install system deps by searching for package managers on PATH

With this change we handle the situation in which we don't know the OS of a
host on which we need to install system packages more cleanly than before.

Also rely on the new PACKAGE:INSTALLED to install the OS bootstrapper in
INSTALLER:CLEANLY-INSTALLED-ONCE.  This allows us to simplify usage of the
property by replacing the ORIGINAL-OS argument with ORIGINAL-OS-ARCHITECTURE.

Making this change does mean that we now have two ways to specify the
different names a package has on different OSs: (i) something like
OS:ETYPECASE where each branch applies a property which invokes an OS-specific
package manager; and (ii) the plists supplied to PACKAGE:INSTALLED.

Signed-off-by: Sean Whitton <spwhitton@spwhitton.name>

1 files changed, 20 insertions, 18 deletions

diff --git a/src/connection/sbcl.lisp b/src/connection/sbcl.lisp
index 206b5ab..db5ac7e 100644
--- a/src/connection/sbcl.lisp
+++ b/src/connection/sbcl.lisp
@@ -18,33 +18,35 @@
 (in-package :consfigurator.connection.sbcl)
 (named-readtables:in-readtable :consfigurator)
 
-(defproplist sbcl-available :posix ()
-  (os:etypecase
-    (debianlike (apt:installed "sbcl" "build-essential"))))
-
 (defparameter *sbcl* '("sbcl" "--noinform" "--noprint"
                        "--disable-debugger" "--no-sysinit" "--no-userinit"))
 
-(defmethod establish-connection ((type (eql :sbcl)) remaining &key)
+(defmethod establish-connection
+    ((type (eql :sbcl)) remaining
+     &key (package-manager nil package-manager-supplied-p))
+  "Start up a remote Lisp image using SBCL.
+
+Specifying PACKAGE-MANAGER avoids the need to see what package managers are
+available on PATH, which can provide a performance improvement."
   (when (lisp-connection-p)
     (warn
      "Looks like you might be starting a fresh Lisp image directly from the root
 Lisp. This can mean that prerequisite data gets extracted from encrypted
 stores and stored unencrypted under ~~/.cache, and as such is not
 recommended."))
-  (unless (zerop (mrun :for-exit "command" "-v" "sbcl"))
-    ;; If we're not the final hop then we don't know the OS of the host to
-    ;; which we're currently connected, so we can't apply SBCL-AVAILABLE.
-    ;;
-    ;; TODO In the case of INSTALLER:CLEANLY-INSTALLED-ONCE this code will
-    ;; have us trying to use apt to install sbcl on a Fedora host, say, upon
-    ;; the first connection, before Debian has been installed.  Perhaps we
-    ;; should just have some code which tries to install sbcl based on the
-    ;; package manager(s) it can find on PATH.  Could reuse that code for
-    ;; CHROOT::%DEBOOTSTRAP-MANUALLY-INSTALLED.
-    (if remaining
-        (failed-change "sbcl not on PATH and don't know how to install.")
-        (sbcl-available)))
+  ;; Allow the user to request no attempt to install the dependencies at all,
+  ;; perhaps because they know they're already manually installed.
+  (unless (and package-manager-supplied-p (not package-manager))
+    (handler-case (package:installed
+                   package-manager '(:apt "sbcl")
+                   package:*consfigurator-system-dependencies*)
+      ;; If we couldn't find any package manager on PATH, just proceed in the
+      ;; hope that everything we need is already installed; we'll find out
+      ;; whether it's actually a problem pretty quickly, when the remote SBCL
+      ;; tries to compile and load the ASDF systems.
+      (package:package-manager-not-found (c)
+        (apply #'warn (simple-condition-format-control c)
+               (simple-condition-format-arguments c)))))
   (let ((requirements (asdf-requirements-for-host-and-features
                        (safe-read-from-string
                         (run :input "(prin1 *features*)" *sbcl*)