ref(client): update and document unit file search paths

deisctl looks for unit files in these directories, in this order:
- the $DEISCTL_UNITS environment variable, if set
- $HOME/.deis/units
- /var/lib/deis/units

Author: mboersma

README.md

@@ -11,7 +11,7 @@ curl -sSL http://deis.io/deisctl/install.sh | sudo sh
 ```
 
 The installer puts `deisctl` in */usr/local/bin* and downloads current Deis unit files
-to *~/.deisctl* one time.
+to */var/lib/deis/units* one time.
 
 To change installation options, save the installer directly from one of these links:
 
@@ -115,7 +115,7 @@ The `deisctl` tool provides a number of other commands, including:
  * `deisctl install <component>` - install a single platform component
  * `deisctl uninstall <component>` - uninstall a single platform component
  * `deisctl scale <component>=<num>` - scale a component to the target number of units
- * `deisctl refresh-units` - download latest unit files to ~/.deisctl
+ * `deisctl refresh-units` - download latest unit files
 
 ## Usage Examples
 

client/unit.go

@@ -14,7 +14,11 @@ import (
 )
 
 // path hierarchy for finding systemd service templates
-var rootPaths = []string{"~/.deisctl/units", "/var/lib/deis/units"}
+var templatePaths = []string{
+	os.Getenv("DEISCTL_UNITS"),
+	"~/.deis/units",
+	"/var/lib/deis/units",
+}
 
 // Units returns a list of units filtered by target
 func (c *FleetClient) Units(target string) (units []string, err error) {
@@ -109,22 +113,16 @@ func readTemplate(component string) (out []byte, err error) {
 	templateName := "deis-" + component + ".service"
 	var templateFile string
 
-	// first look for unit files in GOPATH
-	if os.Getenv("GOPATH") != "" {
-		filename := path.Join(os.Getenv("GOPATH"),
-			path.Join("src", "github.com", "deis", "deisctl", "units", templateName))
+	// look in $DEISCTL_UNITS env var, then the local and global root paths
+	for _, p := range templatePaths {
+		if p == "" {
+			continue
+		}
+		p, _ := ExpandUser(p)
+		filename := path.Join(p, templateName)
 		if _, err := os.Stat(filename); err == nil {
 			templateFile = filename
-		}
-	} else {
-		// otherwise look in rootPaths hierarchy
-		for _, rootPath := range rootPaths {
-			rootPath, _ := ExpandUser(rootPath)
-			filename := path.Join(rootPath, templateName)
-			if _, err := os.Stat(filename); err == nil {
-				templateFile = filename
-				break
-			}
+			break
 		}
 	}
 

cmd/cmd.go

@@ -259,6 +259,11 @@ func Update() error {
 func RefreshUnits() error {
 	usage := `Refreshes local unit files from the master repository.
 
+deisctl looks for unit files in these directories, in this order:
+- the $DEISCTL_UNITS environment variable, if set
+- $HOME/.deis/units
+- /var/lib/deis/units
+
 Usage:
   deisctl refresh-units [-p <target>]