read config from env var

readme.md

@@ -69,18 +69,26 @@ GLOBAL OPTIONS:
 
 start from command line arguments:
 ```shell
-# enable udp
-realm -l 127.0.0.1:5000 -r 1.1.1.1:443 --udp
-
-# specify outbound ip
-realm -l 127.0.0.1:5000 -r 1.1.1.1:443 --through 127.0.0.1
+realm -l 0.0.0.0:5000 -r 1.1.1.1:443
 ```
 
-or use a config file:
+start from config file:
 ```shell
+# use toml
+realm -c config.toml
+
+# use json
 realm -c config.json
 ```
 
+start from environment variable:
+```shell
+CONFIG='{"endpoints":[{"local":"127.0.0.1:5000","remote":"1.1.1.1:443"}]}' realm
+
+export CONFIG=`cat config.json | jq -c `
+realm
+```
+
 ## Configuration
 TOML Example
 ```toml

src/conf/mod.rs

@@ -1,4 +1,5 @@
 use std::fs;
+use std::io::{Result, Error, ErrorKind};
 
 use serde::{Serialize, Deserialize};
 
@@ -45,21 +46,32 @@ impl FullConf {
         }
     }
 
-    pub fn from_config_file(file: &str) -> Self {
-        let config = fs::read_to_string(file)
+    pub fn from_conf_file(file: &str) -> Self {
+        let conf = fs::read_to_string(file)
             .unwrap_or_else(|e| panic!("unable to open {}: {}", file, &e));
-        let toml_err = match toml::from_str(&config) {
-            Ok(x) => return x,
+        match Self::from_conf_str(&conf) {
+            Ok(x) => x,
+            Err(e) => panic!("failed to parse {}: {}", file, &e),
+        }
+    }
+
+    pub fn from_conf_str(conf: &str) -> Result<Self> {
+        let toml_err = match toml::from_str(conf) {
+            Ok(x) => return Ok(x),
             Err(e) => e,
         };
-        let json_err = match serde_json::from_str(&config) {
-            Ok(x) => return x,
+        let json_err = match serde_json::from_str(conf) {
+            Ok(x) => return Ok(x),
             Err(e) => e,
         };
-        panic!(
-            "parse {0} as toml: {1}; parse {0} as json: {2}",
-            file, &toml_err, &json_err
-        );
+
+        Err(Error::new(
+            ErrorKind::Other,
+            format!(
+                "parse as toml: {0}; parse as json: {1}",
+                &toml_err, &json_err
+            ),
+        ))
     }
 
     pub fn add_endpoint(&mut self, endpoint: EndpointConf) -> &mut Self {

src/main.rs

@@ -4,12 +4,15 @@ mod conf;
 mod utils;
 mod relay;
 
+use std::env;
+
 use cfg_if::cfg_if;
 use cmd::CmdInput;
 use conf::FullConf;
 use utils::Endpoint;
 
 const VERSION: &str = "1.5.0-rc6";
+const ENV_CONFIG: &str = "CONFIG";
 
 cfg_if! {
     if #[cfg(all(feature = "mi-malloc"))] {
@@ -24,21 +27,29 @@ cfg_if! {
 }
 
 fn main() {
-    let conf = match cmd::scan() {
-        CmdInput::Endpoint(ep, opts) => {
-            let mut conf = FullConf::default();
-            conf.add_endpoint(ep).apply_global_opts(opts);
-            conf
-        }
-        CmdInput::Config(conf, opts) => {
-            let mut conf = FullConf::from_config_file(&conf);
-            conf.apply_global_opts(opts);
-            conf
+    let conf = || {
+        if let Ok(conf_str) = env::var(ENV_CONFIG) {
+            if let Ok(conf) = FullConf::from_conf_str(&conf_str) {
+                return conf;
+            }
+        };
+
+        match cmd::scan() {
+            CmdInput::Endpoint(ep, opts) => {
+                let mut conf = FullConf::default();
+                conf.add_endpoint(ep).apply_global_opts(opts);
+                conf
+            }
+            CmdInput::Config(conf, opts) => {
+                let mut conf = FullConf::from_conf_file(&conf);
+                conf.apply_global_opts(opts);
+                conf
+            }
+            CmdInput::None => std::process::exit(0),
         }
-        CmdInput::None => std::process::exit(0),
     };
 
-    start_from_conf(conf);
+    start_from_conf(conf());
 }
 
 fn start_from_conf(conf: FullConf) {