Reintroduce L4P_CONFIG environment variable

This points to a user-configured configuration file.

Closes #5.

Signed-off-by: Jacob Kiers <code@kiers.eu>

src/config/config_v1.rs

@@ -1,6 +1,6 @@
 use crate::upstreams::ProxyToUpstream;
 use crate::upstreams::Upstream;
-use log::{debug, warn};
+use log::{debug, info, warn};
 use serde::Deserialize;
 use std::collections::{HashMap, HashSet};
 use std::fs::File;
@@ -119,9 +119,10 @@ fn load_config(path: &str) -> Result<ParsedConfigV1, ConfigError> {
     if !log_level.eq("disable") {
         std::env::set_var("FOURTH_LOG", log_level.clone());
         pretty_env_logger::init_custom_env("FOURTH_LOG");
-        debug!("Set log level to {}", log_level);
     }
 
+    info!("Using config file: {}", &path);
+    debug!("Set log level to {}", log_level);
     debug!("Config version {}", base.version);
 
     let mut parsed_upstream: HashMap<String, Upstream> = HashMap::new();

src/main.rs

@@ -5,7 +5,7 @@ mod upstreams;
 use crate::config::ConfigV1;
 use crate::servers::Server;
 
-use log::{debug, error};
+use log::{debug, error, info};
 use std::path::PathBuf;
 
 fn main() {
@@ -37,20 +37,28 @@ fn main() {
 }
 
 fn find_config() -> Result<String, Vec<String>> {
-    let possible_paths = ["/etc/l4p", ""];
+    let possible_locations = ["/etc/l4p", ""];
     let possible_names = ["l4p.yaml", "config.yaml"];
 
     let mut tried_paths = Vec::<String>::new();
+    let mut possible_paths = Vec::<PathBuf>::new();
 
-    for path in possible_paths
+    if let Ok(env_path) = std::env::var("L4P_CONFIG") {
+        possible_paths.push(PathBuf::from(env_path));
+    }
+
+    possible_paths.append(
+        &mut possible_locations
             .iter()
             .flat_map(|&path| {
                 possible_names
                     .iter()
                     .map(move |&file| PathBuf::new().join(path).join(file))
             })
-        .collect::<Vec<PathBuf>>()
+            .collect::<Vec<PathBuf>>(),
-    {
+    );
+
+    for path in possible_paths {
         let path_str = path.to_string_lossy().to_string();
         if path.exists() {
             return Ok(path_str);