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>

BREAKINGCHANGES_dev.md

@@ -0,0 +1,3 @@
+# Containers step
+
++ New default behavior: Docker is the runtime selected by default. This can be overridden by setting the `container.runtime` option in the configuration TOML to "podman".

config.example.toml

@@ -244,6 +244,8 @@
 [containers]
 # Specify the containers to ignore while updating (Wildcard supported)
 # ignored_containers = ["ghcr.io/rancher-sandbox/rancher-desktop/rdx-proxy:latest", "docker.io*"]
+# Specify the runtime to use for containers (default: "docker", allowed values: "docker", "podman")
+# runtime = "podman"
 
 [lensfun]
 # If disabled, Topgrade invokes `lensfun‑update‑data` without root priviledge, 

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

src/steps/containers.rs

@@ -120,8 +120,9 @@ fn list_containers(crt: &Path, ignored_containers: Option<&Vec<String>>) -> Resu
 }
 
 pub fn run_containers(ctx: &ExecutionContext) -> Result<()> {
-    // Prefer podman, fall back to docker if not present
-    let crt = require("podman").or_else(|_| require("docker"))?;
+    // Check what runtime is specified in the config
+    let container_runtime = ctx.config().containers_runtime().to_string();
+    let crt = require(container_runtime)?;
     debug!("Using container runtime '{}'", crt.display());
 
     print_separator("Containers");