From 3a2ad3d4f4147f683ac78acab88597433a1430a2 Mon Sep 17 00:00:00 2001
From: Jonni Liljamo <jonni@liljamo.com>
Date: Sun, 4 May 2025 13:19:09 +0300
Subject: [PATCH] feat: optionally read tokens from files

---
 README.md             |  8 ++++++++
 src/config.rs         | 20 ++++++++++++++++++++
 src/service/gotify.rs |  3 ++-
 src/service/matrix.rs |  3 ++-
 4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 5078032..00b46a5 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,14 @@ A small API for relaying the same message to multiple services.
 The following example creates a notifier that sends a message to Gotify and
 Matrix.
 
+### `token` fields
+All `token` fields (service and notifier configs) can also be a path to a
+file containing the token, e.g. `/run/secrets/canwa-matrix-token`
+
+canwa will check if the value is a path that exists and reads it if it is.
+If the value is not a path, or it is a path that cannot be read, it will be
+assumed a raw string token.
+
 ### Example `canwa.toml`
 ```toml
 interface = "0.0.0.0"
diff --git a/src/config.rs b/src/config.rs
index 865393f..0d57d35 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -32,8 +32,28 @@ pub trait ServiceConfig {
     fn as_any(&self) -> &dyn std::any::Any;
 }
 
+pub fn deserialize_token<'de, D>(deserializer: D) -> Result<String, D::Error>
+where
+    D: serde::Deserializer<'de>,
+{
+    let token_or_path: String = serde::de::Deserialize::deserialize(deserializer)?;
+    // If the value exists as a path and we can read it, read the file.
+    let path = std::path::Path::new(&token_or_path);
+    if path.exists() {
+        match std::fs::read_to_string(path) {
+            Ok(token) => return Ok(token.trim().into()),
+            Err(err) => {
+                tracing::warn!(msg="token exists as a filesystem path, but could not be read, assuming raw token", %err)
+            }
+        }
+    }
+    // Assume raw token.
+    Ok(token_or_path)
+}
+
 #[derive(Clone, Deserialize)]
 pub struct NotifierConfig {
+    #[serde(deserialize_with = "deserialize_token")]
     pub token: String,
     pub services: Vec<String>,
 }
diff --git a/src/service/gotify.rs b/src/service/gotify.rs
index fa44bfd..07fe2a7 100644
--- a/src/service/gotify.rs
+++ b/src/service/gotify.rs
@@ -8,13 +8,14 @@
 use async_trait::async_trait;
 use serde::{Deserialize, Serialize};
 
-use crate::config::ServiceConfig;
+use crate::config::{ServiceConfig, deserialize_token};
 
 use super::Service;
 
 #[derive(Clone, Deserialize, Serialize)]
 pub struct GotifyConfig {
     pub instance: String,
+    #[serde(deserialize_with = "deserialize_token")]
     pub token: String,
 }
 
diff --git a/src/service/matrix.rs b/src/service/matrix.rs
index 75c8059..d1d15d9 100644
--- a/src/service/matrix.rs
+++ b/src/service/matrix.rs
@@ -9,13 +9,14 @@ use async_trait::async_trait;
 use serde::{Deserialize, Serialize};
 use serde_json::json;
 
-use crate::config::ServiceConfig;
+use crate::config::{ServiceConfig, deserialize_token};
 
 use super::Service;
 
 #[derive(Clone, Deserialize, Serialize)]
 pub struct MatrixConfig {
     pub instance: String,
+    #[serde(deserialize_with = "deserialize_token")]
     pub token: String,
     pub room: String,
 }
-- 
2.44.1