nixos/caddy: Fix default log file for http:// hostnames

Caddy hostnames can begin with http:// to disable automatic HTTPS.
The default value for services.caddy.<host>.logFormat puts the hostname
in the log filename, resulting in a broken path. Similarly, multiple
space-separated host names would not work before.

Since version 2.9.0 (commit 7c52e7a), caddy fails to start if it cannot
open the log file. This caused NixOS test failures (e.g.,
nixosTests.dokuwiki).

Author: lluchs

nixos/modules/services/web-servers/caddy/vhost-options.nix

@@ -58,7 +58,7 @@ in
     logFormat = mkOption {
       type = types.lines;
       default = ''
-        output file ${cfg.logDir}/access-${config.hostName}.log
+        output file ${cfg.logDir}/access-${lib.replaceStrings [ "/" " " ] [ "_" "_" ] config.hostName}.log
       '';
       defaultText = ''
         output file ''${config.services.caddy.logDir}/access-''${hostName}.log