Add connector for Ubuntu Security Api

Gemfile

@@ -43,3 +43,5 @@ group :development, optional: true do
 end
 
 gem "feedjira", "~> 3.2", group: :monitor
+
+gem "faraday", "~> 2.12", group: :monitor

Gemfile.lock

@@ -9,6 +9,12 @@ GEM
     crass (1.0.6)
     diff-lcs (1.5.1)
     docile (1.4.1)
+    faraday (2.12.0)
+      faraday-net_http (>= 2.0, < 3.4)
+      json
+      logger
+    faraday-net_http (3.3.0)
+      net-http
     feedjira (3.2.3)
       loofah (>= 2.3.1, < 3)
       sax-machine (>= 1.0, < 2)
@@ -17,10 +23,13 @@ GEM
     json-stream (1.0.0)
     json-streamer (2.1.0)
       json-stream
+    logger (1.6.1)
     loofah (2.23.1)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)
     method_source (1.1.0)
+    net-http (0.4.1)
+      uri
     nokogiri (1.16.7-x86_64-linux)
       racc (~> 1.4)
     parallel (1.20.1)
@@ -78,13 +87,15 @@ GEM
     test-unit (3.6.2)
       power_assert
     unicode-display_width (2.6.0)
+    uri (0.13.1)
 
 PLATFORMS
   x86_64-linux
 
 DEPENDENCIES
   byebug (~> 11.1)
   bzip2-ffi (~> 1.0)
+  faraday (~> 2.12)
   feedjira (~> 3.2)
   json-streamer (~> 2.1)
   parallel (~> 1.20, < 1.21)

lib/ubuntu_security_api.rb

@@ -0,0 +1,72 @@
+# frozen_string_literal: true
+
+require 'faraday'
+require 'date'
+
+# API doc: https://ubuntu.com/security/api/docs
+class UbuntuSecurityApi
+  attr_accessor :retry
+
+  def initialize(opts={})
+    @base_url = 'https://ubuntu.com'
+    @retry = opts[:retry]
+  end
+
+  def yesterdays_erratum(release=nil)
+    # ASSUMPTION: among the latest 5 USNs there should be at least one older than one day
+    res = latest_errata(release, 5).select { |usn| Date.parse(usn['published']) < Date.today }
+
+    raise 'Could not find USN older than one day among the newest 5' if res.empty?
+
+    res.first
+  end
+
+  def latest_errata(release=nil, limit=nil)
+    opts = {
+      order: 'newest',
+      show_hidden: false
+    }
+    opts[:release] = release unless release.nil?
+
+    opts[:limit] = limit unless limit.nil?
+
+    attempt = @retry
+    begin
+      res = conn.get('/security/notices.json', opts)
+      res.body['notices']
+    rescue Faraday::ServerError
+      raise if attempt.nil? || attempt.zero?
+
+      attempt -= 1
+      retry
+    end
+  end
+
+  def latest_erratum(release=nil)
+    latest_errata(release, 1).first
+  end
+
+  private
+
+  def conn
+    @conn ||= Faraday.new(
+      url: @base_url,
+      headers: { 'Content-Type' => 'application/json' }
+    ) do |builder|
+      # Sets the Content-Type header to application/json on each request.
+      # Also, if the request body is a Hash, it will automatically be encoded as JSON.
+      builder.request :json
+
+      # Parses JSON response bodies.
+      # If the response body is not valid JSON, it will raise a Faraday::ParsingError.
+      builder.response :json
+
+      # Raises an error on 4xx and 5xx responses.
+      builder.response :raise_error
+
+      # Logs requests and responses.
+      # By default, it only logs the request method and URL, and the request/response headers.
+      # builder.response :logger
+    end
+  end
+end

spec/lib/ubuntu_security_api_spec.rb

@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+require './lib/ubuntu_security_api'
+
+RSpec.describe UbuntuSecurityApi do
+  let(:usa) { described_class.new(retry: 3) }
+
+  context 'when get' do
+    let(:conn) { instance_double(Faraday::Connection) }
+    let(:notice) { { 'id' => 'USN-1337-1', 'published' => '2024-10-23T19:45:29.964Z' } }
+    let(:notices) do
+      [
+        notice,
+        { 'id' => 'USN-1237-1', 'published' => '2024-10-22T18:45:29.964Z' },
+        { 'id' => 'USN-1236-1', 'published' => '2024-10-22T17:45:29.964Z' },
+        { 'id' => 'USN-1235-1', 'published' => '2024-10-22T16:45:29.964Z' },
+        { 'id' => 'USN-1234-1', 'published' => '2024-10-22T15:45:29.964Z' }
+      ]
+    end
+    let(:response) { instance_double(Faraday::Response) }
+
+    before do
+      allow(usa).to receive(:conn).and_return(conn)
+      allow(conn).to receive(:get).and_return(response)
+      allow(response).to receive(:body).and_return({ 'notices' => notices })
+    end
+
+    it 'latest errata' do
+      expect(usa.latest_errata).to eq(notices)
+    end
+
+    it 'latest n errata' do
+      allow(response).to receive(:body).and_return({ 'notices' => notices.append({ 'id' => 'too_old' }) })
+      expect(usa.latest_errata(nil, 5)).to eq(notices)
+    end
+
+    it 'latest release erratua' do
+      usa.latest_errata('bionic')
+      expect(conn).to have_received(:get).with('/security/notices.json',
+                                               { release: 'bionic',
+                                                 order: 'newest',
+                                                 show_hidden: false })
+    end
+
+    it 'latest erratum' do
+      allow(response).to receive(:body).and_return({ 'notices' => notices })
+
+      expect(usa.latest_erratum).to eq(notice)
+    end
+
+    it "yesterday's erratum" do
+      notice_today = { 'id' => 'USN-4711-1', 'published' => '2024-10-24T19:45:29.964Z' }
+      allow(response).to receive(:body).and_return({ 'notices' => [notice_today, *notices.slice(0, 4)] })
+      allow(Date).to receive(:today).and_return(Date.new(2024, 10, 24))
+
+      expect(usa.yesterdays_erratum).to eq(notice)
+    end
+
+    it "no yesterday's erratum" do
+      allow(Date).to receive(:today).and_return(Date.new(2024, 10, 22))
+      allow(response).to receive(:body).and_return({ 'notices' => notices })
+
+      expect { usa.yesterdays_erratum }.to raise_error(RuntimeError)
+    end
+
+    # rubocop:disable RSpec/ExampleLength
+    it 'retries on server-error 5XX' do
+      raise_server_error = 2
+
+      allow(conn).to receive(:get).thrice do
+        if raise_server_error.zero?
+          response
+        else
+          raise_server_error -= 1
+          raise Faraday::ServerError
+        end
+      end
+
+      expect(usa.latest_errata).to eq(notices)
+    end
+    # rubocop:enable RSpec/ExampleLength
+
+    it 'fails on client-error 4XX' do
+      allow(response).to receive(:body).and_return({ 'notices' => [] })
+      allow(conn).to receive(:get).and_raise(Faraday::ClientError).once
+
+      expect { usa.latest_errata }.to raise_error(Faraday::ClientError)
+    end
+  end
+end