fix: Accept config to be through file or env vars

config/src/config.rs

@@ -70,17 +70,19 @@ impl ConfigPrefix {
 }
 
 impl Config {
-    pub fn parse(prefix: ConfigPrefix, filename: &PathBuf) -> Result<Self, String> {
+    pub fn parse(prefix: ConfigPrefix, filename: Option<&PathBuf>) -> Result<Self, String> {
         let config_defaults = include_str!("../default_values.toml");
 
-        let mut config_content = std::fs::read_to_string(filename)
-            .map_err(|e| format!("Failed to read config file: {}", e))?;
+        let mut figment_config = Figment::new().merge(Toml::string(config_defaults));
 
-        config_content = Self::substitute_env_vars(config_content)?;
+        if let Some(path) = filename {
+            let mut config_content = std::fs::read_to_string(path)
+            .map_err(|e| format!("Failed to read config file: {}", e))?;
+            config_content = Self::substitute_env_vars(config_content)?;
+            figment_config = figment_config.merge(Toml::string(&config_content));
+        }
 
-        let config: ConfigWrapper = Figment::new()
-            .merge(Toml::string(config_defaults))
-            .merge(Toml::string(&config_content))
+        let config: ConfigWrapper = figment_config
             .merge(Env::prefixed(prefix.get_prefix()).split("__"))
             .extract()
             .map_err(|e| e.to_string())?;
@@ -386,7 +388,7 @@ mod tests {
     fn test_minimal_config() {
         Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from("minimal-config-example.toml"),
+            Some(PathBuf::from("minimal-config-example.toml")).as_ref(),
         )
         .unwrap();
     }
@@ -396,7 +398,7 @@ mod tests {
         // Generate full config by deserializing the minimal config and let the code fill in the defaults.
         let max_config = Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from("minimal-config-example.toml"),
+            Some(PathBuf::from("minimal-config-example.toml")).as_ref(),
         )
         .unwrap();
         let max_config_file: Config = toml::from_str(
@@ -418,7 +420,7 @@ mod tests {
 
         Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from("minimal-config-example.toml"),
+            Some(PathBuf::from("minimal-config-example.toml")).as_ref(),
         )
         .unwrap();
 
@@ -458,7 +460,7 @@ mod tests {
         // This should fail because the subgraphs.network.query_url field is missing
         Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from(temp_minimal_config_path.path()),
+            Some(PathBuf::from(temp_minimal_config_path.path())).as_ref(),
         )
         .unwrap_err();
 
@@ -467,7 +469,7 @@ mod tests {
 
         let config = Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from(temp_minimal_config_path.path()),
+            Some(PathBuf::from(temp_minimal_config_path.path())).as_ref(),
         )
         .unwrap();
 
@@ -485,7 +487,7 @@ mod tests {
 
         let config = Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from("minimal-config-example.toml"),
+            Some(PathBuf::from("minimal-config-example.toml")).as_ref(),
         )
         .unwrap();
 
@@ -569,7 +571,7 @@ mod tests {
         // This should fail because the QUERY_URL env variable is not setup
         Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from(temp_minimal_config_path.path()),
+            Some(PathBuf::from(temp_minimal_config_path.path())).as_ref(),
         )
         .unwrap_err();
 
@@ -578,7 +580,7 @@ mod tests {
 
         let config = Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from(temp_minimal_config_path.path()),
+            Some(PathBuf::from(temp_minimal_config_path.path())).as_ref(),
         )
         .unwrap();
 
@@ -663,7 +665,7 @@ mod tests {
         // Parse the config with new datbase vars
         let config = Config::parse(
             ConfigPrefix::Service,
-            &PathBuf::from(temp_minimal_config_path.path()),
+            Some(PathBuf::from(temp_minimal_config_path.path())).as_ref(),
         )
         .unwrap();
 

service/src/cli.rs

@@ -10,5 +10,5 @@ pub struct Cli {
     /// Path to the configuration file.
     /// See https://github.com/graphprotocol/indexer-rs/tree/main/service for examples.
     #[arg(long, value_name = "FILE", verbatim_doc_comment)]
-    pub config: PathBuf,
+    pub config: Option<PathBuf>,
 }

service/src/service.rs

@@ -130,10 +130,11 @@ pub async fn run() -> anyhow::Result<()> {
     // general configuration options for any indexer service and specific
     // options added for JSON-RPC
     let config =
-        MainConfig::parse(indexer_config::ConfigPrefix::Service, &cli.config).map_err(|e| {
+        MainConfig::parse(indexer_config::ConfigPrefix::Service, cli.config.as_ref()).map_err(|e| {
             error!(
-                "Invalid configuration file `{}`: {}",
-                cli.config.display(),
+                "Invalid configuration file `{}`: {}, if a value is missing you can also use \
+                --config to fill the rest of the values",
+                cli.config.unwrap_or_default().display(),
                 e
             );
             anyhow!(e)

tap-agent/src/config.rs

@@ -4,6 +4,7 @@
 use clap::Parser;
 use indexer_config::{Config as IndexerConfig, ConfigPrefix};
 use reqwest::Url;
+use tracing::error;
 use std::path::PathBuf;
 use std::{collections::HashMap, str::FromStr};
 
@@ -17,7 +18,7 @@ pub struct Cli {
     /// Path to the configuration file.
     /// See https://github.com/graphprotocol/indexer-rs/tree/main/tap-agent for examples.
     #[arg(long, value_name = "FILE", verbatim_doc_comment)]
-    pub config: PathBuf,
+    pub config: Option<PathBuf>,
 }
 
 impl From<IndexerConfig> for Config {
@@ -182,7 +183,15 @@ impl Config {
     pub fn from_cli() -> Result<Self> {
         let cli = Cli::parse();
         let indexer_config =
-            IndexerConfig::parse(ConfigPrefix::Tap, &cli.config).map_err(|e| anyhow::anyhow!(e))?;
+        IndexerConfig::parse(ConfigPrefix::Tap, cli.config.as_ref()).map_err(|e| {
+            error!(
+                "Invalid configuration file `{}`: {}, if a value is missing you can also use \
+                --config to fill the rest of the values",
+                cli.config.unwrap_or_default().display(),
+                e
+            );
+            anyhow::anyhow!(e)
+        })?;
         let config: Config = indexer_config.into();
 
         // Enables tracing under RUST_LOG variable