Add base cli and connection logic

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

Makefile

@@ -29,7 +29,10 @@ GOOS ?= $(shell go env GOOS)
 
 export GO111MODULE=off
 
-all: protos
+all: protos example cli
+
+cli:
+	cd cmd && go build -v -o ../bin/docker
 
 protos:
 	@protobuild --quiet ${PACKAGES}
@@ -39,4 +42,4 @@ example:
 
 FORCE:
 
-.PHONY: protos example
+.PHONY: protos example cli

client/client.go

@@ -27,21 +27,45 @@
 
 package client
 
-import "google.golang.org/grpc"
+import (
+	"context"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	v1 "github.com/docker/api/backend/v1"
+	"google.golang.org/grpc"
+)
+
+// NewContext is a context that is canceled when a signal is
+// sent to the process
+func NewContext() (context.Context, func()) {
+	ctx, cancel := context.WithCancel(context.Background())
+	s := make(chan os.Signal)
+	signal.Notify(s, syscall.SIGTERM, syscall.SIGINT)
+	go func() {
+		<-s
+		cancel()
+	}()
+	return ctx, cancel
+}
 
 // New returns a GRPC client
-func New(address string) (*Client, error) {
-	conn, err := grpc.Dial(address, grpc.WithInsecure())
+func New(address string, timeout time.Duration) (*Client, error) {
+	conn, err := grpc.Dial(address, grpc.WithInsecure(), grpc.WithBlock(), grpc.WithTimeout(timeout))
 	if err != nil {
 		return nil, err
 	}
 	return &Client{
 		conn:          conn,
+		BackendClient: v1.NewBackendClient(conn),
 	}, nil
 }
 
 type Client struct {
 	conn *grpc.ClientConn
+	v1.BackendClient
 }
 
 func (c *Client) Close() error {

cmd/context.go

@@ -0,0 +1,119 @@
+/*
+	Copyright (c) 2019 Docker Inc.
+
+	Permission is hereby granted, free of charge, to any person
+	obtaining a copy of this software and associated documentation
+	files (the "Software"), to deal in the Software without
+	restriction, including without limitation the rights to use, copy,
+	modify, merge, publish, distribute, sublicense, and/or sell copies
+	of the Software, and to permit persons to whom the Software is
+	furnished to do so, subject to the following conditions:
+
+	The above copyright notice and this permission notice shall be
+	included in all copies or substantial portions of the Software.
+
+	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+	EXPRESS OR IMPLIED,
+	INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+	IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+	HOLDERS BE LIABLE FOR ANY CLAIM,
+	DAMAGES OR OTHER LIABILITY,
+	WHETHER IN AN ACTION OF CONTRACT,
+	TORT OR OTHERWISE,
+	ARISING FROM, OUT OF OR IN CONNECTION WITH
+	THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"time"
+
+	"github.com/docker/api/client"
+	"github.com/gogo/protobuf/types"
+	"github.com/pkg/errors"
+	"github.com/urfave/cli"
+)
+
+func init() {
+	// initial hack to get the path of the project's bin dir
+	// into the env of this cli for development
+
+	path := filepath.Join(os.Getenv("GOPATH"), "src/github.com/docker/api/bin")
+	if err := os.Setenv("PATH", fmt.Sprintf("$PATH:%s", path)); err != nil {
+		panic(err)
+	}
+}
+
+var contextCommand = cli.Command{
+	Name:  "context",
+	Usage: "manage contexts",
+	Action: func(clix *cli.Context) error {
+		// return information for the current context
+		ctx, cancel := client.NewContext()
+		defer cancel()
+
+		// get our current context
+		ctx = current(ctx)
+
+		client, err := connect(ctx)
+		if err != nil {
+			return errors.Wrap(err, "cannot connect to backend")
+		}
+		defer client.Close()
+
+		info, err := client.BackendInformation(ctx, &types.Empty{})
+		if err != nil {
+			return errors.Wrap(err, "fetch backend information")
+		}
+		enc := json.NewEncoder(os.Stdout)
+		enc.SetIndent("", " ")
+		return enc.Encode(info)
+	},
+}
+
+// mock information for getting context
+// factor out this into a context store package
+func current(ctx context.Context) context.Context {
+	// test backend address
+	return context.WithValue(ctx, backendAddressKey{}, "127.0.0.1:7654")
+}
+
+func connect(ctx context.Context) (*client.Client, error) {
+	address, err := BackendAddress(ctx)
+	if err != nil {
+		return nil, errors.Wrap(err, "no backend address")
+	}
+	c, err := client.New(address, 500*time.Millisecond)
+	if err != nil {
+		if err != context.DeadlineExceeded {
+			return nil, errors.Wrap(err, "connect to backend")
+		}
+		// the backend is not running so start it
+		cmd := exec.Command("backend-example", "--address", address)
+		go cmd.Wait()
+
+		if err := cmd.Start(); err != nil {
+			return nil, errors.Wrap(err, "start backend")
+		}
+		return client.New(address, 2*time.Second)
+	}
+	return c, nil
+}
+
+type backendAddressKey struct{}
+
+func BackendAddress(ctx context.Context) (string, error) {
+	v, ok := ctx.Value(backendAddressKey{}).(string)
+	if !ok {
+		return "", errors.New("no backend address key")
+	}
+	return v, nil
+}

cmd/main.go

@@ -0,0 +1,63 @@
+/*
+	Copyright (c) 2019 Docker Inc.
+
+	Permission is hereby granted, free of charge, to any person
+	obtaining a copy of this software and associated documentation
+	files (the "Software"), to deal in the Software without
+	restriction, including without limitation the rights to use, copy,
+	modify, merge, publish, distribute, sublicense, and/or sell copies
+	of the Software, and to permit persons to whom the Software is
+	furnished to do so, subject to the following conditions:
+
+	The above copyright notice and this permission notice shall be
+	included in all copies or substantial portions of the Software.
+
+	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+	EXPRESS OR IMPLIED,
+	INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+	IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+	HOLDERS BE LIABLE FOR ANY CLAIM,
+	DAMAGES OR OTHER LIABILITY,
+	WHETHER IN AN ACTION OF CONTRACT,
+	TORT OR OTHERWISE,
+	ARISING FROM, OUT OF OR IN CONNECTION WITH
+	THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*/
+
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/sirupsen/logrus"
+	"github.com/urfave/cli"
+)
+
+func main() {
+	app := cli.NewApp()
+	app.Name = "docker"
+	app.Usage = "Docker for the 2020s"
+	app.UseShortOptionHandling = true
+	app.EnableBashCompletion = true
+	app.Flags = []cli.Flag{
+		cli.BoolFlag{
+			Name:  "debug",
+			Usage: "enable debug output in the logs",
+		},
+	}
+	app.Before = func(clix *cli.Context) error {
+		if clix.GlobalBool("debug") {
+			logrus.SetLevel(logrus.DebugLevel)
+		}
+		return nil
+	}
+	app.Commands = []cli.Command{
+		contextCommand,
+	}
+	if err := app.Run(os.Args); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}

example/backend/main.go

@@ -32,12 +32,12 @@ import (
 	"fmt"
 	"net"
 	"os"
-	"os/signal"
-	"syscall"
 
+	v1 "github.com/docker/api/backend/v1"
+	"github.com/docker/api/client"
 	"github.com/docker/api/server"
 	_ "github.com/gogo/googleapis/google/rpc"
-	_ "github.com/gogo/protobuf/types"
+	"github.com/gogo/protobuf/types"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"github.com/urfave/cli"
@@ -67,7 +67,7 @@ func main() {
 		return nil
 	}
 	app.Action = func(clix *cli.Context) error {
-		ctx, cancel := cancelContext()
+		ctx, cancel := client.NewContext()
 		defer cancel()
 
 		// create a new GRPC server with the provided server package
@@ -80,6 +80,12 @@ func main() {
 		}
 		defer l.Close()
 
+		// create our instance of the backend server implementation
+		backend := &backend{}
+
+		// register our instance with the GRPC server
+		v1.RegisterBackendServer(s, backend)
+
 		// handle context being closed or canceled
 		go func() {
 			<-ctx.Done()
@@ -98,15 +104,11 @@ func main() {
 	}
 }
 
-// cancelContext is a context that is canceled when a signal is
-// sent to the process
-func cancelContext() (context.Context, func()) {
-	ctx, cancel := context.WithCancel(context.Background())
-	s := make(chan os.Signal)
-	signal.Notify(s, syscall.SIGTERM, syscall.SIGINT)
-	go func() {
-		<-s
-		cancel()
-	}()
-	return ctx, cancel
+type backend struct {
+}
+
+func (b *backend) BackendInformation(ctx context.Context, _ *types.Empty) (*v1.BackendInformationResponse, error) {
+	return &v1.BackendInformationResponse{
+		ID: "com.docker.api.backend.example.v1",
+	}, nil
 }