add proxmox-backup-banner binary crate

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>

proxmox-backup-banner/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "proxmox-backup-banner"
+version = "0.1.0"
+authors = ["Proxmox Support Team <support@proxmox.com>"]
+edition = "2018"
+
+[dependencies]
+proxmox = { version = "0.11.5", default-features = false, features = [] }

proxmox-backup-banner/src/main.rs

@@ -0,0 +1,49 @@
+use std::fmt::Write;
+use std::fs;
+use std::net::ToSocketAddrs;
+
+use proxmox::tools;
+
+fn main() {
+    let nodename = tools::nodename();
+    let addr = format!("{}:8007", nodename);
+
+    let mut banner = format!(
+        "
+{:-<78}
+
+Welcome to the Proxmox Backup Server. Please use your web browser to
+configure this server - connect to:
+
+",
+        ""
+    );
+
+    let msg = match addr.to_socket_addrs() {
+        Ok(saddrs) => {
+            let saddrs: Vec<_> = saddrs
+                .filter_map(|s| match !s.ip().is_loopback() {
+                    true => Some(format!(" https://{}/", s)),
+                    false => None,
+                })
+                .collect();
+
+            if !saddrs.is_empty() {
+                saddrs.join("\n")
+            } else {
+                format!(
+                    "hostname '{}' does not resolves to any non-loopback address",
+                    nodename
+                )
+            }
+        }
+        Err(e) => format!("could not resolve hostname '{}': {}", nodename, e),
+    };
+    banner += &msg;
+
+    // unwrap will never fail for write!:
+    // https://github.com/rust-lang/rust/blob/1.39.0/src/liballoc/string.rs#L2318-L2331
+    write!(&mut banner, "\n\n{:-<78}\n\n", "").unwrap();
+
+    fs::write("/etc/issue", banner.as_bytes()).expect("Unable to write banner to issue file");
+}