update default load balance option

README.md

@@ -108,7 +108,7 @@ revese_proxy = [
 
 #### Load Balancing
 
-You can specify multiple backend locations in the `reverse_proxy` array for *load-balancing*. Currently it works in the manner of round-robin.
+You can specify multiple backend locations in the `reverse_proxy` array for *load-balancing* with an appropriate `load_balance` option. Currently it works in the manner of round-robin or in the random fashion. if `load_balance` is not specified, the first backend location is always chosen.
 
 ```toml
 [apps."app_name"]
@@ -117,8 +117,11 @@ reverse_proxy = [
   { location = 'app1.local:8080' },
   { location = 'app2.local:8000' }
 ]
+load_balance = 'round_robin'
 ```
 
+(TODO: Sticky session is currently being implemented)
+
 ### Second Step: Terminating TLS
 
 First of all, you need to specify a port `listen_port_tls` listening the HTTPS traffic, separately from HTTP port (`listen_port`). Then, serving an HTTPS endpoint can be easily done for your desired application just by specifying TLS certificates and private keys in PEM files.

config-example.toml

@@ -52,6 +52,7 @@ upstream = [
   { location = 'www.yahoo.com', tls = true },
   { location = 'www.yahoo.co.jp', tls = true },
 ]
+load_balance = "round_robin" # or "random" or "sticky" (sticky session) or "none" (fix to the first one, default)
 upstream_options = ["override_host", "convert_https_to_2"]
 
 # Non-default destination in "localhost" app, which is routed by "path"
@@ -67,6 +68,7 @@ upstream = [
   { location = 'www.bing.com', tls = true },
   { location = 'www.bing.co.jp', tls = true },
 ]
+load_balance = "random" # or "round_robin" or "sticky" (sticky session) or "none" (fix to the first one, default)
 upstream_options = [
   "override_host",
   "upgrade_insecure_requests",

src/backend/load_balance.rs

@@ -0,0 +1,25 @@
+/// Constants to specify a load balance option
+pub(super) mod load_balance_options {
+  pub const FIX_TO_FIRST: &str = "none";
+  pub const ROUND_ROBIN: &str = "round_robin";
+  pub const RANDOM: &str = "random";
+  pub const STICKY_ROUND_ROBIN: &str = "sticky";
+}
+
+#[derive(Debug, Clone)]
+/// Load Balancing Option
+pub enum LoadBalance {
+  /// Fix to the first upstream. Use if only one upstream destination is specified
+  FixToFirst,
+  /// Simple round robin without session persistance
+  RoundRobin, // TODO: カウンタはここにいれる。randomとかには不要なので
+  /// Randomly chose one upstream server
+  Random,
+  /// Round robin with session persistance using cookie
+  StickyRoundRobin,
+}
+impl Default for LoadBalance {
+  fn default() -> Self {
+    Self::FixToFirst
+  }
+}

src/backend/mod.rs

@@ -1,3 +1,4 @@
+mod load_balance;
 mod upstream;
 mod upstream_opts;
 

src/backend/upstream.rs

@@ -1,4 +1,7 @@
-use super::{BytesName, PathNameBytesExp, UpstreamOption};
+use super::{
+  load_balance::{load_balance_options as lb_opts, LoadBalance},
+  BytesName, PathNameBytesExp, UpstreamOption,
+};
 use crate::log::*;
 use derive_builder::Builder;
 use rand::Rng;
@@ -51,23 +54,6 @@ impl ReverseProxy {
   }
 }
 
-#[allow(dead_code)]
-#[derive(Debug, Clone)]
-/// Load Balancing Option
-pub enum LoadBalance {
-  /// Simple round robin without session persistance
-  RoundRobin,
-  /// Randomly chose one upstream server
-  Random,
-  /// Round robin with session persistance using cookie
-  StickyRoundRobin,
-}
-impl Default for LoadBalance {
-  fn default() -> Self {
-    Self::RoundRobin
-  }
-}
-
 #[derive(Debug, Clone)]
 /// Upstream struct just containing uri without path
 pub struct Upstream {
@@ -87,7 +73,7 @@ pub struct UpstreamGroup {
   /// Path in [[PathNameBytesExp]] that will be used to replace the "path" part of incoming url
   pub replace_path: Option<PathNameBytesExp>,
 
-  #[builder(default)]
+  #[builder(setter(custom), default)]
   /// Load balancing option
   pub lb: LoadBalance,
   #[builder(default)]
@@ -97,6 +83,7 @@ pub struct UpstreamGroup {
   /// Activated upstream options defined in [[UpstreamOption]]
   pub opts: HashSet<UpstreamOption>,
 }
+
 impl UpstreamGroupBuilder {
   pub fn path(&mut self, v: &Option<String>) -> &mut Self {
     let path = match v {
@@ -114,6 +101,24 @@ impl UpstreamGroupBuilder {
     );
     self
   }
+  pub fn lb(&mut self, v: &Option<String>) -> &mut Self {
+    let lb = if let Some(x) = v {
+      match x.as_str() {
+        lb_opts::FIX_TO_FIRST => LoadBalance::FixToFirst,
+        lb_opts::ROUND_ROBIN => LoadBalance::RoundRobin,
+        lb_opts::RANDOM => LoadBalance::Random,
+        lb_opts::STICKY_ROUND_ROBIN => LoadBalance::StickyRoundRobin,
+        _ => {
+          error!("Specified load balancing option is invalid.");
+          LoadBalance::default()
+        }
+      }
+    } else {
+      LoadBalance::default()
+    };
+    self.lb = Some(lb);
+    self
+  }
   pub fn opts(&mut self, v: &Option<Vec<String>>) -> &mut Self {
     let opts = if let Some(opts) = v {
       opts
@@ -128,6 +133,7 @@ impl UpstreamGroupBuilder {
   }
 }
 
+// TODO: カウンタの移動
 #[derive(Debug, Clone, Default)]
 pub struct UpstreamCount(Arc<AtomicUsize>);
 
@@ -135,6 +141,7 @@ impl UpstreamGroup {
   /// Get an enabled option of load balancing [[LoadBalance]]
   pub fn get(&self) -> Option<&Upstream> {
     match self.lb {
+      LoadBalance::FixToFirst => self.upstream.get(0),
       LoadBalance::RoundRobin => {
         let idx = self.increment_cnt();
         self.upstream.get(idx)

src/config/parse.rs

@@ -205,6 +205,7 @@ fn get_reverse_proxy(rp_settings: &[ReverseProxyOption]) -> std::result::Result<
       .upstream(rpo.upstream.iter().map(|x| x.to_upstream().unwrap()).collect())
       .path(&rpo.path)
       .replace_path(&rpo.replace_path)
+      .lb(&rpo.load_balance)
       .opts(&rpo.upstream_options)
       .build()
       .unwrap();

src/config/toml.rs

@@ -57,6 +57,7 @@ pub struct ReverseProxyOption {
   pub replace_path: Option<String>,
   pub upstream: Vec<UpstreamParams>,
   pub upstream_options: Option<Vec<String>>,
+  pub load_balance: Option<String>,
 }
 
 #[derive(Deserialize, Debug, Default)]