Merge pull request #37 from coveo/rebuild-image-if-changed

Add hash to image tag in order to rebuild when the instructions change

config.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"crypto/md5"
 	"errors"
 	"fmt"
 	"github.com/hashicorp/go-getter"
+	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -71,6 +73,23 @@ type TGFConfigBuild struct {
 	source       string
 }
 
+func (cb TGFConfigBuild) hash() string {
+	h := md5.New()
+	io.WriteString(h, cb.Instructions)
+	if cb.Folder != "" {
+		filepath.Walk(cb.Dir(), func(path string, info os.FileInfo, err error) error {
+			if info == nil || info.IsDir() || err != nil {
+				return nil
+			}
+			if !strings.Contains(path, dockerfilePattern) {
+				io.WriteString(h, fmt.Sprintf("%v", info.ModTime()))
+			}
+			return nil
+		})
+	}
+	return fmt.Sprintf("%x", h.Sum(nil))
+}
+
 // Dir returns the folder name relative to the source
 func (cb TGFConfigBuild) Dir() string {
 	if cb.Folder == "" {
@@ -87,7 +106,7 @@ func (cb TGFConfigBuild) GetTag() string {
 	if cb.Tag != "" {
 		return cb.Tag
 	}
-	return filepath.Base(filepath.Dir(cb.source))
+	return fmt.Sprintf("%s-%s", filepath.Base(filepath.Dir(cb.source)), cb.hash())
 }
 
 // InitConfig returns a properly initialized TGF configuration struct

config_test.go

@@ -1,7 +1,9 @@
 package main
 
 import (
+	"crypto/md5"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"math/rand"
 	"os"
@@ -108,7 +110,7 @@ func TestSetConfigDefaultValues(t *testing.T) {
 	assert.Equal(t, "RUN ls test", config.imageBuildConfigs[1].Instructions)
 	assert.Equal(t, "/abspath/my-folder", config.imageBuildConfigs[1].Folder)
 	assert.Equal(t, "/abspath/my-folder", config.imageBuildConfigs[1].Dir())
-	assert.Equal(t, "AWS", config.imageBuildConfigs[1].GetTag())
+	assert.Equal(t, "AWS-"+getHash(config.imageBuildConfigs[1].Instructions), config.imageBuildConfigs[1].GetTag())
 
 	assert.Equal(t, "coveo/stuff", config.Image)
 	assert.Equal(t, "test", *config.ImageTag)
@@ -191,3 +193,9 @@ func randInt() int {
 	random := rand.New(source)
 	return random.Int()
 }
+
+func getHash(value string) string {
+	h := md5.New()
+	io.WriteString(h, value)
+	return fmt.Sprintf("%x", h.Sum(nil))
+}

docker.go

@@ -32,6 +32,7 @@ const (
 	minimumDockerVersion = "1.25"
 	tgfImageVersion      = "TGF_IMAGE_VERSION"
 	dockerSocketFile     = "/var/run/docker.sock"
+	dockerfilePattern    = "TGF_dockerfile"
 )
 
 func callDocker(withDockerMount bool, args ...string) int {
@@ -209,11 +210,11 @@ func getImage() (name string) {
 		if ib.Folder == "" {
 			// There is no explicit folder, so we create a temporary folder to store the docker file
 			temp = must(ioutil.TempDir("", "tgf-dockerbuild")).(string)
-			out = must(os.Create(filepath.Join(temp, "Dockerfile"))).(*os.File)
+			out = must(os.Create(filepath.Join(temp, dockerfilePattern))).(*os.File)
 			folder = temp
 		} else {
 			if ib.Instructions != "" {
-				out = must(ioutil.TempFile(ib.Dir(), "DockerFile")).(*os.File)
+				out = must(ioutil.TempFile(ib.Dir(), dockerfilePattern)).(*os.File)
 				temp = out.Name()
 				dockerFile = temp
 			}