Config versioning

Closes #14

client/src/command/init.rs

@@ -33,7 +33,7 @@ pub async fn run(opts: Opts) -> Result<()> {
     let path = opts.config;
     let data: ConfigData = sub.clone().into();
 
-    let config = Config::new(path, data)?;
+    let config = Config::new(path, data.into())?;
     config.save()?;
 
     eprintln!("Updated nixcache config.");

client/src/config.rs

@@ -22,15 +22,15 @@ pub struct Config {
     pub path: PathBuf,
 }
 impl Config {
-    pub fn new(path: Option<PathBuf>, data: ConfigData) -> Result<Self> {
+    pub fn new(path: Option<PathBuf>, data: ConfigDataVersioned) -> Result<Self> {
         let path = match path {
             Some(path) => path,
             None => get_config_path()?,
         };
 
         Ok(Self {
             path,
-            data,
+            data: data.into(),
         })
     }
 
@@ -44,18 +44,19 @@ impl Config {
         if path.exists() {
             let contents = fs::read(&path)?;
             let s = std::str::from_utf8(&contents)?;
-            let data: ConfigData = toml::from_str(s)?;
+            let data: ConfigDataVersioned = toml::from_str(s)?;
             return Ok(Config {
                 path,
-                data,
+                data: data.into(),
             });
         }
 
         Err(anyhow!("No config found at '{}'.", path.to_string_lossy()))
     }
     /// Saves the configuration back to the system, if possible.
     pub fn save(&self) -> Result<()> {
-        let serialized = toml::to_string(&self.data)?;
+        let config: ConfigDataVersioned = self.data.clone().into();
+        let serialized = toml::to_string(&config)?;
 
         // This isn't atomic, so some other process might chmod it
         // to something else before we write. We don't handle this case.
@@ -78,6 +79,25 @@ impl Config {
     }
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(tag = "version")]
+pub enum ConfigDataVersioned {
+    #[serde(rename = "v1")]
+    V1(ConfigData),
+}
+impl Into<ConfigData> for ConfigDataVersioned {
+    fn into(self) -> ConfigData {
+        match self {
+            ConfigDataVersioned::V1(config) => config,
+        }
+    }
+}
+impl From<ConfigData> for ConfigDataVersioned {
+    fn from(config: ConfigData) -> Self {
+        ConfigDataVersioned::V1(config)
+    }
+}
+
 /// Client configuration.
 #[derive(Debug, Clone, Serialize, Deserialize, Default)]
 pub struct ConfigData {

package.nix

@@ -12,6 +12,8 @@
 let
 demo-url = "127.0.0.1:8080";
 demo-config-server = writeText "config.toml" ''
+version = "v1"
+
 listen = "${demo-url}"
 
 signing_key = "demo.nixcache-0:vjg4zb3o8U3SapIoeG5dWZ9+G4OyqA96J2+nxuoMPCT3a7/zXWgXpuKr+rJWChlyTGeCV2aARebK+ffmh+u2fw=="
@@ -21,6 +23,8 @@ type = "local"
 path = "/tmp/_demo_nixcache"
 '';
 demo-config-client = writeText "config.toml" ''
+version = "v1"
+
 [server]
 endpoint = "http://${demo-url}"
 '';

server/src/config.rs

@@ -27,9 +27,11 @@ pub struct Config {
     /// Signing keypair.
     pub keypair: Keypair,
 }
-impl TryFrom<ConfigInfo> for Config {
+impl TryFrom<ConfigInfoVersioned> for Config {
     type Error = anyhow::Error;
-    fn try_from(config: ConfigInfo) -> Result<Self> {
+    fn try_from(versioned: ConfigInfoVersioned) -> Result<Self> {
+        let config: ConfigInfo = versioned.into();
+
         let token_hs256_secret = config.token_hs256_secret
             .map(|x| decode_token_hs256_secret_base64(&x)).transpose()?;
 
@@ -54,13 +56,27 @@ pub async fn load(path: Option<PathBuf>) -> Result<Config> {
 
     if path.is_file() {
         let data = read_to_string(path)?;
-        let config: ConfigInfo = toml::from_str(&data)?;
+        let config: ConfigInfoVersioned = toml::from_str(&data)?;
         config.try_into()
     } else {
         Err(anyhow!("No config found."))
     }
 }
 
+#[derive(Debug, Clone, Deserialize)]
+#[serde(tag = "version")]
+pub enum ConfigInfoVersioned {
+    #[serde(rename = "v1")]
+    V1(ConfigInfo),
+}
+impl Into<ConfigInfo> for ConfigInfoVersioned {
+    fn into(self) -> ConfigInfo {
+        match self {
+            ConfigInfoVersioned::V1(config) => config,
+        }
+    }
+}
+
 #[derive(Debug, Clone, Deserialize)]
 #[serde(deny_unknown_fields)]
 pub struct ConfigInfo {