Expose the authorized keys tmate feature (#18)

* Expose the authorized keys tmate feature
Described here: https://tmate.io/ in "Access Control"
The variable accepts the file content in raw format (with \n) and dumps it into a file which tmate reads
* Use echo instead of printf
* Add missing quote
* Only setup tmate settings if debug is activated

command/compile.go

@@ -214,6 +214,9 @@ func registerCompile(app *kingpin.Application) {
 	cmd.Flag("tmate-server-ed25519-fingerprint", "tmate server rsa fingerprint").
 		StringVar(&c.Tmate.ED25519)
 
+	cmd.Flag("tmate-authorized-keys", "tmate authorized keys").
+		StringVar(&c.Tmate.AuthorizedKeys)
+
 	// shared pipeline flags
 	c.Flags = internal.ParseFlags(cmd)
 }

command/daemon/config.go

@@ -114,6 +114,7 @@ type Config struct {
 		Port           string `envconfig:"DRONE_TMATE_PORT"`
 		RSA            string `envconfig:"DRONE_TMATE_FINGERPRINT_RSA"`
 		ED25519        string `envconfig:"DRONE_TMATE_FINGERPRINT_ED25519"`
+		AuthorizedKeys string `envconfig:"DRONE_TMATE_AUTHORIZED_KEYS"`
 	}
 }
 

command/daemon/daemon.go

@@ -148,6 +148,7 @@ func (c *daemonCommand) run(*kingpin.ParseContext) error {
 				Port:           config.Tmate.Port,
 				RSA:            config.Tmate.RSA,
 				ED25519:        config.Tmate.ED25519,
+				AuthorizedKeys: config.Tmate.AuthorizedKeys,
 			},
 			Environ: provider.Combine(
 				provider.Static(config.Runner.Environ),

command/exec.go

@@ -348,6 +348,9 @@ func registerExec(app *kingpin.Application) {
 	cmd.Flag("tmate-server-ed25519-fingerprint", "tmate server rsa fingerprint").
 		StringVar(&c.Tmate.ED25519)
 
+	cmd.Flag("tmate-authorized-keys", "tmate authorized keys").
+		StringVar(&c.Tmate.AuthorizedKeys)
+
 	cmd.Flag("debug", "enable debug logging").
 		BoolVar(&c.Debug)
 

engine/compiler/compiler.go

@@ -62,6 +62,7 @@ type Tmate struct {
 	Port           string
 	RSA            string
 	ED25519        string
+	AuthorizedKeys string
 }
 
 // Compiler compiles the Yaml configuration file to an
@@ -247,6 +248,10 @@ func (c *Compiler) Compile(ctx context.Context, args runtime.CompilerArgs) runti
 		envs["DRONE_TMATE_PORT"] = c.Tmate.Port
 		envs["DRONE_TMATE_FINGERPRINT_RSA"] = c.Tmate.RSA
 		envs["DRONE_TMATE_FINGERPRINT_ED25519"] = c.Tmate.ED25519
+
+		if c.Tmate.AuthorizedKeys != "" {
+			envs["DRONE_TMATE_AUTHORIZED_KEYS"] = c.Tmate.AuthorizedKeys
+		}
 	}
 
 	// create the .netrc environment variables if not

engine/compiler/shell/shell.go

@@ -63,14 +63,18 @@ remote_debug() {
 	fi
 }
 
-if [ ! -z "${DRONE_TMATE_HOST}" ]; then
+if [ "${DRONE_BUILD_DEBUG}" = "true" ]; then
+	if [ ! -z "${DRONE_TMATE_HOST}" ]; then
 		echo "set -g tmate-server-host $DRONE_TMATE_HOST" >> $HOME/.tmate.conf
 		echo "set -g tmate-server-port $DRONE_TMATE_PORT" >> $HOME/.tmate.conf
 		echo "set -g tmate-server-rsa-fingerprint $DRONE_TMATE_FINGERPRINT_RSA" >> $HOME/.tmate.conf
 		echo "set -g tmate-server-ed25519-fingerprint $DRONE_TMATE_FINGERPRINT_ED25519" >> $HOME/.tmate.conf
-fi
 
-if [ "${DRONE_BUILD_DEBUG}" = "true" ]; then
+		if [ ! -z "${DRONE_TMATE_AUTHORIZED_KEYS}" ]; then
+			echo "$DRONE_TMATE_AUTHORIZED_KEYS" > $HOME/.tmate.authorized_keys
+			echo "set -g tmate-authorized-keys \"$HOME/.tmate.authorized_keys\"" >> $HOME/.tmate.conf
+		fi
+	fi
 	trap remote_debug EXIT
 fi
 `