cmd: Enhance .env (dotenv) file parsing

Basic support for quoted values, newlines in quoted values, and comments.

Does not support variable or command expansion.

Author: mholt

cmd/main.go

@@ -368,42 +368,68 @@ func loadEnvFromFile(envFile string) error {
 	return nil
 }
 
+// parseEnvFile parses an env file from KEY=VALUE format.
+// It's pretty naive. Limited value quotation is supported,
+// but variable and command expansions are not supported.
 func parseEnvFile(envInput io.Reader) (map[string]string, error) {
 	envMap := make(map[string]string)
 
 	scanner := bufio.NewScanner(envInput)
-	var line string
-	lineNumber := 0
+	var lineNumber int
 
 	for scanner.Scan() {
-		line = strings.TrimSpace(scanner.Text())
+		line := strings.TrimSpace(scanner.Text())
 		lineNumber++
 
-		// skip lines starting with comment
-		if strings.HasPrefix(line, "#") {
-			continue
-		}
-
-		// skip empty line
-		if len(line) == 0 {
+		// skip empty lines and lines starting with comment
+		if line == "" || strings.HasPrefix(line, "#") {
 			continue
 		}
 
+		// split line into key and value
 		fields := strings.SplitN(line, "=", 2)
 		if len(fields) != 2 {
 			return nil, fmt.Errorf("can't parse line %d; line should be in KEY=VALUE format", lineNumber)
 		}
+		key, val := fields[0], fields[1]
 
-		if strings.Contains(fields[0], " ") {
-			return nil, fmt.Errorf("bad key on line %d: contains whitespace", lineNumber)
-		}
-
-		key := fields[0]
-		val := fields[1]
+		// sometimes keys are prefixed by "export " so file can be sourced in bash; ignore it here
+		key = strings.TrimPrefix(key, "export ")
 
+		// validate key and value
 		if key == "" {
 			return nil, fmt.Errorf("missing or empty key on line %d", lineNumber)
 		}
+		if strings.Contains(key, " ") {
+			return nil, fmt.Errorf("invalid key on line %d: contains whitespace: %s", lineNumber, key)
+		}
+		if strings.HasPrefix(val, " ") || strings.HasPrefix(val, "\t") {
+			return nil, fmt.Errorf("invalid value on line %d: whitespace before value: '%s'", lineNumber, val)
+		}
+
+		// remove any trailing comment after value
+		if commentStart := strings.Index(val, "#"); commentStart > 0 {
+			before := val[commentStart-1]
+			if before == '\t' || before == ' ' {
+				val = strings.TrimRight(val[:commentStart], " \t")
+			}
+		}
+
+		// quoted value: support newlines
+		if strings.HasPrefix(val, `"`) {
+			for !(strings.HasSuffix(line, `"`) && !strings.HasSuffix(line, `\"`)) {
+				val = strings.ReplaceAll(val, `\"`, `"`)
+				if !scanner.Scan() {
+					break
+				}
+				lineNumber++
+				line = strings.ReplaceAll(scanner.Text(), `\"`, `"`)
+				val += "\n" + line
+			}
+			val = strings.TrimPrefix(val, `"`)
+			val = strings.TrimSuffix(val, `"`)
+		}
+
 		envMap[key] = val
 	}
 

cmd/main_test.go

@@ -0,0 +1,170 @@
+package caddycmd
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestParseEnvFile(t *testing.T) {
+	for i, tc := range []struct {
+		input     string
+		expect    map[string]string
+		shouldErr bool
+	}{
+		{
+			input: `KEY=value`,
+			expect: map[string]string{
+				"KEY": "value",
+			},
+		},
+		{
+			input: `
+				KEY=value
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"KEY":       "value",
+				"OTHER_KEY": "Some Value",
+			},
+		},
+		{
+			input: `
+				KEY=value
+				INVALID KEY=asdf
+				OTHER_KEY=Some Value
+			`,
+			shouldErr: true,
+		},
+		{
+			input: `
+				KEY=value
+				SIMPLE_QUOTED="quoted value"
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"KEY":           "value",
+				"SIMPLE_QUOTED": "quoted value",
+				"OTHER_KEY":     "Some Value",
+			},
+		},
+		{
+			input: `
+				KEY=value
+				NEWLINES="foo
+	bar"
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"KEY":       "value",
+				"NEWLINES":  "foo\n\tbar",
+				"OTHER_KEY": "Some Value",
+			},
+		},
+		{
+			input: `
+				KEY=value
+				ESCAPED="\"escaped quotes\"
+here"
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"KEY":       "value",
+				"ESCAPED":   "\"escaped quotes\"\nhere",
+				"OTHER_KEY": "Some Value",
+			},
+		},
+		{
+			input: `
+				export KEY=value
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"KEY":       "value",
+				"OTHER_KEY": "Some Value",
+			},
+		},
+		{
+			input: `
+				=value
+				OTHER_KEY=Some Value
+			`,
+			shouldErr: true,
+		},
+		{
+			input: `
+				EMPTY=
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"EMPTY":     "",
+				"OTHER_KEY": "Some Value",
+			},
+		},
+		{
+			input: `
+				EMPTY=""
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"EMPTY":     "",
+				"OTHER_KEY": "Some Value",
+			},
+		},
+		{
+			input: `
+				KEY=value
+				#OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"KEY": "value",
+			},
+		},
+		{
+			input: `
+				KEY=value
+				COMMENT=foo bar  # some comment here
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"KEY":       "value",
+				"COMMENT":   "foo bar",
+				"OTHER_KEY": "Some Value",
+			},
+		},
+		{
+			input: `
+				KEY=value
+				WHITESPACE=   foo 
+				OTHER_KEY=Some Value
+			`,
+			shouldErr: true,
+		},
+		{
+			input: `
+				KEY=value
+				WHITESPACE="   foo bar "
+				OTHER_KEY=Some Value
+			`,
+			expect: map[string]string{
+				"KEY":        "value",
+				"WHITESPACE": "   foo bar ",
+				"OTHER_KEY":  "Some Value",
+			},
+		},
+	} {
+		actual, err := parseEnvFile(strings.NewReader(tc.input))
+		if err != nil && !tc.shouldErr {
+			t.Errorf("Test %d: Got error but shouldn't have: %v", i, err)
+		}
+		if err == nil && tc.shouldErr {
+			t.Errorf("Test %d: Did not get error but should have", i)
+		}
+		if tc.shouldErr {
+			continue
+		}
+		if !reflect.DeepEqual(tc.expect, actual) {
+			t.Errorf("Test %d: Expected %v but got %v", i, tc.expect, actual)
+		}
+	}
+}