allow loading headers from files

src/config.rs

@@ -1,8 +1,12 @@
 use color_eyre::{eyre::WrapErr, Result};
-use serde::Deserialize;
+use serde::{Deserialize, Deserializer};
 use std::fs::read_to_string;
 use tokio::time::Duration;
 use std::collections::HashMap;
+use std::convert::{TryFrom, TryInto};
+use std::path::Path;
+use reqwest::header::{HeaderValue, InvalidHeaderValue};
+use serde::de::Error;
 use serde_json::Value;
 
 #[derive(Debug, Deserialize)]
@@ -16,7 +20,7 @@ pub struct FeedConfig {
     pub feed: String,
     pub hook: String,
     #[serde(default)]
-    pub headers: HashMap<String, String>,
+    pub headers: HashMap<String, HeaderVal>,
     #[serde(default)]
     pub body: Value,
 }
@@ -32,3 +36,32 @@ impl Config {
         Duration::from_secs(self.interval.unwrap_or(30 * 60))
     }
 }
+
+#[derive(Debug)]
+pub struct HeaderVal(String);
+
+impl<'de> Deserialize<'de> for HeaderVal {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de> {
+        let raw = String::deserialize(deserializer)?;
+        let str = load_secret(raw).map_err(|e| D::Error::custom(e))?;
+        Ok(HeaderVal(str))
+    }
+}
+
+impl TryFrom<&HeaderVal> for HeaderValue {
+    type Error = InvalidHeaderValue;
+
+    fn try_from(header: &HeaderVal) -> std::result::Result<Self, Self::Error> {
+        header.0.as_str().try_into()
+    }
+}
+
+fn load_secret(raw: String) -> Result<String, std::io::Error> {
+    let path: &Path = raw.as_ref();
+    if raw.starts_with("/") && path.exists() {
+        let raw = read_to_string(raw)?;
+        Ok(raw.trim().into())
+    } else {
+        Ok(raw)
+    }
+}