpts []worker.Option,
+) (*client.Client, *controller.Controller, *worker.Worker) {
+	t.Setenv("ORCHARD_HOME", t.TempDir())
+
+	devController, devWorker, err := dev.CreateDevControllerAndWorker(t.TempDir(),
+		":0", nil, additionalControllerOpts, additionalWorkerOpts)
+	require.NoError(t, err)
+	t.Cleanup(func() {
+		_ = devWorker.Close()
+	})
+
+	devContext, cancelDevFunc := context.WithCancel(context.Background())
+	t.Cleanup(cancelDevFunc)
+
+	go func() {
+		err := devController.Run(devContext)
+		if err != nil && !errors.Is(err, context.Canceled) && !errors.Is(err, http.ErrServerClosed) {
+			t.Errorf("dev controller failed: %v", err)
+		}
+	}()
+
+	go func() {
+		err := devWorker.Run(devContext)
+		if err != nil && !errors.Is(err, context.Canceled) {
+			t.Errorf("dev worker failed: %v", err)
+		}
+	}()
+
+	time.Sleep(5 * time.Second)
+
+	devClient, err := client.New(client.WithAddress(devController.Address()))
+	require.NoError(t, err)
+
+	return devClient, devController, devWorker
+}