Rebuild when TRUSTED_SERVER env variables change

Author: aram356

CHANGELOG.md

@@ -39,6 +39,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Changed to use log statements
 - Updated fastly.toml for local development
 
+### Fixed
+- Rebuild when `TRUSTED_SERVER__*` env variables change 
+
 ## [1.0.6] - 2025-05-29
 
 ### Changed

crates/common/Cargo.toml

@@ -26,6 +26,11 @@ sha2 = "0.10.9"
 tokio = { version = "1.46", features = ["sync", "macros", "io-util", "rt", "time"] }   
 url = "2.4.1"
 
+[build-dependencies]
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0.91"
+config = "0.15.11"
+
 [dev-dependencies]
 regex = "1.1.1"
 temp-env = "0.3.6"

crates/common/build.rs

@@ -0,0 +1,52 @@
+#[path = "src/settings.rs"]
+mod settings;
+
+use serde_json::Value;
+use std::collections::HashSet;
+
+fn main() {
+    // Watch the settings.rs file for changes
+    println!("cargo:rerun-if-changed=../../trusted-server.toml");
+
+    // Create a default Settings instance and convert to JSON to discover all fields
+    let default_settings = settings::Settings::default();
+    let settings_json = serde_json::to_value(&default_settings).unwrap();
+
+    let mut env_vars = HashSet::new();
+    collect_env_vars(&settings_json, &mut env_vars, vec![]);
+
+    // Print rerun-if-env-changed for each variable
+    let mut sorted_vars: Vec<_> = env_vars.into_iter().collect();
+    sorted_vars.sort();
+
+    for var in sorted_vars {
+        println!("cargo:rerun-if-env-changed={}", var);
+    }
+}
+
+fn collect_env_vars(value: &Value, env_vars: &mut HashSet<String>, path: Vec<String>) {
+    if let Value::Object(map) = value {
+        for (key, val) in map {
+            let mut new_path = path.clone();
+            new_path.push(key.to_uppercase());
+
+            match val {
+                Value::String(_) | Value::Number(_) | Value::Bool(_) => {
+                    // Leaf node - create environment variable
+                    let env_var = format!(
+                        "{}{}{}",
+                        settings::ENVIRONMENT_VARIABLE_PREFIX,
+                        settings::ENVIRONMENT_VARIABLE_SEPARATOR,
+                        new_path.join(settings::ENVIRONMENT_VARIABLE_SEPARATOR)
+                    );
+                    env_vars.insert(env_var);
+                }
+                Value::Object(_) => {
+                    // Recurse into nested objects
+                    collect_env_vars(val, env_vars, new_path);
+                }
+                _ => {}
+            }
+        }
+    }
+}

crates/common/src/settings.rs

@@ -1,47 +1,46 @@
 use std::str;
 
 use config::{Config, ConfigError, Environment, File, FileFormat};
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 
-#[derive(Debug, Deserialize)]
-#[allow(unused)]
+pub const ENVIRONMENT_VARIABLE_PREFIX: &str = "TRUSTED_SERVER";
+pub const ENVIRONMENT_VARIABLE_SEPARATOR: &str = "__";
+
+#[derive(Debug, Default, Deserialize, Serialize)]
 pub struct AdServer {
     pub ad_partner_url: String,
     pub sync_url: String,
 }
 
-#[derive(Debug, Deserialize)]
-#[allow(unused)]
+#[derive(Debug, Default, Deserialize, Serialize)]
 pub struct Publisher {
     pub domain: String,
     pub cookie_domain: String,
     pub origin_url: String,
 }
 
-#[derive(Debug, Deserialize)]
-#[allow(unused)]
+#[derive(Debug, Default, Deserialize, Serialize)]
 pub struct Prebid {
     pub server_url: String,
 }
 
-#[derive(Debug, Deserialize)]
-#[allow(unused)]
+#[derive(Debug, Default, Deserialize, Serialize)]
 pub struct Synthetic {
     pub counter_store: String,
     pub opid_store: String,
     pub secret_key: String,
     pub template: String,
 }
 
-#[derive(Debug, Deserialize)]
-#[allow(unused)]
+#[derive(Debug, Default, Deserialize, Serialize)]
 pub struct Settings {
     pub ad_server: AdServer,
     pub publisher: Publisher,
     pub prebid: Prebid,
     pub synthetic: Synthetic,
 }
 
+#[allow(unused)]
 impl Settings {
     pub fn new() -> Result<Self, ConfigError> {
         let toml_bytes = include_bytes!("../../../trusted-server.toml");
@@ -52,8 +51,8 @@ impl Settings {
 
     pub fn from_toml(toml_str: &str) -> Result<Self, ConfigError> {
         let environment = Environment::default()
-            .prefix("TRUSTED_SERVER")
-            .separator("__");
+            .prefix(ENVIRONMENT_VARIABLE_PREFIX)
+            .separator(ENVIRONMENT_VARIABLE_SEPARATOR);
 
         let toml = File::from_str(toml_str, FileFormat::Toml);
         let config = Config::builder()
@@ -181,7 +180,12 @@ mod tests {
         let toml_str = re.replace(&toml_str, "");
 
         temp_env::with_var(
-            "TRUSTED_SERVER__AD_SERVER__AD_PARTNER_URL",
+            format!(
+                "{}{}AD_SERVER{}AD_PARTNER_URL",
+                ENVIRONMENT_VARIABLE_PREFIX,
+                ENVIRONMENT_VARIABLE_SEPARATOR,
+                ENVIRONMENT_VARIABLE_SEPARATOR
+            ),
             Some("https://change-ad.com/serve"),
             || {
                 let settings = Settings::from_toml(&toml_str);
@@ -200,7 +204,12 @@ mod tests {
         let toml_str = crate_test_settings_str();
 
         temp_env::with_var(
-            "TRUSTED_SERVER__AD_SERVER__AD_PARTNER_URL",
+            format!(
+                "{}{}AD_SERVER{}AD_PARTNER_URL",
+                ENVIRONMENT_VARIABLE_PREFIX,
+                ENVIRONMENT_VARIABLE_SEPARATOR,
+                ENVIRONMENT_VARIABLE_SEPARATOR
+            ),
             Some("https://change-ad.com/serve"),
             || {
                 let settings = Settings::from_toml(&toml_str);