feat(config): env support for nested fields (#276)

* feat(config): env support for nested fields

Signed-off-by: Alexis Asseman <[email protected]>

* docs(config): update env config example

fixes #256

Signed-off-by: Alexis Asseman <[email protected]>

---------

Signed-off-by: Alexis Asseman <[email protected]>

Author: aasseman

Cargo.lock

@@ -19,5 +19,6 @@ serde_ignored = "0.1.10"
 [dev-dependencies]
 sealed_test = "1.1.0"
 serde_test = "1.0.176"
+tempfile = "3.10.1"
 toml = "0.8.12"
 tracing-test = "0.2.5"

config/Cargo.toml

@@ -9,13 +9,16 @@
 # Some of the config below are global graph network values, which you can find here:
 # https://github.com/graphprotocol/indexer/tree/main/docs/networks
 #
-# Pro tip: if you need to load some values from the environment into this config, you
-# can overwrite with environment variables. For example, the following can be replaced
-# by [PREFIX]_DATABASE_POSTGRESURL, where PREFIX can be `INDEXER_SERVICE` or `TAP_AGENT`:
+# If you want to supply some or all of the configuration below using environment variables,
+# use the prefix "INDEXER_SERVICE" or "TAP_AGENT" for indexer-service or tap-agent, respectively,
+# followed by the name of the field, using double underscores "__" for nesting. Example:
 #
-# [database]
-# postgres_url = "postgresql://indexer:${POSTGRES_PASSWORD}@postgres:5432/indexer_components_0"
-
+#       INDEXER_SERVICE_SUBGRAPHS__NETWORK__QUERY_URL = [...]
+#
+#   For
+#
+#       [subgraphs.network]
+#       query_url = [...]
 
 [indexer]
 indexer_address = "0x1111111111111111111111111111111111111111"

config/maximal-config-example.toml

@@ -74,7 +74,7 @@ impl Config {
         let config: ConfigWrapper = Figment::new()
             .merge(Toml::string(config_defaults))
             .merge(Toml::file(filename))
-            .merge(Env::prefixed(prefix.get_prefix()))
+            .merge(Env::prefixed(prefix.get_prefix()).split("__"))
             .extract()
             .map_err(|e| e.to_string())?;
         config.0.validate()?;
@@ -330,4 +330,72 @@ mod tests {
             "Ignoring unknown configuration field: plumbus"
         ));
     }
+
+    // Test that we can fill in mandatory config fields missing from the config file with
+    // environment variables
+    #[sealed_test(files = ["minimal-config-example.toml"])]
+    fn test_fill_in_missing_with_env() {
+        let mut minimal_config: toml::Value = toml::from_str(
+            fs::read_to_string("minimal-config-example.toml")
+                .unwrap()
+                .as_str(),
+        )
+        .unwrap();
+        // Remove the subgraphs.network.query_url field from minimal config
+        minimal_config
+            .get_mut("subgraphs")
+            .unwrap()
+            .get_mut("network")
+            .unwrap()
+            .as_table_mut()
+            .unwrap()
+            .remove("query_url");
+
+        // Save the modified minimal config to a named temporary file using tempfile
+        let temp_minimal_config_path = tempfile::NamedTempFile::new().unwrap();
+        fs::write(
+            temp_minimal_config_path.path(),
+            toml::to_string(&minimal_config).unwrap(),
+        )
+        .unwrap();
+
+        // This should fail because the subgraphs.network.query_url field is missing
+        Config::parse(
+            ConfigPrefix::Service,
+            &PathBuf::from(temp_minimal_config_path.path()),
+        )
+        .unwrap_err();
+
+        let test_value = "http://localhost:8000/testvalue";
+        std::env::set_var("INDEXER_SERVICE_SUBGRAPHS__NETWORK__QUERY_URL", test_value);
+
+        let config = Config::parse(
+            ConfigPrefix::Service,
+            &PathBuf::from(temp_minimal_config_path.path()),
+        )
+        .unwrap();
+
+        assert_eq!(
+            config.subgraphs.network.config.query_url.as_str(),
+            test_value
+        );
+    }
+
+    // Test that we can override nested config values with environment variables
+    #[sealed_test(files = ["minimal-config-example.toml"])]
+    fn test_override_with_env() {
+        let test_value = "http://localhost:8000/testvalue";
+        std::env::set_var("INDEXER_SERVICE_SUBGRAPHS__NETWORK__QUERY_URL", test_value);
+
+        let config = Config::parse(
+            ConfigPrefix::Service,
+            &PathBuf::from("minimal-config-example.toml"),
+        )
+        .unwrap();
+
+        assert_eq!(
+            config.subgraphs.network.config.query_url.as_str(),
+            test_value
+        );
+    }
 }