Add register notification webhook (#764)

I find it super motivating when people use my stuff, so this makes it
_even easier_ to know when someone new signs up!

Cargo.lock

@@ -169,6 +169,7 @@ dependencies = [
  "fs-err",
  "http",
  "rand",
+ "reqwest",
  "serde",
  "serde_json",
  "sodiumoxide",

atuin-server/Cargo.toml

@@ -35,3 +35,7 @@ fs-err = "2.9"
 chronoutil = "0.2.3"
 tower = "0.4"
 tower-http = { version = "0.3", features = ["trace"] }
+reqwest = { version = "0.11", features = [
+  "json",
+  "rustls-tls-native-roots",
+], default-features = false }

atuin-server/src/handlers/user.rs

@@ -1,4 +1,6 @@
 use std::borrow::Borrow;
+use std::collections::HashMap;
+use std::time::Duration;
 
 use axum::{
     extract::{Path, State},
@@ -6,7 +8,7 @@ use axum::{
 };
 use http::StatusCode;
 use sodiumoxide::crypto::pwhash::argon2id13;
-use tracing::{debug, error, instrument};
+use tracing::{debug, error, info, instrument};
 use uuid::Uuid;
 
 use super::{ErrorResponse, ErrorResponseStatus, RespExt};
@@ -16,6 +18,8 @@ use crate::{
     router::AppState,
 };
 
+use reqwest::header::CONTENT_TYPE;
+
 use atuin_common::api::*;
 
 pub fn verify_str(secret: &str, verify: &str) -> bool {
@@ -32,6 +36,30 @@ pub fn verify_str(secret: &str, verify: &str) -> bool {
     }
 }
 
+// Try to send a Discord webhook once - if it fails, we don't retry. "At most once", and best effort.
+// Don't return the status because if this fails, we don't really care.
+async fn send_register_hook(url: &str, username: String, registered: String) {
+    let hook = HashMap::from([
+        ("username", username),
+        ("content", format!("{registered} has just signed up!")),
+    ]);
+
+    let client = reqwest::Client::new();
+
+    let resp = client
+        .post(url)
+        .timeout(Duration::new(5, 0))
+        .header(CONTENT_TYPE, "application/json")
+        .json(&hook)
+        .send()
+        .await;
+
+    match resp {
+        Ok(_) => info!("register webhook sent ok!"),
+        Err(e) => error!("failed to send register webhook: {}", e),
+    }
+}
+
 #[instrument(skip_all, fields(user.username = username.as_str()))]
 pub async fn get<DB: Database>(
     Path(username): Path<String>,
@@ -71,8 +99,8 @@ pub async fn register<DB: Database>(
     let hashed = hash_secret(&register.password);
 
     let new_user = NewUser {
-        email: register.email,
+        email: register.email.clone(),
-        username: register.username,
+        username: register.username.clone(),
         password: hashed,
     };
 
@@ -94,6 +122,16 @@ pub async fn register<DB: Database>(
         token: (&token).into(),
     };
 
+    if let Some(url) = &state.settings.register_webhook_url {
+        // Could probs be run on another thread, but it's ok atm
+        send_register_hook(
+            url,
+            state.settings.register_webhook_username.clone(),
+            register.username,
+        )
+        .await;
+    }
+
     match db.add_session(&new_session).await {
         Ok(_) => Ok(Json(RegisterResponse { session: token })),
         Err(e) => {

atuin-server/src/settings.rs

@@ -15,6 +15,8 @@ pub struct Settings {
     pub db_uri: String,
     pub open_registration: bool,
     pub max_history_length: usize,
+    pub register_webhook_url: Option<String>,
+    pub register_webhook_username: String,
 }
 
 impl Settings {
@@ -37,6 +39,7 @@ impl Settings {
             .set_default("open_registration", false)?
             .set_default("max_history_length", 8192)?
             .set_default("path", "")?
+            .set_default("register_webhook_username", "")?
             .add_source(
                 Environment::with_prefix("atuin")
                     .prefix_separator("_")