fixup

- Add comments
- Rename `Config` to `TomlConfigTable`
- Delete the macros, replace them with inlined functions

Author: tankyleo

rust/server/src/util/config.rs

@@ -11,8 +11,10 @@ const PSQL_VSS_DB_VAR: &str = "VSS_PSQL_VSS_DB";
 const PSQL_TLS_VAR: &str = "VSS_PSQL_TLS";
 const PSQL_CERT_PEM_VAR: &str = "VSS_PSQL_CRT_PEM";
 
+// The structure of the toml config file. Any settings specified therein can be overriden by the corresponding
+// environment variable.
 #[derive(Deserialize, Default)]
-struct Config {
+struct TomlConfigTable {
 	server_config: Option<ServerConfig>,
 	jwt_auth_config: Option<JwtAuthConfig>,
 	postgresql_config: Option<PostgreSQLConfig>,
@@ -43,6 +45,7 @@ struct TlsConfig {
 	crt_pem: Option<String>,
 }
 
+// Encapsulates the result of reading both the environment variables and the config file.
 pub(crate) struct Configuration {
 	pub(crate) bind_address: SocketAddr,
 	pub(crate) rsa_pem: Option<String>,
@@ -52,8 +55,28 @@ pub(crate) struct Configuration {
 	pub(crate) tls_config: Option<Option<String>>,
 }
 
+#[inline]
+fn read_env(env_var: &str) -> Result<Option<String>, String> {
+	match std::env::var(env_var) {
+		Ok(env) => Ok(Some(env)),
+		Err(std::env::VarError::NotPresent) => Ok(None),
+		Err(e) => Err(format!("Failed to load the {} environment variable: {}", env_var, e)),
+	}
+}
+
+#[inline]
+fn read_config<'a, T: std::fmt::Display>(
+	env: Option<T>, config: Option<T>, item: &str, var_name: &str,
+) -> Result<T, String> {
+	env.or(config).ok_or(format!(
+		"{} must be provided in the configuration file or the environment variable {} must be set.",
+		item, var_name
+	))
+}
+
 pub(crate) fn load_configuration(config_file_path: Option<&str>) -> Result<Configuration, String> {
-	let Config { server_config, jwt_auth_config, postgresql_config } = if config_file_path.is_some()
+	let TomlConfigTable { server_config, jwt_auth_config, postgresql_config } = if config_file_path
+		.is_some()
 		&& std::fs::exists(config_file_path.expect("config file path is some"))
 			.map_err(|e| format!("Failed to check presence of configuration file: {}", e))?
 	{
@@ -63,63 +86,39 @@ pub(crate) fn load_configuration(config_file_path: Option<&str>) -> Result<Confi
 		toml::from_str(&config_file)
 			.map_err(|e| format!("Failed to parse configuration file: {}", e))?
 	} else {
-		Config::default() // All fields are set to `None`
+		TomlConfigTable::default() // All fields are set to `None`
 	};
 
-	macro_rules! read_env {
-		($env_var:expr) => {
-			match std::env::var($env_var) {
-				Ok(env) => Some(env),
-				Err(std::env::VarError::NotPresent) => None,
-				Err(e) => {
-					return Err(format!(
-						"Failed to load the {} environment variable: {}",
-						$env_var, e
-					))
-				},
-			}
-		};
-	}
-
-	macro_rules! read_config {
-		($env:expr, $config: expr, $item: expr, $var_name: expr) => {
-			$env.or($config).ok_or(format!(
-				"{} must be provided in the configuration file or the environment variable {} must be set.",
-				$item, $var_name
-			))?
-		};
-	}
-
-	let bind_address_env = read_env!(BIND_ADDR_VAR)
+	let bind_address_env = read_env(BIND_ADDR_VAR)?
 		.map(|addr| {
 			addr.parse().map_err(|e| {
 				format!("Unable to parse the bind address environment variable: {}", e)
 			})
 		})
 		.transpose()?;
-	let bind_address = read_config!(
+	let bind_address = read_config(
 		bind_address_env,
 		server_config.and_then(|c| c.bind_address),
 		"VSS server bind address",
-		BIND_ADDR_VAR
-	);
+		BIND_ADDR_VAR,
+	)?;
 
-	let rsa_pem_env = read_env!(JWT_RSA_PEM_VAR);
+	let rsa_pem_env = read_env(JWT_RSA_PEM_VAR)?;
 	let rsa_pem = rsa_pem_env.or(jwt_auth_config.and_then(|config| config.rsa_pem));
 
-	let username_env = read_env!(PSQL_USER_VAR);
-	let password_env = read_env!(PSQL_PASS_VAR);
-	let address_env: Option<SocketAddr> = read_env!(PSQL_ADDR_VAR)
+	let username_env = read_env(PSQL_USER_VAR)?;
+	let password_env = read_env(PSQL_PASS_VAR)?;
+	let address_env: Option<SocketAddr> = read_env(PSQL_ADDR_VAR)?
 		.map(|address| {
 			address.parse().map_err(|e| {
 				format!("Unable to parse the postgresql address environment variable: {}", e)
 			})
 		})
 		.transpose()?;
-	let default_db_env = read_env!(PSQL_DB_VAR);
-	let vss_db_env = read_env!(PSQL_VSS_DB_VAR);
-	let tls_config_env = read_env!(PSQL_TLS_VAR);
-	let crt_pem_env = read_env!(PSQL_CERT_PEM_VAR);
+	let default_db_env = read_env(PSQL_DB_VAR)?;
+	let vss_db_env = read_env(PSQL_VSS_DB_VAR)?;
+	let tls_config_env = read_env(PSQL_TLS_VAR)?;
+	let crt_pem_env = read_env(PSQL_CERT_PEM_VAR)?;
 
 	let (
 		username_config,
@@ -141,19 +140,19 @@ pub(crate) fn load_configuration(config_file_path: Option<&str>) -> Result<Confi
 	};
 
 	let username =
-		read_config!(username_env, username_config, "PostgreSQL database username", PSQL_USER_VAR);
+		read_config(username_env, username_config, "PostgreSQL database username", PSQL_USER_VAR)?;
 	let password =
-		read_config!(password_env, password_config, "PostgreSQL database password", PSQL_PASS_VAR);
+		read_config(password_env, password_config, "PostgreSQL database password", PSQL_PASS_VAR)?;
 	let address =
-		read_config!(address_env, address_config, "PostgreSQL service address", PSQL_ADDR_VAR);
-	let default_db = read_config!(
+		read_config(address_env, address_config, "PostgreSQL service address", PSQL_ADDR_VAR)?;
+	let default_db = read_config(
 		default_db_env,
 		default_db_config,
 		"PostgreSQL default database name",
-		PSQL_DB_VAR
-	);
+		PSQL_DB_VAR,
+	)?;
 	let vss_db =
-		read_config!(vss_db_env, vss_db_config, "PostgreSQL vss database name", PSQL_VSS_DB_VAR);
+		read_config(vss_db_env, vss_db_config, "PostgreSQL vss database name", PSQL_VSS_DB_VAR)?;
 
 	let tls_config =
 		crt_pem_env.map(|pem| Some(pem)).or(tls_config_env.map(|_| None)).or(tls_config);

rust/server/vss-server-config.toml

@@ -13,6 +13,7 @@ bind_address = "127.0.0.1:8080" # Optional in TOML, can be overridden by env var
 username = "postgres"          # Optional in TOML, can be overridden by env var `VSS_PSQL_USERNAME`
 password = "postgres"          # Optional in TOML, can be overridden by env var `VSS_PSQL_PASSWORD`
 address = "127.0.0.1:5432"     # Optional in TOML, can be overridden by env var `VSS_PSQL_ADDRESS`
+# We first connect to `default_database` to create `vss_database` if it does not exist
 default_database = "postgres"  # Optional in TOML, can be overridden by env var `VSS_PSQL_DEFAULT_DB`
 vss_database = "vss"           # Optional in TOML, can be overridden by env var `VSS_PSQL_VSS_DB`