Containers step: new runtime option to configuration (#896)

* pyenv: fixes #849

* feat: adds `uv` python manager step

* moved new uv step from unix to generic

* containers step: added container runtime option to config

* documented breaking change

---------

Co-authored-by: Lucas Parzianello <lucaspar@users.noreply.github.com>

src/config.rs

@@ -5,7 +5,7 @@ use std::fs::{write, File};
 use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::Command;
-use std::{env, fs};
+use std::{env, fmt, fs};
 
 use clap::{Parser, ValueEnum};
 use clap_complete::Shell;
@@ -181,6 +181,7 @@ pub struct Include {
 pub struct Containers {
     #[merge(strategy = crate::utils::merge_strategies::vec_prepend_opt)]
     ignored_containers: Option<Vec<String>>,
+    runtime: Option<ContainerRuntime>,
 }
 
 #[derive(Deserialize, Default, Debug, Merge)]
@@ -287,6 +288,22 @@ pub enum ArchPackageManager {
     Yay,
 }
 
+#[derive(Clone, Copy, Debug, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ContainerRuntime {
+    Docker,
+    Podman,
+}
+
+impl fmt::Display for ContainerRuntime {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            ContainerRuntime::Docker => write!(f, "docker"),
+            ContainerRuntime::Podman => write!(f, "podman"),
+        }
+    }
+}
+
 #[derive(Deserialize, Default, Debug, Merge)]
 #[serde(deny_unknown_fields)]
 pub struct Linux {
@@ -885,6 +902,16 @@ impl Config {
             .and_then(|containers| containers.ignored_containers.as_ref())
     }
 
+    /// The preferred runtime for container updates (podman / docker).
+    pub fn containers_runtime(&self) -> ContainerRuntime {
+        self.config_file
+            .containers
+            .as_ref()
+            .unwrap()
+            .runtime
+            .unwrap_or(ContainerRuntime::Docker) // defaults to a popular choice
+    }
+
     /// Tell whether the specified step should run.
     ///
     /// If the step appears either in the `--disable` command line argument