Use buildEnv to combine Hydra's Perl dependencies

This makes the Perl search path ($PERL5LIB) much shorter, cutting down
the number of stat() calls when starting hydra-server from ~432000 to
~9000.

deps.nix

@@ -1,41 +0,0 @@
-{ pkgs }:
-
-with pkgs;
-
-[ perlPackages.CatalystAuthenticationStoreDBIxClass
-  perlPackages.CatalystPluginAccessLog
-  perlPackages.CatalystPluginAuthorizationRoles
-  perlPackages.CatalystPluginCaptcha
-  perlPackages.CatalystPluginSessionStateCookie
-  perlPackages.CatalystPluginSessionStoreFastMmap
-  perlPackages.CatalystPluginStackTrace
-  perlPackages.CatalystViewDownload
-  perlPackages.CatalystViewJSON
-  perlPackages.CatalystViewTT
-  perlPackages.CatalystXScriptServerStarman
-  perlPackages.CatalystTraitForRequestProxyBase
-  perlPackages.CryptRandPasswd
-  perlPackages.DBDPg
-  perlPackages.DBDSQLite
-  perlPackages.DataDump
-  perlPackages.DateTime
-  perlPackages.DigestSHA1
-  perlPackages.EmailSender
-  perlPackages.FileSlurp
-  perlPackages.IOCompress
-  perlPackages.IPCRun
-  perlPackages.JSONXS
-  perlPackages.PadWalker
-  perlPackages.CatalystDevel
-  perlPackages.Readonly
-  perlPackages.SQLSplitStatement
-  perlPackages.Starman
-  perlPackages.Switch     # XXX: seems to be an indirect dep of `hydra-build'
-  perlPackages.SysHostnameLong
-  perlPackages.TestMore
-  perlPackages.TextDiff
-  perlPackages.TextTable
-  perlPackages.XMLSimple
-  nixUnstable
-  guile                                  # optional, for Guile + Guix support
-]

doc/dev-notes.txt

@@ -93,11 +93,6 @@
   delete from builds where finished = 0 and not exists (select 1 from buildschedulinginfo s where s.id = builds.id and busy = 1);
 
 
-* Installing deps.nix in a profile for testing:
-
-  $ nix-env -p $NIX_USER_PROFILE_DIR/hydra-deps -f deps.nix -i \* --arg pkgs 'import /etc/nixos/nixpkgs {}'
-  
-
 * select x.project, x.jobset, x.job, x.system, x.id, x.timestamp, r.buildstatus, b.id, b.timestamp
   from (select project, jobset, job, system, max(id) as id from Builds where finished = 1 group by project, jobset, job, system) as a_
   natural join Builds x

release.nix

@@ -47,7 +47,52 @@ rec {
 
     with pkgs;
 
-    let nix = nixUnstable; in
+    let
+
+      nix = nixUnstable;
+
+      perlDeps = buildEnv {
+        name = "hydra-perl-deps";
+        paths = with perlPackages;
+          [ CatalystAuthenticationStoreDBIxClass
+            CatalystPluginAccessLog
+            CatalystPluginAuthorizationRoles
+            CatalystPluginCaptcha
+            CatalystPluginSessionStateCookie
+            CatalystPluginSessionStoreFastMmap
+            CatalystPluginStackTrace
+            CatalystViewDownload
+            CatalystViewJSON
+            CatalystViewTT
+            CatalystXScriptServerStarman
+            CatalystTraitForRequestProxyBase
+            CryptRandPasswd
+            DBDPg
+            DBDSQLite
+            DataDump
+            DateTime
+            DigestSHA1
+            EmailSender
+            FileSlurp
+            IOCompress
+            IPCRun
+            JSONXS
+            PadWalker
+            CatalystDevel
+            Readonly
+            SQLSplitStatement
+            Starman
+            Switch # XXX: seems to be an indirect dep of `hydra-build'
+            SysHostnameLong
+            TestMore
+            TextDiff
+            TextTable
+            XMLSimple
+            nix git
+          ];
+      };
+
+    in
 
     releaseTools.nixBuild {
       name = "hydra";
@@ -55,9 +100,11 @@ rec {
       configureFlags = "--with-nix=${nix}";
 
       buildInputs =
-        [ perl makeWrapper libtool nix unzip nukeReferences pkgconfig boehmgc sqlite
-          git gitAndTools.topGit mercurial subversion bazaar openssl bzip2
-        ] ++ (import ./deps.nix) { inherit pkgs; };
+        [ makeWrapper libtool unzip nukeReferences pkgconfig boehmgc sqlite
+          gitAndTools.topGit mercurial subversion bazaar openssl bzip2
+          guile # optional, for Guile + Guix support
+          perl perlDeps
+        ];
 
       hydraPath = lib.makeSearchPath "bin" (
         [ libxslt sqlite subversion openssh nix coreutils findutils