fix(settings): get message data hmac key setting to work with env variables (#110) r=@philbooth,@vladikoff

Fixes #109

config/default.json

@@ -19,7 +19,7 @@
       { "period": "5 minutes", "limit": 0 }
     ]
   },
-  "message_id_hmac_key": "YOU MUST CHANGE ME",
+  "hmackey": "YOU MUST CHANGE ME",
   "logging": "mozlog",
   "provider": "ses",
   "redis": {

src/message_data/mod.rs

@@ -28,7 +28,7 @@ impl MessageData {
             client: RedisClient::open(
                 format!("redis://{}:{}/", settings.redis.host, settings.redis.port).as_str(),
             ).expect("redis connection error"),
-            hmac_key: settings.message_id_hmac_key.clone(),
+            hmac_key: settings.hmackey.clone(),
         }
     }
 

src/message_data/test.rs

@@ -63,7 +63,7 @@ impl TestFixture {
     pub fn setup(test: &str) -> TestFixture {
         let settings = Settings::new().expect("config error");
         let unhashed_key = format!("fxa-email-service.test.message-data.{}.{}", test, now());
-        let mut hmac = Hmac::<Sha256>::new_varkey(settings.message_id_hmac_key.as_bytes()).unwrap();
+        let mut hmac = Hmac::<Sha256>::new_varkey(settings.hmackey.as_bytes()).unwrap();
         hmac.input(unhashed_key.as_bytes());
         let internal_key = format!("msg:{:x}", hmac.result().code());
         TestFixture {

src/settings/mod.rs

@@ -93,7 +93,7 @@ pub struct Settings {
     pub authdb: AuthDb,
     pub aws: Aws,
     pub bouncelimits: BounceLimits,
-    pub message_id_hmac_key: String,
+    pub hmackey: String,
     pub logging: String,
     #[serde(deserialize_with = "deserialize::provider")]
     pub provider: String,
@@ -130,14 +130,17 @@ impl Settings {
         }
 
         config.merge(File::with_name("config/local").required(false))?;
-        config.merge(Environment::with_prefix("fxa_email"))?;
+        let mut env = Environment::with_prefix("fxa_email");
+        // Event though "_" is the default separator for config-rs right now,
+        // that is going to change for the next versions.
+        // https://github.com/mehcode/config-rs/commit/536f52fed4a22ed158681edce08211845abff985
+        env.separator("_".to_string());
+        config.merge(env)?;
 
         match config.try_into::<Settings>() {
             Ok(settings) => {
                 if let Ok(rocket_env) = env::var("ROCKET_ENV") {
-                    if rocket_env == "production"
-                        && &settings.message_id_hmac_key == "YOU MUST CHANGE ME"
-                    {
+                    if rocket_env == "production" && &settings.hmackey == "YOU MUST CHANGE ME" {
                         panic!("Please set a valid HMAC key.")
                     }
                 }

src/settings/test.rs

@@ -65,6 +65,7 @@ fn env_vars_take_precedence() {
         "FXA_EMAIL_AWS_SQSURLS_DELIVERY",
         "FXA_EMAIL_AWS_SQSURLS_NOTIFICATION",
         "FXA_EMAIL_BOUNCELIMITS_ENABLED",
+        "FXA_EMAIL_MESSAGEDATA_HMACKEY",
         "FXA_EMAIL_PROVIDER",
         "FXA_EMAIL_REDIS_HOST",
         "FXA_EMAIL_REDIS_PORT",
@@ -114,6 +115,7 @@ fn env_vars_take_precedence() {
                 }
             };
             let bounce_limits_enabled = !settings.bouncelimits.enabled;
+            let hmac_key = String::from("something else");
             let provider = if settings.provider == "ses" {
                 "sendgrid"
             } else {
@@ -142,6 +144,7 @@ fn env_vars_take_precedence() {
                 "FXA_EMAIL_BOUNCELIMITS_ENABLED",
                 &bounce_limits_enabled.to_string(),
             );
+            env::set_var("FXA_EMAIL_HMACKEY", &hmac_key.to_string());
             env::set_var("FXA_EMAIL_PROVIDER", &provider);
             env::set_var("FXA_EMAIL_REDIS_HOST", &redis_host);
             env::set_var("FXA_EMAIL_REDIS_PORT", &redis_port.to_string());
@@ -154,6 +157,7 @@ fn env_vars_take_precedence() {
                     assert_eq!(env_settings.authdb.baseuri, auth_db_base_uri);
                     assert_eq!(env_settings.aws.region, aws_region);
                     assert_eq!(env_settings.bouncelimits.enabled, bounce_limits_enabled);
+                    assert_eq!(env_settings.hmackey, hmac_key);
                     assert_eq!(env_settings.provider, provider);
                     assert_eq!(env_settings.redis.host, redis_host);
                     assert_eq!(env_settings.redis.port, redis_port);