reinstall: Ensure podman is installed

Fixes #1104

Make podman dependency of system-reinstall-bootc optional

* Change the spec file to recommend podman instead of requiring it (this
  will make it more palatable to have this package included in distros
  by default)

* Now that it's only recommended, the system-reinstall-bootc binary must
  check whether podman is installed and prompt the user to install it if
  it's not. For now only dnf is supported.

Signed-off-by: Omer Tuchfeld <[email protected]>

Author: omertuc

contrib/packaging/bootc.spec

@@ -50,7 +50,7 @@ Requires: composefs
 # For OS updates
 Requires: ostree
 Requires: skopeo
-Requires: podman
+Recommends: podman
 # For bootloader updates
 Recommends: bootupd
 

system-reinstall-bootc/src/main.rs

@@ -18,6 +18,8 @@ fn run() -> Result<()> {
     // Rootless podman is not supported by bootc
     ensure!(getuid().is_root(), "Must run as the root user");
 
+    podman::ensure_podman_installed()?;
+
     let config = config::ReinstallConfig::load().context("loading config")?;
 
     let mut reinstall_podman_command =

system-reinstall-bootc/src/podman.rs

@@ -1,7 +1,8 @@
-use std::process::Command;
-
 use super::ROOT_KEY_MOUNT_POINT;
-use crate::users::UserKeys;
+use crate::{prompt, users::UserKeys};
+use anyhow::{ensure, Context, Result};
+use bootc_utils::CommandRunExt;
+use std::process::Command;
 
 pub(crate) fn command(image: &str, root_key: &Option<UserKeys>) -> Command {
     let mut podman_command_and_args = [
@@ -58,3 +59,42 @@ pub(crate) fn command(image: &str, root_key: &Option<UserKeys>) -> Command {
 
     command
 }
+
+pub(crate) fn ensure_podman_installed() -> Result<()> {
+    if Command::new("podman").arg("--version").can_execute() {
+        return Ok(());
+    }
+
+    tracing::warn!("Podman was not found on this system. It's required to install a bootc image.");
+
+    ensure!(
+        Command::new("dnf").arg("--version").can_execute(),
+        "Please install podman and try again."
+    );
+
+    let mut dnf_install_command = Command::new("dnf");
+    dnf_install_command
+        .arg("install")
+        // TODO: Is this a bad idea? It answers yes to EVERYTHING. Maybe we should let the
+        // user interact with dnf manually instead... I wish dnf gave us more granular
+        // control over what we can automatically answer yes to.
+        .arg("-y")
+        .arg("podman");
+
+    if prompt::ask_yes_no(
+        format!("Would you like to install podman using dnf? ({dnf_install_command:?})").as_str(),
+        false,
+    )? {
+        dnf_install_command
+            .run_with_cmd_context()
+            .context("installing podman")?;
+
+        // Make sure the installation was actually successful
+        ensure!(
+            Command::new("podman").arg("--version").can_execute(),
+            "podman still doesn't seem to be available, despite the installation. Please install it manually and try again."
+        );
+    }
+
+    Ok(())
+}

utils/src/command.rs

@@ -33,6 +33,11 @@ pub trait CommandRunExt {
     /// Execute the child process, parsing its stdout as JSON. This uses `run` internally
     /// and will return an error if the child process exits abnormally.
     fn run_and_parse_json<T: serde::de::DeserializeOwned>(&mut self) -> Result<T>;
+
+    /// Check if the command can be executed by running it and ignoring its output. Returns `true`
+    /// if the command exists, `false` otherwise. The exit code is ignored. Only run this with
+    /// commands that have no undesired side effects, e.g. `dnf --version`.
+    fn can_execute(&mut self) -> bool;
 }
 
 /// Helpers intended for [`std::process::ExitStatus`].
@@ -146,6 +151,13 @@ impl CommandRunExt for Command {
             // representation that the user can copy paste into their shell
             .context("Failed to run command: {self:#?}")
     }
+
+    fn can_execute(&mut self) -> bool {
+        self.stdout(std::process::Stdio::null())
+            .stderr(std::process::Stdio::null())
+            .status()
+            .is_ok()
+    }
 }
 
 /// Helpers intended for [`tokio::process::Command`].