Stop unnecessarily scan the 'job.MF' file from job blob when rendering ERBs

Indeed we already know the job name and template list, as these data are
persisted when a release is uploaded to the director.

This makes unnecessary to verify that the job name is consistent at ERB
rendering time.

And this consistency check is more relevant when done at the time a release
job is uploaded to the director.

Author: bgandon

src/bosh-director-core/lib/bosh/director/core/templates/job_template_loader.rb

@@ -35,21 +35,13 @@ def initialize(logger, template_blob_cache, link_provider_intents, dns_encoder)
       # @return [JobTemplateRenderer] Object that can render the templates
       def process(instance_job)
         template_dir = extract_template(instance_job)
-        manifest = Psych.load_file(File.join(template_dir, 'job.MF'), aliases: true)
 
         monit_erb_file = File.read(File.join(template_dir, 'monit'))
         monit_source_erb = SourceErb.new('monit', 'monit', monit_erb_file, instance_job.name)
 
         source_erbs = []
 
-        job_name_from_manifest = manifest.fetch('name', {})
-        if job_name_from_manifest != instance_job.name
-          raise Bosh::Director::JobTemplateUnpackFailed,
-            "Inconsistent name in extracted job.MF manifest " +
-              "(exptected: '#{instance_job.name}', got: '#{job_name_from_manifest}')"
-        end
-
-        manifest.fetch('templates', {}).each_pair do |src_name, dest_name|
+        instance_job.model.spec.fetch('templates', {}).each_pair do |src_name, dest_name|
           erb_file = File.read(File.join(template_dir, 'templates', src_name))
           source_erbs << SourceErb.new(src_name, dest_name, erb_file, instance_job.name)
         end

src/bosh-director-core/spec/bosh/director/core/templates/job_template_loader_spec.rb

@@ -95,6 +95,10 @@ module Bosh::Director::Core::Templates
           release: release
         )
 
+        job_model = double('Bosh::Director::Models::Template')
+        expect(job).to receive(:model).and_return(job_model)
+        expect(job_model).to receive(:spec).and_return({ "templates" => { "test" => "test_dst" } })
+
         monit_erb = instance_double(SourceErb)
         job_template_erb = instance_double(SourceErb)
         fake_renderer = instance_double(JobTemplateRenderer)
@@ -137,6 +141,10 @@ module Bosh::Director::Core::Templates
           release: release,
         )
 
+        job_model = double('Bosh::Director::Models::Template')
+        expect(job).to receive(:model).and_return(job_model)
+        expect(job_model).to receive(:spec).and_return({ "templates" => {} })
+
         monit_erb = instance_double(SourceErb)
         fake_renderer = instance_double(JobTemplateRenderer)
 
@@ -182,6 +190,10 @@ module Bosh::Director::Core::Templates
             model: double('Bosh::Director::Models::Template', provides: [])
           )
 
+          job_model = double('Bosh::Director::Models::Template')
+          expect(job).to receive(:model).and_return(job_model)
+          expect(job_model).to receive(:spec).and_return({ "templates" => {} })
+
           job_template_renderer = job_template_loader.process(job)
           expect(job_template_renderer.source_erbs).to eq([])
         end

src/bosh-director/lib/bosh/director/errors.rb

@@ -134,6 +134,7 @@ def self.err(error_code, response_code = BAD_REQUEST)
   JobInvalidLinkSpec = err(80013)
   JobDuplicateLinkName = err(80014)
   JobWithExportedFromMismatch = err(80015)
+  JobInvalidName = err(80016)
 
   ResourceError = err(100001)
   ResourceNotFound = err(100002, NOT_FOUND)

src/bosh-director/lib/bosh/director/jobs/release/release_job.rb

@@ -15,6 +15,7 @@ def update
 
       job_manifest = load_manifest
 
+      validate_name(job_manifest)
       validate_templates(job_manifest)
       validate_monit
       validate_logs(job_manifest)
@@ -75,6 +76,13 @@ def load_manifest
       YAML.load_file(manifest_file, aliases: true)
     end
 
+    def validate_name(job_manifest)
+      unless name == job_manifest['name']
+        raise JobInvalidName, "Inconsistent name for job '#{name}'" +
+          "(exptected: '#{name}', got: '#{job_manifest['name']}')"
+      end
+    end
+
     def validate_templates(job_manifest)
       if job_manifest['templates']
         job_manifest['templates'].each_key do |relative_path|

src/bosh-director/spec/unit/job_renderer_spec.rb

@@ -41,13 +41,21 @@ def perform
 
       before do
         release_version = DeploymentPlan::ReleaseVersion.parse(deployment_model, 'name' => 'fake-release', 'version' => '123')
+
         job1 = DeploymentPlan::Job.new(release_version, 'dummy')
-        job1.bind_existing_model(
-          Models::Template.make(blobstore_id: 'my-blobstore-id', sha1: '16baf0c24e2dac2a21ccdcd4655be403a602f573'),
-        )
+        job1.bind_existing_model(Models::Template.make(
+          name: 'dummy',
+          spec_json: '{ "templates": { "ctl.erb": "bin/dummy_ctl" } }',
+          blobstore_id: 'my-blobstore-id',
+          sha1: '16baf0c24e2dac2a21ccdcd4655be403a602f573'
+        ))
 
         job2 = DeploymentPlan::Job.new(release_version, 'dummy')
-        job2.bind_existing_model(Models::Template.make(blobstore_id: 'my-blobstore-id'))
+        job2.bind_existing_model(Models::Template.make(
+          name: 'dummy',
+          spec_json: '{ "templates": { "ctl.erb": "bin/dummy_ctl" } }',
+          blobstore_id: 'my-blobstore-id')
+        )
 
         allow(instance_plan).to receive_message_chain(:spec, :as_template_spec).and_return('template' => 'spec')
         allow(instance_plan).to receive(:templates).and_return([job1, job2])