feat(write_files): Support write_files cloud-config attr

Fix #3

cloudinit/cloud_config.go

@@ -14,6 +14,7 @@ type CloudConfig struct {
 		Etcd  struct{ Discovery_URL string }
 		Fleet struct{ Autostart bool }
 	}
+	Write_Files []WriteFile
 }
 
 func NewCloudConfig(contents []byte) (*CloudConfig, error) {
@@ -41,6 +42,15 @@ func ApplyCloudConfig(cfg CloudConfig, sshKeyName string) error {
 		}
 	}
 
+	if len(cfg.Write_Files) > 0 {
+		for _, file := range cfg.Write_Files {
+			if err := ProcessWriteFile("/", &file); err != nil {
+				return err
+			}
+			log.Printf("Wrote file %s to filesystem", file.Path)
+		}
+	}
+
 	if cfg.Coreos.Etcd.Discovery_URL != "" {
 		err := PersistEtcdDiscoveryURL(cfg.Coreos.Etcd.Discovery_URL)
 		if err == nil {

cloudinit/cloud_config_test.go

@@ -23,6 +23,10 @@ func TestCloudConfigEmpty(t *testing.T) {
 	if cfg.Coreos.Fleet.Autostart {
 		t.Error("Expected AutostartFleet not to be defined")
 	}
+
+	if len(cfg.Write_Files) != 0 {
+		t.Error("Expected zero Write_Files")
+	}
 }
 
 // Assert that the parsing of a cloud config file "generally works"
@@ -36,6 +40,13 @@ coreos:
 ssh_authorized_keys:
   - foobar
   - foobaz
+write_files:
+  - content: |
+      penny
+      elroy
+    path: /etc/dogepack.conf
+    permissions: '0644'
+    owner: root:dogepack
 `)
 	cfg, err := NewCloudConfig(contents)
 	if err != nil {
@@ -58,6 +69,27 @@ ssh_authorized_keys:
 	if !cfg.Coreos.Fleet.Autostart {
 		t.Error("Expected AutostartFleet to be true")
 	}
+
+	if len(cfg.Write_Files) != 1 {
+		t.Error("Failed to parse correct number of write_files")
+	} else {
+		wf := cfg.Write_Files[0]
+		if wf.Content != "penny\nelroy\n" {
+			t.Errorf("WriteFile has incorrect contents '%s'", wf.Content)
+		}
+		if wf.Encoding != "" {
+			t.Errorf("WriteFile has incorrect encoding %s", wf.Encoding)
+		}
+		if wf.Permissions != "0644" {
+			t.Errorf("WriteFile has incorrect permissions %s", wf.Permissions)
+		}
+		if wf.Path != "/etc/dogepack.conf" {
+			t.Errorf("WriteFile has incorrect path %s", wf.Path)
+		}
+		if wf.Owner != "root:dogepack" {
+			t.Errorf("WriteFile has incorrect owner %s", wf.Owner)
+		}
+	}
 }
 
 // Assert that our interface conversion doesn't panic

cloudinit/write_file.go

@@ -0,0 +1,46 @@
+package cloudinit
+
+import (
+	"errors"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path"
+	"strconv"
+)
+
+type WriteFile struct {
+	Encoding    string
+	Content     string
+	Owner       string
+	Path        string
+	Permissions string
+}
+
+func ProcessWriteFile(base string, wf *WriteFile) error {
+	fullPath := path.Join(base, wf.Path)
+
+	if err := os.MkdirAll(path.Dir(fullPath), os.FileMode(0744)); err != nil {
+		return err
+	}
+
+	// Parse string representation of file mode as octal
+	perm, err := strconv.ParseInt(wf.Permissions, 8, 32)
+	if err != nil {
+		return errors.New("Unable to parse file permissions as octal integer")
+	}
+
+	if err := ioutil.WriteFile(fullPath, []byte(wf.Content), os.FileMode(perm)); err != nil {
+		return err
+	}
+
+	if wf.Owner != "" {
+		// We shell out since we don't have a way to look up unix groups natively
+		cmd := exec.Command("chown", wf.Owner, fullPath)
+		if err := cmd.Run(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

cloudinit/write_file_test.go

@@ -0,0 +1,81 @@
+package cloudinit
+
+import (
+	"io/ioutil"
+	"os"
+	"path"
+	"syscall"
+	"testing"
+)
+
+func TestWriteFileUnencodedContent(t *testing.T) {
+	wf := WriteFile{
+		Path:        "/tmp/foo",
+		Content:     "bar",
+		Permissions: "0644",
+	}
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer syscall.Rmdir(dir)
+
+	if err := ProcessWriteFile(dir, &wf); err != nil {
+		t.Fatalf("Processing of WriteFile failed: %v", err)
+	}
+
+	fullPath := path.Join(dir, "tmp", "foo")
+
+	fi, err := os.Stat(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to stat file: %v", err)
+	}
+
+	if fi.Mode() != os.FileMode(0644) {
+		t.Errorf("File has incorrect mode: %v", fi.Mode())
+	}
+
+	contents, err := ioutil.ReadFile(fullPath)
+	if err != nil {
+		t.Fatalf("Unable to read expected file: %v", err)
+	}
+
+	if string(contents) != "bar" {
+		t.Fatalf("File has incorrect contents")
+	}
+}
+
+func TestWriteFileInvalidPermission(t *testing.T) {
+	wf := WriteFile{
+		Path:        "/tmp/foo",
+		Content:     "bar",
+		Permissions: "pants",
+	}
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer syscall.Rmdir(dir)
+
+	if err := ProcessWriteFile(dir, &wf); err == nil {
+		t.Fatalf("Expected error to be raised when writing file with invalid permission")
+	}
+}
+
+func TestWriteFileEncodedContent(t *testing.T) {
+	wf := WriteFile{
+		Path: "/tmp/foo",
+		Content: "",
+		Encoding: "base64",
+	}
+
+	dir, err := ioutil.TempDir(os.TempDir(), "coreos-cloudinit-")
+	if err != nil {
+		t.Fatalf("Unable to create tempdir: %v", err)
+	}
+	defer syscall.Rmdir(dir)
+
+	if err := ProcessWriteFile(dir, &wf); err == nil {
+		t.Fatalf("Expected error to be raised when writing file with encoding")
+	}
+}