Merge branch '64295-predictable-environment-slugs' into 'master'

Use predictable environment slugs

See merge request gitlab-org/gitlab-ce!30551

1 files changed, 58 insertions, 0 deletions

diff --git a/lib/gitlab/slug/environment.rb b/lib/gitlab/slug/environment.rb
new file mode 100644
index 00000000000..1b87d3bb626
--- /dev/null
+++ b/lib/gitlab/slug/environment.rb
@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+# An environment name is not necessarily suitable for use in URLs, DNS
+# or other third-party contexts, so provide a slugified version. A slug has
+# the following properties:
+#   * contains only lowercase letters (a-z), numbers (0-9), and '-'
+#   * begins with a letter
+#   * has a maximum length of 24 bytes (OpenShift limitation)
+#   * cannot end with `-`
+module Gitlab
+  module Slug
+    class Environment
+      attr_reader :name
+
+      def initialize(name)
+        @name = name
+      end
+
+      def generate
+        # Lowercase letters and numbers only
+        slugified = name.to_s.downcase.gsub(/[^a-z0-9]/, '-')
+
+        # Must start with a letter
+        slugified = 'env-' + slugified unless slugified.match?(/^[a-z]/)
+
+        # Repeated dashes are invalid (OpenShift limitation)
+        slugified.squeeze!('-')
+
+        slugified =
+          if slugified.size > 24 || slugified != name
+            # Maximum length: 24 characters (OpenShift limitation)
+            shorten_and_add_suffix(slugified)
+          else
+            # Cannot end with a dash (Kubernetes label limitation)
+            slugified.chomp('-')
+          end
+
+        slugified
+      end
+
+      private
+
+      def shorten_and_add_suffix(slug)
+        slug = slug[0..16]
+        slug << '-' unless slug.ends_with?('-')
+        slug << suffix
+      end
+
+      # Slugifying a name may remove the uniqueness guarantee afforded by it being
+      # based on name (which must be unique). To compensate, we add a predictable
+      # 6-byte suffix in those circumstances. This is not *guaranteed* uniqueness,
+      # but the chance of collisions is vanishingly small
+      def suffix
+        Digest::SHA2.hexdigest(name.to_s).to_i(16).to_s(36).last(6)
+      end
+    end
+  end
+end