Get basic nginx and acme setup working

This should enable DNS-01 acme for all khs openstack servers,
thus removing the pain of setting up acme for those servers.

Do note that this might not really be needed that much anymore,
as I should be able to hit them over IPv6, but for ease of mind,
this will enable ACME trivially, also for non https workloads, as well
as servers without open ports.

Do note that currently there's a global unifi firewall rule in place to
allow port 80 and 443 to my own servers over ipv6, I'd like to remove this
and have Nix configure firewall rules for each server individually, as
requested in the setup.

rust/program/openbao-helper/src/main.rs

@@ -232,13 +232,22 @@ unsafe fn execvpe<SA: AsRef<CStr>, SEK: AsRef<OsStr>, SEV: AsRef<OsStr>>(
     args: &[SA],
     environ: &[(SEK, SEV)],
 ) -> anyhow::Result<Infallible> {
-    let environ: Vec<_> = environ
+    let environ = environ
         .iter()
         .map(|(k, v)| {
-            CString::new(Format!("{k}={v}"))
-                .with_context(|| format!("Environment variable {k} contains null bytes"))?
+            CString::new(format!(
+                "{k}={v}",
+                k = k.as_ref().display(),
+                v = v.as_ref().display()
+            ))
+            .with_context(|| {
+                format!(
+                    "Environment variable {k} contains null bytes",
+                    k = k.as_ref().display()
+                )
+            })
         })
-        .collect();
+        .collect::<anyhow::Result<Vec<CString>>>()?;
     Ok(nix::unistd::execvpe(filename, args, &environ)?)
 }