Add ability to restrict which accounts can work with stacks

README.md

@@ -91,10 +91,14 @@ stacks:
   staging:
     myapp-vpc:
       template: myapp_vpc.rb
+      allowed_accounts: '123456789'
       tags:
         purpose: front-end
     myapp-db:
       template: myapp_db.rb
+      allowed_accounts:
+        - '1234567890'
+        - '9876543210'
       tags:
         purpose: back-end
     myapp-web:
@@ -545,6 +549,44 @@ end
 
 Note though that if a dynamic with the same name exists in your `templates/dynamics/` directory it will get loaded since it has higher precedence.
 
+## Allowed accounts
+
+The AWS account the command is executing in can be restricted to a specific list of allowed accounts. This is useful in reducing the possibility of applying non-production changes in a production account. Each stack definition can specify the `allowed_accounts` property with an array of AWS account IDs the stack is allowed to work with.
+
+This is an opt-in feature which is enabled by specifying at least one account to allow.
+
+Unlike other stack defaults, the `allowed_accounts` property values specified in the stack definition override values specified in the stack defaults (i.e., other stack property values are merged together with those specified in the stack defaults). This allows specifying allowed accounts in the stack defaults (inherited by all stacks) and override them for specific stacks. See below example config for an example.
+
+```yaml
+stack_defaults:
+  allowed_accounts: '555555555'
+stacks:
+  us-east-1:
+    myapp-vpc: # only allow account 555555555 (inherited from the stack defaults)
+      template: myapp_vpc.rb
+      tags:
+        purpose: front-end
+    myapp-db:
+      template: myapp_db.rb
+      allowed_accounts: # only allow these accounts (overrides the stack defaults)
+        - '1234567890'
+        - '9876543210'
+      tags:
+        purpose: back-end
+    myapp-web:
+      template: myapp_web.rb
+      allowed_accounts: [] # allow all accounts (overrides the stack defaults)
+      tags:
+        purpose: front-end
+    myapp-redis:
+      template: myapp_redis.rb
+      allowed_accounts: '888888888' # only allow this account (overrides the stack defaults)
+      tags:
+        purpose: back-end
+```
+
+In the cases where you want to bypass the account check, there is StackMaster flag `--skip-account-check` that can be used.
+
 ## Commands
 
 ```bash

features/apply_with_allowed_accounts.feature

@@ -0,0 +1,55 @@
+Feature: Apply command with allowed accounts
+
+  Background:
+    Given a file named "stack_master.yml" with:
+      """
+      stack_defaults:
+        allowed_accounts:
+          - '11111111'
+      stacks:
+        us_east_1:
+          myapp_vpc:
+            template: myapp.rb
+          myapp_db:
+            template: myapp.rb
+            allowed_accounts: '22222222'
+          myapp_web:
+            template: myapp.rb
+            allowed_accounts: []
+      """
+    And a directory named "templates"
+    And a file named "templates/myapp.rb" with:
+      """
+      SparkleFormation.new(:myapp) do
+        description "Test template"
+        set!('AWSTemplateFormatVersion', '2010-09-09')
+      end
+      """
+
+  Scenario: Run apply with stack inheriting allowed accounts from stack defaults
+    Given I stub the following stack events:
+      | stack_id | event_id | stack_name | logical_resource_id | resource_status | resource_type              | timestamp           |
+      | 1        | 1        | myapp-vpc  | myapp-vpc           | CREATE_COMPLETE | AWS::CloudFormation::Stack | 2020-10-29 00:00:00 |
+    When I use the account "11111111"
+    And I run `stack_master apply us-east-1 myapp-vpc`
+    And the output should match /2020-10-29 00:00:00 (\+|\-)[0-9]{4} myapp-vpc AWS::CloudFormation::Stack CREATE_COMPLETE/
+    Then the exit status should be 0
+
+  Scenario: Run apply with stack overriding allowed accounts with its own list
+    Given I stub the following stack events:
+      | stack_id | event_id | stack_name | logical_resource_id | resource_status | resource_type              | timestamp           |
+      | 1        | 1        | myapp-db   | myapp-db            | CREATE_COMPLETE | AWS::CloudFormation::Stack | 2020-10-29 00:00:00 |
+    When I use the account "11111111"
+    And I run `stack_master apply us-east-1 myapp-db`
+    And the output should contain all of these lines:
+      | Account '11111111' is not an allowed account. Allowed accounts are ["22222222"].|
+    Then the exit status should be 0
+
+  Scenario: Run apply with stack overriding allowed accounts to allow all accounts
+    Given I stub the following stack events:
+      | stack_id | event_id | stack_name | logical_resource_id | resource_status | resource_type              | timestamp           |
+      | 1        | 1        | myapp-web  | myapp-web           | CREATE_COMPLETE | AWS::CloudFormation::Stack | 2020-10-29 00:00:00 |
+    When I use the account "33333333"
+    And I run `stack_master apply us-east-1 myapp-web`
+    And the output should match /2020-10-29 00:00:00 (\+|\-)[0-9]{4} myapp-web AWS::CloudFormation::Stack CREATE_COMPLETE/
+    Then the exit status should be 0

features/step_definitions/identity_steps.rb

@@ -0,0 +1,11 @@
+Given(/^I use the account "([^"]*)"$/) do |account_id|
+  Aws.config[:sts] = {
+    stub_responses: {
+      get_caller_identity: {
+        account: account_id,
+        arn: 'an-arn',
+        user_id: 'a-user-id'
+      }
+    }
+  }
+end

lib/stack_master.rb

@@ -38,6 +38,7 @@ module StackMaster
   autoload :PagedResponseAccumulator, 'stack_master/paged_response_accumulator'
   autoload :StackDefinition, 'stack_master/stack_definition'
   autoload :TemplateCompiler, 'stack_master/template_compiler'
+  autoload :Identity, 'stack_master/identity'
 
   autoload :StackDiffer, 'stack_master/stack_differ'
   autoload :Validator, 'stack_master/validator'
@@ -97,6 +98,7 @@ module StackEvents
   NON_INTERACTIVE_DEFAULT = false
   DEBUG_DEFAULT = false
   QUIET_DEFAULT = false
+  SKIP_ACCOUNT_CHECK_DEFAULT = false
 
   def interactive?
     !non_interactive?
@@ -136,6 +138,16 @@ def quiet?
 
   def reset_flags
     @quiet = QUIET_DEFAULT
+    @skip_account_check = SKIP_ACCOUNT_CHECK_DEFAULT
+  end
+
+  def skip_account_check!
+    @skip_account_check = true
+  end
+  @skip_account_check = SKIP_ACCOUNT_CHECK_DEFAULT
+
+  def skip_account_check?
+    @skip_account_check
   end
 
   attr_accessor :non_interactive_answer

lib/stack_master/cli.rb

@@ -34,6 +34,9 @@ def execute!
       global_option '-q', '--quiet', 'Do not output the resulting Stack Events, just return immediately' do
         StackMaster.quiet!
       end
+      global_option '--skip-account-check', 'Do not check if command is allowed to execute in account' do
+        StackMaster.skip_account_check!
+      end
 
       command :apply do |c|
         c.syntax = 'stack_master apply [region_or_alias] [stack_name]'
@@ -178,18 +181,22 @@ def execute!
             return
           end
 
+          stack_name = Utils.underscore_to_hyphen(args[1])
+          allowed_accounts = []
+
           # Because delete can work without a stack_master.yml
           if options.config and File.file?(options.config)
             config = load_config(options.config)
             region = Utils.underscore_to_hyphen(config.unalias_region(args[0]))
+            allowed_accounts = config.find_stack(region, stack_name)&.allowed_accounts
           else
             region = args[0]
           end
 
-          stack_name = Utils.underscore_to_hyphen(args[1])
-
-          StackMaster.cloud_formation_driver.set_region(region)
-          StackMaster::Commands::Delete.perform(region, stack_name)
+          execute_if_allowed_account(allowed_accounts) do
+            StackMaster.cloud_formation_driver.set_region(region)
+            StackMaster::Commands::Delete.perform(region, stack_name)
+          end
         end
       end
 
@@ -223,15 +230,35 @@ def execute_stacks_command(command, args, options)
           success = false
         end
         stack_definitions = stack_definitions.select do |stack_definition|
-          StackStatus.new(config, stack_definition).changed?
+          running_in_allowed_account?(stack_definition.allowed_accounts) && StackStatus.new(config, stack_definition).changed?
         end if options.changed
         stack_definitions.each do |stack_definition|
           StackMaster.cloud_formation_driver.set_region(stack_definition.region)
           StackMaster.stdout.puts "Executing #{command.command_name} on #{stack_definition.stack_name} in #{stack_definition.region}"
-          success = false unless command.perform(config, stack_definition, options).success?
+          success = execute_if_allowed_account(stack_definition.allowed_accounts) do
+            command.perform(config, stack_definition, options).success?
+          end
         end
       end
       success
     end
+
+    def execute_if_allowed_account(allowed_accounts, &block)
+      raise ArgumentError, "Block required to execute this method" unless block_given?
+      if running_in_allowed_account?(allowed_accounts)
+        block.call
+      else
+        StackMaster.stdout.puts "Account '#{identity.account}' is not an allowed account. Allowed accounts are #{allowed_accounts}."
+        false
+      end
+    end
+
+    def running_in_allowed_account?(allowed_accounts)
+      StackMaster.skip_account_check? || identity.running_in_allowed_account?(allowed_accounts)
+    end
+
+    def identity
+      @identity ||= StackMaster::Identity.new
+    end
   end
 end

lib/stack_master/commands/status.rb

@@ -16,12 +16,13 @@ def perform
         progress if @show_progress
         status = @config.stacks.map do |stack_definition|
           stack_status = StackStatus.new(@config, stack_definition)
+          allowed_accounts = stack_definition.allowed_accounts
           progress.increment if @show_progress
           {
             region: stack_definition.region,
             stack_name: stack_definition.stack_name,
-            stack_status: stack_status.status,
-            different: stack_status.changed_message,
+            stack_status: running_in_allowed_account?(allowed_accounts) ? stack_status.status : "Disallowed account",
+            different: running_in_allowed_account?(allowed_accounts) ? stack_status.changed_message : "N/A",
           }
         end
         tp.set :max_width, self.window_size
@@ -41,6 +42,14 @@ def progress
       def sort_params(hash)
         hash.sort.to_h
       end
+
+      def running_in_allowed_account?(allowed_accounts)
+        StackMaster.skip_account_check? || identity.running_in_allowed_account?(allowed_accounts)
+      end
+
+      def identity
+        @identity ||= StackMaster::Identity.new
+      end
     end
   end
 end

lib/stack_master/config.rb

@@ -116,6 +116,7 @@ def load_stacks(stacks)
             'base_dir' => @base_dir,
             'template_dir' => @template_dir,
             'additional_parameter_lookup_dirs' => @region_to_aliases[region])
+          stack_attributes['allowed_accounts'] = attributes['allowed_accounts'] if attributes['allowed_accounts']
           @stacks << StackDefinition.new(stack_attributes)
         end
       end

lib/stack_master/identity.rb

@@ -0,0 +1,23 @@
+module StackMaster
+  class Identity
+    def running_in_allowed_account?(allowed_accounts)
+      allowed_accounts.nil? || allowed_accounts.empty? || allowed_accounts.include?(account)
+    end
+
+    def account
+      @account ||= sts.get_caller_identity.account
+    end
+
+    private
+
+    attr_reader :sts
+
+    def region
+      @region ||= ENV['AWS_REGION'] || Aws.config[:region] || Aws.shared_config.region || 'us-east-1'
+    end
+
+    def sts
+      @sts ||= Aws::STS::Client.new(region: region)
+    end
+  end
+end

lib/stack_master/stack_definition.rb

@@ -5,6 +5,7 @@ class StackDefinition
                   :template,
                   :tags,
                   :role_arn,
+                  :allowed_accounts,
                   :notification_arns,
                   :base_dir,
                   :template_dir,
@@ -23,8 +24,10 @@ def initialize(attributes = {})
       @notification_arns = []
       @s3 = {}
       @files = []
+      @allowed_accounts = nil
       super
       @template_dir ||= File.join(@base_dir, 'templates')
+      @allowed_accounts = Array(@allowed_accounts)
     end
 
     def ==(other)
@@ -34,6 +37,7 @@ def ==(other)
         @template == other.template &&
         @tags == other.tags &&
         @role_arn == other.role_arn &&
+        @allowed_accounts == other.allowed_accounts &&
         @notification_arns == other.notification_arns &&
         @base_dir == other.base_dir &&
         @secret_file == other.secret_file &&

spec/fixtures/stack_master.yml

@@ -2,6 +2,8 @@ region_aliases:
   production: us-east-1
   staging: ap-southeast-2
 stack_defaults:
+  allowed_accounts:
+    - '555555555'
   tags:
     application: my-awesome-blog
   s3:
@@ -35,6 +37,7 @@ stacks:
       role_arn: test_service_role_arn2
     myapp_web:
       template: myapp_web.rb
+      allowed_accounts: '1234567890'
     myapp_vpc_with_secrets:
       template: myapp_vpc.json
   ap-southeast-2:
@@ -45,5 +48,8 @@ stacks:
       role_arn: test_service_role_arn4
     myapp_web:
       template: myapp_web
+      allowed_accounts:
+        - '1234567890'
+        - '9876543210'
       tags:
         test_override: 2