feat: cache eresources config in Redis

app/models/eresources.rb

@@ -1,18 +1,13 @@
 # frozen_string_literal: true
 
-require "json"
-require "down"
-require "fileutils"
-require "caching/eresources_cache"
-
 class Eresources
   include ActiveModel::Model
 
   attr_accessor :entries
 
   def initialize
-    @entries = Caching::EresourcesCache.instance.fetch(["eresources_config"], race_condition_ttl: 10.seconds, expires_in: 4.hours) do
-      fetch_latest_config
+    @entries = Rails.cache.fetch("eresources_config", expires_in: 4.hours) do
+      fetch_config
     end
   end
 
@@ -39,51 +34,18 @@ def known_url(url)
 
   private
 
-  def fetch_latest_config
-    Rails.logger.info "Fetching latest eResources config"
-
-    config = nil
-    begin
-      tempfile = Down.download(ENV["ERESOURCES_CONFIG_URL"], headers: {"User-Agent" => "nla-blacklight/#{Rails.configuration.version}"})
-      if tempfile.present? && tempfile.status.include?("200") && valid_json?(tempfile)
-        same = if File.exist? current_config_path
-          FileUtils.compare_file(current_config_path, tempfile.path)
-        else
-          false
-        end
-
-        if same
-          Rails.logger.info "eResources config has not changed. Keeping current config."
-        elsif File.exist?(current_config_path) && ((File.size(current_config_path) - File.size(tempfile.path)).abs / File.size(current_config_path) > 0.5)
-          # compare the filesizes
-          Rails.logger.error "Suspicious difference in file size between latest and current config. Keeping current config."
-        else
-          FileUtils.mv(tempfile.path, current_config_path)
-          Rails.logger.info "eResources config updated"
-        end
-      else
-        Rails.logger.error "Failed to retrieve latest eResources config. Keeping current config."
-      end
-    rescue Down::ServerError
-      Rails.logger.error "Failed to retrieve latest eResources config. Keeping current config."
-    ensure
-      if File.exist? current_config_path
-        config = JSON.parse File.read(current_config_path)
+  def fetch_config
+    res = Faraday.get(ENV["ERESOURCES_CONFIG_URL"], nil, {content_type: "application/json", accept: "application/json"})
+    if res.status == 200
+      if res.body.present?
+        JSON.parse(res.body)
       end
-    end
-
-    config
-  end
-
-  def valid_json?(tempfile)
-    !!begin
-      JSON.parse(File.read(tempfile))
-    rescue
+    else
+      Rails.logger.error "Failed to retrieve eResources config"
       nil
     end
-  end
-
-  def current_config_path
-    "#{ENV.fetch("BLACKLIGHT_TMP_PATH", "./tmp")}/cache/eresources.cfg"
+  rescue => e
+    Rails.logger.error "Failed to retrieve eResources config: #{e.message}"
+    nil
   end
 end

spec/models/eresources_spec.rb

@@ -28,35 +28,6 @@
       end
     end
 
-    context "when the eResources manager returns a non-200 status" do
-      let(:current_config) { [{current_config: true}] }
-
-      it "keeps the current config" do
-        stub_const("ENV", ENV.to_hash.merge("ERESOURCES_CONFIG_URL" => "http://eresource-manager.example.com/service-fail"))
-
-        expect(cache.exist?("eresources_config")).to be(false)
-
-        # setup the current_config
-        File.write("#{ENV["BLACKLIGHT_TMP_PATH"]}/cache/eresources.cfg", current_config.to_json)
-
-        described_class.new
-        expect(cache.read("eresources_config")).to eq JSON.parse current_config.to_json
-      end
-
-      # rubocop:disable RSpec/NestedGroups
-      context "when there is no previous config" do
-        it "returns an empty array" do
-          stub_const("ENV", ENV.to_hash.merge("ERESOURCES_CONFIG_URL" => "http://eresource-manager.example.com/service-fail"))
-
-          expect(cache.exist?("eresources_config")).to be(false)
-
-          described_class.new
-          expect(cache.read("eresources_config")).to be_nil
-        end
-      end
-      # rubocop:enable RSpec/NestedGroups
-    end
-
     context "when the latest config is the same as the current config" do
       # setup the current_config
       let(:current_config) { File.read("spec/files/eresources/config.txt") }
@@ -71,20 +42,6 @@
         expect(cache.read("eresources_config")).to eq JSON.parse current_config
       end
     end
-
-    context "when file size difference is too great" do
-      let(:current_config) { [{current_config: true}] }
-
-      it "keeps the current config" do
-        expect(cache.exist?("eresources_config")).to be(false)
-
-        # setup the current_config
-        File.write("#{ENV["BLACKLIGHT_TMP_PATH"]}/cache/eresources.cfg", current_config.to_json)
-
-        described_class.new
-        expect(cache.read("eresources_config")).to eq JSON.parse current_config.to_json
-      end
-    end
   end
 
   describe "#url_append" do

spec/support/webmock.rb

@@ -12,7 +12,7 @@
     WebMock.stub_request(:get, "http://eresource-manager.example.com/")
       .with(
         headers: {
-          "Accept" => "*/*",
+          "Accept" => "application/json",
           "Accept-Encoding" => "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
         }
       )
@@ -21,7 +21,7 @@
     WebMock.stub_request(:get, "http://eresource-manager.example.com/service-fail")
       .with(
         headers: {
-          "Accept" => "*/*",
+          "Accept" => "application/json",
           "Accept-Encoding" => "gzip;q=1.0,deflate;q=0.6,identity;q=0.3"
         }
       )