make the hooks usable by the whole catalogue

- hooks load the _stack files of every directory between the stack path root
  and the stack, outermost first: make included both $(dir)/*.mk and
  $(dir)/*/*.mk, so a stack in a subdirectory saw its parent's settings
- a group may be declared in <group>/<group>.env, where the stack lives
- MYOS_STACK_DIR lets a hook read a file it ships next to itself
- myos_filter no longer confuses a literal * in a make pattern with a wildcard,
  and the list helpers no longer let the shell expand a * into filenames
- MACHINE, SYSTEM, HOST and DOMAINNAME join the framework variables a hook sees
- the make shim gains $(call myos-var,NAME), so a .mk target can read a
  setting that now lives in a hook, and it picks up the .mk of every stack
  directory rather than only the project's

lib/hooks.sh

@@ -1,30 +1,69 @@
 #shellcheck shell=sh
+# shellcheck disable=SC1090  # hooks are sourced by a path built at run time
 # hooks: the per-stack settings that used to live in a .mk file.
 #
-# A stack may ship, next to its compose files:
+# A stack directory may ship, next to its compose files:
 #   _stack.env       settings shared by every stack of the directory
 #   _stack.sh        the same, computed
-#   <name>.env       dotenv, for plain values
+#   <name>.env       settings of one stack
 #   <name>.env.<env> the same, for one environment
-#   <name>.sh        shell, for values that have to be computed (fabio tags, JWTs)
+#   <name>.sh        computed settings of one stack
 #   <name>.mk        the legacy make snippet, still read for its groups
 #
-# A .sh hook runs with the myos helpers available (myos_tagprefix, myos_uri,
-# myos_var) and sets variables directly. This is what lets a stack of the
-# catalogue work on a machine that has no make.
+# A .sh hook declares lazy defaults (see lib/var.sh): functions named
+# myos_default_<VARIABLE>, called only when the variable has no value and
+# called again at each reference. That is a make `?=` on a recursive variable,
+# and it is what lets a stack of the catalogue work without make installed.
+#
+# The _stack hooks of every directory between the stack path root and the stack
+# itself are loaded, outermost first: make included both $(dir)/*.mk and
+# $(dir)/*/*.mk, so a stack in a subdirectory saw its parent's settings.
 
-# myos_stack_hooks DIR NAME  load the hooks of one stack, most specific last
+# myos_stack_hooks DIR NAME  load the hooks that apply to one stack
 myos_stack_hooks() {
   _hdir=$1; _hname=$2
-  for _h in "$_hdir/_stack.env" "$_hdir/$_hname.env" "$_hdir/$_hname.env.$ENV"; do
-    [ -f "$_h" ] && myos_dotenv_load "$_h"
+
+  # the stack path entry this directory belongs to
+  _root=
+  _IFS=$IFS; IFS=:
+  for _r in $(myos_path); do
+    IFS=$_IFS
+    case $_hdir in "$_r"|"$_r"/*) _root=$_r; break ;; esac
+    IFS=:
   done
-  for _h in "$_hdir/_stack.sh" "$_hdir/$_hname.sh" "$_hdir/$_hname.$ENV.sh"; do
-    if [ -f "$_h" ]; then
-      myos_debug "hook $_h"
-      # shellcheck source=/dev/null
-      . "$_h"
-    fi
+  IFS=$_IFS
+
+  # every directory from the root down to the stack, outermost first
+  _chain=$_hdir
+  if [ -n "$_root" ]; then
+    _d=$_hdir
+    while [ "$_d" != "$_root" ] && [ "$_d" != "/" ] && [ -n "$_d" ]; do
+      _d=$(dirname "$_d")
+      _chain="$_d
+$_chain"
+    done
+  fi
+
+  for _d in $_chain; do
+    myos_hook_load "$_d/_stack.env" dotenv
+    myos_hook_load "$_d/_stack.sh" shell
   done
+  myos_hook_load "$_hdir/$_hname.env" dotenv
+  myos_hook_load "$_hdir/$_hname.env.$ENV" dotenv
+  myos_hook_load "$_hdir/$_hname.sh" shell
+  myos_hook_load "$_hdir/$_hname.$ENV.sh" shell
   return 0
 }
+
+# myos_hook_load FILE KIND
+myos_hook_load() {
+  [ -f "$1" ] || return 0
+  myos_debug "hook $1"
+  # a hook may need to read a file it ships next to itself
+  # shellcheck disable=SC2034  # read by the hooks sourced below
+  MYOS_STACK_DIR=$(dirname "$1")
+  case $2 in
+    dotenv) myos_dotenv_load "$1" ;;
+    shell)  . "$1" ;;
+  esac
+}