config: Refactor parsing of secrets section

crates/config/Cargo.toml

@@ -15,6 +15,7 @@ workspace = true
 tokio.workspace = true
 tracing.workspace = true
 anyhow.workspace = true
+futures = "0.3.31"
 
 camino = { workspace = true, features = ["serde1"] }
 chrono.workspace = true

crates/config/src/sections/secrets.rs

@@ -8,6 +8,7 @@ use std::borrow::Cow;
 
 use anyhow::{Context, bail};
 use camino::Utf8PathBuf;
+use futures::future::{try_join, try_join_all};
 use mas_jose::jwk::{JsonWebKey, JsonWebKeySet};
 use mas_keystore::{Encrypter, Keystore, PrivateKey};
 use rand::{
@@ -27,23 +28,156 @@ fn example_secret() -> &'static str {
     "0000111122223333444455556666777788889999aaaabbbbccccddddeeeeffff"
 }
 
-#[derive(JsonSchema, Serialize, Deserialize, Clone, Debug)]
-pub struct KeyConfig {
-    kid: String,
-
-    #[serde(skip_serializing_if = "Option::is_none")]
-    password: Option<String>,
+/// Password config option.
+///
+/// It either holds the password value directly or references a file where the
+/// password is stored.
+#[derive(Clone, Debug)]
+pub enum Password {
+    File(Utf8PathBuf),
+    Value(String),
+}
 
-    #[serde(skip_serializing_if = "Option::is_none")]
+/// Password fields as serialized in JSON.
+#[derive(JsonSchema, Serialize, Deserialize, Clone, Debug)]
+struct PasswordRaw {
     #[schemars(with = "Option<String>")]
     password_file: Option<Utf8PathBuf>,
+    password: Option<String>,
+}
 
-    #[serde(skip_serializing_if = "Option::is_none")]
-    key: Option<String>,
+impl TryFrom<PasswordRaw> for Option<Password> {
+    type Error = anyhow::Error;
 
-    #[serde(skip_serializing_if = "Option::is_none")]
+    fn try_from(value: PasswordRaw) -> Result<Self, Self::Error> {
+        match (value.password, value.password_file) {
+            (None, None) => Ok(None),
+            (None, Some(path)) => Ok(Some(Password::File(path))),
+            (Some(password), None) => Ok(Some(Password::Value(password))),
+            (Some(_), Some(_)) => bail!("Cannot specify both `password` and `password_file`"),
+        }
+    }
+}
+
+impl From<Option<Password>> for PasswordRaw {
+    fn from(value: Option<Password>) -> Self {
+        match value {
+            Some(Password::File(path)) => PasswordRaw {
+                password_file: Some(path),
+                password: None,
+            },
+            Some(Password::Value(password)) => PasswordRaw {
+                password_file: None,
+                password: Some(password),
+            },
+            None => PasswordRaw {
+                password_file: None,
+                password: None,
+            },
+        }
+    }
+}
+
+/// Key config option.
+///
+/// It either holds the key value directly or references a file where the key is
+/// stored.
+#[derive(Clone, Debug)]
+pub enum Key {
+    File(Utf8PathBuf),
+    Value(String),
+}
+
+/// Key fields as serialized in JSON.
+#[derive(JsonSchema, Serialize, Deserialize, Clone, Debug)]
+struct KeyRaw {
     #[schemars(with = "Option<String>")]
     key_file: Option<Utf8PathBuf>,
+    key: Option<String>,
+}
+
+impl TryFrom<KeyRaw> for Key {
+    type Error = anyhow::Error;
+
+    fn try_from(value: KeyRaw) -> Result<Key, Self::Error> {
+        match (value.key, value.key_file) {
+            (None, None) => bail!("Missing `key` or `key_file`"),
+            (None, Some(path)) => Ok(Key::File(path)),
+            (Some(key), None) => Ok(Key::Value(key)),
+            (Some(_), Some(_)) => bail!("Cannot specify both `key` and `key_file`"),
+        }
+    }
+}
+
+impl From<Key> for KeyRaw {
+    fn from(value: Key) -> Self {
+        match value {
+            Key::File(path) => KeyRaw {
+                key_file: Some(path),
+                key: None,
+            },
+            Key::Value(key) => KeyRaw {
+                key_file: None,
+                key: Some(key),
+            },
+        }
+    }
+}
+
+/// A single key with its key ID and optional password.
+#[serde_as]
+#[derive(JsonSchema, Serialize, Deserialize, Clone, Debug)]
+pub struct KeyConfig {
+    kid: String,
+
+    #[schemars(with = "PasswordRaw")]
+    #[serde_as(as = "serde_with::TryFromInto<PasswordRaw>")]
+    #[serde(flatten)]
+    password: Option<Password>,
+
+    #[schemars(with = "KeyRaw")]
+    #[serde_as(as = "serde_with::TryFromInto<KeyRaw>")]
+    #[serde(flatten)]
+    key: Key,
+}
+
+impl KeyConfig {
+    /// Returns the password in case any is provided.
+    ///
+    /// If `password_file` was given, the password is read from that file.
+    async fn password(&self) -> anyhow::Result<Option<Cow<String>>> {
+        Ok(match &self.password {
+            Some(Password::File(path)) => Some(Cow::Owned(tokio::fs::read_to_string(path).await?)),
+            Some(Password::Value(password)) => Some(Cow::Borrowed(password)),
+            None => None,
+        })
+    }
+
+    /// Returns the key.
+    ///
+    /// If `key_file` was given, the key is read from that file.
+    async fn key(&self) -> anyhow::Result<Cow<String>> {
+        Ok(match &self.key {
+            Key::File(path) => Cow::Owned(tokio::fs::read_to_string(path).await?),
+            Key::Value(key) => Cow::Borrowed(key),
+        })
+    }
+
+    /// Returns the JSON Web Key derived from this key config.
+    ///
+    /// Password and/or key are read from file if they’re given as path.
+    async fn json_web_key(&self) -> anyhow::Result<JsonWebKey<mas_keystore::PrivateKey>> {
+        let (key, password) = try_join(self.key(), self.password()).await?;
+
+        let private_key = match password {
+            Some(password) => PrivateKey::load_encrypted(key.as_bytes(), password.as_bytes())?,
+            None => PrivateKey::load(key.as_bytes())?,
+        };
+
+        Ok(JsonWebKey::new(private_key)
+            .with_kid(self.kid.clone())
+            .with_use(mas_iana::jose::JsonWebKeyUse::Sig))
+    }
 }
 
 /// Application secrets
@@ -72,49 +206,9 @@ impl SecretsConfig {
     /// Returns an error when a key could not be imported
     #[tracing::instrument(name = "secrets.load", skip_all)]
     pub async fn key_store(&self) -> anyhow::Result<Keystore> {
-        let mut keys = Vec::with_capacity(self.keys.len());
-        for item in &self.keys {
-            let password = match (&item.password, &item.password_file) {
-                (None, None) => None,
-                (Some(_), Some(_)) => {
-                    bail!("Cannot specify both `password` and `password_file`")
-                }
-                (Some(password), None) => Some(Cow::Borrowed(password)),
-                (None, Some(path)) => Some(Cow::Owned(tokio::fs::read_to_string(path).await?)),
-            };
-
-            // Read the key either embedded in the config file or on disk
-            let key = match (&item.key, &item.key_file) {
-                (None, None) => bail!("Missing `key` or `key_file`"),
-                (Some(_), Some(_)) => bail!("Cannot specify both `key` and `key_file`"),
-                (Some(key), None) => {
-                    // If the key was embedded in the config file, assume it is formatted as PEM
-                    if let Some(password) = password {
-                        PrivateKey::load_encrypted_pem(key, password.as_bytes())?
-                    } else {
-                        PrivateKey::load_pem(key)?
-                    }
-                }
-                (None, Some(path)) => {
-                    // When reading from disk, it might be either PEM or DER. `PrivateKey::load*`
-                    // will try both.
-                    let key = tokio::fs::read(path).await?;
-                    if let Some(password) = password {
-                        PrivateKey::load_encrypted(&key, password.as_bytes())?
-                    } else {
-                        PrivateKey::load(&key)?
-                    }
-                }
-            };
-
-            let key = JsonWebKey::new(key)
-                .with_kid(item.kid.clone())
-                .with_use(mas_iana::jose::JsonWebKeyUse::Sig);
-            keys.push(key);
-        }
+        let web_keys = try_join_all(self.keys.iter().map(KeyConfig::json_web_key)).await?;
 
-        let keys = JsonWebKeySet::new(keys);
-        Ok(Keystore::new(keys))
+        Ok(Keystore::new(JsonWebKeySet::new(web_keys)))
     }
 
     /// Derive an [`Encrypter`] out of the config
@@ -127,40 +221,7 @@ impl SecretsConfig {
 impl ConfigurationSection for SecretsConfig {
     const PATH: Option<&'static str> = Some("secrets");
 
-    fn validate(&self, figment: &figment::Figment) -> Result<(), figment::Error> {
-        for (index, key) in self.keys.iter().enumerate() {
-            let annotate = |mut error: figment::Error| {
-                error.metadata = figment
-                    .find_metadata(&format!("{root}.keys", root = Self::PATH.unwrap()))
-                    .cloned();
-                error.profile = Some(figment::Profile::Default);
-                error.path = vec![
-                    Self::PATH.unwrap().to_owned(),
-                    "keys".to_owned(),
-                    index.to_string(),
-                ];
-                Err(error)
-            };
-
-            if key.key.is_none() && key.key_file.is_none() {
-                return annotate(figment::Error::from(
-                    "Missing `key` or `key_file`".to_owned(),
-                ));
-            }
-
-            if key.key.is_some() && key.key_file.is_some() {
-                return annotate(figment::Error::from(
-                    "Cannot specify both `key` and `key_file`".to_owned(),
-                ));
-            }
-
-            if key.password.is_some() && key.password_file.is_some() {
-                return annotate(figment::Error::from(
-                    "Cannot specify both `password` and `password_file`".to_owned(),
-                ));
-            }
-        }
-
+    fn validate(&self, _figment: &figment::Figment) -> Result<(), figment::Error> {
         Ok(())
     }
 }
@@ -186,9 +247,7 @@ impl SecretsConfig {
         let rsa_key = KeyConfig {
             kid: Alphanumeric.sample_string(&mut rng, 10),
             password: None,
-            password_file: None,
-            key: Some(rsa_key.to_pem(pem_rfc7468::LineEnding::LF)?.to_string()),
-            key_file: None,
+            key: Key::Value(rsa_key.to_pem(pem_rfc7468::LineEnding::LF)?.to_string()),
         };
 
         let span = tracing::info_span!("ec_p256");
@@ -204,9 +263,7 @@ impl SecretsConfig {
         let ec_p256_key = KeyConfig {
             kid: Alphanumeric.sample_string(&mut rng, 10),
             password: None,
-            password_file: None,
-            key: Some(ec_p256_key.to_pem(pem_rfc7468::LineEnding::LF)?.to_string()),
-            key_file: None,
+            key: Key::Value(ec_p256_key.to_pem(pem_rfc7468::LineEnding::LF)?.to_string()),
         };
 
         let span = tracing::info_span!("ec_p384");
@@ -222,9 +279,7 @@ impl SecretsConfig {
         let ec_p384_key = KeyConfig {
             kid: Alphanumeric.sample_string(&mut rng, 10),
             password: None,
-            password_file: None,
-            key: Some(ec_p384_key.to_pem(pem_rfc7468::LineEnding::LF)?.to_string()),
-            key_file: None,
+            key: Key::Value(ec_p384_key.to_pem(pem_rfc7468::LineEnding::LF)?.to_string()),
         };
 
         let span = tracing::info_span!("ec_k256");
@@ -240,9 +295,7 @@ impl SecretsConfig {
         let ec_k256_key = KeyConfig {
             kid: Alphanumeric.sample_string(&mut rng, 10),
             password: None,
-            password_file: None,
-            key: Some(ec_k256_key.to_pem(pem_rfc7468::LineEnding::LF)?.to_string()),
-            key_file: None,
+            key: Key::Value(ec_k256_key.to_pem(pem_rfc7468::LineEnding::LF)?.to_string()),
         };
 
         Ok(Self {
@@ -255,8 +308,7 @@ impl SecretsConfig {
         let rsa_key = KeyConfig {
             kid: "abcdef".to_owned(),
             password: None,
-            password_file: None,
-            key: Some(
+            key: Key::Value(
                 indoc::indoc! {r"
                   -----BEGIN PRIVATE KEY-----
                   MIIBVQIBADANBgkqhkiG9w0BAQEFAASCAT8wggE7AgEAAkEAymS2RkeIZo7pUeEN
@@ -271,13 +323,11 @@ impl SecretsConfig {
                 "}
                 .to_owned(),
             ),
-            key_file: None,
         };
         let ecdsa_key = KeyConfig {
             kid: "ghijkl".to_owned(),
             password: None,
-            password_file: None,
-            key: Some(
+            key: Key::Value(
                 indoc::indoc! {r"
                   -----BEGIN PRIVATE KEY-----
                   MIGEAgEAMBAGByqGSM49AgEGBSuBBAAKBG0wawIBAQQgqfn5mYO/5Qq/wOOiWgHA
@@ -287,7 +337,6 @@ impl SecretsConfig {
                 "}
                 .to_owned(),
             ),
-            key_file: None,
         };
 
         Self {

docs/config.schema.json

@@ -1538,6 +1538,7 @@
       }
     },
     "KeyConfig": {
+      "description": "A single key with its key ID and optional password.",
       "type": "object",
       "required": [
         "kid"
@@ -1546,17 +1547,17 @@
         "kid": {
           "type": "string"
         },
-        "password": {
-          "type": "string"
-        },
         "password_file": {
           "type": "string"
         },
-        "key": {
+        "password": {
           "type": "string"
         },
         "key_file": {
           "type": "string"
+        },
+        "key": {
+          "type": "string"
         }
       }
     },