Initial merge of faas-containerd

This patch completes part of the work in #20 by porting the code
for faas-containerd in-tree. When tested, I was able to deploy
and then remove figlet from the store on `x86_64`.

In a follow-up PR, duplication will be removed where possible
and consolidated with updated documentation.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

cmd/provider.go

@@ -0,0 +1,94 @@
+package cmd
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"net/http"
+	"os"
+	"path"
+
+	"github.com/alexellis/faasd/pkg/provider/config"
+	"github.com/alexellis/faasd/pkg/provider/handlers"
+	"github.com/containerd/containerd"
+	bootstrap "github.com/openfaas/faas-provider"
+	"github.com/openfaas/faas-provider/proxy"
+	"github.com/openfaas/faas-provider/types"
+	"github.com/spf13/cobra"
+)
+
+var providerCmd = &cobra.Command{
+	Use:   "provider",
+	Short: "Run the faasd faas-provider",
+	RunE:  runProvider,
+}
+
+func runProvider(_ *cobra.Command, _ []string) error {
+
+	config, providerConfig, err := config.ReadFromEnv(types.OsEnv{})
+	if err != nil {
+		return err
+	}
+
+	log.Printf("faas-containerd starting..\tService Timeout: %s\n", config.WriteTimeout.String())
+
+	wd, err := os.Getwd()
+	if err != nil {
+		return err
+	}
+
+	writeHostsErr := ioutil.WriteFile(path.Join(wd, "hosts"),
+		[]byte(`127.0.0.1	localhost`), 0644)
+
+	if writeHostsErr != nil {
+		return fmt.Errorf("cannot write hosts file: %s", writeHostsErr)
+	}
+
+	writeResolvErr := ioutil.WriteFile(path.Join(wd, "resolv.conf"),
+		[]byte(`nameserver 8.8.8.8`), 0644)
+
+	if writeResolvErr != nil {
+		return fmt.Errorf("cannot write resolv.conf file: %s", writeResolvErr)
+	}
+
+	cni, err := handlers.InitNetwork()
+	if err != nil {
+		return err
+	}
+
+	client, err := containerd.New(providerConfig.Sock)
+	if err != nil {
+		return err
+	}
+
+	defer client.Close()
+
+	invokeResolver := handlers.NewInvokeResolver(client)
+
+	bootstrapHandlers := types.FaaSHandlers{
+		FunctionProxy:        proxy.NewHandlerFunc(*config, invokeResolver),
+		DeleteHandler:        handlers.MakeDeleteHandler(client, cni),
+		DeployHandler:        handlers.MakeDeployHandler(client, cni),
+		FunctionReader:       handlers.MakeReadHandler(client),
+		ReplicaReader:        handlers.MakeReplicaReaderHandler(client),
+		ReplicaUpdater:       handlers.MakeReplicaUpdateHandler(client, cni),
+		UpdateHandler:        handlers.MakeUpdateHandler(client, cni),
+		HealthHandler:        func(w http.ResponseWriter, r *http.Request) {},
+		InfoHandler:          handlers.MakeInfoHandler(Version, GitCommit),
+		ListNamespaceHandler: listNamespaces(),
+	}
+
+	log.Printf("Listening on TCP port: %d\n", *config.TCPPort)
+	bootstrap.Serve(&bootstrapHandlers, config)
+
+	return nil
+}
+
+func listNamespaces() func(w http.ResponseWriter, r *http.Request) {
+	return func(w http.ResponseWriter, r *http.Request) {
+		list := []string{""}
+		out, _ := json.Marshal(list)
+		w.Write(out)
+	}
+}