eris: allow various log formats

Supports plain, pretty, json and pretty-json

src/config.rs

@@ -85,6 +85,22 @@ pub struct Args {
         help = "Log level: trace, debug, info, warn, error"
     )]
     pub log_level: String,
+
+    #[clap(
+        long,
+        default_value = "pretty",
+        help = "Log format: plain, pretty, json, pretty-json"
+    )]
+    pub log_format: String,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, Default)]
+pub enum LogFormat {
+    Plain,
+    #[default]
+    Pretty,
+    Json,
+    PrettyJson,
 }
 
 // Trap pattern structure. It can be either a plain string
@@ -145,6 +161,7 @@ pub struct Config {
     pub data_dir: String,
     pub config_dir: String,
     pub cache_dir: String,
+    pub log_format: LogFormat,
 }
 
 impl Default for Config {
@@ -206,6 +223,7 @@ impl Default for Config {
             data_dir: "./data".to_string(),
             config_dir: "./conf".to_string(),
             cache_dir: "./cache".to_string(),
+            log_format: LogFormat::Pretty,
         }
     }
 }
@@ -406,6 +424,7 @@ mod tests {
             base_dir: Some(PathBuf::from("/tmp/eris")),
             config_file: None,
             log_level: "debug".to_string(),
+            log_format: "pretty".to_string(),
         };
 
         let config = Config::from_args(&args);