Utilise make plutôt que gruntjs pour le build.

.gitlab-ci.yml

@@ -2,15 +2,16 @@ stages:
   - build
 
 build:
-  image: node:10
+  image: node:10-alpine
   stage: build
   tags: [docker]
   interruptible: true
   variables:
     NPM_CONFIG_CACHE: "$CI_PROJECT_DIR/.npm"
+  before_script:
+    - apk update && apk add make
   script:
-    - npm install
-    - npm run build
+    - make
   artifacts:
     name: dist
     expire_in: 2 years

Gruntfile.js

-const loadGruntTasks = require("load-grunt-tasks");
-
-module.exports = grunt => {
-  const BUILD_DIR = "build/";
-  const DIST_DIR = "dist/";
-
-  loadGruntTasks(grunt, { pattern: ["grunt-*", "grunt-contrib-*"] });
-
-  grunt.initConfig({
-    pkg: grunt.file.readJSON("package.json"),
-
-    copy: {
-      revealSources: {
-        expand: true,
-        cwd: "node_modules/reveal.js/.",
-        src: [
-          "{js,lib,plugin}/**",
-          "css/{reveal.scss,reset.css}",
-          "css/print/**",
-          "css/theme/template/**",
-          "index.html",
-          "package*.json",
-          "Gruntfile.js"
-        ],
-        dest: BUILD_DIR
-      },
-      themeSources: {
-        expand: true,
-        cwd: "src/",
-        src: ["**"],
-        dest: BUILD_DIR
-      },
-      dist: {
-        expand: true,
-        cwd: BUILD_DIR,
-        src: ["{js,lib,plugin}/**", "css/**/*.css", "index.html"],
-        dest: DIST_DIR
-      }
-    },
-
-    exec: {
-      npmInstall: {
-        command: "npm install",
-        options: {
-          cwd: BUILD_DIR
-        }
-      },
-      buildRevealJs: {
-        command: "grunt css jshint",
-        options: {
-          cwd: BUILD_DIR
-        }
-      }
-    },
-
-    clean: [BUILD_DIR + "**", DIST_DIR + "**"]
-  });
-
-  grunt.registerTask("default", ["installRevealJs", "build"]);
-
-  grunt.registerTask("installRevealJs", [
-    "copy:revealSources",
-    "exec:npmInstall"
-  ]);
-
-  grunt.registerTask("build", [
-    "copy:themeSources",
-    "exec:buildRevealJs",
-    "copy:dist"
-  ]);
-};

Makefile

+.PHONY: all clean dist
+
+all: dist
+
+clean:
+	npx rimraf build/ dist/ node_modules/
+
+dist: build/js/reveal.min.js build/css/theme/irstea.css | dist/
+	cp -a build/{js,lib,plugin} dist/
+	mkdir -p dist/css/theme
+	cp -a build/css/{print,*.css} dist/css
+	cp -a build/css/theme/irstea.css dist/css/theme
+
+build/js/reveal.min.js: build/node_modules/
+	cd build; node_modules/.bin/grunt jshint uglify
+
+build/css/theme/irstea.css: build/css/theme/source/irstea.scss build/node_modules/
+	cd build; node_modules/.bin/grunt css
+
+build/css/theme/source/irstea.scss: build/
+	cp -a src/* build/
+
+build/node_modules/: build/package.json
+	cd build; npm install
+
+build/gruntfile.js build/package.json: node_modules/ | build/
+	cp -a node_modules/reveal.js/{css,js,lib,plugin,package.json,gruntfile.js} build/
+
+node_modules/: package.json
+	npm install
+
+build/ dist/:
+	mkdir -p $@

package.json

@@ -16,12 +16,6 @@
   "author": "Guillaume Perréal",
   "license": "MIT",
   "devDependencies": {
-    "grunt": "^1.0.4",
-    "grunt-cli": "^1.3.2",
-    "grunt-contrib-clean": "^2.0.0",
-    "grunt-contrib-copy": "^1.0.0",
-    "grunt-exec": "^3.0.0",
-    "load-grunt-tasks": "^5.1.0",
     "reveal.js": "^3.8.0"
   }
 }