auto-installer: add fetch answer binary

it is supposed to be run first and fetch an answer file.

The initial implementation searches for a partition/filesystem called
'proxmoxinst' or 'PROXMOXINST' with an 'answer.toml' file in the root
directory.

Once it has an answer file, it will call the 'proxmox-auto-installer'
and pipe in the contents via stdin.

Tested-by: Christoph Heiss <c.heiss@proxmox.com>
Reviewed-by: Christoph Heiss <c.heiss@proxmox.com>
Signed-off-by: Aaron Lauterer <a.lauterer@proxmox.com>
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

Makefile

@@ -20,6 +20,7 @@ PREFIX = /usr
 BINDIR = $(PREFIX)/bin
 USR_BIN := \
 	   proxmox-tui-installer\
+	   proxmox-fetch-answer\
 	   proxmox-auto-installer
 
 COMPILED_BINS := \
@@ -121,7 +122,8 @@ $(COMPILED_BINS): cargo-build
 .PHONY: cargo-build
 cargo-build:
 	$(CARGO) build --package proxmox-tui-installer --bin proxmox-tui-installer \
-		--package proxmox-auto-installer --bin proxmox-auto-installer $(CARGO_BUILD_ARGS)
+		--package proxmox-auto-installer --bin proxmox-auto-installer \
+		--bin proxmox-fetch-answer $(CARGO_BUILD_ARGS)
 
 %-banner.png: %-banner.svg
 	rsvg-convert -o $@ $<

proxmox-auto-installer/src/bin/proxmox-fetch-answer.rs

@@ -0,0 +1,71 @@
+use anyhow::{anyhow, Error, Result};
+use log::{error, info, LevelFilter};
+use proxmox_auto_installer::{fetch_plugins::partition::FetchFromPartition, log::AutoInstLogger};
+use std::io::Write;
+use std::process::{Command, ExitCode, Stdio};
+
+static LOGGER: AutoInstLogger = AutoInstLogger;
+
+pub fn init_log() -> Result<()> {
+    AutoInstLogger::init("/tmp/fetch_answer.log")?;
+    log::set_logger(&LOGGER)
+        .map(|()| log::set_max_level(LevelFilter::Info))
+        .map_err(|err| anyhow!(err))
+}
+
+fn fetch_answer() -> Result<String> {
+    match FetchFromPartition::get_answer() {
+        Ok(answer) => return Ok(answer),
+        Err(err) => info!("Fetching answer file from partition failed: {err}"),
+    }
+    // TODO: add more options to get an answer file, e.g. download from url where url could be
+    // fetched via txt records on predefined subdomain, kernel param, dhcp option, ...
+
+    Err(Error::msg("Could not find any answer file!"))
+}
+
+fn main() -> ExitCode {
+    if let Err(err) = init_log() {
+        panic!("could not initialize logging: {err}");
+    }
+
+    info!("Fetching answer file");
+    let answer = match fetch_answer() {
+        Ok(answer) => answer,
+        Err(err) => {
+            error!("Aborting: {}", err);
+            return ExitCode::FAILURE;
+        }
+    };
+
+    let mut child = match Command::new("proxmox-auto-installer")
+        .stdout(Stdio::inherit())
+        .stdin(Stdio::piped())
+        .stderr(Stdio::null())
+        .spawn()
+    {
+        Ok(child) => child,
+        Err(err) => panic!("Failed to start automatic installation: {err}"),
+    };
+
+    let mut stdin = child.stdin.take().expect("Failed to open stdin");
+    std::thread::spawn(move || {
+        stdin
+            .write_all(answer.as_bytes())
+            .expect("Failed to write to stdin");
+    });
+
+    match child.wait() {
+        Ok(status) => {
+            if status.success() {
+                ExitCode::SUCCESS
+            } else {
+                ExitCode::FAILURE // Will be trapped
+            }
+        }
+        Err(err) => {
+            error!("Auto installer exited: {err}");
+            ExitCode::FAILURE
+        }
+    }
+}

proxmox-auto-installer/src/fetch_plugins/mod.rs

@@ -0,0 +1,2 @@
+pub mod partition;
+mod utils;

proxmox-auto-installer/src/fetch_plugins/partition.rs

@@ -0,0 +1,32 @@
+use anyhow::{Error, Result};
+use std::{fs::read_to_string, path::Path};
+use log::info;
+
+use crate::fetch_plugins::utils::mount_proxmoxinst_part;
+
+static ANSWER_FILE: &str = "answer.toml";
+
+pub struct FetchFromPartition;
+
+impl FetchFromPartition {
+    /// Returns the contents of the answer file
+    pub fn get_answer() -> Result<String> {
+        info!("Checking for answer file on partition.");
+        let mount_path = mount_proxmoxinst_part()?;
+        let answer = Self::get_answer_file(&mount_path)?;
+        info!("Found answer file on partition.");
+        Ok(answer)
+    }
+
+    /// Searches for answer file and returns contents if found
+    fn get_answer_file(mount_path: &str) -> Result<String> {
+        let answer_path = Path::new(mount_path).join(ANSWER_FILE);
+        match answer_path.try_exists() {
+            Ok(true) => Ok(read_to_string(answer_path)?),
+            _ => Err(Error::msg(format!(
+                "could not find answer file expected at: {}",
+                answer_path.display()
+            ))),
+        }
+    }
+}

proxmox-auto-installer/src/fetch_plugins/utils.rs

@@ -0,0 +1,81 @@
+use anyhow::{bail, Error, Result};
+use log::{info, warn};
+use std::{
+    fs::{self, create_dir_all},
+    path::{Path, PathBuf},
+    process::Command,
+};
+
+static ANSWER_MP: &str = "/mnt/answer";
+static PARTLABEL: &str = "proxmoxinst";
+static SEARCH_PATH: &str = "/dev/disk/by-label";
+
+/// Searches for upper and lower case existence of the partlabel in the search_path
+///
+/// # Arguemnts
+/// * `partlabel_source` - Partition Label, used as upper and lower case
+/// * `search_path` - Path where to search for the partiiton label
+pub fn scan_partlabels(partlabel_source: &str, search_path: &str) -> Result<PathBuf> {
+    let partlabel = partlabel_source.to_uppercase();
+    let path = Path::new(search_path).join(&partlabel);
+    match path.try_exists() {
+        Ok(true) => {
+            info!("Found partition with label '{partlabel}'");
+            return Ok(path);
+        }
+        Ok(false) => info!("Did not detect partition with label '{partlabel}'"),
+        Err(err) => info!("Encountered issue, accessing '{}': {}", path.display(), err),
+    }
+
+    let partlabel = partlabel_source.to_lowercase();
+    let path = Path::new(search_path).join(&partlabel);
+    match path.try_exists() {
+        Ok(true) => {
+            info!("Found partition with label '{partlabel}'");
+            return Ok(path);
+        }
+        Ok(false) => info!("Did not detect partition with label '{partlabel}'"),
+        Err(err) => info!("Encountered issue, accessing '{}': {}", path.display(), err),
+    }
+    bail!("Could not detect upper or lower case labels for '{partlabel_source}'");
+}
+
+/// Will search and mount a partition/FS labeled proxmoxinst in lower or uppercase to ANSWER_MP;
+pub fn mount_proxmoxinst_part() -> Result<String> {
+    if let Ok(true) = check_if_mounted(ANSWER_MP) {
+        info!("Skipping: '{ANSWER_MP}' is already mounted.");
+        return Ok(ANSWER_MP.into());
+    }
+    let part_path = scan_partlabels(PARTLABEL, SEARCH_PATH)?;
+    info!("Mounting partition at {ANSWER_MP}");
+    // create dir for mountpoint
+    create_dir_all(ANSWER_MP)?;
+    match Command::new("mount")
+        .args(["-o", "ro"])
+        .arg(part_path)
+        .arg(ANSWER_MP)
+        .output()
+    {
+        Ok(output) => {
+            if output.status.success() {
+                Ok(ANSWER_MP.into())
+            } else {
+                warn!("Error mounting: {}", String::from_utf8(output.stderr)?);
+                Ok(ANSWER_MP.into())
+            }
+        }
+        Err(err) => Err(Error::msg(format!("Error mounting: {err}"))),
+    }
+}
+
+fn check_if_mounted(target_path: &str) -> Result<bool> {
+    let mounts = fs::read_to_string("/proc/mounts")?;
+    for line in mounts.lines() {
+        if let Some(mp) = line.split(' ').nth(1) {
+            if mp == target_path {
+                return Ok(true);
+            }
+        }
+    }
+    Ok(false)
+}

proxmox-auto-installer/src/lib.rs

@@ -1,4 +1,5 @@
 pub mod answer;
+pub mod fetch_plugins;
 pub mod log;
 pub mod udevinfo;
 pub mod utils;