This patch adds a new "--disable-version-links" configuration option
that allows installing to the standard GNU installation directories
instead of having to add symlinks in /etc/ganeti/{lib,share} that
points to the right $ganeti/{lib,share}/$version.  Mainly to reduce
service complexity, and because Guix users can install as many versions
of Ganeti they can muster without resorting to such hacks.

diff --git a/Makefile.am b/Makefile.am
--- a/Makefile.am
+++ b/Makefile.am
@@ -66,11 +66,16 @@ SHELL_ENV_INIT = autotools/shell-env-init
 # so, if some currently architecture-independent executable is replaced by an
 # architecture-dependent one (and hence has to go under $(versiondir)), add a link
 # under $(versionedsharedir) but do not change the external links.
+#
+# As of Ganeti 3.0, it is possible to disable this behavior by passing
+# --disable-version-links, in which case the standard GNU installation
+# directories are used.
 if USE_VERSION_FULL
 DIRVERSION=$(VERSION_FULL)
 else
 DIRVERSION=$(VERSION_MAJOR).$(VERSION_MINOR)
 endif
+if USE_VERSION_LINKS
 versiondir = $(libdir)/ganeti/$(DIRVERSION)
 defaultversiondir = $(libdir)/ganeti/default
 versionedsharedir = $(prefix)/share/ganeti/$(DIRVERSION)
@@ -90,6 +95,18 @@ gntpythondir = $(versionedsharedir)
 pkgpython_bindir = $(versionedsharedir)
 gnt_python_sbindir = $(versionedsharedir)
 tools_pythondir = $(versionedsharedir)
+else
+myexeclibdir = $(pkglibdir)
+pkgpython_rpc_stubdir = $(pkgpythondir)/rpc/stub
+gntpythondir = $(sbindir)
+pkgpython_bindir = $(pkglibdir)
+gnt_python_sbindir = $(sbindir)
+tools_pythondir = $(pkglibdir)
+versionedsharedir = $(pkglibdir)
+# This is a hack but works because the only user does $(versiondir)$(datadir).
+versiondir =
+endif !USE_VERSION_LINKS
+
 
 clientdir = $(pkgpythondir)/client
 cmdlibdir = $(pkgpythondir)/cmdlib
@@ -2356,6 +2373,7 @@ src/AutoConf.hs: Makefile src/AutoConf.hs.in $(PRINT_PY_CONSTANTS) \
 	    -DVERSION_SUFFIX="$(VERSION_SUFFIX)" \
 	    -DVERSION_FULL="$(VERSION_FULL)" \
 	    -DDIRVERSION="$(DIRVERSION)" \
+	    -DUSE_VERSION_LINKS="$(USE_VERSION_LINKS)" \
 	    -DLOCALSTATEDIR="$(localstatedir)" \
 	    -DSYSCONFDIR="$(sysconfdir)" \
 	    -DSSH_CONFIG_DIR="$(SSH_CONFIG_DIR)" \
@@ -2857,6 +2875,7 @@ install-exec-local:
 	@mkdir_p@ "$(DESTDIR)${localstatedir}/lib/ganeti" \
 	  "$(DESTDIR)${localstatedir}/log/ganeti" \
 	  "$(DESTDIR)${localstatedir}/run/ganeti"
+if USE_VERSION_LINKS
 	for dir in $(SYMLINK_TARGET_DIRS); do \
 	  @mkdir_p@  $(DESTDIR)$$dir; \
 	done
@@ -2892,7 +2911,8 @@ install-exec-local:
 if INSTALL_SYMLINKS
 	$(LN_S) -f $(versionedsharedir) $(DESTDIR)$(sysconfdir)/ganeti/share
 	$(LN_S) -f $(versiondir) $(DESTDIR)$(sysconfdir)/ganeti/lib
-endif
+endif INSTALL_SYMLINKS
+endif USE_VERSION_LINKS
 
 .PHONY: apidoc
 if WANT_HSAPIDOC
diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
@@ -29,6 +29,23 @@ AC_SUBST([BINDIR], $bindir)
 AC_SUBST([SBINDIR], $sbindir)
 AC_SUBST([MANDIR], $mandir)
 
+# --enable-version-links
+AC_ARG_ENABLE([version-links],
+  [AS_HELP_STRING([--enable-version-links],
+                  m4_normalize([install ganeti to version-specific
+                  subdirectories to allow installing multiple versions
+                  in parallel (default: enabled)]))],
+  [[if test "$enableval" != no; then
+      USE_VERSION_LINKS=True
+    else
+      USE_VERSION_LINKS=False
+    fi
+  ]],
+  [USE_VERSION_LINKS=True
+  ])
+AC_SUBST(USE_VERSION_LINKS, $USE_VERSION_LINKS)
+AM_CONDITIONAL([USE_VERSION_LINKS], [test "$USE_VERSION_LINKS" = True])
+
 # --enable-versionfull
 AC_ARG_ENABLE([versionfull],
   [AS_HELP_STRING([--enable-versionfull],
diff --git a/lib/bootstrap.py b/lib/bootstrap.py
--- a/lib/bootstrap.py
+++ b/lib/bootstrap.py
@@ -944,7 +944,7 @@ def SetupNodeDaemon(opts, cluster_name, node, ssh_port):
                          debug=opts.debug, verbose=opts.verbose,
                          use_cluster_key=True, ask_key=opts.ssh_key_check,
                          strict_host_check=opts.ssh_key_check,
-                         ensure_version=True)
+                         ensure_version=constants.USE_VERSION_LINKS)
 
   _WaitForSshDaemon(node, ssh_port)
   _WaitForNodeDaemon(node)
diff --git a/src/AutoConf.hs.in b/src/AutoConf.hs.in
--- a/src/AutoConf.hs.in
+++ b/src/AutoConf.hs.in
@@ -64,6 +64,9 @@ versionFull = "VERSION_FULL"
 dirVersion :: String
 dirVersion = "DIRVERSION"
 
+useVersionLinks :: Bool
+useVersionLinks = USE_VERSION_LINKS
+
 localstatedir :: String
 localstatedir = "LOCALSTATEDIR"
 
diff --git a/src/Ganeti/Constants.hs b/src/Ganeti/Constants.hs
--- a/src/Ganeti/Constants.hs
+++ b/src/Ganeti/Constants.hs
@@ -164,5 +164,8 @@ versionRevision = AutoConf.versionRevision
 dirVersion :: String
 dirVersion = AutoConf.dirVersion
 
+useVersionLinks :: Bool
+useVersionLinks = AutoConf.useVersionLinks
+
 osApiV10 :: Int
 osApiV10 = 10