Add a docker-spk build subcommand.

Author: zenhack

README.md

@@ -43,7 +43,19 @@ overridden with the `-keyring` flag).
 Edit the file to match your app. In particular, you will want to change
 the command used to launch the app, near the bottom of the file.
 
-Then, get a Docker image to convert. Invoke:
+Then, create a `Dockerfile` in the current directory, which will be
+responsible for building the filesystem for your app. Finally, from the
+directory containing `Dockerfile` and `sandstorm-pkgdef.capnp`, run:
+
+```
+docker-spk build
+```
+
+This will build the docker image and then package it into a `.spk` file.
+with the name derived from the app name and version defined in
+`sandstorm-manifest.capnp`.
+
+Alternatively, you can package an already-built docker image:
 
 ```
 docker-spk pack -image <image-name>
@@ -52,8 +64,7 @@ docker-spk pack -image <image-name>
 ...to use the image `<image-name>`, fetched from a running Docker
 daemon.
 
-This will create an `.spk` file, with the name derived from the app name
-and version defined in `sandstorm-manifest.capnp`.
+This will skip the build step and just create the `.spk`.
 
 You can also use `docker save` to fetch the image manually and specify
 the file name via `-imagefile`:
@@ -70,7 +81,6 @@ seeing how to package apps with `docker-spk`.
 
 # Reference
 
-
 See `docker-spk -h`.
 
 # License

build.go

@@ -1,7 +1,12 @@
 package main
 
 import (
+	"bufio"
 	"flag"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
 	"strings"
 )
 
@@ -44,6 +49,39 @@ func (f *buildFlags) Parse() {
 	f.pkgDefVar = pkgDefParts[1]
 }
 
+var buildOkRegexp = regexp.MustCompile("Successfully built ([0-9a-fA-F]+)")
+
 func buildCmd() {
+	bFlags := &buildFlags{}
+	bFlags.Register()
+	bFlags.Parse()
+
+	cmd := exec.Command("docker", "build", ".")
+	cmd.Stderr = os.Stderr
+	out, err := cmd.StdoutPipe()
+	chkfatal("Creating pipe for docker build", err)
+	chkfatal("Starting docker build", cmd.Start())
+	r := bufio.NewScanner(out)
+
+	image := ""
+	for r.Scan() {
+		line := r.Text()
+		fmt.Println(line)
+		subs := buildOkRegexp.FindStringSubmatch(line)
+		if subs != nil && len(subs) == 2 {
+			image = subs[1]
+		}
+	}
+	chkfatal("Parsing output from docker build", err)
+	chkfatal("Problem invoking docker build", cmd.Wait())
+	if image == "" {
+		fmt.Fprintln(os.Stderr,
+			"Could not determine image id built by docker build.")
+		os.Exit(1)
+	}
 
+	doPack(&packFlags{
+		buildFlags: *bFlags,
+		image:      image,
+	})
 }

main.go

@@ -59,8 +59,9 @@ func usageErr(info string) {
 
 func main() {
 	subCommands := map[string]func(){
-		"pack": packCmd,
-		"init": initCmd,
+		"pack":  packCmd,
+		"init":  initCmd,
+		"build": buildCmd,
 	}
 	flag.Usage = func() {
 		keys := []string{}

pack.go

@@ -112,7 +112,10 @@ func packCmd() {
 	pFlags := &packFlags{}
 	pFlags.Register()
 	pFlags.Parse()
+	doPack(pFlags)
+}
 
+func doPack(pFlags *packFlags) {
 	metadata := getPkgMetadata(pFlags.pkgDefFile, pFlags.pkgDefVar)
 
 	keyring, err := loadKeyring(*keyringPath)