server/config: revamp

- Adds options `socket_path` and `password_file`

example-config.toml

@@ -1,8 +1,22 @@
 # This should go to `/etc/mysqladm/config.toml`
 
+[server]
+# Note that this gets ignored if you are using socket activation.
+socket_path = "/var/run/mysqladm/mysqladm.sock"
+
 [mysql]
+
+# if you use a socket, the host and port will be ignored
+# socket_path = "/var/run/mysql/mysql.sock"
+
 host = "localhost"
 port = 3306
+
+# The username and password can be omitted if you are using
+# socket based authentication. However, the vendored systemd
+# service is running as DynamicUser, so by default you need
+# to at least specify the username.
 username = "root"
 password = "secret"
+
 timeout = 2 # seconds

src/core/bootstrap.rs

@@ -7,7 +7,7 @@ use tokio::net::UnixStream as TokioUnixStream;
 
 use crate::{
     core::common::{UnixUser, DEFAULT_CONFIG_PATH, DEFAULT_SOCKET_PATH},
-    server::{config::read_config_form_path, server_loop::handle_requests_for_single_session},
+    server::{config::read_config_from_path, server_loop::handle_requests_for_single_session},
 };
 
 // TODO: this function is security critical, it should be integration tested
@@ -140,7 +140,7 @@ fn run_forked_server(
     server_socket: StdUnixStream,
     unix_user: UnixUser,
 ) -> anyhow::Result<()> {
-    let config = read_config_form_path(Some(config_path))?;
+    let config = read_config_from_path(Some(config_path))?;
 
     let result: anyhow::Result<()> = tokio::runtime::Builder::new_current_thread()
         .enable_all()

src/server/config.rs

@@ -21,21 +21,37 @@ pub struct ServerConfig {
 #[derive(Debug, Clone, Deserialize, Serialize)]
 #[serde(rename = "mysql")]
 pub struct MysqlConfig {
-    pub host: String,
+    pub socket_path: Option<PathBuf>,
+    pub host: Option<String>,
     pub port: Option<u16>,
-    pub username: String,
-    pub password: String,
+    pub username: Option<String>,
+    pub password: Option<String>,
+    pub password_file: Option<PathBuf>,
     pub timeout: Option<u64>,
 }
 
 #[derive(Parser, Debug, Clone)]
 pub struct ServerConfigArgs {
+    /// Path to the socket of the MySQL server.
+    #[arg(long, value_name = "PATH", global = true)]
+    socket_path: Option<PathBuf>,
+
     /// Hostname of the MySQL server.
-    #[arg(long, value_name = "HOST", global = true)]
+    #[arg(
+        long,
+        value_name = "HOST",
+        global = true,
+        conflicts_with = "socket_path"
+    )]
     mysql_host: Option<String>,
 
     /// Port of the MySQL server.
-    #[arg(long, value_name = "PORT", global = true)]
+    #[arg(
+        long,
+        value_name = "PORT",
+        global = true,
+        conflicts_with = "socket_path"
+    )]
     mysql_port: Option<u16>,
 
     /// Username to use for the MySQL connection.
@@ -44,7 +60,7 @@ pub struct ServerConfigArgs {
 
     /// Path to a file containing the MySQL password.
     #[arg(long, value_name = "PATH", global = true)]
-    mysql_password_file: Option<String>,
+    mysql_password_file: Option<PathBuf>,
 
     /// Seconds to wait for the MySQL connection to be established.
     #[arg(long, value_name = "SECONDS", global = true)]
@@ -57,30 +73,40 @@ pub fn read_config_from_path_with_arg_overrides(
     config_path: Option<PathBuf>,
     args: ServerConfigArgs,
 ) -> anyhow::Result<ServerConfig> {
-    let config = read_config_form_path(config_path)?;
+    let config = read_config_from_path(config_path)?;
 
-    let mysql = &config.mysql;
+    let mysql = config.mysql;
 
-    let password = if let Some(path) = args.mysql_password_file {
+    let password = if let Some(path) = &args.mysql_password_file {
+        Some(
             fs::read_to_string(path)
                 .context("Failed to read MySQL password file")
-            .map(|s| s.trim().to_owned())?
+                .map(|s| s.trim().to_owned())?,
+        )
+    } else if let Some(path) = &mysql.password_file {
+        Some(
+            fs::read_to_string(path)
+                .context("Failed to read MySQL password file")
+                .map(|s| s.trim().to_owned())?,
+        )
     } else {
         mysql.password.to_owned()
     };
 
     Ok(ServerConfig {
         mysql: MysqlConfig {
-            host: args.mysql_host.unwrap_or(mysql.host.to_owned()),
+            socket_path: args.socket_path.or(mysql.socket_path),
+            host: args.mysql_host.or(mysql.host),
             port: args.mysql_port.or(mysql.port),
-            username: args.mysql_user.unwrap_or(mysql.username.to_owned()),
+            username: args.mysql_user.or(mysql.username.to_owned()),
             password,
+            password_file: args.mysql_password_file.or(mysql.password_file),
             timeout: args.mysql_connect_timeout.or(mysql.timeout),
         },
     })
 }
 
-pub fn read_config_form_path(config_path: Option<PathBuf>) -> anyhow::Result<ServerConfig> {
+pub fn read_config_from_path(config_path: Option<PathBuf>) -> anyhow::Result<ServerConfig> {
     let config_path = config_path.unwrap_or_else(|| PathBuf::from(DEFAULT_CONFIG_PATH));
 
     log::debug!("Reading config from {:?}", &config_path);
@@ -97,30 +123,51 @@ pub fn read_config_form_path(config_path: Option<PathBuf>) -> anyhow::Result<Ser
         ))
 }
 
-/// Use the provided configuration to establish a connection to a MySQL server.
-pub async fn create_mysql_connection_from_config(
-    config: &MysqlConfig,
-) -> anyhow::Result<MySqlConnection> {
+fn log_config(config: &MysqlConfig) {
     let mut display_config = config.clone();
-    "<REDACTED>".clone_into(&mut display_config.password);
+    display_config.password = display_config
+        .password
+        .as_ref()
+        .map(|_| "<REDACTED>".to_owned());
     log::debug!(
         "Connecting to MySQL server with parameters: {:#?}",
         display_config
     );
+}
+
+/// Use the provided configuration to establish a connection to a MySQL server.
+pub async fn create_mysql_connection_from_config(
+    config: &MysqlConfig,
+) -> anyhow::Result<MySqlConnection> {
+    log_config(config);
+
+    let mut mysql_options = MySqlConnectOptions::new()
+        .database("mysql");
+
+    if let Some(username) = &config.username {
+        mysql_options = mysql_options.username(username);
+    }
+
+    if let Some(password) = &config.password {
+        mysql_options = mysql_options.password(password);
+    }
+
+    if let Some(socket_path) = &config.socket_path {
+        mysql_options = mysql_options.socket(socket_path);
+    } else if let Some(host) = &config.host {
+        mysql_options = mysql_options.host(host);
+        mysql_options = mysql_options.port(config.port.unwrap_or(DEFAULT_PORT));
+    } else {
+        anyhow::bail!("No MySQL host or socket path provided");
+    }
 
     match tokio::time::timeout(
         Duration::from_secs(config.timeout.unwrap_or(DEFAULT_TIMEOUT)),
-        MySqlConnectOptions::new()
-            .host(&config.host)
-            .username(&config.username)
-            .password(&config.password)
-            .port(config.port.unwrap_or(DEFAULT_PORT))
-            .database("mysql")
-            .connect(),
+        mysql_options.connect(),
     )
     .await
     {
-        Ok(connection) => connection.context("Failed to connect to MySQL"),
-        Err(_) => Err(anyhow!("Timed out after 2 seconds")).context("Failed to connect to MySQL"),
+        Ok(connection) => connection.context("Failed to connect to the database"),
+        Err(_) => Err(anyhow!("Timed out after 2 seconds")).context("Failed to connect to the database"),
     }
 }