apply: Default to the "boot" goal if --reboot is passed

Fixes #113.

manual/src/release-notes.md

@@ -12,6 +12,7 @@
 - The `--no-substitutes` option under the `apply` subcommand has been renamed to `--no-substitute` ([#59](https://github.com/zhaofengli/colmena/issues/59)).
 - The [`meta.nodeSpecialArgs`](./reference/meta.md#nodespecialargs) option has been added. It allows specifying node-specific `specialArgs` passed to NixOS modules ([#100](https://github.com/zhaofengli/colmena/pull/100)).
 - The [`repl`](./reference/cli.html#colmena-repl) subcommand has been added. It allows you to start an [interactive REPL](./features/eval.md#interactive-repl) with access to the complete node configurations.
+- The default goal for `colmena apply` is now `boot` if `--reboot` is specified, and `switch` otherwise ([#113](https://github.com/zhaofengli/colmena/issues/113)).
 
 ## [Release 0.3.1](https://github.com/zhaofengli/colmena/releases/tag/v0.3.1) (2022/08/18)
 

src/command/apply.rs

@@ -127,7 +127,18 @@ pub fn subcommand() -> ClapCommand<'static> {
         .about("Apply configurations on remote machines")
         .arg(Arg::new("goal")
             .help("Deployment goal")
-            .long_help("Same as the targets for switch-to-configuration.\n\"push\" means only copying the closures to remote nodes.")
+            .long_help(r#"The goal of the deployment.
+
+Same as the targets for switch-to-configuration, with the following extra pseudo-goals:
+
+- build: Only build the system profiles
+- push: Only copy the closures to remote nodes
+- keys: Only upload the keys to the remote nodes
+
+`switch` is the default goal unless `--reboot` is passed, in which case `boot` is the default.
+"#)
+            .default_value("switch")
+            .default_value_if("reboot", None, Some("boot"))
             .default_value("switch")
             .index(1)
             .possible_values(&["build", "push", "switch", "boot", "test", "dry-activate", "keys"]))