Configure all lading programs through files (#99)

Previously we allowed for some lading programs to be configured through
command-line flags. This makes lading challenging to use in contexts where
file-based configuration is more convenient, so we now have every lading binary
read a config file from under `/etc/lading`.

Signed-off-by: Brian L. Troutwine <[email protected]>

lading_blackholes/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "lading_blackholes"
-version = "0.4.8"
+version = "0.5.0"
 authors = ["Brian L. Troutwine <[email protected]>"]
 edition = "2018"
 license = "MIT"
@@ -13,6 +13,7 @@ description = "Blackhole programs with some instrumentation"
 tower = { version = "0.4", default-features = false, features = ["timeout", "limit", "load-shed"] }
 metrics = { version = "0.17", default-features = false, features = ["std"] }
 metrics-exporter-prometheus = { version = "0.6", default-features = false, features = ["tokio-exporter"] }
+toml = "0.5"
 
 [dependencies.argh]
 version = "0.1"

lading_blackholes/src/bin/http_blackhole.rs

@@ -5,7 +5,8 @@ use hyper::{body, header};
 use hyper::{Body, Request, Response, Server, StatusCode};
 use metrics_exporter_prometheus::PrometheusBuilder;
 use once_cell::unsync::OnceCell;
-use serde::Serialize;
+use serde::{Deserialize, Serialize};
+use std::io::Read;
 use std::net::SocketAddr;
 use std::str::FromStr;
 use std::time::Duration;
@@ -20,7 +21,11 @@ fn default_concurrent_requests_max() -> usize {
     100
 }
 
-#[derive(Debug, Copy, Clone)]
+fn default_config_path() -> String {
+    "/etc/lading/http_blackhole.toml".to_string()
+}
+
+#[derive(Debug, Copy, Clone, Deserialize)]
 enum BodyVariant {
     Nothing,
     AwsKinesis,
@@ -44,20 +49,25 @@ fn default_body_variant() -> BodyVariant {
 #[derive(FromArgs)]
 /// `http_blackhole` options
 struct Opts {
+    /// path on disk to the configuration file
+    #[argh(option, default = "default_config_path()")]
+    config_path: String,
+}
+
+#[derive(Debug, Deserialize)]
+/// Main configuration struct for this program
+struct Config {
     /// number of worker threads to use in this program
-    #[argh(option)]
     pub worker_threads: u16,
     /// number of concurrent HTTP connections to allow
-    #[argh(option, default = "default_concurrent_requests_max()")]
+    #[serde(default = "default_concurrent_requests_max")]
     pub concurrent_requests_max: usize,
     /// address -- IP plus port -- to bind to
-    #[argh(option)]
     pub binding_addr: SocketAddr,
     /// address -- IP plus port -- for prometheus exporting to bind to
-    #[argh(option)]
     pub prometheus_addr: SocketAddr,
     /// the body variant to respond with, default nothing
-    #[argh(option, default = "default_body_variant()")]
+    #[serde(default = "default_body_variant")]
     pub body_variant: BodyVariant,
 }
 
@@ -159,16 +169,27 @@ impl HttpServer {
     }
 }
 
-fn main() {
+fn get_config() -> Config {
     let ops: Opts = argh::from_env();
-    let httpd = HttpServer::new(ops.binding_addr, ops.prometheus_addr);
+    let mut file: std::fs::File = std::fs::OpenOptions::new()
+        .read(true)
+        .open(ops.config_path)
+        .unwrap();
+    let mut contents = String::new();
+    file.read_to_string(&mut contents).unwrap();
+    toml::from_str(&contents).unwrap()
+}
+
+fn main() {
+    let config: Config = get_config();
+    let httpd = HttpServer::new(config.binding_addr, config.prometheus_addr);
     let runtime = Builder::new_multi_thread()
-        .worker_threads(ops.worker_threads as usize)
+        .worker_threads(config.worker_threads as usize)
         .enable_io()
         .enable_time()
         .build()
         .unwrap();
     runtime
-        .block_on(httpd.run(ops.body_variant, ops.concurrent_requests_max))
+        .block_on(httpd.run(config.body_variant, config.concurrent_requests_max))
         .unwrap();
 }

lading_blackholes/src/bin/udp_blackhole.rs

@@ -1,31 +1,52 @@
 use argh::FromArgs;
 use metrics::counter;
+use metrics_exporter_prometheus::PrometheusBuilder;
+use serde::Deserialize;
 use std::io;
+use std::io::Read;
 use std::net::SocketAddr;
 use tokio::net::UdpSocket;
 use tokio::runtime::Builder;
 
+fn default_config_path() -> String {
+    "/etc/lading/udp_blackhole.toml".to_string()
+}
+
 #[derive(FromArgs)]
 /// `udp_blackhole` options
 struct Opts {
+    /// path on disk to the configuration file
+    #[argh(option, default = "default_config_path()")]
+    config_path: String,
+}
+
+/// Main configuration struct for this program
+#[derive(Debug, Deserialize)]
+pub struct Config {
     /// number of worker threads to use in this program
-    #[argh(option)]
     pub worker_threads: u16,
     /// address -- IP plus port -- to bind to
-    #[argh(option)]
     pub binding_addr: SocketAddr,
+    /// Address and port for prometheus exporter
+    pub prometheus_addr: SocketAddr,
 }
 
 struct Server {
     addr: SocketAddr,
+    prom_addr: SocketAddr,
 }
 
 impl Server {
-    fn new(addr: SocketAddr) -> Self {
-        Self { addr }
+    fn new(addr: SocketAddr, prom_addr: SocketAddr) -> Self {
+        Self { addr, prom_addr }
     }
 
     async fn run(self) -> Result<(), io::Error> {
+        let _: () = PrometheusBuilder::new()
+            .listen_address(self.prom_addr)
+            .install()
+            .unwrap();
+
         let socket = UdpSocket::bind(&self.addr).await?;
         let mut buf: Vec<u8> = vec![0; 4096];
 
@@ -36,11 +57,22 @@ impl Server {
     }
 }
 
-fn main() {
+fn get_config() -> Config {
     let ops: Opts = argh::from_env();
-    let server = Server::new(ops.binding_addr);
+    let mut file: std::fs::File = std::fs::OpenOptions::new()
+        .read(true)
+        .open(ops.config_path)
+        .unwrap();
+    let mut contents = String::new();
+    file.read_to_string(&mut contents).unwrap();
+    toml::from_str(&contents).unwrap()
+}
+
+fn main() {
+    let config: Config = get_config();
+    let server = Server::new(config.binding_addr, config.prometheus_addr);
     let runtime = Builder::new_multi_thread()
-        .worker_threads(ops.worker_threads as usize)
+        .worker_threads(config.worker_threads as usize)
         .enable_io()
         .build()
         .unwrap();

lading_common/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "lading_common"
-version = "0.4.8"
+version = "0.5.0"
 authors = ["Brian L. Troutwine <[email protected]>"]
 edition = "2018"
 license = "MIT"

lading_generators/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "lading_generators"
 readme = "README.md"
-version = "0.4.8"
+version = "0.5.0"
 authors = ["Brian L. Troutwine <[email protected]>"]
 edition = "2018"
 license = "MIT"

lading_generators/src/bin/file_gen.rs

@@ -10,11 +10,15 @@ use std::net::SocketAddr;
 use std::{fs, mem};
 use tokio::runtime::Builder;
 
+fn default_config_path() -> String {
+    "/etc/lading/file_gen.toml".to_string()
+}
+
 #[derive(FromArgs)]
 /// `file_gen` options
 struct Opts {
     /// path on disk to the configuration file
-    #[argh(option)]
+    #[argh(option, default = "default_config_path()")]
     config_path: String,
 }
 

lading_generators/src/bin/http_gen.rs

@@ -8,11 +8,15 @@ use std::io::Read;
 use std::net::SocketAddr;
 use tokio::runtime::Builder;
 
+fn default_config_path() -> String {
+    "/etc/lading/http_gen.toml".to_string()
+}
+
 #[derive(FromArgs)]
 /// `http_gen` options
 struct Opts {
     /// path on disk to the configuration file
-    #[argh(option)]
+    #[argh(option, default = "default_config_path()")]
     config_path: String,
 }
 

lading_generators/src/bin/kafka_gen.rs

@@ -8,11 +8,15 @@ use std::io::Read;
 use std::net::SocketAddr;
 use tokio::runtime::Builder;
 
+fn default_config_path() -> String {
+    "/etc/lading/kafka_gen.toml".to_string()
+}
+
 #[derive(FromArgs)]
 /// `kafka_gen` options
 struct Opts {
     /// path on disk to the configuration file
-    #[argh(option)]
+    #[argh(option, default = "default_config_path()")]
     config_path: String,
 }
 

lading_generators/src/bin/tcp_gen.rs

@@ -8,11 +8,15 @@ use std::io::Read;
 use std::net::SocketAddr;
 use tokio::runtime::Builder;
 
+fn default_config_path() -> String {
+    "/etc/lading/tcp_gen.toml".to_string()
+}
+
 #[derive(FromArgs)]
 /// `tcp_gen` options
 struct Opts {
     /// path on disk to the configuration file
-    #[argh(option)]
+    #[argh(option, default = "default_config_path()")]
     config_path: String,
 }