implemented better routing system, config parsing from yaml.

src/config/mod.rs

@@ -0,0 +1,49 @@
+// config is written as a YAML file, the path will be passed to the program.
+//
+// the high level structure of the config is that we
+// first define the individual backends (ip + port) we are going
+// to load balance around.
+//
+// next we define some clusters, which are really more like a short
+// alias for a group of backends.
+//
+// next we define the rules. these are written as a list of
+// "ip/subnet:port" for the clients, and then a list of clusters
+// for which backends these are balanced around. and of course
+// specify which algorithm to use.
+pub mod loader;
+
+use std::collections::HashMap;
+use serde::Deserialize;
+
+#[derive(Debug, Deserialize)]
+pub struct AppConfig {
+    pub backends: Vec<BackendConfig>,
+    #[serde(default)]
+    pub clusters: HashMap<String, Vec<String>>,
+    pub rules: Vec<RuleConfig>,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct BackendConfig {
+    pub id: String,
+    pub ip: String,
+    pub port: u16,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct RuleConfig {
+    pub clients: Vec<String>,
+    pub targets: Vec<String>,
+    pub strategy: LoadBalancerStrategy,
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(tag = "type")]
+pub enum LoadBalancerStrategy {
+    RoundRobin,
+    Adaptive {
+        coefficients: [f64; 4],
+        alpha: f64,
+    },
+}