Set warning header for outdated CF CLIs

Introduces a new (optional) middleware which will warn CF CLI users if their version is below `min_cli_version`.
Needs to be explicitly enabled by setting the config flag `warn_if_below_min_cli_version` to `true`.

lib/cloud_controller/config_schemas/base/api_schema.rb

@@ -16,6 +16,7 @@ class ApiSchema < VCAP::Config
             external_protocol: String,
             internal_service_hostname: String,
             optional(:internal_service_port) => Integer,
+            optional(:warn_if_below_min_cli_version) => bool,
             info: {
               name: String,
               build: String,

lib/cloud_controller/rack_app_builder.rb

@@ -11,6 +11,7 @@
 require 'new_relic_custom_attributes'
 require 'zipkin'
 require 'block_v3_only_roles'
+require 'below_min_cli_warning'
 
 module VCAP::CloudController
   class RackAppBuilder
@@ -24,6 +25,7 @@ def build(config, request_metrics, request_logs)
         use CloudFoundry::Middleware::RequestMetrics, request_metrics
         use CloudFoundry::Middleware::Cors, config.get(:allowed_cors_domains)
         use CloudFoundry::Middleware::VcapRequestId
+        use CloudFoundry::Middleware::BelowMinCliWarning if config.get(:warn_if_below_min_cli_version)
         use CloudFoundry::Middleware::NewRelicCustomAttributes if config.get(:newrelic_enabled)
         use Honeycomb::Rack::Middleware, client: Honeycomb.client if config.get(:honeycomb)
         use CloudFoundry::Middleware::SecurityContextSetter, configurer

middleware/below_min_cli_warning.rb

@@ -0,0 +1,54 @@
+module CloudFoundry
+  module Middleware
+    class BelowMinCliWarning
+      def initialize(app)
+        @app = app
+        @min_cli_version = Gem::Version.new(VCAP::CloudController::Config.config.get(:info, :min_cli_version))
+      end
+
+      def call(env)
+        status, headers, body = @app.call(env)
+
+        included_endpoints = %w[/v3/spaces /v3/organizations /v2/spaces /v2/organizations]
+
+        if included_endpoints.any? { |ep| env['REQUEST_PATH'].include?(ep) } && is_below_min_cli_version?(env['HTTP_USER_AGENT'])
+          # Ensure existing warnings are appended by ',' (unicode %2C)
+          new_warning = env['X-Cf-Warnings'].nil? ? escaped_warning : "#{env['X-Cf-Warnings']}%2C#{escaped_warning}"
+          headers['X-Cf-Warnings'] = new_warning
+        end
+
+        [status, headers, body]
+      end
+
+      def escaped_warning
+        CGI.escape("\u{1F6A8} [WARNING] Outdated CF CLI version - please upgrade: https://github.com/cloudfoundry/cli/releases/latest \u{1F6A8}\n")
+      end
+
+      def is_below_min_cli_version?(user_agent_string)
+        regex = %r{
+            [cC][fF]      # match 'cf', case insensitive
+            [^/]*        # match any character that are not '/'
+            /            # match '/' character
+            (\d+\.\d+\.\d+)  # capture the version number (expecting 3 groups of digits separated by '.')
+            (?:\+|\s)     # match '+' character or a whitespace, non-capturing group
+          }x
+
+        match = user_agent_string.match(regex)
+        return false unless match
+
+        current_version = Gem::Version.new(match[1])
+
+        current_version < @min_cli_version
+      rescue StandardError => e
+        logger.warn("Warning: An error occurred while checking user agent version: #{e.message}")
+        false
+      end
+
+      private
+
+      def logger
+        @logger = Steno.logger('cc.deprecated_cf_cli_warning')
+      end
+    end
+  end
+end

spec/unit/lib/cloud_controller/rack_app_builder_spec.rb

@@ -216,6 +216,28 @@ module VCAP::CloudController
           expect(CloudFoundry::Middleware::CefLogs).to have_received(:new).with(anything, fake_logger, TestConfig.config_instance.get(:local_route))
         end
       end
+
+      describe 'Deprecated CF CLI Warning' do
+        before do
+          allow(CloudFoundry::Middleware::BelowMinCliWarning).to receive(:new)
+        end
+
+        context 'with min_cf_cli_version provided' do
+          before do
+            builder.build(TestConfig.override(info: { min_cli_version: '7.0.0' }, warn_if_below_min_cli_version: true), request_metrics, request_logs).to_app
+          end
+
+          it 'enables the DeprecatedCfCliWarning middleware' do
+            expect(CloudFoundry::Middleware::BelowMinCliWarning).to have_received(:new)
+          end
+        end
+
+        context 'without min_cf_cli_version provided' do
+          it 'does not enable the DeprecatedCfCliWarning middleware' do
+            expect(CloudFoundry::Middleware::BelowMinCliWarning).not_to have_received(:new)
+          end
+        end
+      end
     end
   end
 end

spec/unit/middleware/below_min_cli_warning_spec.rb

@@ -0,0 +1,79 @@
+require 'spec_helper'
+require 'below_min_cli_warning'
+
+module CloudFoundry
+  module Middleware
+    RSpec.describe BelowMinCliWarning do
+      subject { described_class.new(app) }
+      let(:app) { double(:app, call: [200, {}, 'a body']) }
+      let(:env) { { 'HTTP_USER_AGENT' => 'mocked-user-agent', 'REQUEST_PATH' => '/v3/organizations' } }
+
+      before { TestConfig.override(info: { min_cli_version: '7.0.0' }, warn_if_below_min_cli_version: true) }
+
+      describe 'deprecated cf cli version middleware is called' do
+        context 'called with outdated cf cli version' do
+          before { allow(subject).to receive(:is_below_min_cli_version?).and_return(true) }
+
+          it 'sets X-Cf-Warnings header' do
+            _, headers = subject.call(env)
+            expect(headers['X-Cf-Warnings']).to eq(subject.escaped_warning)
+          end
+
+          it 'appends to the existing X-Cf-Warnings header' do
+            _, headers = subject.call(env.merge!({ 'X-Cf-Warnings' => 'a-warning' }))
+            expect(headers['X-Cf-Warnings']).to eq("a-warning%2C#{subject.escaped_warning}")
+          end
+        end
+
+        context 'called with current cf cli version' do
+          before { allow(subject).to receive(:is_below_min_cli_version?).and_return(false) }
+
+          it 'does not add X-Cf-Warnings header' do
+            _, headers = subject.call(env)
+            expect(headers['X-Cf-Warnings']).to be_nil
+          end
+        end
+
+        context 'checks the request path' do
+          before { allow(subject).to receive(:is_below_min_cli_version?).and_return(true) }
+
+          %w[/v3/processes /v2/services /something/stats].each do |endpoint|
+            it "does not set X-Cf-Warnings header for #{endpoint}" do
+              _, headers = subject.call(env.merge!({ 'REQUEST_PATH' => endpoint }))
+              expect(headers['X-Cf-Warnings']).to be_nil
+            end
+          end
+
+          %w[/v3/spaces /v2/spaces /v3/organizations /v2/organizations].each do |endpoint|
+            it "sets X-Cf-Warnings header for #{endpoint}" do
+              _, headers = subject.call(env.merge!({ 'REQUEST_PATH' => endpoint }))
+              expect(headers['X-Cf-Warnings']).to eq(subject.escaped_warning)
+            end
+          end
+        end
+      end
+
+      describe 'is_outdated_cf_cli_user_agent?' do
+        ['some-client',
+         'cf7/7.5.0+0ad1d6398.2022-06-04 (go1.17.10; amd64 windows)',
+         'cf/7.7.2+b663981.2023-08-31 (go1.20.7; amd64 linux)',
+         'cf/8.7.5+8aa8625.2023-11-20 (go1.21.4; arm64 darwin)',
+         'cf8.exe/8.3.0+e6f8a853a.2022-03-11 (go1.17.7; amd64 windows)',
+         'cf8/8.7.4+db5d612.2023-10-20 (go1.21.3; amd64 linux)',
+         'cf.exe/7.4.0+e55633fed.2021-11-15 (go1.16.6; amd64 windows)',
+         'Cf/8.5.0+73aa161.2022-09-12 (go1.18.5; arm64 darwin)'].each do |user_agent|
+          it("returns false for #{user_agent}") { expect(subject).not_to be_is_below_min_cli_version(user_agent) }
+        end
+
+        ['cf/6.46.0+29d6257f1.2019-07-09 (go1.12.7; amd64 windows)',
+         'CF/6.46.0+29d6257f1.2019-07-09 (go1.12.7; amd64 windows)',
+         'Cf/6.46.0+29d6257f1.2019-07-09 (go1.12.7; amd64 windows)',
+         'cf.exe/6.6.0+e25762999.2023-02-16 (go1.19.5; amd64 windows)',
+         'cf/6.43.0 (go1.10.8; amd64 linux)',
+         'cf6/6.53.0+bommel'].each do |user_agent|
+          it("returns true for #{user_agent}") { expect(subject).to be_is_below_min_cli_version(user_agent) }
+        end
+      end
+    end
+  end
+end