feat: Enable .env file loading using env feature (#1308)

Related issues:
- #1236

This PR adds conditional support for loading a local `.env` for
environment variables. This support is only enabled when compiling the
client binary with the `env` feature or when passing `--all-features` to
Cargo. This is not enabled by default for production environments.

Users can add a `.env` to the root directory of their local copy of
their Fuel node (or wherever their working directory is).

This helps users provide CLI arguments in a way that is more convenient
and more secure than entering these values in an IDE directly:
- Users can reuse environment variables across IDEs (e.g., VS Code and
CLion) and IDE configurations seamlessly, rather than specifying them in
each IDE specific configuration
- Users can avoid putting secrets in shared commands or configurations
- CLion users can greatly shorten their `run` commands, which is helpful
since the configuration window does not word wrap long commands

The `.env` is also added to `.gitignore` to prevent users from uploading
individual environment configurations that may include secrets.

This approach acts as a sort of stop gap for handling secrets before we
have SOPS.

This PR also renames the internal `eth_client` component of the relayer
configuration to `relayer`. This allow users to use the environment
variable name `RELAYER` to supply this value. Prior to this, the CLI
expected an environment variable called `ETH_CLIENT`, even though the
CLI argument is named `relayer`.

Note: Due to the order in which the initialization functions are called,
we cannot supply `RUST_LOG` in the .env file; this has to be provided
elsewhere or directly to Cargo.

.gitignore

@@ -12,3 +12,4 @@ version-compatibility/Cargo.lock
 benches/benches-outputs/Cargo.lock
 benches/benches-outputs/src/test_gas_costs_output.rs
 .idea
+.env

CHANGELOG.md

@@ -10,6 +10,7 @@ Description of the upcoming release here.
 
 ### Added
 
+- [#1308](https://github.com/FuelLabs/fuel-core/pull/1308): Add support for loading .env files when compiling with the `env` feature. This allows users to conveniently supply CLI arguments in a secure and IDE-agnostic way. 
 - [#1263](https://github.com/FuelLabs/fuel-core/pull/1263): Add gas benchmarks for `ED19` and `ECR1` instructions.
 - [#1286](https://github.com/FuelLabs/fuel-core/pull/1286): Include readable names for test cases where missing.
 - [#1304](https://github.com/FuelLabs/fuel-core/pull/1304): Implemented `submit_and_await_commit_with_receipts` method for `FuelClient`.

bin/fuel-core/Cargo.toml

@@ -20,6 +20,7 @@ anyhow = { workspace = true }
 clap = { workspace = true, features = ["derive", "env"] }
 const_format = { version = "0.2", optional = true }
 dirs = "4.0"
+dotenvy = { version = "0.15", optional = true }
 fuel-core = { workspace = true }
 humantime = "2.1"
 lazy_static = { workspace = true }
@@ -38,12 +39,13 @@ url = { version = "2.2", optional = true }
 test-case = { workspace = true }
 
 [features]
-debug = ["fuel-core/debug"]
+debug = ["env", "fuel-core/debug"]
 default = ["debug", "metrics", "relayer", "rocksdb"]
+env = ["dep:dotenvy"]
 metrics = ["fuel-core/metrics"]
 p2p = ["fuel-core/p2p", "const_format"]
 relayer = ["fuel-core/relayer", "dep:url", "dep:serde_json"]
 rocksdb = ["fuel-core/rocksdb"]
 rocksdb-production = ["fuel-core/rocksdb-production"]
 # features to enable in production, but increase build times
-production = ["metrics", "relayer", "rocksdb-production", "p2p"]
+production = ["env", "metrics", "relayer", "rocksdb-production", "p2p"]

bin/fuel-core/src/cli.rs

@@ -4,14 +4,22 @@ use std::{
     path::PathBuf,
     str::FromStr,
 };
-use tracing::warn;
+use tracing::{
+    info,
+    warn,
+};
 use tracing_subscriber::{
     filter::EnvFilter,
     layer::SubscriberExt,
     registry,
     Layer,
 };
 
+#[cfg(feature = "env")]
+use dotenvy::dotenv;
+#[cfg(feature = "env")]
+use tracing::error;
+
 lazy_static::lazy_static! {
     pub static ref DEFAULT_DB_PATH: PathBuf = dirs::home_dir().unwrap().join(".fuel").join("db");
 }
@@ -41,6 +49,22 @@ pub enum Fuel {
 pub const LOG_FILTER: &str = "RUST_LOG";
 pub const HUMAN_LOGGING: &str = "HUMAN_LOGGING";
 
+#[cfg(feature = "env")]
+fn init_environment() -> Option<PathBuf> {
+    match dotenv() {
+        Ok(path) => Some(path),
+        Err(e) => {
+            error!("Unable to load .env environment variables: {e}. Please check that you have created a .env file in your working directory.");
+            None
+        }
+    }
+}
+
+#[cfg(not(feature = "env"))]
+fn init_environment() -> Option<PathBuf> {
+    None
+}
+
 pub async fn init_logging() -> anyhow::Result<()> {
     let filter = match env::var_os(LOG_FILTER) {
         Some(_) => {
@@ -87,6 +111,11 @@ pub async fn init_logging() -> anyhow::Result<()> {
 }
 
 pub async fn run_cli() -> anyhow::Result<()> {
+    init_logging().await?;
+    if let Some(path) = init_environment() {
+        let path = path.display();
+        info!("Loading environment variables from {path}");
+    }
     let opt = Opt::try_parse();
     if opt.is_err() {
         let command = run::Command::try_parse();

bin/fuel-core/src/cli/run.rs

@@ -1,7 +1,6 @@
 #![allow(unused_variables)]
 use crate::{
     cli::{
-        init_logging,
         run::consensus::PoATriggerArgs,
         DEFAULT_DB_PATH,
     },
@@ -333,7 +332,6 @@ impl Command {
 }
 
 pub async fn exec(command: Command) -> anyhow::Result<()> {
-    init_logging().await?;
     let config = command.get_config()?;
     let network_name = {
         #[cfg(feature = "p2p")]

bin/fuel-core/src/cli/run/relayer.rs

@@ -25,7 +25,7 @@ pub struct RelayerArgs {
     #[arg(long = "relayer", env)]
     #[arg(required_if_eq("enable_relayer", "true"))]
     #[arg(requires_if(IsPresent, "enable_relayer"))]
-    pub eth_client: Option<url::Url>,
+    pub relayer: Option<url::Url>,
 
     /// Ethereum contract address. Create EthAddress into fuel_types
     #[arg(long = "relayer-v2-listening-contracts", value_parser = parse_h160, env)]
@@ -71,7 +71,7 @@ impl RelayerArgs {
         let config = Config {
             da_deploy_height: DaBlockHeight(self.da_deploy_height),
             da_finalization: DaBlockHeight(self.da_finalization),
-            eth_client: self.eth_client,
+            relayer: self.relayer,
             eth_v2_listening_contracts: self.eth_v2_listening_contracts,
             log_page_size: self.log_page_size,
             sync_minimum_duration: Duration::from_secs(self.sync_minimum_duration_secs),

bin/fuel-core/src/cli/snapshot.rs

@@ -51,7 +51,6 @@ pub async fn exec(command: Command) -> anyhow::Result<()> {
 
 #[cfg(any(feature = "rocksdb", feature = "rocksdb-production"))]
 pub async fn exec(command: Command) -> anyhow::Result<()> {
-    use crate::cli::init_logging;
     use anyhow::Context;
     use fuel_core::{
         chain_config::{
@@ -60,7 +59,6 @@ pub async fn exec(command: Command) -> anyhow::Result<()> {
         },
         database::Database,
     };
-    init_logging().await?;
     let path = command.database_path;
     let data_source =
         fuel_core::state::rocks_db::RocksDb::default_open(&path, None).context(

crates/services/relayer/src/config.rs

@@ -22,7 +22,7 @@ pub struct Config {
     /// Number of da blocks after which messages/stakes/validators become finalized.
     pub da_finalization: DaBlockHeight,
     /// Uri address to ethereum client.
-    pub eth_client: Option<url::Url>,
+    pub relayer: Option<url::Url>,
     // TODO: Create `EthAddress` into `fuel_core_types`.
     /// Ethereum contract address.
     pub eth_v2_listening_contracts: Vec<H160>,
@@ -58,7 +58,7 @@ impl Default for Config {
         Self {
             da_deploy_height: DaBlockHeight::from(Self::DEFAULT_DA_DEPLOY_HEIGHT),
             da_finalization: DaBlockHeight::from(Self::DEFAULT_DA_FINALIZATION),
-            eth_client: None,
+            relayer: None,
             eth_v2_listening_contracts: vec![H160::from_str(
                 "0x03E4538018285e1c03CCce2F92C9538c87606911",
             )

crates/services/relayer/src/service.rs

@@ -348,7 +348,7 @@ pub fn new_service<D>(database: D, config: Config) -> anyhow::Result<Service<D>>
 where
     D: RelayerDb + Clone + 'static,
 {
-    let url = config.eth_client.clone().ok_or_else(|| {
+    let url = config.relayer.clone().ok_or_else(|| {
         anyhow::anyhow!(
             "Tried to start Relayer without setting an eth_client in the config"
         )

tests/tests/relayer.rs

@@ -95,7 +95,7 @@ async fn relayer_can_download_logs() {
     let eth_node = Arc::new(eth_node);
     let eth_node_handle = spawn_eth_node(eth_node).await;
 
-    relayer_config.eth_client = Some(
+    relayer_config.relayer = Some(
         format!("http://{}", eth_node_handle.address)
             .as_str()
             .try_into()
@@ -153,7 +153,7 @@ async fn messages_are_spendable_after_relayer_is_synced() {
     let eth_node = Arc::new(eth_node);
     let eth_node_handle = spawn_eth_node(eth_node).await;
 
-    relayer_config.eth_client = Some(
+    relayer_config.relayer = Some(
         format!("http://{}", eth_node_handle.address)
             .as_str()
             .try_into()