groundwork for TCP healthcheck in #8

5 files changed, 50 insertions, 12 deletions

diff --git a/src/config/environment.rs b/src/config/environment.rs
index d051d6d..797f422 100644
--- a/src/config/environment.rs
+++ b/src/config/environment.rs
@@ -26,14 +26,15 @@ use Error;
 /// Obtain a Roughenough server configuration ([ServerConfig](trait.ServerConfig.html))
 /// from environment variables.
 ///
-///   Config parameter | Environment Variable
-///   ---------------- | --------------------
-///   port             | `ROUGHENOUGH_PORT`
-///   interface        | `ROUGHENOUGH_INTERFACE`
-///   seed             | `ROUGHENOUGH_SEED`
-///   batch_size       | `ROUGHENOUGH_BATCH_SIZE`
-///   status_interval  | `ROUGHENOUGH_STATUS_INTERVAL`
-///   key_protection   | `ROUGHENOUGH_KEY_PROTECTION`
+///   Config parameter  | Environment Variable
+///   ----------------  | --------------------
+///   port              | `ROUGHENOUGH_PORT`
+///   interface         | `ROUGHENOUGH_INTERFACE`
+///   seed              | `ROUGHENOUGH_SEED`
+///   batch_size        | `ROUGHENOUGH_BATCH_SIZE`
+///   status_interval   | `ROUGHENOUGH_STATUS_INTERVAL`
+///   key_protection    | `ROUGHENOUGH_KEY_PROTECTION`
+///   health_check_port | `ROUGHENOUGH_HEALTH_CHECK_PORT`
 ///
 pub struct EnvironmentConfig {
     port: u16,
@@ -42,6 +43,7 @@ pub struct EnvironmentConfig {
     batch_size: u8,
     status_interval: Duration,
     key_protection: KeyProtection,
+    health_check_port: Option<u16>,
 }
 
 const ROUGHENOUGH_PORT: &str = "ROUGHENOUGH_PORT";
@@ -50,6 +52,7 @@ const ROUGHENOUGH_SEED: &str = "ROUGHENOUGH_SEED";
 const ROUGHENOUGH_BATCH_SIZE: &str = "ROUGHENOUGH_BATCH_SIZE";
 const ROUGHENOUGH_STATUS_INTERVAL: &str = "ROUGHENOUGH_STATUS_INTERVAL";
 const ROUGHENOUGH_KEY_PROTECTION: &str = "ROUGHENOUGH_KEY_PROTECTION";
+const ROUGHENOUGH_HEALTH_CHECK_PORT: &str = "ROUGHENOUGH_HEALTH_CHECK_PORT";
 
 impl EnvironmentConfig {
     pub fn new() -> Result<Self, Error> {
@@ -60,6 +63,7 @@ impl EnvironmentConfig {
             batch_size: DEFAULT_BATCH_SIZE,
             status_interval: DEFAULT_STATUS_INTERVAL,
             key_protection: KeyProtection::Plaintext,
+            health_check_port: None,
         };
 
         if let Ok(port) = env::var(ROUGHENOUGH_PORT) {
@@ -97,6 +101,14 @@ impl EnvironmentConfig {
                 .unwrap_or_else(|_| panic!("invalid key_protection value: {}", key_protection));
         }
 
+        if let Ok(health_check_port) = env::var(ROUGHENOUGH_HEALTH_CHECK_PORT) {
+            let val: u16 = health_check_port
+                .parse()
+                .unwrap_or_else(|_| panic!("invalid health_check_port: {}", health_check_port));
+
+            cfg.health_check_port = Some(val);
+        };
+
         Ok(cfg)
     }
 }
@@ -125,4 +137,8 @@ impl ServerConfig for EnvironmentConfig {
     fn key_protection(&self) -> &KeyProtection {
         &self.key_protection
     }
+
+    fn health_check_port(&self) -> Option<u16> {
+        self.health_check_port
+    }
 }
diff --git a/src/config/file.rs b/src/config/file.rs
index b1e856b..b70392d 100644
--- a/src/config/file.rs
+++ b/src/config/file.rs
@@ -43,6 +43,7 @@ pub struct FileConfig {
     batch_size: u8,
     status_interval: Duration,
     key_protection: KeyProtection,
+    health_check_port: Option<u16>,
 }
 
 impl FileConfig {
@@ -69,6 +70,7 @@ impl FileConfig {
             batch_size: DEFAULT_BATCH_SIZE,
             status_interval: DEFAULT_STATUS_INTERVAL,
             key_protection: KeyProtection::Plaintext,
+            health_check_port: None,
         };
 
         for (key, value) in cfg[0].as_hash().unwrap() {
@@ -93,6 +95,10 @@ impl FileConfig {
                         .unwrap_or_else(|_| panic!("invalid key_protection value: {:?}", value));
                     config.key_protection = val
                 }
+                "health_check_port" => {
+                    let val = value.as_i64().unwrap() as u16;
+                    config.health_check_port = Some(val);
+                }
                 unknown => {
                     return Err(Error::InvalidConfiguration(format!(
                         "unknown config key: {}",
@@ -130,4 +136,8 @@ impl ServerConfig for FileConfig {
     fn key_protection(&self) -> &KeyProtection {
         &self.key_protection
     }
+
+    fn health_check_port(&self) -> Option<u16> {
+        self.health_check_port
+    }
 }
diff --git a/src/config/memory.rs b/src/config/memory.rs
index aaf2e08..47480d6 100644
--- a/src/config/memory.rs
+++ b/src/config/memory.rs
@@ -29,6 +29,7 @@ pub struct MemoryConfig {
     pub batch_size: u8,
     pub status_interval: Duration,
     pub key_protection: KeyProtection,
+    pub health_check_port: Option<u16>,
 }
 
 impl MemoryConfig {
@@ -41,6 +42,7 @@ impl MemoryConfig {
             batch_size: DEFAULT_BATCH_SIZE,
             status_interval: DEFAULT_STATUS_INTERVAL,
             key_protection: KeyProtection::Plaintext,
+            health_check_port: None
         }
     }
 }
@@ -69,4 +71,8 @@ impl ServerConfig for MemoryConfig {
     fn key_protection(&self) -> &KeyProtection {
         &self.key_protection
     }
+
+    fn health_check_port(&self) -> Option<u16> {
+        self.health_check_port
+    }
 }
diff --git a/src/config/mod.rs b/src/config/mod.rs
index 772e1ee..b0ff9b4 100644
--- a/src/config/mod.rs
+++ b/src/config/mod.rs
@@ -60,6 +60,7 @@ pub const DEFAULT_STATUS_INTERVAL: Duration = Duration::from_secs(600);
 /// `batch_size` | `ROUGHENOUGH_BATCH_SIZE` | Optional | The maximum number of requests to process in one batch. All nonces in a batch are used to build a Merkle tree, the root of which is signed. Defaults to [DEFAULT_BATCH_SIZE](constant.DEFAULT_BATCH_SIZE.html) requests per batch.
 /// `status_interval` | `ROUGHENOUGH_STATUS_INTERVAL` | Optional | Number of _seconds_ between each logged status update. Default value is [DEFAULT_STATUS_INTERVAL](constant.DEFAULT_STATUS_INTERVAL.html).
 /// `key_protection` | `ROUGHENOUGH_KEY_PROTECTION` | Optional | Encryption method (if any) applied to the `seed`.  Defaults to "`plaintext`" (no encryption, `seed` is in the clear).
+/// `health_check_port` | `ROUGHENOUGH_HEALTH_CHECK_PORT` | Optional | If present, the TCP port to respond to Google-style HTTP "legacy health check".
 ///
 /// Implementations of this trait obtain a valid configuration from different back-end
 /// sources. See:
@@ -91,8 +92,13 @@ pub trait ServerConfig {
     /// Defaults to "`plaintext`" (no encryption, seed is in the clear).
     fn key_protection(&self) -> &KeyProtection;
 
+    /// [Optional] If present, the TCP port to respond to Google-style HTTP "legacy health check".
+    /// This is a *very* simplistic check, it emits a fixed HTTP response to all TCP connections.
+    /// https://cloud.google.com/load-balancing/docs/health-checks#legacy-health-checks
+    fn health_check_port(&self) -> Option<u16>;
+
     /// Convenience function to create a `SocketAddr` from the provided `interface` and `port`
-    fn socket_addr(&self) -> Result<SocketAddr, Error> {
+    fn udp_socket_addr(&self) -> Result<SocketAddr, Error> {
         let addr = format!("{}:{}", self.interface(), self.port());
         match addr.parse() {
             Ok(v) => Ok(v),
@@ -152,10 +158,10 @@ pub fn is_valid_config(cfg: &Box<ServerConfig>) -> bool {
     }
 
     if is_valid {
-        match cfg.socket_addr() {
+        match cfg.udp_socket_addr() {
             Err(e) => {
                 error!(
-                    "failed to create socket {}:{} {:?}",
+                    "failed to create UDP socket {}:{} {:?}",
                     cfg.interface(),
                     cfg.port(),
                     e
diff --git a/src/server.rs b/src/server.rs
index a187508..66e3715 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -112,7 +112,7 @@ impl Server {
         let response_counter = AtomicUsize::new(0);
         let keep_running = Arc::new(AtomicBool::new(true));
 
-        let sock_addr = config.socket_addr().expect("");
+        let sock_addr = config.udp_socket_addr().expect("");
         let socket = UdpSocket::bind(&sock_addr).expect("failed to bind to socket");
 
         let poll_duration = Some(Duration::from_millis(100));