implement hash for config

src/domain/config.rs

@@ -4,8 +4,9 @@ use std::{fs, io};
 
 use crate::origin::Descr;
 
-use mockall::automock;
+use hex::ToHex;
 use serde::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
 
 #[derive(Debug, PartialEq, Eq, Serialize, Deserialize)]
 /// Values which the owner of a domain can configure when they install a domain.
@@ -13,6 +14,14 @@ pub struct Config {
     pub origin_descr: Descr,
 }
 
+impl Config {
+    pub fn hash(&self) -> Result<String, Box<dyn Error>> {
+        let mut h = Sha256::new();
+        serde_json::to_writer(&mut h, self)?;
+        Ok(h.finalize().encode_hex::<String>())
+    }
+}
+
 #[derive(thiserror::Error, Debug)]
 pub enum GetError {
     #[error("not found")]