Merge branch 'zj-mattermost-slash-config' into 'master'

Mattermost slash auto config

Closes #24769

See merge request !8070

27 files changed, 763 insertions, 115 deletions

diff --git a/app/assets/stylesheets/pages/projects.scss b/app/assets/stylesheets/pages/projects.scss
index e16a553bcda..d6aa4c4c032 100644
--- a/app/assets/stylesheets/pages/projects.scss
+++ b/app/assets/stylesheets/pages/projects.scss
@@ -880,3 +880,23 @@ pre.light-well {
     width: 30%;
   }
 }
+
+.services-installation-info .row {
+  margin-bottom: 10px;
+}
+
+.service-installation {
+  padding: 32px;
+  margin: 32px;
+  border-radius: 3px;
+  background-color: $white-light;
+
+  h3 {
+    margin-top: 0;
+  }
+
+  hr {
+    margin: 32px 0;
+    border-color: $border-color;
+  }
+}
diff --git a/app/controllers/projects/mattermosts_controller.rb b/app/controllers/projects/mattermosts_controller.rb
new file mode 100644
index 00000000000..d87dff2a80e
--- /dev/null
+++ b/app/controllers/projects/mattermosts_controller.rb
@@ -0,0 +1,43 @@
+class Projects::MattermostsController < Projects::ApplicationController
+  include TriggersHelper
+  include ActionView::Helpers::AssetUrlHelper
+
+  layout 'project_settings'
+
+  before_action :authorize_admin_project!
+  before_action :service
+  before_action :teams, only: [:new]
+
+  def new
+  end
+
+  def create
+    result, message = @service.configure(current_user, configure_params)
+
+    if result
+      flash[:notice] = 'This service is now configured'
+      redirect_to edit_namespace_project_service_path(
+        @project.namespace, @project, service)
+    else
+      flash[:alert] = message || 'Failed to configure service'
+      redirect_to new_namespace_project_mattermost_path(
+        @project.namespace, @project)
+    end
+  end
+
+  private
+
+  def configure_params
+    params.require(:mattermost).permit(:trigger, :team_id).merge(
+      url: service_trigger_url(@service),
+      icon_url: asset_url('gitlab_logo.png'))
+  end
+
+  def teams
+    @teams ||= @service.list_teams(current_user)
+  end
+
+  def service
+    @service ||= @project.find_or_initialize_service('mattermost_slash_commands')
+  end
+end
diff --git a/app/helpers/mattermost_helper.rb b/app/helpers/mattermost_helper.rb
new file mode 100644
index 00000000000..49ac12db832
--- /dev/null
+++ b/app/helpers/mattermost_helper.rb
@@ -0,0 +1,9 @@
+module MattermostHelper
+  def mattermost_teams_options(teams)
+    teams_options = teams.map do |id, options|
+      [options['display_name'] || options['name'], id]
+    end
+
+    teams_options.compact.unshift(['Select team...', '0'])
+  end
+end
diff --git a/app/models/project_services/mattermost_slash_commands_service.rb b/app/models/project_services/mattermost_slash_commands_service.rb
index 10740275669..6c78c0af71c 100644
--- a/app/models/project_services/mattermost_slash_commands_service.rb
+++ b/app/models/project_services/mattermost_slash_commands_service.rb
@@ -18,4 +18,34 @@ class MattermostSlashCommandsService < ChatSlashCommandsService
   def to_param
     'mattermost_slash_commands'
   end
+
+  def configure(user, params)
+    token = Mattermost::Command.new(user).
+      create(command(params))
+
+    update(active: true, token: token) if token
+  rescue Mattermost::Error => e
+    [false, e.message]
+  end
+
+  def list_teams(user)
+    Mattermost::Team.new(user).all
+  rescue Mattermost::Error => e
+    [[], e.message]
+  end
+
+  private
+
+  def command(params)
+    pretty_project_name = project.name_with_namespace
+
+    params.merge(
+      auto_complete: true,
+      auto_complete_desc: "Perform common operations on: #{pretty_project_name}",
+      auto_complete_hint: '[help]',
+      description: "Perform common operations on: #{pretty_project_name}",
+      display_name: "GitLab / #{pretty_project_name}",
+      method: 'P',
+      user_name: 'GitLab')
+  end
 end
diff --git a/app/views/projects/mattermosts/_no_teams.html.haml b/app/views/projects/mattermosts/_no_teams.html.haml
new file mode 100644
index 00000000000..605c7f61dee
--- /dev/null
+++ b/app/views/projects/mattermosts/_no_teams.html.haml
@@ -0,0 +1,12 @@
+%p
+  You aren’t a member of any team on the Mattermost instance at
+  %strong= Gitlab.config.mattermost.host
+%p
+  To install this service,
+  = link_to "#{Gitlab.config.mattermost.host}/select_team", target: '__blank' do
+    join a team
+    = icon('external-link')
+  and try again.
+%hr
+.clearfix
+  = link_to 'Go back', edit_namespace_project_service_path(@project.namespace, @project, @service), class: 'btn btn-lg pull-right'
diff --git a/app/views/projects/mattermosts/_team_selection.html.haml b/app/views/projects/mattermosts/_team_selection.html.haml
new file mode 100644
index 00000000000..7980f7c9a72
--- /dev/null
+++ b/app/views/projects/mattermosts/_team_selection.html.haml
@@ -0,0 +1,44 @@
+%p
+  This service will be installed on the Mattermost instance at
+  %strong= link_to Gitlab.config.mattermost.host, Gitlab.config.mattermost.host
+%hr
+= form_for(:mattermost, method: :post, url: namespace_project_mattermost_path(@project.namespace, @project)) do |f|
+  %h4 Team
+  %p
+    = @teams.one? ? 'The team' : 'Select the team'
+    where the slash commands will be used in
+  - selected_id = @teams.keys.first if @teams.one?
+  = f.select(:team_id, mattermost_teams_options(@teams), {}, { class: 'form-control', selected: "#{selected_id}", disabled: @teams.one? })
+  .help-block
+    - if @teams.one?
+      This is the only team where you are an administrator.
+    - else
+      The list shows teams where you are administrator
+    To create a team, ask your Mattermost system administrator.
+    To create a team,
+    = link_to "#{Gitlab.config.mattermost.host}/create_team" do
+      use Mattermost's interface
+      = icon('external-link')
+  %hr
+  %h4 Command trigger word
+  %p Choose the word that will trigger commands
+  = f.text_field(:trigger, value: @project.path, class: 'form-control')
+  .help-block
+    %p
+      Trigger word must be unique, and can't begin with a slash or contain any spaces.
+      Use the word that works best for your team.
+    %p
+      Suggestions:
+      %code= 'gitlab'
+      %code= @project.path # Path contains no spaces, but dashes
+      %code= @project.path_with_namespace
+    %p
+      Reserved:
+      = link_to 'https://docs.mattermost.com/help/messaging/executing-commands.html#built-in-commands', target: '__blank' do
+        see list of built-in slash commands
+        = icon('external-link')
+  %hr
+  .clearfix
+    .pull-right
+      = link_to 'Cancel', edit_namespace_project_service_path(@project.namespace, @project, @service), class: 'btn btn-lg'
+      = f.submit 'Install', class: 'btn btn-save btn-lg'
diff --git a/app/views/projects/mattermosts/new.html.haml b/app/views/projects/mattermosts/new.html.haml
new file mode 100644
index 00000000000..96b1d2aee61
--- /dev/null
+++ b/app/views/projects/mattermosts/new.html.haml
@@ -0,0 +1,8 @@
+.service-installation
+  .inline.pull-right
+    = custom_icon('mattermost_logo', size: 48)
+  %h3 Install Mattermost Command
+  - if @teams.empty?
+    = render 'no_teams'
+  - else
+    = render 'team_selection'
diff --git a/app/views/projects/services/_form.html.haml b/app/views/projects/services/_form.html.haml
index db51c4f8a4e..fc338dcf887 100644
--- a/app/views/projects/services/_form.html.haml
+++ b/app/views/projects/services/_form.html.haml
@@ -8,7 +8,6 @@
   .col-lg-9
     = form_for(@service, as: :service, url: namespace_project_service_path(@project.namespace, @project, @service.to_param), method: :put, html: { class: 'form-horizontal' }) do |form|
       = render 'shared/service_settings', form: form, subject: @service
-
       .footer-block.row-content-block
         = form.submit 'Save changes', class: 'btn btn-save'
         &nbsp;
diff --git a/app/views/projects/services/mattermost_slash_commands/_detailed_help.html.haml b/app/views/projects/services/mattermost_slash_commands/_detailed_help.html.haml
new file mode 100644
index 00000000000..8ca4c51a064
--- /dev/null
+++ b/app/views/projects/services/mattermost_slash_commands/_detailed_help.html.haml
@@ -0,0 +1,91 @@
+- run_actions_text = "Perform common operations on this project: #{@project.name_with_namespace}"
+
+To setup this service:
+%ul.list-unstyled
+  %li
+    1.
+    = link_to 'Enable custom slash commands', 'https://docs.mattermost.com/developer/slash-commands.html#enabling-custom-commands'
+    on your Mattermost installation
+  %li
+    2.
+    = link_to 'Add a slash command', 'https://docs.mattermost.com/developer/slash-commands.html#set-up-a-custom-command'
+    in Mattermost with these options:
+
+%hr
+
+.help-form
+  .form-group
+    = label_tag :display_name, 'Display name', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.input-group
+      = text_field_tag :display_name, "GitLab / #{@project.name_with_namespace}", class: 'form-control input-sm', readonly: 'readonly'
+      .input-group-btn
+        = clipboard_button(clipboard_target: '#display_name')
+
+  .form-group
+    = label_tag :description, 'Description', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.input-group
+      = text_field_tag :description, run_actions_text, class: 'form-control input-sm', readonly: 'readonly'
+      .input-group-btn
+        = clipboard_button(clipboard_target: '#description')
+
+  .form-group
+    = label_tag nil, 'Command trigger word', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.text-block
+      %p Fill in the word that works best for your team.
+      %p
+        Suggestions:
+        %code= 'gitlab'
+        %code= @project.path # Path contains no spaces, but dashes
+        %code= @project.path_with_namespace
+
+  .form-group
+    = label_tag :request_url, 'Request URL', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.input-group
+      = text_field_tag :request_url, service_trigger_url(subject), class: 'form-control input-sm', readonly: 'readonly'
+      .input-group-btn
+        = clipboard_button(clipboard_target: '#request_url')
+
+  .form-group
+    = label_tag nil, 'Request method', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.text-block POST
+
+  .form-group
+    = label_tag :response_username, 'Response username', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.input-group
+      = text_field_tag :response_username, 'GitLab', class: 'form-control input-sm', readonly: 'readonly'
+      .input-group-btn
+        = clipboard_button(clipboard_target: '#response_username')
+
+  .form-group
+    = label_tag :response_icon, 'Response icon', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.input-group
+      = text_field_tag :response_icon, asset_url('gitlab_logo.png'), class: 'form-control input-sm', readonly: 'readonly'
+      .input-group-btn
+        = clipboard_button(clipboard_target: '#response_icon')
+
+  .form-group
+    = label_tag nil, 'Autocomplete', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.text-block Yes
+
+  .form-group
+    = label_tag :autocomplete_hint, 'Autocomplete hint', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.input-group
+      = text_field_tag :autocomplete_hint, '[help]', class: 'form-control input-sm', readonly: 'readonly'
+      .input-group-btn
+        = clipboard_button(clipboard_target: '#autocomplete_hint')
+
+  .form-group
+    = label_tag :autocomplete_description, 'Autocomplete description', class: 'col-sm-2 col-xs-12 control-label'
+    .col-sm-10.col-xs-12.input-group
+      = text_field_tag :autocomplete_description, run_actions_text, class: 'form-control input-sm', readonly: 'readonly'
+      .input-group-btn
+        = clipboard_button(clipboard_target: '#autocomplete_description')
+
+%hr
+
+%ul.list-unstyled
+  %li
+    3. After adding the slash command, paste the
+
+    %strong token
+    into the field below
diff --git a/app/views/projects/services/mattermost_slash_commands/_help.html.haml b/app/views/projects/services/mattermost_slash_commands/_help.html.haml
index 01a77a952d1..63b797cd391 100644
--- a/app/views/projects/services/mattermost_slash_commands/_help.html.haml
+++ b/app/views/projects/services/mattermost_slash_commands/_help.html.haml
@@ -1,4 +1,4 @@
-- run_actions_text = "Perform common operations on this project: #{@project.name_with_namespace}"
+- enabled = Gitlab.config.mattermost.enabled
 
 .well
   This service allows GitLab users to perform common operations on this
@@ -7,93 +7,9 @@
   See list of available commands in Mattermost after setting up this service,
   by entering
   %code /&lt;command_trigger_word&gt; help
-  %br
-  %br
-  To setup this service:
-  %ul.list-unstyled
-    %li
-      1.
-      = link_to 'Enable custom slash commands', 'https://docs.mattermost.com/developer/slash-commands.html#enabling-custom-commands'
-      on your Mattermost installation
-    %li
-      2.
-      = link_to 'Add a slash command', 'https://docs.mattermost.com/developer/slash-commands.html#set-up-a-custom-command'
-      in Mattermost with these options:
-
-  %hr
-
-  .help-form
-    .form-group
-      = label_tag :display_name, 'Display name', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.input-group
-        = text_field_tag :display_name, "GitLab / #{@project.name_with_namespace}", class: 'form-control input-sm', readonly: 'readonly'
-        .input-group-btn
-          = clipboard_button(clipboard_target: '#display_name')
-
-    .form-group
-      = label_tag :description, 'Description', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.input-group
-        = text_field_tag :description, run_actions_text, class: 'form-control input-sm', readonly: 'readonly'
-        .input-group-btn
-          = clipboard_button(clipboard_target: '#description')
-
-    .form-group
-      = label_tag nil, 'Command trigger word', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.text-block
-        %p Fill in the word that works best for your team.
-        %p
-          Suggestions:
-          %code= 'gitlab'
-          %code= @project.path # Path contains no spaces, but dashes
-          %code= @project.path_with_namespace
-
-    .form-group
-      = label_tag :request_url, 'Request URL', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.input-group
-        = text_field_tag :request_url, service_trigger_url(subject), class: 'form-control input-sm', readonly: 'readonly'
-        .input-group-btn
-          = clipboard_button(clipboard_target: '#request_url')
-
-    .form-group
-      = label_tag nil, 'Request method', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.text-block POST
-
-    .form-group
-      = label_tag :response_username, 'Response username', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.input-group
-        = text_field_tag :response_username, 'GitLab', class: 'form-control input-sm', readonly: 'readonly'
-        .input-group-btn
-          = clipboard_button(clipboard_target: '#response_username')
-
-    .form-group
-      = label_tag :response_icon, 'Response icon', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.input-group
-        = text_field_tag :response_icon, asset_url('gitlab_logo.png'), class: 'form-control input-sm', readonly: 'readonly'
-        .input-group-btn
-          = clipboard_button(clipboard_target: '#response_icon')
-
-    .form-group
-      = label_tag nil, 'Autocomplete', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.text-block Yes
-
-    .form-group
-      = label_tag :autocomplete_hint, 'Autocomplete hint', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.input-group
-        = text_field_tag :autocomplete_hint, '[help]', class: 'form-control input-sm', readonly: 'readonly'
-        .input-group-btn
-          = clipboard_button(clipboard_target: '#autocomplete_hint')
-
-    .form-group
-      = label_tag :autocomplete_description, 'Autocomplete description', class: 'col-sm-2 col-xs-12 control-label'
-      .col-sm-10.col-xs-12.input-group
-        = text_field_tag :autocomplete_description, run_actions_text, class: 'form-control input-sm', readonly: 'readonly'
-        .input-group-btn
-          = clipboard_button(clipboard_target: '#autocomplete_description')
 
-  %hr
+  - unless enabled
+    = render 'projects/services/mattermost_slash_commands/detailed_help', subject: @service
 
-  %ul.list-unstyled
-    %li
-      3. After adding the slash command, paste the
-      %strong token
-      into the field below
+- if enabled
+  = render 'projects/services/mattermost_slash_commands/installation_info', subject: @service
diff --git a/app/views/projects/services/mattermost_slash_commands/_installation_info.html.haml b/app/views/projects/services/mattermost_slash_commands/_installation_info.html.haml
new file mode 100644
index 00000000000..c929eee3bb9
--- /dev/null
+++ b/app/views/projects/services/mattermost_slash_commands/_installation_info.html.haml
@@ -0,0 +1,7 @@
+.services-installation-info
+  - unless @service.activated?
+    .row
+      .col-sm-9.col-sm-offset-3
+        = link_to new_namespace_project_mattermost_path(@project.namespace, @project), class: 'btn btn-lg' do
+          = custom_icon('mattermost_logo', size: 15)
+          = 'Add to Mattermost'
diff --git a/app/views/shared/icons/_mattermost_logo.svg.erb b/app/views/shared/icons/_mattermost_logo.svg.erb
new file mode 100644
index 00000000000..83fbd1a407d
--- /dev/null
+++ b/app/views/shared/icons/_mattermost_logo.svg.erb
@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="<%= size %>" height="<%= size %>" version="1" viewBox="0 0 501 501"><path d="M236 .7C137.7 7.5 54 68.2 18.2 158.5c-32 81-19.6 172.8 33 242.5 39.8 53 97.2 87 164.3 97 16.5 2.7 48 3.2 63.5 1.2 48.7-6.3 92.2-24.6 129-54.2 13-10.5 33-31.2 42.2-43.7 26.4-35.5 42.8-75.8 49-120.3 1.6-12.3 1.6-48.7 0-61-4-28.3-12-54.8-24.2-79.5-12.8-26-26.5-45.3-46.8-65.8C417.8 64 400.2 49 398.4 49c-.6 0-.4 10.5.3 26l1.3 26 7 8.7c19 23.7 32.8 53.5 38.2 83 2.5 14 3 43 1 55.8-4.5 27.8-15.2 54-31 76.5-8.6 12.2-28 31.6-40.2 40.2-24 17-50 27.6-80 33-10 1.8-49 1.8-59 0-43-7.7-78.8-26-107.2-54.8-29.3-29.7-46.5-64-52.4-104.4-2-14-1.5-42 1-55C90 121.4 132 72 192 49.7c8-3 18.4-5.8 29.5-8.2 1.7-.4 34.4-38 35.3-40.6.3-1-10.2-1-20.8-.4z"/><path d="M322.2 24.6c-1.3.8-8.4 9.3-16 18.7-7.4 9.5-22.4 28-33.2 41.2-51 62.2-66 81.6-70.6 91-6 12-8.4 21-9 33-1.2 19.8 5 36 19 50C222 268 230 273 243 277.2c9 3 10.4 3.2 24 3.2 13.8 0 15 0 22.6-3 23.2-9 39-28.4 45-55.7 2-8.2 2-28.7.4-79.7l-2-72c-1-36.8-1.4-41.8-3-44-2-3-4.8-3.6-7.8-1.4z"/></svg>
diff --git a/changelogs/unreleased/mattermost-slash-auto-config.yml b/changelogs/unreleased/mattermost-slash-auto-config.yml
new file mode 100644
index 00000000000..43014d38769
--- /dev/null
+++ b/changelogs/unreleased/mattermost-slash-auto-config.yml
@@ -0,0 +1,4 @@
+---
+title: Allow to auto-configure Mattermost
+merge_request: 8070
+author:
diff --git a/config/gitlab.yml.example b/config/gitlab.yml.example
index 2d1d48bf9da..42e5f105d46 100644
--- a/config/gitlab.yml.example
+++ b/config/gitlab.yml.example
@@ -586,4 +586,4 @@ test:
         admin_group: ''
 
 staging:
-  <<: *base
+  <<: *base
\ No newline at end of file
diff --git a/config/routes/project.rb b/config/routes/project.rb
index 335fccb617b..baabd22b840 100644
--- a/config/routes/project.rb
+++ b/config/routes/project.rb
@@ -76,6 +76,8 @@ constraints(ProjectUrlConstrainer.new) do
         end
       end
 
+      resource :mattermost, only: [:new, :create]
+
       resources :deploy_keys, constraints: { id: /\d+/ }, only: [:index, :new, :create] do
         member do
           put :enable
diff --git a/lib/mattermost/client.rb b/lib/mattermost/client.rb
new file mode 100644
index 00000000000..ec2903b7ec6
--- /dev/null
+++ b/lib/mattermost/client.rb
@@ -0,0 +1,41 @@
+module Mattermost
+  class ClientError < Mattermost::Error; end
+
+  class Client
+    attr_reader :user
+
+    def initialize(user)
+      @user = user
+    end
+
+    private
+
+    def with_session(&blk)
+      Mattermost::Session.new(user).with_session(&blk)
+    end
+
+    def json_get(path, options = {})
+      with_session do |session|
+        json_response session.get(path, options)
+      end
+    end
+
+    def json_post(path, options = {})
+      with_session do |session|
+        json_response session.post(path, options)
+      end
+    end
+
+    def json_response(response)
+      json_response = JSON.parse(response.body)
+
+      unless response.success?
+        raise Mattermost::ClientError.new(json_response['message'] || 'Undefined error')
+      end
+
+      json_response
+    rescue JSON::JSONError
+      raise Mattermost::ClientError.new('Cannot parse response')
+    end
+  end
+end
diff --git a/lib/mattermost/command.rb b/lib/mattermost/command.rb
new file mode 100644
index 00000000000..d1e4bb0eccf
--- /dev/null
+++ b/lib/mattermost/command.rb
@@ -0,0 +1,10 @@
+module Mattermost
+  class Command < Client
+    def create(params)
+      response = json_post("/api/v3/teams/#{params[:team_id]}/commands/create",
+        body: params.to_json)
+
+      response['token']
+    end
+  end
+end
diff --git a/lib/mattermost/error.rb b/lib/mattermost/error.rb
new file mode 100644
index 00000000000..014df175be0
--- /dev/null
+++ b/lib/mattermost/error.rb
@@ -0,0 +1,3 @@
+module Mattermost
+  class Error < StandardError; end
+end
diff --git a/lib/mattermost/session.rb b/lib/mattermost/session.rb
index fb8d7d97f8a..377cb7b1021 100644
--- a/lib/mattermost/session.rb
+++ b/lib/mattermost/session.rb
@@ -1,5 +1,12 @@
 module Mattermost
-  class NoSessionError < StandardError; end
+  class NoSessionError < Mattermost::Error
+    def message
+      'No session could be set up, is Mattermost configured with Single Sign On?'
+    end
+  end
+
+  class ConnectionError < Mattermost::Error; end
+
   # This class' prime objective is to obtain a session token on a Mattermost
   # instance with SSO configured where this GitLab instance is the provider.
   #
@@ -17,6 +24,8 @@ module Mattermost
     include Doorkeeper::Helpers::Controller
     include HTTParty
 
+    LEASE_TIMEOUT = 60
+
     base_uri Settings.mattermost.host
 
     attr_accessor :current_resource_owner, :token
@@ -26,12 +35,16 @@ module Mattermost
     end
 
     def with_session
-      raise NoSessionError unless create
-
-      begin
-        yield self
-      ensure
-        destroy
+      with_lease do
+        raise Mattermost::NoSessionError unless create
+
+        begin
+          yield self
+        rescue Errno::ECONNREFUSED
+          raise Mattermost::NoSessionError
+        ensure
+          destroy
+        end
       end
     end
 
@@ -58,11 +71,15 @@ module Mattermost
     end
 
     def get(path, options = {})
-      self.class.get(path, options.merge(headers: @headers))
+      handle_exceptions do
+        self.class.get(path, options.merge(headers: @headers))
+      end
     end
 
     def post(path, options = {})
-      self.class.post(path, options.merge(headers: @headers))
+      handle_exceptions do
+        self.class.post(path, options.merge(headers: @headers))
+      end
     end
 
     private
@@ -111,5 +128,33 @@ module Mattermost
         response.headers['token']
       end
     end
+
+    def with_lease
+      lease_uuid = lease_try_obtain
+      raise NoSessionError unless lease_uuid
+
+      begin
+        yield
+      ensure
+        Gitlab::ExclusiveLease.cancel(lease_key, lease_uuid)
+      end
+    end
+
+    def lease_key
+      "mattermost:session"
+    end
+
+    def lease_try_obtain
+      lease = ::Gitlab::ExclusiveLease.new(lease_key, timeout: LEASE_TIMEOUT)
+      lease.try_obtain
+    end
+
+    def handle_exceptions
+      yield
+    rescue HTTParty::Error => e
+      raise Mattermost::ConnectionError.new(e.message)
+    rescue Errno::ECONNREFUSED
+      raise Mattermost::ConnectionError.new(e.message)
+    end
   end
 end
diff --git a/lib/mattermost/team.rb b/lib/mattermost/team.rb
new file mode 100644
index 00000000000..784eca6ab5a
--- /dev/null
+++ b/lib/mattermost/team.rb
@@ -0,0 +1,7 @@
+module Mattermost
+  class Team < Client
+    def all
+      json_get('/api/v3/teams/all')
+    end
+  end
+end
diff --git a/spec/controllers/projects/mattermosts_controller_spec.rb b/spec/controllers/projects/mattermosts_controller_spec.rb
new file mode 100644
index 00000000000..2ae635a1244
--- /dev/null
+++ b/spec/controllers/projects/mattermosts_controller_spec.rb
@@ -0,0 +1,58 @@
+require 'spec_helper'
+
+describe Projects::MattermostsController do
+  let!(:project) { create(:empty_project) }
+  let!(:user) { create(:user) }
+
+  before do
+    project.team << [user, :master]
+    sign_in(user)
+  end
+
+  describe 'GET #new' do
+    before do
+      allow_any_instance_of(MattermostSlashCommandsService).
+        to receive(:list_teams).and_return([])
+
+      get(:new,
+          namespace_id: project.namespace.to_param,
+          project_id: project.to_param)
+    end
+
+    it 'accepts the request' do
+      expect(response).to have_http_status(200)
+    end
+  end
+
+  describe 'POST #create' do
+    let(:mattermost_params) { { trigger: 'http://localhost:3000/trigger', team_id: 'abc' } }
+
+    subject do
+      post(:create,
+           namespace_id: project.namespace.to_param,
+           project_id: project.to_param,
+           mattermost: mattermost_params)
+    end
+
+    context 'no request can be made to mattermost' do
+      it 'shows the error' do
+        allow_any_instance_of(MattermostSlashCommandsService).to receive(:configure).and_return([false, "error message"])
+
+        expect(subject).to redirect_to(new_namespace_project_mattermost_url(project.namespace, project))
+      end
+    end
+
+    context 'the request is succesull' do
+      before do
+        allow_any_instance_of(Mattermost::Command).to receive(:create).and_return('token')
+      end
+
+      it 'redirects to the new page' do
+        subject
+        service = project.services.last
+
+        expect(subject).to redirect_to(edit_namespace_project_service_url(project.namespace, project, service))
+      end
+    end
+  end
+end
diff --git a/spec/features/projects/services/mattermost_slash_command_spec.rb b/spec/features/projects/services/mattermost_slash_command_spec.rb
index f474e7e891b..274d50e7ce4 100644
--- a/spec/features/projects/services/mattermost_slash_command_spec.rb
+++ b/spec/features/projects/services/mattermost_slash_command_spec.rb
@@ -4,29 +4,26 @@ feature 'Setup Mattermost slash commands', feature: true do
   include WaitForAjax
 
   let(:user) { create(:user) }
-  let(:project) { create(:project) }
+  let(:project) { create(:empty_project) }
   let(:service) { project.create_mattermost_slash_commands_service }
+  let(:mattermost_enabled) { true }
 
   before do
+    Settings.mattermost['enabled'] = mattermost_enabled
     project.team << [user, :master]
     login_as(user)
+    visit edit_namespace_project_service_path(project.namespace, project, service)
   end
 
-  describe 'user visites the mattermost slash command config page', js: true do
+  describe 'user visits the mattermost slash command config page', js: true do
     it 'shows a help message' do
-      visit edit_namespace_project_service_path(project.namespace, project, service)
-
       wait_for_ajax
 
       expect(page).to have_content("This service allows GitLab users to perform common")
     end
-  end
-
-  describe 'saving a token' do
-    let(:token) { ('a'..'z').to_a.join }
 
     it 'shows the token after saving' do
-      visit edit_namespace_project_service_path(project.namespace, project, service)
+      token = ('a'..'z').to_a.join
 
       fill_in 'service_token', with: token
       click_on 'Save'
@@ -35,14 +32,21 @@ feature 'Setup Mattermost slash commands', feature: true do
 
       expect(value).to eq(token)
     end
-  end
 
-  describe 'the trigger url' do
-    it 'shows the correct url' do
-      visit edit_namespace_project_service_path(project.namespace, project, service)
+    describe 'mattermost service is enabled' do
+      it 'shows the add to mattermost button' do
+        expect(page).to have_link 'Add to Mattermost'
+      end
+    end
+
+    describe 'mattermost service is not enabled' do
+      let(:mattermost_enabled) { false }
+
+      it 'shows the correct trigger url' do
+        value = find_field('request_url').value
 
-      value = find_field('request_url').value
-      expect(value).to match("api/v3/projects/#{project.id}/services/mattermost_slash_commands/trigger")
+        expect(value).to match("api/v3/projects/#{project.id}/services/mattermost_slash_commands/trigger")
+      end
     end
   end
 end
diff --git a/spec/lib/mattermost/client_spec.rb b/spec/lib/mattermost/client_spec.rb
new file mode 100644
index 00000000000..dc11a414717
--- /dev/null
+++ b/spec/lib/mattermost/client_spec.rb
@@ -0,0 +1,24 @@
+require 'spec_helper'
+
+describe Mattermost::Client do
+  let(:user) { build(:user) }
+
+  subject { described_class.new(user) }
+
+  context 'JSON parse error' do
+    before do
+      Struct.new("Request", :body, :success?)
+    end
+
+    it 'yields an error on malformed JSON' do
+      bad_json = Struct::Request.new("I'm not json", true)
+      expect { subject.send(:json_response, bad_json) }.to raise_error(Mattermost::ClientError)
+    end
+
+    it 'shows a client error if the request was unsuccessful' do
+      bad_request = Struct::Request.new("true", false)
+
+      expect { subject.send(:json_response, bad_request) }.to raise_error(Mattermost::ClientError)
+    end
+  end
+end
diff --git a/spec/lib/mattermost/command_spec.rb b/spec/lib/mattermost/command_spec.rb
new file mode 100644
index 00000000000..5ccf1100898
--- /dev/null
+++ b/spec/lib/mattermost/command_spec.rb
@@ -0,0 +1,61 @@
+require 'spec_helper'
+
+describe Mattermost::Command do
+  let(:params) { { 'token' => 'token', team_id: 'abc' } }
+
+  before do
+    Mattermost::Session.base_uri('http://mattermost.example.com')
+
+    allow_any_instance_of(Mattermost::Client).to receive(:with_session).
+      and_yield(Mattermost::Session.new(nil))
+  end
+
+  describe '#create' do
+    let(:params) do
+      { team_id: 'abc',
+        trigger: 'gitlab'
+      }
+    end
+
+    subject { described_class.new(nil).create(params) }
+
+    context 'for valid trigger word' do
+      before do
+        stub_request(:post, 'http://mattermost.example.com/api/v3/teams/abc/commands/create').
+          with(body: {
+            team_id: 'abc',
+            trigger: 'gitlab' }.to_json).
+          to_return(
+            status: 200,
+            headers: { 'Content-Type' => 'application/json' },
+            body: { token: 'token' }.to_json
+          )
+      end
+
+      it 'returns a token' do
+        is_expected.to eq('token')
+      end
+    end
+
+    context 'for error message' do
+      before do
+        stub_request(:post, 'http://mattermost.example.com/api/v3/teams/abc/commands/create').
+          to_return(
+            status: 500,
+            headers: { 'Content-Type' => 'application/json' },
+            body: {
+              id: 'api.command.duplicate_trigger.app_error',
+              message: 'This trigger word is already in use. Please choose another word.',
+              detailed_error: '',
+              request_id: 'obc374man7bx5r3dbc1q5qhf3r',
+              status_code: 500
+            }.to_json
+          )
+      end
+
+      it 'raises an error with message' do
+        expect { subject }.to raise_error(Mattermost::Error, 'This trigger word is already in use. Please choose another word.')
+      end
+    end
+  end
+end
diff --git a/spec/lib/mattermost/session_spec.rb b/spec/lib/mattermost/session_spec.rb
index 3c2eddbd221..74d12e37181 100644
--- a/spec/lib/mattermost/session_spec.rb
+++ b/spec/lib/mattermost/session_spec.rb
@@ -95,5 +95,29 @@ describe Mattermost::Session, type: :request do
         end
       end
     end
+
+    context 'with lease' do
+      before do
+        allow(subject).to receive(:lease_try_obtain).and_return('aldkfjsldfk')
+      end
+
+      it 'tries to obtain a lease' do
+        expect(subject).to receive(:lease_try_obtain)
+        expect(Gitlab::ExclusiveLease).to receive(:cancel)
+
+        # Cannot setup a session, but we should still cancel the lease
+        expect { subject.with_session }.to raise_error(Mattermost::NoSessionError)
+      end
+    end
+
+    context 'without lease' do
+      before do
+        allow(subject).to receive(:lease_try_obtain).and_return(nil)
+      end
+
+      it 'returns a NoSessionError error' do
+        expect { subject.with_session }.to raise_error(Mattermost::NoSessionError)
+      end
+    end
   end
 end
diff --git a/spec/lib/mattermost/team_spec.rb b/spec/lib/mattermost/team_spec.rb
new file mode 100644
index 00000000000..2d14be6bcc2
--- /dev/null
+++ b/spec/lib/mattermost/team_spec.rb
@@ -0,0 +1,66 @@
+require 'spec_helper'
+
+describe Mattermost::Team do
+  before do
+    Mattermost::Session.base_uri('http://mattermost.example.com')
+
+    allow_any_instance_of(Mattermost::Client).to receive(:with_session).
+      and_yield(Mattermost::Session.new(nil))
+  end
+
+  describe '#all' do
+    subject { described_class.new(nil).all }
+
+    context 'for valid request' do
+      let(:response) do
+        [{
+           "id" => "xiyro8huptfhdndadpz8r3wnbo",
+           "create_at" => 1482174222155,
+           "update_at" => 1482174222155,
+           "delete_at" => 0,
+           "display_name" => "chatops",
+           "name" => "chatops",
+           "email" => "admin@example.com",
+           "type" => "O",
+           "company_name" => "",
+           "allowed_domains" => "",
+           "invite_id" => "o4utakb9jtb7imctdfzbf9r5ro",
+           "allow_open_invite" => false }]
+      end
+
+      before do
+        stub_request(:get, 'http://mattermost.example.com/api/v3/teams/all').
+          to_return(
+            status: 200,
+            headers: { 'Content-Type' => 'application/json' },
+            body: response.to_json
+          )
+      end
+
+      it 'returns a token' do
+        is_expected.to eq(response)
+      end
+    end
+
+    context 'for error message' do
+      before do
+        stub_request(:get, 'http://mattermost.example.com/api/v3/teams/all').
+          to_return(
+            status: 500,
+            headers: { 'Content-Type' => 'application/json' },
+            body: {
+              id: 'api.team.list.app_error',
+              message: 'Cannot list teams.',
+              detailed_error: '',
+              request_id: 'obc374man7bx5r3dbc1q5qhf3r',
+              status_code: 500
+            }.to_json
+          )
+      end
+
+      it 'raises an error with message' do
+        expect { subject }.to raise_error(Mattermost::Error, 'Cannot list teams.')
+      end
+    end
+  end
+end
diff --git a/spec/models/project_services/mattermost_slash_commands_service_spec.rb b/spec/models/project_services/mattermost_slash_commands_service_spec.rb
index 1ae1483e2a4..d6f4fbd7265 100644
--- a/spec/models/project_services/mattermost_slash_commands_service_spec.rb
+++ b/spec/models/project_services/mattermost_slash_commands_service_spec.rb
@@ -2,4 +2,123 @@ require 'spec_helper'
 
 describe MattermostSlashCommandsService, :models do
   it_behaves_like "chat slash commands service"
+
+  context 'Mattermost API' do
+    let(:project) { create(:empty_project) }
+    let(:service) { project.build_mattermost_slash_commands_service }
+    let(:user) { create(:user)}
+
+    before do
+      Mattermost::Session.base_uri("http://mattermost.example.com")
+
+      allow_any_instance_of(Mattermost::Client).to receive(:with_session).
+        and_yield(Mattermost::Session.new(nil))
+    end
+
+    describe '#configure' do
+      subject do
+        service.configure(user, team_id: 'abc',
+                                trigger: 'gitlab', url: 'http://trigger.url',
+                                icon_url: 'http://icon.url/icon.png')
+      end
+
+      context 'the requests succeeds' do
+        before do
+          stub_request(:post, 'http://mattermost.example.com/api/v3/teams/abc/commands/create').
+            with(body: {
+              team_id: 'abc',
+              trigger: 'gitlab',
+              url: 'http://trigger.url',
+              icon_url: 'http://icon.url/icon.png',
+              auto_complete: true,
+              auto_complete_desc: "Perform common operations on: #{project.name_with_namespace}",
+              auto_complete_hint: '[help]',
+              description: "Perform common operations on: #{project.name_with_namespace}",
+              display_name: "GitLab / #{project.name_with_namespace}",
+              method: 'P',
+              user_name: 'GitLab' }.to_json).
+            to_return(
+              status: 200,
+              headers: { 'Content-Type' => 'application/json' },
+              body: { token: 'token' }.to_json
+            )
+        end
+
+        it 'saves the service' do
+          expect { subject }.to change { project.services.count }.by(1)
+        end
+
+        it 'saves the token' do
+          subject
+
+          expect(service.reload.token).to eq('token')
+        end
+      end
+
+      context 'an error is received' do
+        before do
+          stub_request(:post, 'http://mattermost.example.com/api/v3/teams/abc/commands/create').
+            to_return(
+              status: 500,
+              headers: { 'Content-Type' => 'application/json' },
+              body: {
+                id: 'api.command.duplicate_trigger.app_error',
+                message: 'This trigger word is already in use. Please choose another word.',
+                detailed_error: '',
+                request_id: 'obc374man7bx5r3dbc1q5qhf3r',
+                status_code: 500
+              }.to_json
+            )
+        end
+
+        it 'shows error messages' do
+          succeeded, message = subject
+
+          expect(succeeded).to be(false)
+          expect(message).to eq('This trigger word is already in use. Please choose another word.')
+        end
+      end
+    end
+
+    describe '#list_teams' do
+      subject do
+        service.list_teams(user)
+      end
+
+      context 'the requests succeeds' do
+        before do
+          stub_request(:get, 'http://mattermost.example.com/api/v3/teams/all').
+            to_return(
+              status: 200,
+              headers: { 'Content-Type' => 'application/json' },
+              body: ['list'].to_json
+            )
+        end
+
+        it 'returns a list of teams' do
+          expect(subject).not_to be_empty
+        end
+      end
+
+      context 'an error is received' do
+        before do
+          stub_request(:get, 'http://mattermost.example.com/api/v3/teams/all').
+            to_return(
+              status: 500,
+              headers: { 'Content-Type' => 'application/json' },
+              body: {
+                message: 'Failed to get team list.'
+              }.to_json
+            )
+        end
+
+        it 'shows error messages' do
+          teams, message = subject
+
+          expect(teams).to be_empty
+          expect(message).to eq('Failed to get team list.')
+        end
+      end
+    end
+  end
 end