2 files changed, 215 insertions, 0 deletions
diff --git a/runsc/cmd/install.go b/runsc/cmd/install.go
new file mode 100644
index 000000000..441c1db0d
--- /dev/null
+++ b/runsc/cmd/install.go
@@ -0,0 +1,210 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cmd
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"path"
+
+	"flag"
+	"github.com/google/subcommands"
+)
+
+// Install implements subcommands.Command.
+type Install struct {
+	ConfigFile   string
+	Runtime      string
+	Experimental bool
+}
+
+// Name implements subcommands.Command.Name.
+func (*Install) Name() string {
+	return "install"
+}
+
+// Synopsis implements subcommands.Command.Synopsis.
+func (*Install) Synopsis() string {
+	return "adds a runtime to docker daemon configuration"
+}
+
+// Usage implements subcommands.Command.Usage.
+func (*Install) Usage() string {
+	return `install [flags] <name> [-- [args...]] -- if provided, args are passed to the runtime
+`
+}
+
+// SetFlags implements subcommands.Command.SetFlags.
+func (i *Install) SetFlags(fs *flag.FlagSet) {
+	fs.StringVar(&i.ConfigFile, "config_file", "/etc/docker/daemon.json", "path to Docker daemon config file")
+	fs.StringVar(&i.Runtime, "runtime", "runsc", "runtime name")
+	fs.BoolVar(&i.Experimental, "experimental", false, "enable experimental features")
+}
+
+// Execute implements subcommands.Command.Execute.
+func (i *Install) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
+	// Grab the name and arguments.
+	runtimeArgs := f.Args()
+
+	// Extract the executable.
+	path, err := os.Executable()
+	if err != nil {
+		log.Fatalf("Error reading current exectuable: %v", err)
+	}
+
+	// Load the configuration file.
+	c, err := readConfig(i.ConfigFile)
+	if err != nil {
+		log.Fatalf("Error reading config file %q: %v", i.ConfigFile, err)
+	}
+
+	// Add the given runtime.
+	var rts map[string]interface{}
+	if i, ok := c["runtimes"]; ok {
+		rts = i.(map[string]interface{})
+	} else {
+		rts = make(map[string]interface{})
+		c["runtimes"] = rts
+	}
+	rts[i.Runtime] = struct {
+		Path        string   `json:"path,omitempty"`
+		RuntimeArgs []string `json:"runtimeArgs,omitempty"`
+	}{
+		Path:        path,
+		RuntimeArgs: runtimeArgs,
+	}
+
+	// Set experimental if required.
+	if i.Experimental {
+		c["experimental"] = true
+	}
+
+	// Write out the runtime.
+	if err := writeConfig(c, i.ConfigFile); err != nil {
+		log.Fatalf("Error writing config file %q: %v", i.ConfigFile, err)
+	}
+
+	// Success.
+	log.Printf("Added runtime %q with arguments %v to %q.", i.Runtime, runtimeArgs, i.ConfigFile)
+	return subcommands.ExitSuccess
+}
+
+// Uninstall implements subcommands.Command.
+type Uninstall struct {
+	ConfigFile string
+	Runtime    string
+}
+
+// Name implements subcommands.Command.Name.
+func (*Uninstall) Name() string {
+	return "uninstall"
+}
+
+// Synopsis implements subcommands.Command.Synopsis.
+func (*Uninstall) Synopsis() string {
+	return "removes a runtime from docker daemon configuration"
+}
+
+// Usage implements subcommands.Command.Usage.
+func (*Uninstall) Usage() string {
+	return `uninstall [flags] <name>
+`
+}
+
+// SetFlags implements subcommands.Command.SetFlags.
+func (u *Uninstall) SetFlags(fs *flag.FlagSet) {
+	fs.StringVar(&u.ConfigFile, "config_file", "/etc/docker/daemon.json", "path to Docker daemon config file")
+	fs.StringVar(&u.Runtime, "runtime", "runsc", "runtime name")
+}
+
+// Execute implements subcommands.Command.Execute.
+func (u *Uninstall) Execute(_ context.Context, f *flag.FlagSet, args ...interface{}) subcommands.ExitStatus {
+	log.Printf("Removing runtime %q from %q.", u.Runtime, u.ConfigFile)
+
+	c, err := readConfig(u.ConfigFile)
+	if err != nil {
+		log.Fatalf("Error reading config file %q: %v", u.ConfigFile, err)
+	}
+
+	var rts map[string]interface{}
+	if i, ok := c["runtimes"]; ok {
+		rts = i.(map[string]interface{})
+	} else {
+		log.Fatalf("runtime %q not found", u.Runtime)
+	}
+	if _, ok := rts[u.Runtime]; !ok {
+		log.Fatalf("runtime %q not found", u.Runtime)
+	}
+	delete(rts, u.Runtime)
+
+	if err := writeConfig(c, u.ConfigFile); err != nil {
+		log.Fatalf("Error writing config file %q: %v", u.ConfigFile, err)
+	}
+	return subcommands.ExitSuccess
+}
+
+func readConfig(path string) (map[string]interface{}, error) {
+	// Read the configuration data.
+	configBytes, err := ioutil.ReadFile(path)
+	if err != nil && !os.IsNotExist(err) {
+		return nil, err
+	}
+
+	// Unmarshal the configuration.
+	c := make(map[string]interface{})
+	if len(configBytes) > 0 {
+		if err := json.Unmarshal(configBytes, &c); err != nil {
+			return nil, err
+		}
+	}
+
+	return c, nil
+}
+
+func writeConfig(c map[string]interface{}, filename string) error {
+	// Marshal the configuration.
+	b, err := json.MarshalIndent(c, "", "    ")
+	if err != nil {
+		return err
+	}
+
+	// Copy the old configuration.
+	old, err := ioutil.ReadFile(filename)
+	if err != nil {
+		if !os.IsNotExist(err) {
+			return fmt.Errorf("error reading config file %q: %v", filename, err)
+		}
+	} else {
+		if err := ioutil.WriteFile(filename+"~", old, 0644); err != nil {
+			return fmt.Errorf("error backing up config file %q: %v", filename, err)
+		}
+	}
+
+	// Make the necessary directories.
+	if err := os.MkdirAll(path.Dir(filename), 0755); err != nil {
+		return fmt.Errorf("error creating config directory for %q: %v", filename, err)
+	}
+
+	// Write the new configuration.
+	if err := ioutil.WriteFile(filename, b, 0644); err != nil {
+		return fmt.Errorf("error writing config file %q: %v", filename, err)
+	}
+
+	return nil
+}
diff --git a/runsc/main.go b/runsc/main.go
index 70f06dbb8..0ff68160d 100644
--- a/runsc/main.go
+++ b/runsc/main.go
@@ -88,6 +88,11 @@ func main() {
 	subcommands.Register(help, "")
 	subcommands.Register(subcommands.FlagsCommand(), "")
 
+	// Installation helpers.
+	const helperGroup = "helpers"
+	subcommands.Register(new(cmd.Install), helperGroup)
+	subcommands.Register(new(cmd.Uninstall), helperGroup)
+
 	// Register user-facing runsc commands.
 	subcommands.Register(new(cmd.Checkpoint), "")
 	subcommands.Register(new(cmd.Create), "")