feat: Add support for DB_PASS_FILE

This commit introduces support for reading the database password from a file specified by the `DB_PASS_FILE` environment variable or the `--pass-file` CLI flag.

- Added `--pass-file` flag and `DB_PASS_FILE` environment variable.
- Updated logic in `cmd/root.go` to read the password from the specified file.
- Ensured that an explicitly set password via `DB_PASS` or `--pass` takes precedence.
- Updated documentation in `docs/configuration.md`.
- Added tests in `cmd/dump_test.go` to cover the new functionality and precedence logic.

Author: google-labs-jules[bot]

cmd/dump_test.go

@@ -40,6 +40,20 @@ func TestDumpCmd(t *testing.T) {
 			DBConn:           database.Connection{Host: "abc", Port: defaultPort},
 			FilenamePattern:  "db_backup_{{ .now }}.{{ .compression }}",
 		}, core.TimerOptions{Frequency: defaultFrequency, Begin: defaultBegin}, nil},
+		{"file URL with pass-file", []string{"--server", "abc", "--target", "file:///foo/bar", "--pass-file", "testdata/password.txt"}, "", false, core.DumpOptions{
+			Targets:          []storage.Storage{file.New(*fileTargetURL)},
+			MaxAllowedPacket: defaultMaxAllowedPacket,
+			Compressor:       &compression.GzipCompressor{},
+			DBConn:           database.Connection{Host: "abc", Port: defaultPort, Pass: "testpassword"},
+			FilenamePattern:  "db_backup_{{ .now }}.{{ .compression }}",
+		}, core.TimerOptions{Frequency: defaultFrequency, Begin: defaultBegin}, nil},
+		{"file URL with pass and pass-file (pass takes precedence)", []string{"--server", "abc", "--target", "file:///foo/bar", "--pass", "explicitpass", "--pass-file", "testdata/password.txt"}, "", false, core.DumpOptions{
+			Targets:          []storage.Storage{file.New(*fileTargetURL)},
+			MaxAllowedPacket: defaultMaxAllowedPacket,
+			Compressor:       &compression.GzipCompressor{},
+			DBConn:           database.Connection{Host: "abc", Port: defaultPort, Pass: "explicitpass"},
+			FilenamePattern:  "db_backup_{{ .now }}.{{ .compression }}",
+		}, core.TimerOptions{Frequency: defaultFrequency, Begin: defaultBegin}, nil},
 		{"file URL with prune", []string{"--server", "abc", "--target", "file:///foo/bar", "--retention", "1h"}, "", false, core.DumpOptions{
 			Targets:          []storage.Storage{file.New(*fileTargetURL)},
 			MaxAllowedPacket: defaultMaxAllowedPacket,

cmd/root.go

@@ -167,6 +167,18 @@ func rootCmd(execs execs) (*cobra.Command, error) {
 				cmdConfig.dbconn.Pass = dbPass
 			}
 
+			// read password from file if pass is not set and pass-file is set
+			if cmdConfig.dbconn.Pass == "" {
+				dbPassFile := v.GetString("pass-file")
+				if dbPassFile != "" {
+					passBytes, err := os.ReadFile(dbPassFile)
+					if err != nil {
+						return fmt.Errorf("failed to read password from file %s: %w", dbPassFile, err)
+					}
+					cmdConfig.dbconn.Pass = strings.TrimSpace(string(passBytes))
+				}
+			}
+
 			// these are not from the config file, as they are generic credentials, used across all targets.
 			// the config file uses specific ones per target
 			cmdConfig.creds = credentials.Creds{
@@ -222,6 +234,9 @@ func rootCmd(execs execs) (*cobra.Command, error) {
 	// pass via CLI or env var
 	pflags.String("pass", "", "password for database server")
 
+	// pass-file via CLI or env var
+	pflags.String("pass-file", "", "path to file containing password for database server")
+
 	// debug via CLI or env var or default
 	pflags.IntP("verbose", "v", 0, "set log level, 1 is debug, 2 is trace")
 	pflags.Bool("debug", false, "set log level to debug, equivalent of --verbose=1; if both set, --version always overrides")

cmd/testdata/password.txt

@@ -0,0 +1 @@
+testpassword

docs/configuration.md

@@ -68,6 +68,7 @@ The following are the environment variables, CLI flags and configuration file op
 | port to use to connect to database. Optional. | BR | `port` | `DB_PORT` | `database.port` | 3306 |
 | username for the database | BR | `user` | `DB_USER` | `database.credentials.username` |  |
 | password for the database | BR | `pass` | `DB_PASS` | `database.credentials.password` |  |
+| path to file containing password for the database. `pass` takes precedence if both are set. | BR | `pass-file` | `DB_PASS_FILE` |  |  |
 | names of databases to dump, comma-separated | B | `include` | `DB_DUMP_INCLUDE` | `dump.include` | all databases in the server |
 | names of databases to exclude from the dump | B | `exclude` | `DB_DUMP_EXCLUDE` | `dump.exclude` |  |
 | do not include `USE <database>;` statement in the dump | B | `no-database-name` | `NO_DATABASE_NAME` | `dump.noDatabaseName` | `false` |