feat: add config for tmp directory

internal/config/config.go

@@ -120,6 +120,7 @@ type HTTP struct {
 // A Docker describes Docker engine settings.
 type Docker struct {
 	Bin string `json:"bin"`
+	Tmp string `json:"tmp"`
 }
 
 // setBoxDefaults sets default box properties

internal/config/load.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"strings"
 
@@ -176,8 +177,30 @@ 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"
+		} else {
+			bin := cfg.Docker.Bin
+			_, err := exec.LookPath(bin)
+			if err != nil {
+				return nil, err
+			}
+		}
+		if cfg.Docker.Tmp == "" {
+			cfg.Docker.Tmp = tempDir()
+		} else {
+			tmp := cfg.Docker.Tmp
+			dir, err := expandTilde(tmp)
+			if err != nil {
+				return nil, err
+			}
+			err = os.MkdirAll(dir, 0o755)
+			if err != nil {
+				return nil, err
+			}
+			cfg.Docker.Tmp = dir
+		}
 	}
 
 	return cfg, err
@@ -232,6 +255,24 @@ func readBoxesFile(path string) (map[string]*Box, error) {
 	return boxes, err
 }
 
+// tempDir returns the directory to use for temporary files.
+var tempDir = os.TempDir
+
+// 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 +1,25 @@
 package config
 
 import (
+	"path/filepath"
 	"testing"
 
 	"github.com/nalgeon/be"
 )
 
 func TestRead(t *testing.T) {
 	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, "")
+
 	// alpine box
 	be.True(t, cfg.Boxes["custom-alpine"] != nil)
 	be.Equal(t, cfg.Boxes["custom-alpine"].Image, "custom/alpine")
@@ -23,3 +29,24 @@ func TestRead(t *testing.T) {
 	be.True(t, cfg.Commands["python"] != nil)
 	be.True(t, cfg.Commands["python"]["run"] != nil)
 }
+
+func TestReadDocker(t *testing.T) {
+	temp := filepath.Join(t.TempDir(), "TEMP")
+	tempDir = func() string { return temp }
+
+	cfg, err := readConfig(filepath.Join("testdata", "docker.json"))
+
+	be.Err(t, err, nil)
+	be.Equal(t, cfg.Docker.Bin, "docker")
+	be.Equal(t, cfg.Docker.Tmp, temp)
+}
+
+func TestExpandTilde(t *testing.T) {
+	home := filepath.Join(t.TempDir(), "HOME")
+	userHomeDir = func() (string, error) { return home, nil }
+
+	tmp, err := expandTilde("~/tmp")
+	be.Err(t, err, nil)
+
+	be.Equal(t, tmp, home+"/tmp")
+}

internal/config/testdata/docker.json

@@ -0,0 +1,10 @@
+{
+    "box": {
+    },
+    "step": {
+    },
+    "docker": {
+	 "bin": "",
+	 "tmp": ""
+    }
+}

internal/engine/docker.go

@@ -32,18 +32,19 @@ type Docker struct {
 	cfg *config.Config
 	cmd *config.Command
 	exe string // docker
+	tmp string // TMPDIR
 }
 
 // NewDocker creates a new Docker engine for a specific command.
 func NewDocker(cfg *config.Config, sandbox, command string) Engine {
 	cmd := cfg.Commands[sandbox][command]
-	return &Docker{cfg, cmd, cfg.Docker.Bin}
+	return &Docker{cfg, cmd, cfg.Docker.Bin, cfg.Docker.Tmp}
 }
 
 // Exec executes the command and returns the output.
 func (e *Docker) Exec(req Request) Execution {
 	// all steps operate in the same temp directory
-	dir, err := fileio.MkdirTemp(0777)
+	dir, err := fileio.MkdirTemp(e.tmp, 0777)
 	if err != nil {
 		err = NewExecutionError("create temp dir", err)
 		return Fail(req.ID, err)

internal/fileio/fileio.go

@@ -141,8 +141,8 @@ func JoinDir(dir string, name string) (string, error) {
 
 // MkdirTemp creates a new temporary directory with given permissions
 // and returns the pathname of the new directory.
-func MkdirTemp(perm fs.FileMode) (string, error) {
-	dir, err := os.MkdirTemp("", "")
+func MkdirTemp(dir string, perm fs.FileMode) (string, error) {
+	dir, err := os.MkdirTemp(dir, "")
 	if err != nil {
 		return "", err
 	}

internal/fileio/fileio_test.go

@@ -281,7 +281,7 @@ func TestJoinDir(t *testing.T) {
 func TestMkdirTemp(t *testing.T) {
 	t.Run("default permissions", func(t *testing.T) {
 		const perm = 0755
-		dir, err := MkdirTemp(perm)
+		dir, err := MkdirTemp("", perm)
 		be.Err(t, err, nil)
 		defer func() { _ = os.Remove(dir) }()
 
@@ -292,7 +292,7 @@ func TestMkdirTemp(t *testing.T) {
 
 	t.Run("non-default permissions", func(t *testing.T) {
 		const perm = 0777
-		dir, err := MkdirTemp(perm)
+		dir, err := MkdirTemp(t.TempDir(), perm)
 		be.Err(t, err, nil)
 		defer func() { _ = os.Remove(dir) }()