build: Default to "https://mirror.hydra.gnu.org/" for substitutes.

* config-daemon.ac: Check for (gnutls) and define 'GUIX_SUBSTITUTE_URLS'.
* nix/nix-daemon/guix-daemon.cc (main): Use GUIX_SUBSTITUTE_URLS.
* guix/store.scm (%default-substitute-urls): Use 'https' when (gnutls)
is available.
* doc/guix.texi (Binary Installation): Mention mirrors
(Invoking guix-daemon): Mention mirror.hydra.gnu.org.
(Substitutes): Mention mirrors.
(Invoking guix archive): Show https URLs.

1 files changed, 14 insertions, 0 deletions

diff --git a/config-daemon.ac b/config-daemon.ac
index c74ec94d312..63174d62c79 100644
--- a/config-daemon.ac
+++ b/config-daemon.ac
@@ -110,6 +110,20 @@ if test "x$guix_build_daemon" = "xyes"; then
   dnl Check for <linux/fs.h> (for immutable file support).
   AC_CHECK_HEADERS([linux/fs.h])
 
+  dnl Determine the appropriate default list of substitute URLs.
+  GUILE_MODULE_AVAILABLE([have_gnutls], [(gnutls)])
+  if test "x$have_gnutls" = "xyes"; then
+    guix_substitute_urls="https://mirror.hydra.gnu.org https://hydra.gnu.org"
+  else
+    AC_MSG_WARN([GnuTLS is missing, substitutes will be downloaded in the clear])
+    guix_substitute_urls="http://mirror.hydra.gnu.org http://hydra.gnu.org"
+  fi
+  AC_MSG_CHECKING([for default substitute URLs])
+  AC_MSG_RESULT([$guix_substitute_urls])
+
+  AC_DEFINE_UNQUOTED([GUIX_SUBSTITUTE_URLS], ["$guix_substitute_urls"],
+    [Default list of substitute URLs used by 'guix-daemon'.])
+
   dnl Check whether the 'offload' build hook can be built (uses
   dnl 'restore-file-set', which requires unbuffered custom binary input
   dnl ports from Guile >= 2.0.10.)