feat: read device.id from credentials.toml when basic auth mode

Signed-off-by: Rina Fujino <rina.fujino.23@gmail.com>

crates/common/tedge_config/src/tedge_config_cli/models/auth_method.rs

@@ -57,3 +57,22 @@ impl AuthMethod {
         }
     }
 }
+
+pub fn try_get_device_id_from_credentials_file(credentials_path: &Utf8Path) -> Option<String> {
+    if let Ok(contents) = std::fs::read_to_string(credentials_path) {
+        if let Ok(credentials) = toml::from_str::<CredentialsFile>(&contents) {
+            return Some(credentials.c8y.device_id);
+        }
+    }
+    None
+}
+
+#[derive(Debug, serde::Deserialize)]
+struct CredentialsFile {
+    c8y: C8y,
+}
+
+#[derive(Debug, serde::Deserialize)]
+struct C8y {
+    device_id: String,
+}

crates/common/tedge_config/src/tedge_config_cli/tedge_config.rs

@@ -1,4 +1,5 @@
 use super::models::timestamp::TimeFormat;
+use crate::auth_method::try_get_device_id_from_credentials_file;
 use crate::auth_method::AuthMethod;
 use crate::AptConfig;
 use crate::AutoFlag;
@@ -1195,6 +1196,20 @@ fn default_http_bind_address(dto: &TEdgeConfigDto) -> IpAddr {
 }
 
 fn device_id(reader: &TEdgeConfigReader) -> Result<String, ReadError> {
+    let c8y_profile: Option<&ProfileName> = None;
+    let c8y_config = reader.c8y.try_get(c8y_profile)?;
+
+    if c8y_config
+        .auth_method
+        .is_basic(&c8y_config.credentials_path)
+    {
+        if let Some(device_id) =
+            try_get_device_id_from_credentials_file(&c8y_config.credentials_path)
+        {
+            return Ok(device_id);
+        }
+    }
+
     let pem = PemCertificate::from_pem_file(&reader.device.cert_path)
         .map_err(|err| cert_error_into_config_error(ReadOnlyKey::DeviceId.to_cow_str(), err))?;
     let device_id = pem