knot: put runtime paths outside the nix store

Otherwise knot tries to write to non-writable directories.
This for example breaks dnssec signing.
While it's possible to overwrite these path in the configuration,
having a sane defaults is nicer.

pkgs/servers/dns/knot-dns/default.nix

@@ -1,5 +1,6 @@
 { stdenv, fetchurl, pkgconfig, gnutls, liburcu, lmdb, libcap_ng, libidn2, libunistring
 , systemd, nettle, libedit, zlib, libiconv, libintl
+, autoreconfHook
 }:
 
 let inherit (stdenv.lib) optional optionals; in
@@ -16,7 +17,19 @@ stdenv.mkDerivation rec {
 
   outputs = [ "bin" "out" "dev" ];
 
-  nativeBuildInputs = [ pkgconfig ];
+  configureFlags = [
+    "--with-configdir=/etc/knot"
+    "--with-rundir=/run/knot"
+    "--with-storage=/var/lib/knot"
+  ];
+
+  patches = [
+    # Don't try to create directories like /var/lib/knot at build time.
+    # They are later created from NixOS itself.
+    ./dont-create-run-time-dirs.patch
+  ];
+
+  nativeBuildInputs = [ pkgconfig autoreconfHook ];
   buildInputs = [
     gnutls liburcu libidn2 libunistring
     nettle libedit
@@ -33,7 +46,9 @@ stdenv.mkDerivation rec {
   doCheck = true;
   doInstallCheck = false; # needs pykeymgr?
 
-  postInstall = ''rm -r "$out"/var "$out"/lib/*.la'';
+  postInstall = ''
+    rm -r "$out"/lib/*.la
+  '';
 
   meta = with stdenv.lib; {
     description = "Authoritative-only DNS server from .cz domain registry";

pkgs/servers/dns/knot-dns/dont-create-run-time-dirs.patch

@@ -0,0 +1,32 @@
+diff --git a/samples/Makefile.am b/samples/Makefile.am
+index c253c91..107401d 100644
+--- a/samples/Makefile.am
++++ b/samples/Makefile.am
+@@ -19,11 +19,6 @@ EXTRA_DIST = knot.sample.conf.in example.com.zone
+ 
+ if HAVE_DAEMON
+ 
+-install-data-local: knot.sample.conf
+-	if [ \! -f $(DESTDIR)/$(config_dir)/knot.sample.conf ]; then \
+-	  $(INSTALL) -d $(DESTDIR)/$(config_dir); \
+-	  $(INSTALL_DATA) knot.sample.conf $(srcdir)/example.com.zone $(DESTDIR)/$(config_dir); \
+-	fi
+ uninstall-local:
+ 	-rm -rf $(DESTDIR)/$(config_dir)/knot.sample.conf \
+ 	        $(DESTDIR)/$(config_dir)/example.com.zone
+diff --git a/src/utils/Makefile.inc b/src/utils/Makefile.inc
+index e6765d9..d859d23 100644
+--- a/src/utils/Makefile.inc
++++ b/src/utils/Makefile.inc
+@@ -79,11 +79,6 @@ endif HAVE_DNSTAP
+ endif HAVE_UTILS
+ 
+ if HAVE_DAEMON
+-# Create storage and run-time directories
+-install-data-hook:
+-	$(INSTALL) -d $(DESTDIR)/@config_dir@
+-	$(INSTALL) -d $(DESTDIR)/@run_dir@
+-	$(INSTALL) -d $(DESTDIR)/@storage_dir@
+ 
+ sbin_PROGRAMS = knotc knotd
+