service-mango-health: read env variable for more configuration entries (#901)

bin/service-mango-fills/src/postgres_config.rs

@@ -1,8 +1,10 @@
 use serde_derive::Deserialize;
+use services_mango_lib::env_helper::string_or_env;
 use services_mango_lib::postgres_configuration::PostgresTlsConfig;
 
 #[derive(Clone, Debug, Deserialize)]
 pub struct PostgresConfig {
+    #[serde(deserialize_with = "string_or_env")]
     pub connection_string: String,
     /// Number of parallel postgres connections used for insertions
     pub connection_count: u64,

bin/service-mango-health/src/configuration.rs

@@ -1,12 +1,16 @@
 use serde_derive::Deserialize;
+use services_mango_lib::env_helper::string_or_env;
 use services_mango_lib::postgres_configuration::PostgresConfiguration;
 use std::collections::HashSet;
 
 #[derive(Clone, Debug, Deserialize)]
 pub struct Configuration {
     pub postgres: Option<PostgresConfiguration>,
+    #[serde(deserialize_with = "string_or_env")]
     pub rpc_http_url: String,
+    #[serde(deserialize_with = "string_or_env")]
     pub rpc_ws_url: String,
+    #[serde(deserialize_with = "string_or_env")]
     pub mango_group: String,
     pub computing_configuration: ComputingConfiguration,
     pub logging_configuration: LoggingConfiguration,

lib/services-mango-lib/src/env_helper.rs

@@ -0,0 +1,21 @@
+use serde::{Deserialize, Deserializer};
+use std::env;
+
+/// Get a string content, or the content of an Env variable it the string start with $
+///
+/// Example:
+///  - "abc" -> "abc"
+///  - "$something" -> read env variable named something and return it's content
+///
+/// *WARNING*: May kill the program if we are asking for anv environment variable that does not exist
+pub fn string_or_env<'de, D>(deserializer: D) -> Result<String, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let value_or_env = String::deserialize(deserializer)?;
+    let value = match &value_or_env.chars().next().unwrap() {
+        '$' => env::var(&value_or_env[1..]).expect("reading from env"),
+        _ => value_or_env,
+    };
+    Ok(value)
+}

lib/services-mango-lib/src/lib.rs

@@ -1,3 +1,4 @@
+pub mod env_helper;
 pub mod postgres_configuration;
 pub mod postgres_connection;
 pub mod retry_counter;

lib/services-mango-lib/src/postgres_configuration.rs

@@ -1,7 +1,9 @@
+use crate::env_helper::string_or_env;
 use serde::Deserialize;
 
 #[derive(Clone, Debug, Deserialize, Default)]
 pub struct PostgresConfiguration {
+    #[serde(deserialize_with = "string_or_env")]
     pub connection_string: String,
     pub allow_invalid_certs: bool,
     pub tls: Option<PostgresTlsConfig>,

lib/services-mango-lib/src/postgres_connection.rs

@@ -51,14 +51,8 @@ pub async fn connect(
     };
 
     let config = config.clone();
-    let connection_string = match &config.connection_string.chars().next().unwrap() {
-        '$' => {
-            env::var(&config.connection_string[1..]).expect("reading connection string from env")
-        }
-        _ => config.connection_string.clone(),
-    };
 
-    let (client, connection) = tokio_postgres::connect(&connection_string, tls).await?;
+    let (client, connection) = tokio_postgres::connect(&config.connection_string, tls).await?;
 
     let handle = tokio::spawn(async move { connection.await });