Revert "fix: Use $VAR instead of ${VAR} (for Airflow)"

This reverts commit 8e05224.

It was actually mot needed :)

Author: sbernauer

crates/stackable-operator/src/databases/databases/postgresql.rs

@@ -106,7 +106,7 @@ impl SQLAlchemyDatabaseConnection for PostgresqlConnection {
                 "postgresql+psycopg2://${{env:{username_env_name}}}:${{env:{password_env_name}}}@{host}:{port}/{database}{parameters}",
             ),
             TemplatingMechanism::BashEnvSubstitution => format!(
-                "postgresql+psycopg2://${username_env_name}:${password_env_name}@{host}:{port}/{database}{parameters}",
+                "postgresql+psycopg2://${{{username_env_name}}}:${{{password_env_name}}}@{host}:{port}/{database}{parameters}",
             ),
         };
         SQLAlchemyDatabaseConnectionDetails {
@@ -142,7 +142,7 @@ impl CeleryDatabaseConnection for PostgresqlConnection {
                 "db+postgresql://${{env:{username_env_name}}}:${{env:{password_env_name}}}@{host}:{port}/{database}{parameters}",
             ),
             TemplatingMechanism::BashEnvSubstitution => format!(
-                "db+postgresql://${username_env_name}:${password_env_name}@{host}:{port}/{database}{parameters}",
+                "db+postgresql://${{{username_env_name}}}:${{{password_env_name}}}@{host}:{port}/{database}{parameters}",
             ),
         };
         CeleryDatabaseConnectionDetails {

crates/stackable-operator/src/databases/databases/redis.rs

@@ -61,7 +61,7 @@ impl CeleryDatabaseConnection for RedisConnection {
                 "redis://${{env:{username_env_name}}}:${{env:{password_env_name}}}@{host}:{port}/{database_id}",
             ),
             TemplatingMechanism::BashEnvSubstitution => format!(
-                "redis://${username_env_name}:${password_env_name}@{host}:{port}/{database_id}",
+                "redis://${{{username_env_name}}}:${{{password_env_name}}}@{host}:{port}/{database_id}",
             ),
         };
         CeleryDatabaseConnectionDetails {

crates/stackable-operator/src/databases/drivers/celery.rs

@@ -81,7 +81,7 @@ impl CeleryDatabaseConnection for GenericCeleryDatabaseConnection {
         let uri_env_var = env_var_from_secret(&uri_env_name, &self.uri_secret, "uri");
         let uri_template = match templating_mechanism {
             TemplatingMechanism::ConfigUtils => format!("${{env:{uri_env_name}}}"),
-            TemplatingMechanism::BashEnvSubstitution => format!("${uri_env_name}"),
+            TemplatingMechanism::BashEnvSubstitution => format!("${{{uri_env_name}}}"),
         };
 
         CeleryDatabaseConnectionDetails {

crates/stackable-operator/src/databases/drivers/sqlalchemy.rs

@@ -81,7 +81,7 @@ impl SQLAlchemyDatabaseConnection for GenericSQLAlchemyDatabaseConnection {
         let uri_env_var = env_var_from_secret(&uri_env_name, &self.uri_secret, "uri");
         let uri_template = match templating_mechanism {
             TemplatingMechanism::ConfigUtils => format!("${{env:{uri_env_name}}}"),
-            TemplatingMechanism::BashEnvSubstitution => format!("${uri_env_name}"),
+            TemplatingMechanism::BashEnvSubstitution => format!("${{{uri_env_name}}}"),
         };
 
         SQLAlchemyDatabaseConnectionDetails {

crates/stackable-operator/src/databases/mod.rs

@@ -28,9 +28,6 @@ pub enum TemplatingMechanism {
     #[default]
     ConfigUtils,
 
-    /// Let `bash` substitute the env variable, e.g. `$EXAMPLE_USERNAME`.
-    ///
-    /// Please note that we use `$VAR` over `${VAR}`, as for *some* reason Airflow correctly expands
-    /// the first while failing to expand the latter.
+    /// Let `bash` substitute the env variable, e.g. `${EXAMPLE_USERNAME}`.
     BashEnvSubstitution,
 }