Add configuration to skip missing templates

- since `contents` is called multiple times and does work, it's now memoized

CHANGELOG.md

@@ -7,6 +7,7 @@
 * Development: adjust require's to be able to run CLI from any folder
 * Enable defining vars at the env block level, rather than only on template blocks
 * Create directories for rendered files as needed
+* Add the `skip_missing_template` config for templates
 
 #### 0.11.0
 

README.md

@@ -98,6 +98,13 @@ test:
       vars:
         test_specific_key: and_the_value
 
+    extra_test_config:
+      # normally there's an error for missing templates, but this can be allowed via config
+      skip_missing_template: true
+      # config files are also processed through ERB, so paths can be made dynamic
+      path: config/templates/<%= ENV['extra_test_file'] %>.yml
+      dest: config/extra_test_config.yml
+
 production:
   # vars can be defined at the environment level, which are available to these templates
   vars:

lib/consult/template.rb

@@ -19,6 +19,10 @@ def initialize(name, config)
     end
 
     def render(save: true)
+      if contents.empty? && @config[:skip_missing_template]
+        return
+      end
+
       # Attempt to render
       renderer = ERB.new(contents, nil, '-')
       result = renderer.result(binding)
@@ -76,20 +80,34 @@ def ordered_locations
 
     # Concatenate all the source templates together, in the order provided
     def contents
-      ordered_locations.map do |location|
+      @_contents ||= ordered_locations.map do |location|
         location.to_s.start_with?('consul') ? consul_contents(location) : disk_contents(location)
-      end.join
+      end.compact.join
     end
 
     def consul_contents(location)
       [@config[location]].compact.flatten.map do |key|
-        Diplomat::Kv.get(key, {}, :return, :return).force_encoding 'utf-8'
+        Diplomat::Kv.get(key, {}, :reject, :return).force_encoding 'utf-8'
+      rescue Diplomat::KeyNotFound
+        if @config[:skip_missing_template]
+          STDERR.puts "Consult: Skipping missing template: #{name}"
+          next
+        end
+
+        raise
       end.join
     end
 
     def disk_contents(location)
       [public_send(location)].compact.flatten.map do |file_path|
         File.read file_path, encoding: 'utf-8'
+      rescue Errno::ENOENT
+        if @config[:skip_missing_template]
+          STDERR.puts "Consult: Skipping missing template: #{name}"
+          next
+        end
+
+        raise
       end.join
     end
   end

spec/lib/template_spec.rb

@@ -16,8 +16,24 @@
       vars: {another_var: 'another value'}
     }
   end
+  let(:missing_template_file_config) do
+    {
+      skip_missing_template: true,
+      path: 'x/y/z.txt',
+      dest: 'rendered/nope/skip_missing_template_file',
+    }
+  end
+  let(:missing_template_key_config) do
+    {
+      skip_missing_template: true,
+      consul_key: 'x/y/z.txt',
+      dest: 'rendered/nope/skip_missing_template_key',
+    }
+  end
   let(:template) { Consult::Template.new(name, config) }
   let(:fail_template) { Consult::Template.new('aziz', fail_config) }
+  let(:missing_template_file) { Consult::Template.new('missing', missing_template_file_config) }
+  let(:missing_template_key) { Consult::Template.new('missing', missing_template_key_config) }
 
   before :all do
     Consult.load config_dir: 'spec/support'
@@ -59,6 +75,20 @@
     expect { fail_template.render }.to output(/Error rendering template*/).to_stderr_from_any_process
   end
 
+  context 'skip_missing_template' do
+    it 'allows missing template files' do
+      expect { missing_template_file.render }.to output(/Consult: Skipping missing template: missing/).to_stderr_from_any_process
+      expect(missing_template_file.render).to be_nil
+      expect(File.exist?(missing_template_file.dest)).to be(false)
+    end
+
+    it 'allows missing template keys' do
+      expect { missing_template_key.render }.to output(/Consult: Skipping missing template: missing/).to_stderr_from_any_process
+      expect(missing_template_key.render).to be_nil
+      expect(File.exist?(missing_template_key.dest)).to be(false)
+    end
+  end
+
   it 'should obey location order' do
     size = rand(4) + 1
     locations = %i[path paths consul_key consul_keys].sample(size).shuffle

spec/support/config/consult.yml

@@ -82,6 +82,11 @@ shared:
       vars:
         aziz: 'Light!'
 
+    missing_template_file:
+      skip_missing_template: true
+      path: x/y/z.txt
+      dest: rendered/nope/skip_missing_template
+
 test:
   vars:
     test_env_override: some value