From 9379e2033d1c1b506a595d4eaf855f599b8e07f0 Mon Sep 17 00:00:00 2001
From: Anioke Sebastian <aniokechukwudi7@gmail.com>
Date: Mon, 9 Mar 2026 01:29:52 +0100
Subject: [PATCH] fix: load and validate required env vars at startup (#24)

---
 .env.example  | 19 ++++++++++---------
 Cargo.lock    |  7 +++++++
 Cargo.toml    |  3 ++-
 src/config.rs | 43 +++++++++++++++++++++++++++++++++++++++++++
 src/main.rs   |  8 +++++++-
 5 files changed, 69 insertions(+), 11 deletions(-)
 create mode 100644 src/config.rs

diff --git a/.env.example b/.env.example
index c89843b..7a520f9 100644
--- a/.env.example
+++ b/.env.example
@@ -1,12 +1,13 @@
-# Copy this file to .env and customize values as needed for your local
-# development or CI environment.
+# Copy this file to .env and replace placeholder values.
 
-# Soroban network selection (profile name). Valid values: testnet, mainnet, sandbox
-SOROBAN_NETWORK=testnet
+# Target Stellar network (for example: testnet, mainnet).
+STELLAR_NETWORK=testnet
 
-# Override the RPC endpoint and network passphrase if necessary
-SOROBAN_RPC_URL=https://rpc.testnet.soroban.stellar.org
-SOROBAN_NETWORK_PASSPHRASE="Test SDF Network ; September 2015"
+# Platform account secret seed used for signing platform transactions.
+STELLAR_PLATFORM_SECRET=SBXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+
+# Horizon REST API endpoint for the selected network.
+HORIZON_URL=https://horizon-testnet.stellar.org
 
-# Example keypair file path; tools may read this
-# SOROBAN_KEY_FILE=./keys/contract-key.json
+# Soroban RPC endpoint for the selected network.
+SOROBAN_RPC_URL=https://rpc.testnet.soroban.stellar.org
diff --git a/Cargo.lock b/Cargo.lock
index 8d505a3..e081a8a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -193,6 +193,7 @@ checksum = "c2459377285ad874054d797f3ccebf984978aa39129f6eafde5cdc8315b612f8"
 name = "contract-fox"
 version = "0.1.0"
 dependencies = [
+ "dotenvy",
  "ed25519-dalek",
  "reqwest",
  "serde",
@@ -432,6 +433,12 @@ dependencies = [
  "stellar-strkey",
 ]
 
+[[package]]
+name = "dotenvy"
+version = "0.15.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1aaf95b3e5c8f23aa320147307562d361db0ae0d51242340f558153b4eb2439b"
+
 [[package]]
 name = "downcast-rs"
 version = "1.2.1"
diff --git a/Cargo.toml b/Cargo.toml
index a5d05b4..df54428 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,4 +25,5 @@ tokio       = { version = "1", features = ["rt-multi-thread", "macros"] }
 stellar-strkey  = "0.0.8"
 ed25519-dalek   = "2"
 tracing     = "0.1"
-tracing-subscriber = { version = "0.3", features = ["env-filter", "json"] }
+tracing-subscriber = { version = "0.3", features = ["env-filter", "json"] }
+dotenvy = "0.15"
diff --git a/src/config.rs b/src/config.rs
new file mode 100644
index 0000000..6a51152
--- /dev/null
+++ b/src/config.rs
@@ -0,0 +1,43 @@
+use std::env;
+
+use thiserror::Error;
+
+#[derive(Debug, Clone)]
+pub struct Config {
+    pub stellar_network: String,
+    pub stellar_platform_secret: String,
+    pub horizon_url: String,
+    pub soroban_rpc_url: String,
+}
+
+#[derive(Debug, Error)]
+pub enum ConfigError {
+    #[error("missing required environment variable: {0}")]
+    MissingEnvVar(&'static str),
+
+    #[error("environment variable {name} cannot be empty")]
+    EmptyEnvVar { name: &'static str },
+}
+
+impl Config {
+    pub fn from_env() -> Result<Self, ConfigError> {
+        dotenvy::dotenv().ok();
+
+        Ok(Self {
+            stellar_network: read_required_env("STELLAR_NETWORK")?,
+            stellar_platform_secret: read_required_env("STELLAR_PLATFORM_SECRET")?,
+            horizon_url: read_required_env("HORIZON_URL")?,
+            soroban_rpc_url: read_required_env("SOROBAN_RPC_URL")?,
+        })
+    }
+}
+
+fn read_required_env(name: &'static str) -> Result<String, ConfigError> {
+    let value = env::var(name).map_err(|_| ConfigError::MissingEnvVar(name))?;
+
+    if value.trim().is_empty() {
+        return Err(ConfigError::EmptyEnvVar { name });
+    }
+
+    Ok(value)
+}
diff --git a/src/main.rs b/src/main.rs
index 3dfcc60..6e7612d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,4 @@
+pub mod config;
 pub mod errors;
 
 pub mod friendbot;
@@ -5,4 +6,9 @@ pub mod horizon;
 mod setup;
 pub mod utils;
 
-fn main() {}
+fn main() {
+    if let Err(err) = config::Config::from_env() {
+        eprintln!("Startup configuration error: {err}");
+        std::process::exit(1);
+    }
+}