diff --git a/Cargo.lock b/Cargo.lock
index 5458cb0..5cae829 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -26,6 +26,21 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "android-tzdata"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e999941b234f3131b00bc13c22d06e8c5ff726d1b6318ac7eb276997bbb4fef0"
+
+[[package]]
+name = "android_system_properties"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "819e7219dbd41043ac279b19830f2efc897156490d7fd6ea916720117ee66311"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "anyhow"
 version = "1.0.71"
@@ -155,6 +170,19 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "chrono"
+version = "0.4.31"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f2c685bad3eb3d45a01354cedb7d5faa66194d1d58ba6e267a8de788f79db38"
+dependencies = [
+ "android-tzdata",
+ "iana-time-zone",
+ "num-traits",
+ "serde",
+ "windows-targets",
+]
+
 [[package]]
 name = "cookie"
 version = "0.16.2"
@@ -227,6 +255,41 @@ version = "0.8.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e496a50fda8aacccc86d7529e2c1e0892dbd0f898a6b5645b5561b89c3210efa"
 
+[[package]]
+name = "darling"
+version = "0.20.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0209d94da627ab5605dcccf08bb18afa5009cfbef48d8a8b7d7bdbc79be25c5e"
+dependencies = [
+ "darling_core",
+ "darling_macro",
+]
+
+[[package]]
+name = "darling_core"
+version = "0.20.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "177e3443818124b357d8e76f53be906d60937f0d3a90773a664fa63fa253e621"
+dependencies = [
+ "fnv",
+ "ident_case",
+ "proc-macro2",
+ "quote",
+ "strsim",
+ "syn",
+]
+
+[[package]]
+name = "darling_macro"
+version = "0.20.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "836a9bbc7ad63342d6d6e7b815ccab164bc77a2d95d84bc3117a8c0d5c98e2d5"
+dependencies = [
+ "darling_core",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "encoding_rs"
 version = "0.8.32"
@@ -236,6 +299,12 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "equivalent"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5443807d6dff69373d433ab9ef5378ad8df50ca6298caf15de6e52e24aaf54d5"
+
 [[package]]
 name = "errno"
 version = "0.3.1"
@@ -377,7 +446,7 @@ dependencies = [
  "futures-sink",
  "futures-util",
  "http",
- "indexmap",
+ "indexmap 1.9.3",
  "slab",
  "tokio",
  "tokio-util",
@@ -390,6 +459,12 @@ version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8a9ee70c43aaf417c914396645a0fa852624801b24ebb7ae78fe8272889ac888"
 
+[[package]]
+name = "hashbrown"
+version = "0.14.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7dfda62a12f55daeae5015f81b0baea145391cb4520f86c248fc615d72640d12"
+
 [[package]]
 name = "heck"
 version = "0.4.1"
@@ -402,6 +477,12 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "fed44880c466736ef9a5c5b5facefb5ed0785676d0c02d612db14e54f0d84286"
 
+[[package]]
+name = "hex"
+version = "0.4.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7f24254aa9a54b5c858eaee2f5bccdb46aaf0e486a595ed5fd8f86ba55232a70"
+
 [[package]]
 name = "http"
 version = "0.2.9"
@@ -495,6 +576,35 @@ dependencies = [
  "tokio-native-tls",
 ]
 
+[[package]]
+name = "iana-time-zone"
+version = "0.1.57"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2fad5b825842d2b38bd206f3e81d6957625fd7f0a361e345c30e01a0ae2dd613"
+dependencies = [
+ "android_system_properties",
+ "core-foundation-sys",
+ "iana-time-zone-haiku",
+ "js-sys",
+ "wasm-bindgen",
+ "windows",
+]
+
+[[package]]
+name = "iana-time-zone-haiku"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f31827a206f56af32e590ba56d5d2d085f558508192593743f16b2306495269f"
+dependencies = [
+ "cc",
+]
+
+[[package]]
+name = "ident_case"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9e0384b61958566e926dc50660321d12159025e767c18e043daf26b70104c39"
+
 [[package]]
 name = "idna"
 version = "0.2.3"
@@ -533,7 +643,19 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bd070e393353796e801d209ad339e89596eb4c8d430d18ede6a1cced8fafbd99"
 dependencies = [
  "autocfg",
- "hashbrown",
+ "hashbrown 0.12.3",
+ "serde",
+]
+
+[[package]]
+name = "indexmap"
+version = "2.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8adf3ddd720272c6ea8bf59463c04e0f93d0bbf7c5439b691bca2987e0270897"
+dependencies = [
+ "equivalent",
+ "hashbrown 0.14.1",
+ "serde",
 ]
 
 [[package]]
@@ -617,6 +739,7 @@ dependencies = [
  "lazy-regex",
  "serde",
  "serde_json",
+ "serde_with",
  "strum_macros",
  "tokio",
  "tower-cookies",
@@ -724,6 +847,15 @@ dependencies = [
  "tempfile",
 ]
 
+[[package]]
+name = "num-traits"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39e3200413f237f41ab11ad6d161bc7239c84dcb631773ccd7de3dfe4b5c267c"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "num_cpus"
 version = "1.16.0"
@@ -1142,6 +1274,35 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_with"
+version = "3.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1ca3b16a3d82c4088f343b7480a93550b3eabe1a358569c2dfe38bbcead07237"
+dependencies = [
+ "base64",
+ "chrono",
+ "hex",
+ "indexmap 1.9.3",
+ "indexmap 2.0.2",
+ "serde",
+ "serde_json",
+ "serde_with_macros",
+ "time",
+]
+
+[[package]]
+name = "serde_with_macros"
+version = "3.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e6be15c453eb305019bfa438b1593c731f36a289a7853f7707ee29e870b3b3c"
+dependencies = [
+ "darling",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "signal-hook-registry"
 version = "1.4.1"
@@ -1186,6 +1347,12 @@ dependencies = [
  "windows-sys 0.48.0",
 ]
 
+[[package]]
+name = "strsim"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
+
 [[package]]
 name = "strum_macros"
 version = "0.25.3"
@@ -1619,6 +1786,15 @@ version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
 
+[[package]]
+name = "windows"
+version = "0.48.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e686886bc078bc1b0b600cac0147aadb815089b6e4da64016cbd754b6342700f"
+dependencies = [
+ "windows-targets",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.42.0"
diff --git a/Cargo.toml b/Cargo.toml
index 330aaa8..5956b28 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,6 +10,7 @@ tokio = { version = "1.32.0", features = ["full"] }
 # Serde / json
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1"
+serde_with = "3"
 # Axum
 axum = { version = "0.6.20" }
 tower-http = { version = "0.4.4", features = ["fs"] }
diff --git a/src/error.rs b/src/error.rs
index 8452bab..e414b15 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -1,9 +1,11 @@
 use axum::http::StatusCode;
 use axum::response::{IntoResponse, Response};
+use serde::Serialize;
 
 pub type Result<T> = core::result::Result<T, Error>;
 
-#[derive(Clone, Debug, strum_macros::AsRefStr)]
+#[derive(Clone, Debug, Serialize, strum_macros::AsRefStr)]
+#[serde(tag = "type", content = "data")]
 pub enum Error {
     LoginFail,
 
diff --git a/src/log.rs b/src/log.rs
new file mode 100644
index 0000000..eef3b00
--- /dev/null
+++ b/src/log.rs
@@ -0,0 +1,65 @@
+use std::time::SystemTime;
+
+use crate::{Error, Result};
+use crate::ctx::Ctx;
+use crate::error::ClientError;
+use axum::http::{Method, Uri};
+use serde::Serialize;
+use serde_json::{json, Value};
+use serde_with::skip_serializing_none;
+use uuid::Uuid;
+
+pub async fn log_request(
+    uuid: Uuid,
+    req_method: Method,
+    uri: Uri,
+    ctx: Option<Ctx>,
+    service_error: Option<&Error>,
+    client_error: Option<ClientError>,
+    ) -> Result<()> {
+    let timestamp = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_millis();
+
+    let error_type = service_error.map(|se| se.as_ref().to_string());
+    let error_data = serde_json::to_value(service_error).ok().and_then(|mut v| v.get_mut("data").map(|v| v.take()));
+
+    // Create the RequestLogLine.
+    let log_line = RequestLogLine {
+        uuid: uuid.to_string(),
+        timestamp: timestamp.to_string(),
+
+        req_path: uri.path().to_string(),
+        req_method: req_method.to_string(),
+
+        user_id: ctx.map(|ctx| ctx.user_id()),
+
+        client_error_type: client_error.map(|e| e.as_ref().to_string()),
+
+        error_type,
+        error_data,
+    };
+
+    println!("    ->> log request: \n{}", json!(log_line));
+
+    // TODO: Send to cloud-watch or something.
+
+    Ok(())
+}
+
+#[skip_serializing_none]
+#[derive(Serialize)]
+struct RequestLogLine {
+    uuid: String,      // uuid string formatted
+    timestamp: String, // (should be iso8601)
+
+    // -- User and context attributes.
+    user_id: Option<u64>,
+
+    // -- http request attributes.
+    req_path: String,
+    req_method: String,
+
+    // -- Errors attributes.
+    client_error_type: Option<String>,
+    error_type: Option<String>,
+    error_data: Option<Value>,
+}
diff --git a/src/main.rs b/src/main.rs
index b8eb052..5f1c582 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -3,6 +3,8 @@
 use crate::model::ModelController;
 
 pub use self::error::{Error, Result};
+use self::ctx::Ctx;
+use self::log::log_request;
 
 use std::net::SocketAddr;
 
@@ -20,6 +22,7 @@ use uuid::Uuid;
 
 mod ctx;
 mod error;
+mod log;
 mod web;
 mod model;
 
@@ -57,7 +60,7 @@ async fn main() -> Result<()>{
 /// Map the response to add headers, etc.
 ///
 /// * `res`: the response to map
-async fn main_response_mapper(res: Response) -> Response {
+async fn main_response_mapper(ctx: Option<Ctx>, uri: Uri, req_method: Method,  res: Response) -> Response {
     println!("->> {:<12} - main_response_mapper", "RES_MAPPER");
     let uuid = Uuid::new_v4();
 
@@ -82,8 +85,9 @@ async fn main_response_mapper(res: Response) -> Response {
             (*status_code, Json(client_error_body)).into_response()
         });
 
-    // -- TODO: Build and log the server log line.
-    println!("    ->> server log line - {uuid} - Error: {service_error:?}");
+    // -- Build and log the server log line.
+    let client_error = client_status_error.unzip().1;
+    log_request(uuid, req_method, uri, ctx, service_error, client_error).await;
 
     println!();
     error_response.unwrap_or(res)