refactor: extract kms module to external_services crate (#793)

Cargo.lock

@@ -1618,6 +1618,22 @@ version = "2.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0206175f82b8d6bf6652ff7d71a1e27fd2e4efde587fd368662814d6ec1d9ce0"
 
+[[package]]
+name = "external_services"
+version = "0.1.0"
+dependencies = [
+ "aws-config",
+ "aws-sdk-kms",
+ "base64 0.21.0",
+ "common_utils",
+ "error-stack",
+ "once_cell",
+ "router_env",
+ "serde",
+ "thiserror",
+ "tokio",
+]
+
 [[package]]
 name = "fake"
 version = "2.5.0"
@@ -3433,8 +3449,6 @@ dependencies = [
  "async-bb8-diesel",
  "async-trait",
  "awc",
- "aws-config",
- "aws-sdk-kms",
  "base64 0.21.0",
  "bb8",
  "blake3",
@@ -3448,6 +3462,7 @@ dependencies = [
  "dyn-clone",
  "encoding_rs",
  "error-stack",
+ "external_services",
  "frunk",
  "frunk_core",
  "futures",

crates/drainer/src/env.rs

@@ -18,6 +18,7 @@ pub mod logger {
             vec![
                 "drainer",
                 "common_utils",
+                "external_services",
                 "redis_interface",
                 "router_env",
                 "storage_models",

crates/external_services/Cargo.toml

@@ -0,0 +1,25 @@
+[package]
+name = "external_services"
+description = "Interactions of the router with external systems"
+version = "0.1.0"
+edition = "2021"
+rust-version = "1.65"
+readme = "README.md"
+license = "Apache-2.0"
+
+[features]
+kms = ["dep:aws-config", "dep:aws-sdk-kms"]
+
+[dependencies]
+aws-config = { version = "0.54.1", optional = true }
+aws-sdk-kms = { version = "0.24.0", optional = true }
+base64 = "0.21.0"
+error-stack = "0.3.1"
+once_cell = "1.17.1"
+serde = { version = "1.0.155", features = ["derive"] }
+thiserror = "1.0.39"
+tokio = "1.26.0"
+
+# First party crates
+common_utils = { version = "0.1.0", path = "../common_utils" }
+router_env = { version = "0.1.0", path = "../router_env", features = ["log_extra_implicit_fields", "log_custom_entries_to_extra"] }

crates/external_services/README.md

@@ -0,0 +1,4 @@
+# External Services
+
+This crate includes interactions with external systems, which may be shared
+across crates within this workspace.

crates/external_services/src/kms.rs

@@ -1,23 +1,35 @@
+//! Interactions with the AWS KMS SDK
+
 use aws_config::meta::region::RegionProviderChain;
 use aws_sdk_kms::{types::Blob, Client, Region};
 use base64::Engine;
+use common_utils::errors::CustomResult;
 use error_stack::{IntoReport, ResultExt};
+use router_env::logger;
 
-use crate::{
-    configs::settings,
-    consts,
-    core::errors::{self, CustomResult},
-    logger,
-    routes::metrics,
-};
+use crate::{consts, metrics};
 
 static KMS_CLIENT: tokio::sync::OnceCell<KmsClient> = tokio::sync::OnceCell::const_new();
 
+/// Returns a shared KMS client, or initializes a new one if not previously initialized.
 #[inline]
-pub async fn get_kms_client(config: &settings::Kms) -> &KmsClient {
+pub async fn get_kms_client(config: &KmsConfig) -> &KmsClient {
     KMS_CLIENT.get_or_init(|| KmsClient::new(config)).await
 }
 
+/// Configuration parameters required for constructing a [`KmsClient`].
+#[derive(Clone, Debug, Default, serde::Deserialize)]
+#[serde(default)]
+pub struct KmsConfig {
+    /// The AWS key identifier of the KMS key used to encrypt or decrypt data.
+    pub key_id: String,
+
+    /// The AWS region to send KMS requests to.
+    pub region: String,
+}
+
+/// Client for KMS operations.
+#[derive(Debug)]
 pub struct KmsClient {
     inner_client: Client,
     key_id: String,
@@ -25,7 +37,7 @@ pub struct KmsClient {
 
 impl KmsClient {
     /// Constructs a new KMS client.
-    pub async fn new(config: &settings::Kms) -> Self {
+    pub async fn new(config: &KmsConfig) -> Self {
         let region_provider = RegionProviderChain::first_try(Region::new(config.region.clone()));
         let sdk_config = aws_config::from_env().region(region_provider).load().await;
 
@@ -39,11 +51,11 @@ impl KmsClient {
     /// the SDK has the values required to interact with the AWS KMS APIs (`AWS_ACCESS_KEY_ID` and
     /// `AWS_SECRET_ACCESS_KEY`) either set in environment variables, or that the SDK is running in
     /// a machine that is able to assume an IAM role.
-    pub async fn decrypt(&self, data: impl AsRef<[u8]>) -> CustomResult<String, errors::KmsError> {
+    pub async fn decrypt(&self, data: impl AsRef<[u8]>) -> CustomResult<String, KmsError> {
         let data = consts::BASE64_ENGINE
             .decode(data)
             .into_report()
-            .change_context(errors::KmsError::Base64DecodingFailed)?;
+            .change_context(KmsError::Base64DecodingFailed)?;
         let ciphertext_blob = Blob::new(data);
 
         let decrypt_output = self
@@ -61,16 +73,51 @@ impl KmsClient {
                 error
             })
             .into_report()
-            .change_context(errors::KmsError::DecryptionFailed)?;
+            .change_context(KmsError::DecryptionFailed)?;
 
         decrypt_output
             .plaintext
-            .ok_or(errors::KmsError::MissingPlaintextDecryptionOutput)
+            .ok_or(KmsError::MissingPlaintextDecryptionOutput)
             .into_report()
             .and_then(|blob| {
                 String::from_utf8(blob.into_inner())
                     .into_report()
-                    .change_context(errors::KmsError::Utf8DecodingFailed)
+                    .change_context(KmsError::Utf8DecodingFailed)
+            })
+    }
+}
+
+/// Errors that could occur during KMS operations.
+#[derive(Debug, thiserror::Error)]
+pub enum KmsError {
+    /// An error occurred when base64 decoding input data.
+    #[error("Failed to base64 decode input data")]
+    Base64DecodingFailed,
+
+    /// An error occurred when KMS decrypting input data.
+    #[error("Failed to KMS decrypt input data")]
+    DecryptionFailed,
+
+    /// The KMS decrypted output does not include a plaintext output.
+    #[error("Missing plaintext KMS decryption output")]
+    MissingPlaintextDecryptionOutput,
+
+    /// An error occurred UTF-8 decoding KMS decrypted output.
+    #[error("Failed to UTF-8 decode decryption output")]
+    Utf8DecodingFailed,
+}
+
+impl KmsConfig {
+    /// Verifies that the [`KmsClient`] configuration is usable.
+    pub fn validate(&self) -> Result<(), &'static str> {
+        use common_utils::{ext_traits::ConfigExt, fp_utils::when};
+
+        when(self.key_id.is_default_or_empty(), || {
+            Err("KMS AWS key ID must not be empty")
+        })?;
+
+        when(self.region.is_default_or_empty(), || {
+            Err("KMS AWS region must not be empty")
         })
     }
 }

crates/external_services/src/lib.rs

@@ -0,0 +1,27 @@
+//! Interactions with external systems.
+
+#![forbid(unsafe_code)]
+#![warn(missing_docs, missing_debug_implementations)]
+
+#[cfg(feature = "kms")]
+pub mod kms;
+
+/// Crate specific constants
+#[cfg(feature = "kms")]
+pub mod consts {
+    /// General purpose base64 engine
+    pub(crate) const BASE64_ENGINE: base64::engine::GeneralPurpose =
+        base64::engine::general_purpose::STANDARD;
+}
+
+/// Metrics for interactions with external systems.
+#[cfg(feature = "kms")]
+pub mod metrics {
+    use router_env::{counter_metric, global_meter, metrics_context};
+
+    metrics_context!(CONTEXT);
+    global_meter!(GLOBAL_METER, "EXTERNAL_SERVICES");
+
+    #[cfg(feature = "kms")]
+    counter_metric!(AWS_KMS_FAILURES, GLOBAL_METER); // No. of AWS KMS API failures
+}

crates/router/Cargo.toml

@@ -11,7 +11,7 @@ build = "src/build.rs"
 
 [features]
 default = ["kv_store", "stripe", "oltp", "olap", "accounts_cache"]
-kms = ["aws-config", "aws-sdk-kms"]
+kms = ["external_services/kms"]
 basilisk = ["kms"]
 stripe = ["dep:serde_qs"]
 sandbox = ["kms", "stripe", "basilisk"]
@@ -31,8 +31,6 @@ actix-rt = "2.8.0"
 actix-web = "4.3.1"
 async-bb8-diesel = { git = "https://github.com/juspay/async-bb8-diesel", rev = "9a71d142726dbc33f41c1fd935ddaa79841c7be5" }
 async-trait = "0.1.66"
-aws-config = { version = "0.54.1", optional = true }
-aws-sdk-kms = { version = "0.24.0", optional = true }
 base64 = "0.21.0"
 bb8 = "0.8"
 blake3 = "1.3.3"
@@ -83,6 +81,7 @@ uuid = { version = "1.3.0", features = ["serde", "v4"] }
 # First party crates
 api_models = { version = "0.1.0", path = "../api_models" }
 common_utils = { version = "0.1.0", path = "../common_utils" }
+external_services = { version = "0.1.0", path = "../external_services" }
 masking = { version = "0.1.0", path = "../masking" }
 redis_interface = { version = "0.1.0", path = "../redis_interface" }
 router_derive = { version = "0.1.0", path = "../router_derive" }

crates/router/src/configs/settings.rs

@@ -6,6 +6,8 @@ use std::{
 
 use common_utils::ext_traits::ConfigExt;
 use config::{Environment, File};
+#[cfg(feature = "kms")]
+use external_services::kms;
 use redis_interface::RedisSettings;
 pub use router_env::config::{Log, LogConsole, LogFile, LogTelemetry};
 use serde::{Deserialize, Deserializer};
@@ -59,7 +61,7 @@ pub struct Settings {
     pub bank_config: BankRedirectConfig,
     pub api_keys: ApiKeys,
     #[cfg(feature = "kms")]
-    pub kms: Kms,
+    pub kms: kms::KmsConfig,
 }
 
 #[derive(Debug, Deserialize, Clone, Default)]
@@ -337,14 +339,6 @@ pub struct ApiKeys {
     pub hash_key: String,
 }
 
-#[cfg(feature = "kms")]
-#[derive(Debug, Deserialize, Clone, Default)]
-#[serde(default)]
-pub struct Kms {
-    pub key_id: String,
-    pub region: String,
-}
-
 impl Settings {
     pub fn new() -> ApplicationResult<Self> {
         Self::with_config_path(None)
@@ -420,7 +414,9 @@ impl Settings {
         self.drainer.validate()?;
         self.api_keys.validate()?;
         #[cfg(feature = "kms")]
-        self.kms.validate()?;
+        self.kms
+            .validate()
+            .map_err(|error| ApplicationError::InvalidConfigurationValueError(error.into()))?;
 
         Ok(())
     }

crates/router/src/configs/validations.rs

@@ -184,22 +184,3 @@ impl super::settings::ApiKeys {
         })
     }
 }
-
-#[cfg(feature = "kms")]
-impl super::settings::Kms {
-    pub fn validate(&self) -> Result<(), ApplicationError> {
-        use common_utils::fp_utils::when;
-
-        when(self.key_id.is_default_or_empty(), || {
-            Err(ApplicationError::InvalidConfigurationValueError(
-                "KMS AWS key ID must not be empty".into(),
-            ))
-        })?;
-
-        when(self.region.is_default_or_empty(), || {
-            Err(ApplicationError::InvalidConfigurationValueError(
-                "KMS AWS region must not be empty".into(),
-            ))
-        })
-    }
-}

crates/router/src/core/api_keys.rs

@@ -1,10 +1,10 @@
 use common_utils::date_time;
 use error_stack::{report, IntoReport, ResultExt};
+#[cfg(feature = "kms")]
+use external_services::kms;
 use masking::{PeekInterface, StrongSecret};
 use router_env::{instrument, tracing};
 
-#[cfg(feature = "kms")]
-use crate::services::kms;
 use crate::{
     configs::settings,
     consts,
@@ -21,7 +21,7 @@ static HASH_KEY: tokio::sync::OnceCell<StrongSecret<[u8; PlaintextApiKey::HASH_K
 
 pub async fn get_hash_key(
     api_key_config: &settings::ApiKeys,
-    #[cfg(feature = "kms")] kms_config: &settings::Kms,
+    #[cfg(feature = "kms")] kms_config: &kms::KmsConfig,
 ) -> errors::RouterResult<&'static StrongSecret<[u8; PlaintextApiKey::HASH_KEY_LEN]>> {
     HASH_KEY
         .get_or_try_init(|| async {
@@ -119,7 +119,7 @@ impl PlaintextApiKey {
 pub async fn create_api_key(
     store: &dyn StorageInterface,
     api_key_config: &settings::ApiKeys,
-    #[cfg(feature = "kms")] kms_config: &settings::Kms,
+    #[cfg(feature = "kms")] kms_config: &kms::KmsConfig,
     api_key: api::CreateApiKeyRequest,
     merchant_id: String,
 ) -> RouterResponse<api::CreateApiKeyResponse> {

crates/router/src/core/payment_methods/transformers.rs

@@ -1,10 +1,10 @@
 use common_utils::ext_traits::StringExt;
 use error_stack::ResultExt;
+#[cfg(feature = "kms")]
+use external_services::kms;
 use josekit::jwe;
 use serde::{Deserialize, Serialize};
 
-#[cfg(feature = "kms")]
-use crate::services::kms;
 use crate::{
     configs::settings,
     core::errors::{self, CustomResult},
@@ -149,7 +149,7 @@ pub fn get_dotted_jws(jws: encryption::JwsBody) -> String {
 pub async fn get_decrypted_response_payload(
     jwekey: &settings::Jwekey,
     jwe_body: encryption::JweBody,
-    #[cfg(feature = "kms")] kms_config: &settings::Kms,
+    #[cfg(feature = "kms")] kms_config: &kms::KmsConfig,
 ) -> CustomResult<String, errors::VaultError> {
     #[cfg(feature = "kms")]
     let public_key = kms::get_kms_client(kms_config)
@@ -192,7 +192,7 @@ pub async fn get_decrypted_response_payload(
 pub async fn mk_basilisk_req(
     jwekey: &settings::Jwekey,
     jws: &str,
-    #[cfg(feature = "kms")] kms_config: &settings::Kms,
+    #[cfg(feature = "kms")] kms_config: &kms::KmsConfig,
 ) -> CustomResult<encryption::JweBody, errors::VaultError> {
     let jws_payload: Vec<&str> = jws.split('.').collect();
 
@@ -247,7 +247,7 @@ pub async fn mk_add_card_request_hs(
     card: &api::CardDetail,
     customer_id: &str,
     merchant_id: &str,
-    #[cfg(feature = "kms")] kms_config: &settings::Kms,
+    #[cfg(feature = "kms")] kms_config: &kms::KmsConfig,
 ) -> CustomResult<services::Request, errors::VaultError> {
     let merchant_customer_id = if cfg!(feature = "sandbox") {
         format!("{customer_id}::{merchant_id}")
@@ -409,7 +409,7 @@ pub async fn mk_get_card_request_hs(
     customer_id: &str,
     merchant_id: &str,
     card_reference: &str,
-    #[cfg(feature = "kms")] kms_config: &settings::Kms,
+    #[cfg(feature = "kms")] kms_config: &kms::KmsConfig,
 ) -> CustomResult<services::Request, errors::VaultError> {
     let merchant_customer_id = if cfg!(feature = "sandbox") {
         format!("{customer_id}::{merchant_id}")
@@ -501,7 +501,7 @@ pub async fn mk_delete_card_request_hs(
     customer_id: &str,
     merchant_id: &str,
     card_reference: &str,
-    #[cfg(feature = "kms")] kms_config: &settings::Kms,
+    #[cfg(feature = "kms")] kms_config: &kms::KmsConfig,
 ) -> CustomResult<services::Request, errors::VaultError> {
     let merchant_customer_id = if cfg!(feature = "sandbox") {
         format!("{customer_id}::{merchant_id}")

crates/router/src/core/payment_methods/vault.rs

@@ -1,6 +1,8 @@
 use common_utils::generate_id_with_default_len;
 use error_stack::{IntoReport, ResultExt};
 #[cfg(feature = "basilisk")]
+use external_services::kms;
+#[cfg(feature = "basilisk")]
 use josekit::jwe;
 use masking::PeekInterface;
 use router_env::{instrument, tracing};
@@ -18,11 +20,7 @@ use crate::{
     utils::{self, StringExt},
 };
 #[cfg(feature = "basilisk")]
-use crate::{
-    core::payment_methods::transformers as payment_methods,
-    services::{self, kms},
-    utils::BytesExt,
-};
+use crate::{core::payment_methods::transformers as payment_methods, services, utils::BytesExt};
 #[cfg(feature = "basilisk")]
 use crate::{
     db,
@@ -407,7 +405,7 @@ pub fn get_key_id(keys: &settings::Jwekey) -> &str {
 #[cfg(feature = "basilisk")]
 async fn get_locker_jwe_keys(
     keys: &settings::Jwekey,
-    kms_config: &settings::Kms,
+    kms_config: &kms::KmsConfig,
 ) -> CustomResult<(String, String), errors::EncryptionError> {
     let key_id = get_key_id(keys);
     let (encryption_key, decryption_key) = if key_id == keys.locker_key_identifier1 {

crates/router/src/env.rs

@@ -20,6 +20,7 @@ pub mod logger {
                 "actix_server",
                 "api_models",
                 "common_utils",
+                "external_services",
                 "masking",
                 "redis_interface",
                 "router_derive",

crates/router/src/services.rs

@@ -1,8 +1,6 @@
 pub mod api;
 pub mod authentication;
 pub mod encryption;
-#[cfg(feature = "kms")]
-pub mod kms;
 pub mod logger;
 
 use std::sync::{atomic, Arc};

crates/router_env/tests/env.rs

@@ -1,5 +1,7 @@
+#[cfg(feature = "vergen")]
 use router_env as env;
 
+#[cfg(feature = "vergen")]
 #[tokio::test]
 async fn basic() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
     println!("CARGO_PKG_VERSION : {:?}", env!("CARGO_PKG_VERSION"));
@@ -19,6 +21,7 @@ async fn basic() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
     Ok(())
 }
 
+#[cfg(feature = "vergen")]
 #[tokio::test]
 async fn env_macro() -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
     println!("version : {:?}", env::version!());