diff --git a/config/initializers/action_mailer.rb b/config/initializers/action_mailer.rb
index d2b97d6e..22cfb6c0 100644
--- a/config/initializers/action_mailer.rb
+++ b/config/initializers/action_mailer.rb
@@ -1,3 +1,3 @@
-YAML.load_file(Rails.root.join('config', 'action_mailer.yml'))[Rails.env].each do |key, value|
+CodeOcean::Config.new(:action_mailer).read.each do |key, value|
   CodeOcean::Application.config.action_mailer.send(:"#{key}=", value.respond_to?(:symbolize_keys) ? value.symbolize_keys : value)
 end
diff --git a/config/initializers/sendmail.rb b/config/initializers/sendmail.rb
index 95c3b3fc..cbb09a44 100644
--- a/config/initializers/sendmail.rb
+++ b/config/initializers/sendmail.rb
@@ -1,3 +1,3 @@
 if CodeOcean::Application.config.action_mailer.delivery_method == :sendmail
-  CodeOcean::Application.config.action_mailer.sendmail_settings = CodeOcean::Config.new('sendmail').read
+  CodeOcean::Application.config.action_mailer.sendmail_settings = CodeOcean::Config.new(:sendmail).read
 end
diff --git a/config/initializers/smtp.rb b/config/initializers/smtp.rb
index a4b4c1d5..5db96f29 100644
--- a/config/initializers/smtp.rb
+++ b/config/initializers/smtp.rb
@@ -1,3 +1,3 @@
 if CodeOcean::Application.config.action_mailer.delivery_method == :smtp
-  CodeOcean::Application.config.action_mailer.sendmail_settings = CodeOcean::Config.new('smtp').read
+  CodeOcean::Application.config.action_mailer.sendmail_settings = CodeOcean::Config.new(:smtp).read
 end
diff --git a/lib/code_ocean/config.rb b/lib/code_ocean/config.rb
index 26d3df9e..9570bb7f 100644
--- a/lib/code_ocean/config.rb
+++ b/lib/code_ocean/config.rb
@@ -4,11 +4,17 @@ module CodeOcean
       @filename = filename
     end
 
-    def read
-      path = Rails.root.join('config', "#{@filename}.yml")
-      if File.exists?(path)
-        YAML.load_file(path)[Rails.env].symbolize_keys
+    def read(options = {})
+      path = Rails.root.join('config', "#{@filename}.yml#{options[:erb] ? '.erb' : ''}")
+      if ::File.exists?(path)
+        content = options[:erb] ? YAML.load(ERB.new(::File.new(path, 'r').read).result) : YAML.load_file(path)
+        content[Rails.env].with_indifferent_access
+      else
+        raise Error.new("Configuration file not found: #{path}")
       end
     end
   end
+
+  class Config::Error < RuntimeError
+  end
 end
diff --git a/lib/docker_client.rb b/lib/docker_client.rb
index c3a87c51..f9bdf050 100644
--- a/lib/docker_client.rb
+++ b/lib/docker_client.rb
@@ -1,5 +1,4 @@
 class DockerClient
-  CONFIG_PATH = Rails.root.join('config', 'docker.yml.erb')
   CONTAINER_WORKSPACE_PATH = '/workspace'
   LOCAL_WORKSPACE_ROOT = Rails.root.join('tmp', 'files', Rails.env)
 
@@ -29,7 +28,7 @@ class DockerClient
   private :command_substitutions
 
   def self.config
-    YAML.load(ERB.new(File.new(CONFIG_PATH, 'r').read).result)[Rails.env].with_indifferent_access
+    @config ||= CodeOcean::Config.new(:docker).read(erb: true)
   end
 
   def copy_file_to_workspace(options = {})
diff --git a/spec/lib/code_ocean/config_spec.rb b/spec/lib/code_ocean/config_spec.rb
new file mode 100644
index 00000000..0df99834
--- /dev/null
+++ b/spec/lib/code_ocean/config_spec.rb
@@ -0,0 +1,48 @@
+require 'rails_helper'
+
+describe CodeOcean::Config do
+  describe '#read' do
+    let(:content) { {foo: 'bar'} }
+    let(:filename) { :foo }
+
+    context 'with a .yml file' do
+      let(:path) { Rails.root.join('config', "#{filename}.yml") }
+      let(:read) { CodeOcean::Config.new(filename).read }
+
+      context 'when the file is present' do
+        before(:each) { File.write(path, {Rails.env => content}.to_yaml) }
+        after(:each) { FileUtils.rm(path) }
+
+        it 'returns the environment-specific content' do
+          expect(read).to eq(content.with_indifferent_access)
+        end
+      end
+
+      context 'when the file is not present' do
+        it 'raises an error' do
+          expect { read }.to raise_error(CodeOcean::Config::Error)
+        end
+      end
+    end
+
+    context 'with a .yml.erb file' do
+      let(:path) { Rails.root.join('config', "#{filename}.yml.erb") }
+      let(:read) { CodeOcean::Config.new(filename).read(erb: true) }
+
+      context 'when the file is present' do
+        before(:each) { File.write(path, {Rails.env => content}.to_yaml) }
+        after(:each) { FileUtils.rm(path) }
+
+        it 'returns the environment-specific content' do
+          expect(read).to eq(content.with_indifferent_access)
+        end
+      end
+
+      context 'when the file is not present' do
+        it 'raises an error' do
+          expect { read }.to raise_error(CodeOcean::Config::Error)
+        end
+      end
+    end
+  end
+end