Add lint checker for blog posts categories

Based on the recently updated
https://about.gitlab.com/handbook/marketing/blog/#categories

Rakefile

@@ -6,6 +6,7 @@ desc 'Run all lint tasks'
 task lint: ['lint:scss',
             'lint:features:solutions',
             'lint:features:links',
+            'lint:blog:categories',
             'lint:docs_ee'] do
 end
@@ -62,6 +63,49 @@ namespace :lint do
     end
   end
+  namespace :blog do
+    desc "Ensure every post has one of the right categories"
+    task :categories do
+      ## Taken from Jekyll
+      ## https://github.com/jekyll/jekyll/blob/3.5-stable/lib/jekyll/document.rb#L13
+      YAML_FRONT_MATTER_REGEXP = /\A(---\s*\n.*?\n?)^((---|\.\.\.)\s*$\n?)/m
+
+      ## Categories as defined in
+      ## https://about.gitlab.com/handbook/marketing/blog/#categories
+      CATEGORIES = ['releases',
+                    'engineering',
+                    'open source',
+                    'culture',
+                    'insights',
+                    'GitLab news'].freeze
+
+      count = 0
+
+      Dir['source/posts/*'].each do |post|
+        content = File.read(post)
+        data = content.scan(YAML_FRONT_MATTER_REGEXP).last.first
+        ## Disable Rubocop due to https://github.com/ruby/psych/issues/262
+        ## We only parse the file, so there's no security issue anyway
+        # rubocop:disable Security/YAMLLoad
+        to_yaml = YAML.load(data)
+        # rubocop:enable Security/YAMLLoad
+
+        unless CATEGORIES.include? to_yaml['categories']
+          puts "=> Missing proper category in #{post}"
+          count += 1
+        end
+      end
+
+      if count.positive?
+        puts
+        puts "#{count} missing or wrong defined categories found. To get this sorted, read:"
+        puts 'https://about.gitlab.com/handbook/marketing/blog/#categories'
+
+        exit count
+      end
+    end
+  end
+
   desc "Check that all docs point to /ee/"
   task :docs_ee do
     abort unless system('./scripts/docs_ee_check.sh')

source/handbook/marketing/blog/index.html.md

@@ -273,7 +273,7 @@ title: "This is the post title"
 author: Firstname Lastname
 author_gitlab: GitLab.com username # included in February, 2017
 author_twitter: Twitter username
-categories: technical overview
+categories: engineering
 image_title: '/images/blogimages/post-cover-image.jpg'
 description: "Short description for the blog post" # included in August, 2016
 tags: tag1, tag2, tag3 # added June, 2018
@@ -352,18 +352,22 @@ Use only **one** of the following categories per post.
 **Do not** change the capitalization, spelling, or anything else,
 otherwise you'll create another category, which is something we don't want to do accidentally.
-- releases – release posts, security updates, patch releases, etc.
-- engineering – technical, actionable content. Anything covering how to do something, use something, or solve a problem should fall under this category
-- open source – stories from or about our community, users, or the wider open source community
-- culture – posts about remote work, working together, or GitLab culture
-- insights – industry, data, newsjacking, developer survey, etc.
-- GitLab news – company or product announcements, policy changes, events, etc.
+- `releases` – release posts, security updates, patch releases, etc.
+- `engineering` – technical, actionable content. Anything covering how to do something, use something, or solve a problem should fall under this category
+- `open source` – stories from or about our community, users, or the wider open source community
+- `culture` – posts about remote work, working together, or GitLab culture
+- `insights` – industry, data, newsjacking, developer survey, etc.
+- `GitLab news` – company or product announcements, policy changes, events, etc.
 We're working on improving category pages and tagging, but for now you can find posts under the same category by navigating to
 `https://about.gitlab.com/blog/categories/category-name/`. Dashes will be automatically added
 to multi-word categories and all of them will be lowercased in the URL. For example, the
 category "GitLab news" will be available under `https://about.gitlab.com/blog/categories/gitlab-news/`.
+Note that there's a CI test that checks for wrong or missing categories. If one of
+the above should change or a new category is added, don't forget to also change the
+[categories that are in the checker](https://gitlab.com/gitlab-com/www-gitlab-com/blob/8a8aef34a6a7c2c5413024bef2163935748d8701/Rakefile#L88-93).
+
 #### Cover image
 Do not leave the post without a cover image (`image_title`), unless you have a strong reason to do so.

source/posts/2011-10-24-gitlab-v1-1-vmware-image.html.md

@@ -4,6 +4,7 @@ wordpress_id: 8
 wordpress_url: http://blog.gitlabhq.com/?p=7
 date: 2011-10-24 12:17:18 +00:00
 comments: false
+categories: releases
 ---
 <h3>1. Download (501 MB)
 <a title="ubuntu server 10.04" href="http://downloads.gitlabhq.com/gitlab-ubuntu-server-10.04-amd64.zip">http://downloads.gitlabhq.com/gitlab-ubuntu-server-10.04-amd64.zip</a>

source/posts/2011-11-07-new-design-is-coming.html.md

@@ -4,6 +4,7 @@ wordpress_id: 25
 wordpress_url: http://blog.gitlabhq.com/?p=25
 date: 2011-11-07 21:37:44 +00:00
 comments: false
+categories: GitLab news
 ---
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/11/gitlab_issues1.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/11/gitlab_issues1.png" alt="" title="Issues" width="974" class="alignnone size-full wp-image-27" /></a>

source/posts/2011-11-08-install-guide-from-ryan-wersal.html.md

@@ -4,5 +4,6 @@ wordpress_id: 36
 wordpress_url: http://blog.gitlabhq.com/?p=36
 date: 2011-11-08 09:08:10 +00:00
 comments: false
+categories: GitLab news
 ---
 <a href="http://www.ryanwersal.com/blog/2011/10/18/installing-gitlab-on-ubuntu-server/" title="installing-gitlab-on-ubuntu-server">Install guide from Ryan Wersal</a>

source/posts/2011-11-16-new-feature-network-graph.html.md

@@ -4,5 +4,6 @@ wordpress_id: 39
 wordpress_url: http://blog.gitlabhq.com/?p=39
 date: 2011-11-16 07:32:49 +00:00
 comments: false
+categories: GitLab news
 ---
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/11/network1.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/11/network1.png" alt="" title="network" width="602" class="size-full wp-image-40" /></a>

source/posts/2011-11-16-new-feature-project-activities.html.md

@@ -4,5 +4,6 @@ wordpress_id: 48
 wordpress_url: http://blog.gitlabhq.com/?p=48
 date: 2011-11-16 19:52:19 +00:00
 comments: false
+categories: GitLab news
 ---
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/11/project_activities1.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/11/project_activities1.png" alt="" title="project_activities" width="602" class="alignnone size-full wp-image-49" /></a>

source/posts/2011-11-17-features-for-pronto-v1-2-0.html.md

@@ -4,6 +4,7 @@ wordpress_id: 52
 wordpress_url: http://blog.gitlabhq.com/?p=52
 date: 2011-11-17 14:34:11 +00:00
 comments: false
+categories: releases
 ---
 <ol>
 	<li><h3>New design</h3></li>

source/posts/2011-11-22-pronto-released.html.md

 --- 
 title: Pronto released
 wordpress_id: 69
+categories: releases
 wordpress_url: http://blog.gitlabhq.com/?p=69
 date: 2011-11-22 20:28:54 +00:00
 comments: false

source/posts/2011-11-22-whats-next.html.md

@@ -4,6 +4,7 @@ wordpress_id: 84
 wordpress_url: http://blog.gitlabhq.com/?p=84
 date: 2011-11-22 23:05:13 +00:00
 comments: false
+categories: releases
 ---
 'Pronto' released. We are on our way to version 2. The main goal is <strong>gitolite</strong> support. I think of some other features I find useful for project:
 <ul>

source/posts/2011-11-24-issue-prototype.html.md

@@ -4,6 +4,7 @@ wordpress_id: 96
 wordpress_url: http://blog.gitlabhq.com/?p=96
 date: 2011-11-24 23:51:01 +00:00
 comments: false
+categories: GitLab news
 ---
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/11/11660251.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/11/11660251.png" alt="" title="issue with branch" width="602" class="alignnone size-full wp-image-97" /></a>

source/posts/2011-11-27-dark-colors-for-code-review.html.md

@@ -4,6 +4,7 @@ wordpress_id: 100
 wordpress_url: http://blog.gitlabhq.com/?p=100
 date: 2011-11-27 15:30:43 +00:00
 comments: false
+categories: GitLab news
 ---
 I prefer dark colors so i Implemented ability to switch for dark one.
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/11/11715191.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/11/11715191.png" alt="" title="1171519" width="602" class="aligncenter size-full wp-image-101" /></a>

source/posts/2011-11-27-issues-become-simplier.html.md

@@ -4,6 +4,7 @@ wordpress_id: 103
 wordpress_url: http://blog.gitlabhq.com/?p=103
 date: 2011-11-27 15:34:27 +00:00
 comments: false
+categories: GitLab news
 ---
 We decided to keep issue show page simplier.
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/11/issues_11.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/11/issues_11.png" alt="" title="issues_1" width="602"  class="aligncenter size-full wp-image-105" /></a>

source/posts/2011-11-28-merge-requests-v1.html.md

@@ -4,6 +4,7 @@ wordpress_id: 108
 wordpress_url: http://blog.gitlabhq.com/?p=108
 date: 2011-11-28 21:05:56 +00:00
 comments: false
+categories: GitLab news
 ---
 Merge requests list
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/11/gitlab_merge_requests_11.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/11/gitlab_merge_requests_11.png" alt="" title="gitlab_merge_requests_1" width="601" class="aligncenter size-full wp-image-109" /></a>

source/posts/2011-12-01-new-commit-show-page.html.md

@@ -4,6 +4,7 @@ wordpress_id: 114
 wordpress_url: http://blog.gitlabhq.com/?p=114
 date: 2011-12-01 09:54:07 +00:00
 comments: false
+categories: GitLab news
 ---
 We restyled commit page & added anchors to line numbers
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/12/commits1.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/12/commits1.png" alt="" title="commits" width="1059" height="883" class="aligncenter size-full wp-image-115" /></a>

source/posts/2011-12-07-new-access-privilegies.html.md

@@ -4,6 +4,7 @@ wordpress_id: 119
 wordpress_url: http://blog.gitlabhq.com/?p=119
 date: 2011-12-07 14:25:25 +00:00
 comments: false
+categories: GitLab news
 ---
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/12/gitLab_access1.png"><img class="aligncenter size-full wp-image-120" title="gitLab_access" src="http://blog.gitlabhq.com/wp-content/uploads/2011/12/gitLab_access1.png" alt="" width="1162" height="782" /></a>

source/posts/2011-12-09-useful-dashboard-first-try.html.md

@@ -4,6 +4,7 @@ wordpress_id: 128
 wordpress_url: http://blog.gitlabhq.com/?p=128
 date: 2011-12-09 16:31:11 +00:00
 comments: false
+categories: GitLab news
 ---
 Activities (old dashboard page)
 <a href="http://blog.gitlabhq.com/wp-content/uploads/2011/12/dashboard11.png"><img src="http://blog.gitlabhq.com/wp-content/uploads/2011/12/dashboard11.png" alt="" title="dashboard1" width="1096" height="557" class="aligncenter size-full wp-image-129" /></a>

source/posts/2011-12-22-gitlabhq-v2-0-moderno.html.md

@@ -4,6 +4,7 @@ wordpress_id: 153
 wordpress_url: http://blog.gitlabhq.com/?p=153
 date: 2011-12-22 09:54:45 +00:00
 comments: false
+categories: releases
 ---
 <h2>Giltab v2.0 'Moderno' released!</h2>
 <p>We finally moved from gitosis to gitolite. It'll allow us to make a lot of useful features in future.</p>

source/posts/2012-01-05-2-1-pre.html.md

@@ -4,6 +4,7 @@ wordpress_id: 183
 wordpress_url: http://blog.gitlabhq.com/?p=183
 date: 2012-01-05 18:23:58 +00:00
 comments: false
+categories: releases
 ---
 For last week we made some changes to gitlab so we are a bit closer to 2.1 release.

source/posts/2012-01-13-design-changes.html.md

@@ -4,6 +4,7 @@ wordpress_id: 191
 wordpress_url: http://blog.gitlabhq.com/?p=191
 date: 2012-01-13 21:43:55 +00:00
 comments: false
+categories: GitLab news
 ---
 We made changes to design & layout of gitlab. 
 Goal of changes is to reach bigger working area & minimalistic UI.