refactor config module

config.yml

@@ -3,4 +3,4 @@ mqtt:
   client_id: "weather_portal_dev"
   user: "homeassistant"
   # password comes from env
-jwt_key: apuOQZyML+8PixmVDP4nXU4M # loaded from env on prod
+jwt_secret: apuOQZyML+8PixmVDP4nXU4M # loaded from env on prod

src/config.gleam

@@ -1,5 +1,10 @@
 import envoy
 import glaml
+import gleam/dict
+import gleam/erlang/node
+import gleam/io
+import gleam/list
+import gleam/option.{type Option, None, Some}
 import gleam/result
 import simplifile
 
@@ -9,7 +14,7 @@ pub type Config {
     mqtt_user: String,
     mqtt_pw: String,
     mqtt_client_id: String,
-    jwt_key: String,
+    jwt_secret: String,
   )
 }
 
@@ -30,71 +35,59 @@ fn parse_yaml(contents: String) -> Result(glaml.Document, String) {
   }
 }
 
-fn compile_config(doc: glaml.Document) -> Result(Config, String) {
-  let root = glaml.document_root(doc)
+fn get_config_value(
+  root: glaml.Node,
+  yaml_key: Option(String),
+  env_var: Option(String),
+) -> String {
+  let from_env = case env_var {
+    Some(var) -> envoy.get(var)
+    None -> Error(Nil)
+  }
 
-  // Extract values from YAML
-  use mqtt_host_result <- result.try(
-    glaml.select_sugar(root, "mqtt.host")
-    |> result.map_error(fn(_) { "mqtt.host not found in config.yml" }),
-  )
-  use mqtt_user_result <- result.try(
-    glaml.select_sugar(root, "mqtt.user")
-    |> result.map_error(fn(_) { "mqtt.user not found in config.yml" }),
-  )
-  use mqtt_client_id_result <- result.try(
-    glaml.select_sugar(root, "mqtt.client_id")
-    |> result.map_error(fn(_) { "mqtt.client_id not found in config.yml" }),
-  )
-  use jwt_key_result <- result.try(
-    glaml.select_sugar(root, "jwt_key")
-    |> result.map_error(fn(_) { "jwt_key not found in config.yml" }),
-  )
-
-  // Extract strings from nodes
-  case
-    mqtt_host_result,
-    mqtt_user_result,
-    jwt_key_result,
-    mqtt_client_id_result
-  {
-    glaml.NodeStr(host),
-      glaml.NodeStr(user),
-      glaml.NodeStr(key),
-      glaml.NodeStr(client_id)
-    -> {
-      let yaml_config =
-        Config(
-          mqtt_host: host,
-          mqtt_user: user,
-          mqtt_pw: "placeholder",
-          mqtt_client_id: client_id,
-          jwt_key: key,
-        )
-
-      // Override with env vars
-      let final_config =
-        Config(
-          mqtt_host: envoy.get("MQTT_HOST")
-            |> result.unwrap(yaml_config.mqtt_host),
-          mqtt_user: envoy.get("MQTT_USER")
-            |> result.unwrap(yaml_config.mqtt_user),
-          mqtt_pw: envoy.get("MQTT_PW")
-            |> result.unwrap(yaml_config.mqtt_pw),
-          mqtt_client_id: envoy.get("MQTT_CLIENT_ID")
-            |> result.unwrap(yaml_config.mqtt_client_id),
-          jwt_key: envoy.get("JWT_KEY")
-            |> result.unwrap(yaml_config.jwt_key),
-        )
-
-      Ok(final_config)
+  case from_env {
+    Ok(val) -> val
+    Error(_) -> {
+      // Fall back to YAML if env var not found
+      case yaml_key {
+        Some(key) -> {
+          let assert Ok(node) = glaml.select_sugar(root, key)
+          let assert glaml.NodeStr(str) = node
+          str
+        }
+        None -> {
+          panic as { "Config value not found in environment or YAML" }
+        }
+      }
     }
-    _, _, _, _ -> Error("Config values must be strings in config.yml")
   }
 }
 
-pub fn load_config() -> Result(Config, String) {
+fn compile_config(doc: glaml.Document) -> Config {
+  let root = glaml.document_root(doc)
+  let get = fn(yaml_key: option.Option(String), env_var: option.Option(String)) -> String {
+    get_config_value(root, yaml_key, env_var)
+  }
+
+  Config(
+    mqtt_host: get(Some("mqtt.host"), None),
+    mqtt_pw: get(None, Some("MQTT_PW")),
+    mqtt_user: get(Some("mqtt.user"), None),
+    jwt_secret: get(Some("jwt_secret"), Some("JWT_SECRET")),
+    mqtt_client_id: get(Some("mqtt.client_id"), Some("MQTT_CLIENT_ID")),
+  )
+}
+
+fn get_doc() -> Result(glaml.Document, String) {
   use file_content <- result.try(load_file())
   use doc <- result.try(parse_yaml(file_content))
-  compile_config(doc)
+  Ok(doc)
+}
+
+pub fn load_config() -> Config {
+  let doc = get_doc()
+  case doc {
+    Ok(doc) -> compile_config(doc)
+    Error(err) -> panic as { "fail to load config: " <> err }
+  }
 }

src/weather_portal.gleam

@@ -5,18 +5,8 @@ import mqtt_dummy
 import sensors
 
 pub fn main() -> Nil {
-  case config.load_config() {
-    Ok(cfg) -> {
-      io.println("Config loaded successfully!")
-      io.println("MQTT Host: " <> cfg.mqtt_host)
-      io.println("MQTT User: " <> cfg.mqtt_user)
-      io.println("MQTT PW: " <> cfg.mqtt_pw)
-      io.println("JWT Key: " <> cfg.jwt_key)
-    }
-    Error(err) -> {
-      io.println("Failed to load config: " <> err)
-    }
-  }
+  let cfg = config.load_config()
+  io.println("Config loaded successfully!")
 
   let assert Ok(subject) = mqtt_dummy.start()
   let mailbox = mqtt_dummy.subscribe(subject)

test/config_test.gleam

@@ -1,4 +1,5 @@
 import config
+import envoy
 import gleeunit
 import gleeunit/should
 
@@ -8,7 +9,8 @@ pub fn main() -> Nil {
 
 // gleeunit test functions end in `_test`
 pub fn file_read_test() {
-  let assert Ok(cfg) = config.load_config()
+  envoy.set("MQTT_PW", "TEST")
+  let cfg = config.load_config()
 
   cfg.mqtt_host
   |> should.equal("192.168.1.11")

test/sensors_test.gleam

@@ -6,7 +6,6 @@ pub fn main() -> Nil {
   gleeunit.main()
 }
 
-// gleeunit test functions end in `_test`
 pub fn file_read_test() {
   let reading =
     sensors.sensor_name(sensors.Temperature)