Revise docker layer

Adjust the documentation to be more clear how to activate the new lsp feature.
Simplify layer setup code.
Provide missing company-lsp integration in feature list.
Remove obsolete tests for a loaded lsp layer as the docker layer loads it
itself already.

layers/+tools/docker/README.org

@@ -11,7 +11,6 @@
   - [[#docker][Docker]]
   - [[#linting][Linting]]
   - [[#lsp][LSP]]
-- [[#options][Options]]
 - [[#usage][Usage]]
   - [[#tramp-access-to-docker-containers][TRAMP access to docker containers]]
 - [[#key-bindings][Key bindings]]
@@ -26,6 +25,7 @@ This layer integrates basic container management into Spacemacs.
 - =Docker= container and image management via [[https://github.com/Silex/docker.el][docker.el]]
 - =docker-compose= integration via [[https://github.com/Silex/docker.el][docker.el]]
 - Syntax checking via [[https://github.com/hadolint/hadolint][hadolint]]
+- Code-Completion via =company-lsp=
 
 * Install
 ** Docker
@@ -37,31 +37,27 @@ You will also need the native package [[https://www.docker.com/][Docker]] for th
 
 ** Linting
 For syntax checking the external library [[https://github.com/hadolint/hadolint][hadolint]] is necessary.
+It can either be downloaded from [[https://github.com/hadolint/hadolint/releases/latest][=here=]] or
+build locally with stack as shown below:
+#+BEGIN_SRC sh
+  stack install hadolint
+#+END_SRC
 
 ** LSP
-This layer can be used with [[https://github.com/rcjsuen/dockerfile-language-server-nodejs][=dockerfile-language-server-nodejs=]] and emacs
+This layer can be enhanced with [[https://github.com/rcjsuen/dockerfile-language-server-nodejs][=dockerfile-language-server-nodejs=]] and emacs
 [[https://github.com/emacs-lsp/lsp-mode][=lsp-mode=]] to provide richer, IDE-like capabilities.
-To use this layer with lsp, you must do the following:
-
-1. Add =lsp= to =dotspacemacs-configuration-layers=.
-2. Install =dockerfile-language-server-nodejs= package with:
-
-   #+BEGIN_SRC sh
-     npm i -g dockerfile-language-server-nodejs
-   #+END_SRC
-
-3. Enable layer integration with lsp as described in section below.
-
-* Options
-This layer also includes experimental support for =lsp-mode=. To enable language
-server functionality with this layer, follow [[#lsp][the instructions for installation]],
-and then install this layer with:
-
+To do so set the layer variable =docker-dockerfile-backend= to =lsp= like shown below:
 #+BEGIN_SRC emacs-lisp
   (setq-default dotspacemacs-configuration-layers
                 '((docker :variables docker-dockerfile-backend 'lsp)))
 #+END_SRC
 
+In addition you need to install the lsp server's executable in your system.
+This can be done via npm:
+#+BEGIN_SRC sh
+  npm i -g dockerfile-language-server-nodejs
+#+END_SRC
+
 * Usage
 ** TRAMP access to docker containers
 This relies on the [[https://github.com/emacs-pe/docker-tramp.el][docker-tramp]] package which uses =docker exec= available in

layers/+tools/docker/config.el

@@ -13,5 +13,5 @@
 
 ;; Variables
 
-(defvar docker-dockerfile-backend nil
-  "The backend to use for IDE features. Possible values are `lsp'.")
+(defvar docker-dockerfile-backend 'nil
+  "The backend to use for IDE features. Possible values are `lsp' or `nil'.")

layers/+tools/docker/funcs.el

@@ -9,21 +9,7 @@
 ;;
 ;;; License: GPLv3
 
-(defun spacemacs//docker-dockerfile-backend ()
-  "Returns selected backend."
-  ;; backend must be choosed explicitly with this layer
-  docker-dockerfile-backend)
-
 (defun spacemacs//docker-dockerfile-setup-backend ()
   "Conditionally setup docker backend."
-  (pcase (spacemacs//docker-dockerfile-backend)
-    (`lsp (spacemacs//docker-dockerfile-setup-lsp))))
-
-
-;; lsp
-
-(defun spacemacs//docker-dockerfile-setup-lsp ()
-  "Setup lsp backend."
-  (if (configuration-layer/layer-used-p 'lsp)
-      (lsp)
-    (message "`lsp' layer is not installed, please add `lsp' layer to your dotfile.")))
+  (pcase docker-dockerfile-backend
+    (`lsp (lsp))))

layers/+tools/docker/packages.el

@@ -54,15 +54,12 @@
 (defun docker/init-dockerfile-mode ()
   (use-package dockerfile-mode
     :defer t
-    :init
-    (add-hook 'dockerfile-mode-hook #'spacemacs//docker-dockerfile-setup-backend)
+    :init (add-hook 'dockerfile-mode-local-vars-hook #'spacemacs//docker-dockerfile-setup-backend)
     :config
-    (progn
-      (spacemacs/declare-prefix-for-mode 'dockerfile-mode
-        "mc" "compile")
-      (spacemacs/set-leader-keys-for-major-mode 'dockerfile-mode
-        "cb" 'dockerfile-build-buffer
-        "cB" 'dockerfile-build-no-cache-buffer))))
+    (spacemacs/declare-prefix-for-mode 'dockerfile-mode "mc" "compile")
+    (spacemacs/set-leader-keys-for-major-mode 'dockerfile-mode
+      "cb" 'dockerfile-build-buffer
+      "cB" 'dockerfile-build-no-cache-buffer)))
 
 (defun docker/post-init-flycheck ()
   (spacemacs/enable-flycheck 'dockerfile-mode))