Enable passwordless sudo for the user

Currently admin user is part of the sudoers
group, adding the user for passwordless sudo
from this issue Azure#69

Signed-off-by: Bala Konda Reddy M <bala12352@gmail.com>

libazureinit/src/user.rs

@@ -50,6 +50,18 @@ pub(crate) fn provision_ssh(
     Ok(())
 }
 
+pub fn add_user_for_passwordless_sudo(
+    username: &str,
+) -> Result<(), Error>{
+    let mut sudoers_file = std::fs::OpenOptions::new()
+        .append(true)
+        .create(true)
+        .open("/etc/sudoers")?;
+    write!(sudoers_file, "{} ALL=(ALL) NOPASSWD: ALL \n", username.to_string())?;
+    sudoers_file.flush()?;
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
 

src/main.rs

@@ -99,6 +99,12 @@ async fn provision() -> Result<(), anyhow::Error> {
         || format!("Unabled to set an empty password for user '{username}'"),
     )?;
 
+    // Add user for the passwordless sudo
+    user::add_user_for_passwordless_sudo(
+        username.as_str())
+        .with_context(|| format!(
+            "Unable to add user for the passwordless sudo '{username}'"))?;
+
     user::set_ssh_keys(instance_metadata.compute.public_keys, &username)
         .with_context(|| "Failed to write ssh public keys.")?;