Add readyset_database configuration option

In order to connect to a Readyset instance via PostgreSQL, it may be
required to specify the database name.  This patch adds an optional
configuration for specifying the database when connecting to Readyset.

Author: davisjc

README.md

@@ -46,6 +46,7 @@ Configure `/etc/readyset_proxysql_scheduler.cnf` as follow:
 * `proxysql_port` - (Required) - ProxySQL admin port
 * `readyset_user` - (Required) - Readyset application user
 * `readyset_password` - (Required) - Readyset application password
+* `readyset_database` - (Optional) - Readyset application database
 * `source_hostgroup` - (Required) - Hostgroup running your Read workload
 * `readyset_hostgroup` - (Required) - Hostgroup where Readyset is configure
 * `warmup_time_s` - (Optional) - Time in seconds to mirror a query supported before redirecting the query to Readyset (Default `0` - no mirror)

src/config.rs

@@ -77,6 +77,7 @@ pub struct Config {
     pub proxysql_port: u16,
     pub readyset_user: String,
     pub readyset_password: String,
+    pub readyset_database: Option<String>,
     pub source_hostgroup: u16,
     pub readyset_hostgroup: u16,
     #[serde(default)]

src/proxysql.rs

@@ -53,6 +53,7 @@ impl ProxySQL {
             config.proxysql_port,
             &config.proxysql_user,
             &config.proxysql_password,
+            None,
         ) {
             Ok(conn) => conn,
             Err(err) => panic!("Failed to create ProxySQL connection: {err}"),

src/readyset.rs

@@ -116,6 +116,7 @@ impl Readyset {
             port,
             &config.readyset_user,
             &config.readyset_password,
+            config.readyset_database.as_deref(),
         ) {
             Ok(conn) => conn,
             Err(err) => {

src/sql_connection.rs

@@ -35,6 +35,7 @@ impl SQLConnection {
         port: u16,
         user: &str,
         pass: &str,
+        database: Option<&str>,
     ) -> Result<Self> {
         Ok(match database_type {
             DatabaseType::MySQL => Self::MySQL(Conn::new(
@@ -43,25 +44,31 @@ impl SQLConnection {
                     .tcp_port(port)
                     .user(Some(user))
                     .pass(Some(pass))
+                    .db_name(database)
                     .prefer_socket(false)
                     .read_timeout(Some(TIMEOUT))
                     .write_timeout(Some(TIMEOUT))
                     .tcp_connect_timeout(Some(TIMEOUT)),
             )?),
-            DatabaseType::PostgreSQL => Self::PostgreSQL(
-                Config::new()
-                    .host(hostname)
-                    .port(port)
-                    .user(user)
-                    .password(pass)
-                    .connect_timeout(TIMEOUT)
-                    .tcp_user_timeout(TIMEOUT)
-                    .connect(MakeTlsConnector::new(
+            DatabaseType::PostgreSQL => {
+                let mut config = Config::new();
+                config.host(hostname);
+                config.port(port);
+                config.user(user);
+                config.password(pass);
+                if let Some(database) = database {
+                    config.dbname(database);
+                }
+                config.connect_timeout(TIMEOUT);
+                config.tcp_user_timeout(TIMEOUT);
+                Self::PostgreSQL(
+                    config.connect(MakeTlsConnector::new(
                         TlsConnector::builder()
                             .danger_accept_invalid_certs(true)
                             .build()?,
                     ))?,
-            ),
+                )
+            }
         })
     }