Allow options to be set from environment variables

src/main.rs

@@ -18,30 +18,36 @@ mod output;
 #[clap(version, author, about)]
 struct Opts {
     /// Home Assistant host
-    #[clap(short, long)]
+    #[clap(short, long, env = "HNP_HOST")]
     host: String,
 
     /// Media player entity ID
-    #[clap(short, long)]
+    #[clap(short, long, env = "HNP_ENTITY")]
     entity: String,
 
     /// API token
-    #[clap(short, long, env)]
+    #[clap(short, long, env = "HNP_TOKEN")]
     token: Option<String>,
 
     /// File with the API token
-    #[clap(long, env)]
+    #[clap(long, env, env = "HNP_TOKEN_FILE")]
     token_file: Option<PathBuf>,
 
     /// Use HTTP instead of HTTPS
-    #[clap(short, long)]
+    #[clap(short, long, env = "HNP_INSECURE")]
     insecure: bool,
 
     /// Output format
-    #[clap(arg_enum, short, long, default_value = "waybar")]
+    #[clap(
+        arg_enum,
+        short,
+        long,
+        env = "HNP_OUTPUT_FORMAT",
+        default_value = "waybar"
+    )]
     format: output::OutputFormat,
 
-    #[clap(short, long)]
+    #[clap(short, long, env = "HNP_DEBUG")]
     debug: bool,
 
     #[clap(subcommand)]