Implement a status page storage client for AWS S3

The S3 client returns platform-agnostic data to allow
an easier way adding a more generic interface later.

ee/lib/status_page/storage.rb

+# frozen_string_literal: true
+
+module StatusPage
+  module Storage
+    class Error < StandardError
+      def initialize(bucket:, error:, **args)
+        super(
+          "Error occured #{error.class.name.inspect} " \
+          "for bucket #{bucket.inspect}. " \
+          "Arguments: #{args.inspect}"
+        )
+      end
+    end
+  end
+end

ee/lib/status_page/storage/object.rb

+# frozen_string_literal: true
+
+module StatusPage
+  module Storage
+    # Represents a platform-agnostic object class.
+    Object = Struct.new(:key, :content, :modified_at, keyword_init: true)
+  end
+end

ee/lib/status_page/storage/s3_client.rb

+# frozen_string_literal: true
+
+module StatusPage
+  module Storage
+    # Implements a minimal AWS S3 client.
+    class S3Client
+      def initialize(region:, bucket_name:, access_key_id:, secret_access_key:)
+        @bucket_name = bucket_name
+        @client = Aws::S3::Client.new(
+          region: region,
+          credentials: Aws::Credentials.new(access_key_id, secret_access_key)
+        )
+      end
+
+      # Stores +content+ as +key+ in storage
+      #
+      # Note: We are making sure that
+      # * we control +content+ (not the user)
+      # * this upload is done a background job (not in a web request)
+      def upload_object(key, content)
+        wrap_errors(key: key) do
+          client.put_object(bucket: bucket_name, key: key, body: content)
+        end
+
+        true
+      end
+
+      private
+
+      attr_reader :client, :bucket_name
+
+      def wrap_errors(**args)
+        yield
+      rescue Aws::Errors::ServiceError => e
+        raise Error, bucket: bucket_name, error: e, **args
+      end
+    end
+  end
+end

ee/spec/lib/status_page/storage/s3_client_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe StatusPage::Storage::S3Client, :aws_s3 do
+  let(:region) { 'eu-west-1' }
+  let(:bucket_name) { 'bucket_name' }
+  let(:access_key_id) { 'key_id' }
+  let(:secret_access_key) { 'secret' }
+
+  let(:client) do
+    described_class.new(
+      region: region, bucket_name: bucket_name, access_key_id: access_key_id,
+      secret_access_key: secret_access_key
+    )
+  end
+
+  describe '#upload_object' do
+    let(:key) { 'key' }
+    let(:content) { 'content' }
+
+    subject(:result) { client.upload_object(key, content) }
+
+    context 'when successful' do
+      it 'returns true' do
+        stub_responses(:put_object)
+
+        expect(result).to eq(true)
+      end
+    end
+
+    context 'when failed' do
+      let(:aws_error) { 'SomeError' }
+
+      it 'raises an error' do
+        stub_responses(:put_object, aws_error)
+
+        msg = error_message(aws_error, key: key)
+        expect { result }.to raise_error(StatusPage::Storage::Error, msg)
+      end
+    end
+  end
+
+  private
+
+  def stub_responses(*args)
+    s3_client = client.instance_variable_get(:@client)
+    s3_client.stub_responses(*args)
+  end
+
+  def error_message(error_class, **args)
+    %{Error occured "Aws::S3::Errors::#{error_class}" } \
+      "for bucket #{bucket_name.inspect}. Arguments: #{args.inspect}"
+  end
+end

ee/spec/support/aws.rb

+# frozen_string_literal: true
+
+RSpec.configure do |config|
+  config.around(:each, :aws_s3) do |example|
+    (Aws.config[:s3] ||= {})[:stub_responses] = true
+    example.run
+  ensure
+    Aws.config[:s3].delete(:stub_responses)
+  end
+end