feat: allow using tilde in tmp dir

Author: afbjorklund

internal/config/load.go

@@ -176,8 +176,22 @@ func readConfig(path string) (*Config, error) {
 	}
 	if cfg.Docker == nil {
 		cfg.Docker = &Docker{Bin: "docker"}
-	} else if cfg.Docker.Bin == "" {
-		cfg.Docker.Bin = "docker"
+	} else {
+		if cfg.Docker.Bin == "" {
+			cfg.Docker.Bin = "docker"
+		}
+		if cfg.Docker.Tmp != "" {
+			tmp := cfg.Docker.Tmp
+			dir, err := expandTilde(tmp)
+			if err != nil {
+				return nil, err
+			}
+			err = os.MkdirAll(dir, 0755)
+			if err != nil {
+				return nil, err
+			}
+			cfg.Docker.Tmp = dir
+		}
 	}
 
 	return cfg, err
@@ -232,6 +246,21 @@ func readBoxesFile(path string) (map[string]*Box, error) {
 	return boxes, err
 }
 
+// userHomeDir returns the current user's home directory.
+var userHomeDir = os.UserHomeDir
+
+// expandTilde expands strings like "~/.local" with the path.
+func expandTilde(dir string) (string, error) {
+	if strings.HasPrefix(dir, "~/") {
+		homeDir, err := userHomeDir()
+		if err != nil {
+			return "", err
+		}
+		dir = strings.Replace(dir, "~", homeDir, 1)
+	}
+	return dir, nil
+}
+
 // readCommands reads command configs from a set of JSON files in the given path.
 func readCommands(cfg *Config, path string, pattern string) (*Config, error) {
 	logx.Debug("reading commands from %s/%s", path, pattern)

internal/config/load_test.go

@@ -1,19 +1,27 @@
 package config
 
 import (
+	"path/filepath"
 	"testing"
 
 	"github.com/nalgeon/be"
 )
 
 func TestRead(t *testing.T) {
+	home := filepath.Join(t.TempDir(), "HOME")
+	userHomeDir = func() (string, error) { return home, nil }
+
 	cfg, err := Read("testdata")
 	be.Err(t, err, nil)
 	be.Equal(t, cfg.PoolSize, 8)
 	be.Equal(t, cfg.Verbose, true)
 	be.Equal(t, cfg.Box.Memory, 64)
 	be.Equal(t, cfg.Step.User, "sandbox")
 
+	// docker
+	be.Equal(t, cfg.Docker.Bin, "docker")
+	be.Equal(t, cfg.Docker.Tmp, home+"/tmp")
+
 	// alpine box
 	be.True(t, cfg.Boxes["custom-alpine"] != nil)
 	be.Equal(t, cfg.Boxes["custom-alpine"].Image, "custom/alpine")

internal/config/testdata/codapi.json

@@ -1,6 +1,10 @@
 {
     "pool_size": 8,
     "verbose": true,
+    "docker": {
+	 "bin": "",
+	 "tmp": "~/tmp"
+    },
     "box": {
         "memory": 64
     },