install.func: support optional POST_INSTALL_SCRIPT (var_post_install_script) hook in customize()

Author: MickLesk

misc/install.func

@@ -485,6 +485,8 @@ motd_ssh() {
 # - Creates /usr/bin/update script for easy application updates
 # - Injects SSH authorized keys if SSH_AUTHORIZED_KEY variable is set
 # - Sets proper permissions on SSH directories and key files
+# - Runs an optional user-supplied post-install script (POST_INSTALL_SCRIPT or
+#   var_post_install_script in *.vars) at the very end of the install
 # ------------------------------------------------------------------------------
 customize() {
   if [[ "$PASSWORD" == "" ]]; then
@@ -509,5 +511,32 @@ EOF
     chmod 700 /root/.ssh
     chmod 600 /root/.ssh/authorized_keys
   fi
+
+  # Optional user-supplied post-install script.
+  # Either POST_INSTALL_SCRIPT (env / install-script) or var_post_install_script
+  # (defaults.vars / mydefaults) may point to a path or URL of a shell script
+  # that will be executed at the very end of the install.
+  local _post_script="${POST_INSTALL_SCRIPT:-${var_post_install_script:-}}"
+  if [[ -n "$_post_script" ]]; then
+    msg_info "Running post-install script"
+    local _post_local=""
+    if [[ "$_post_script" =~ ^https?:// ]]; then
+      _post_local="$(mktemp --suffix=.sh)"
+      if ! curl -fsSL "$_post_script" -o "$_post_local"; then
+        msg_error "Failed to download post-install script: $_post_script"
+        rm -f "$_post_local"
+      else
+        bash "$_post_local" || msg_error "Post-install script exited with non-zero status"
+        rm -f "$_post_local"
+        msg_ok "Ran post-install script"
+      fi
+    elif [[ -f "$_post_script" ]]; then
+      bash "$_post_script" || msg_error "Post-install script exited with non-zero status"
+      msg_ok "Ran post-install script"
+    else
+      msg_error "Post-install script not found: $_post_script"
+    fi
+  fi
+
   post_progress_to_api
 }