Merge branch 'ci/build_dependencies' into 'master'

Let the CI runner know about builds that this build depends on

This allows us to implement artifacts passing: runner will download artifacts from all prior builds. It will happen automatically, and always, as long as artifacts are enabled.

## The changes:

This MR exposes list of prior builds in CI::API::Builds.

**The API response when asking for builds**

```json
{
  "id": 48584,
  "ref": "0.1.1",
  "tag": true,
  "sha": "d63117656af6ff57d99e50cc270f854691f335ad",
  "status": "success",
  "name": "pages",
  "token": "9dd60b4f1a439d1765357446c1084c",
  "stage": "test",
  "project_id": 479,
  "project_name": "test",
  "commands": "echo commands",
  "repo_url": "http://gitlab-ci-token:token@gitlab.example/group/test.git",
  "before_sha": "0000000000000000000000000000000000000000",
  "allow_git_fetch": false,
  "options": {
    "image": "docker:image",
    "artifacts": {
      "paths": [
        "public"
      ]
    },
    "cache": {
      "paths": [
        "vendor"
      ]
    }
  },
  "timeout": 3600,
  "variables": [
    {
      "key": "CI_BUILD_TAG",
      "value": "0.1.1",
      "public": true
    }
  ],
  "dependencies": {
    "builds": [
      {
        "id": 48584,
        "ref": "0.1.1",
        "tag": true,
        "sha": "d63117656af6ff57d99e50cc270f854691f335ad",
        "status": "success",
        "name": "build",
        "token": "9dd60b4f1a439d1765357446c1084c",
        "stage": "build",
        "project_id": 479,
        "project_name": "test",
        "artifacts_file": {
          "filename": "artifacts.zip",
          "size": 0
        }
      }
    ]
  }
}
```

## How it will work?

**Example:**
```
build:
  type: build
  script:
  - echo TEST > test_file
  artifacts:
    untracked: true

rspec:
  type: test
  script:
  - test-my-project

staging:
  type: deploy
  script:
  - scp test_file root@server.com:
```

**The flow:**
1. We run `build`. The `build` creates a file `test_file`. This file gets archived and send us build artifacts.
2. We run `rspec`. The `rspec` downloads build artifacts from `build`. Uses the `test_file`.
3. We run `staging`. The `staging` downloads build artifacts from `build` and `rspec`, but since the `rspec` doesn't have build artifacts we skip that build. Deploys the `test_file`.

This partially implements the https://gitlab.com/gitlab-org/gitlab-ce/issues/3423.

In the next release we will introduce option to configure what artifacts are received.

/cc @grzesiek @DouweM @sytse @rspeicher


See merge request !2437

9 files changed, 121 insertions, 19 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 418dd16e5b6..3995c3aa8e7 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -20,6 +20,7 @@ v 8.4.0 (unreleased)
   - Fix signup for OAuth providers that don't provide a name
   - Implement new UI for group page
   - Implement search inside emoji picker
+  - Let the CI runner know about builds that this build depends on
   - Add API support for looking up a user by username (Stan Hu)
   - Add project permissions to all project API endpoints (Stan Hu)
   - Link to milestone in "Milestone changed" system note
diff --git a/app/models/ci/build.rb b/app/models/ci/build.rb
index 6cc26abce66..16a5b03f591 100644
--- a/app/models/ci/build.rb
+++ b/app/models/ci/build.rb
@@ -128,6 +128,14 @@ module Ci
       !self.commit.latest_builds_for_ref(self.ref).include?(self)
     end
 
+    def depends_on_builds
+      # Get builds of the same type
+      latest_builds = self.commit.builds.similar(self).latest
+
+      # Return builds from previous stages
+      latest_builds.where('stage_idx < ?', stage_idx)
+    end
+
     def trace_html
       html = Ci::Ansi2html::convert(trace) if trace.present?
       html || ''
diff --git a/app/uploaders/artifact_uploader.rb b/app/uploaders/artifact_uploader.rb
index 1b0ae6c0056..1cd93263c9f 100644
--- a/app/uploaders/artifact_uploader.rb
+++ b/app/uploaders/artifact_uploader.rb
@@ -32,6 +32,10 @@ class ArtifactUploader < CarrierWave::Uploader::Base
     self.class.storage == CarrierWave::Storage::File
   end
 
+  def filename
+    file.try(:filename)
+  end
+
   def exists?
     file.try(:exists?)
   end
diff --git a/doc/ci/api/builds.md b/doc/ci/api/builds.md
index 3b5008ccdb4..018ca22dbbd 100644
--- a/doc/ci/api/builds.md
+++ b/doc/ci/api/builds.md
@@ -18,18 +18,62 @@ Returns:
 
 ```json
 {
-  "id" : 79,
-  "commands" : "",
-  "path" : "",
-  "ref" : "",
-  "sha" : "",
-  "project_id" : 6,
-  "repo_url" : "git@demo.gitlab.com:gitlab/gitlab-shell.git",
-  "before_sha" : ""
+  "id": 48584,
+  "ref": "0.1.1",
+  "tag": true,
+  "sha": "d63117656af6ff57d99e50cc270f854691f335ad",
+  "status": "success",
+  "name": "pages",
+  "token": "9dd60b4f1a439d1765357446c1084c",
+  "stage": "test",
+  "project_id": 479,
+  "project_name": "test",
+  "commands": "echo commands",
+  "repo_url": "http://gitlab-ci-token:token@gitlab.example/group/test.git",
+  "before_sha": "0000000000000000000000000000000000000000",
+  "allow_git_fetch": false,
+  "options": {
+    "image": "docker:image",
+    "artifacts": {
+      "paths": [
+        "public"
+      ]
+    },
+    "cache": {
+      "paths": [
+        "vendor"
+      ]
+    }
+  },
+  "timeout": 3600,
+  "variables": [
+    {
+      "key": "CI_BUILD_TAG",
+      "value": "0.1.1",
+      "public": true
+    }
+  ],
+  "depends_on_builds": [
+    {
+      "id": 48584,
+      "ref": "0.1.1",
+      "tag": true,
+      "sha": "d63117656af6ff57d99e50cc270f854691f335ad",
+      "status": "success",
+      "name": "build",
+      "token": "9dd60b4f1a439d1765357446c1084c",
+      "stage": "build",
+      "project_id": 479,
+      "project_name": "test",
+      "artifacts_file": {
+        "filename": "artifacts.zip",
+        "size": 0
+      }
+    }
+  ]
 }
 ```
 
-
 ### Update details of an existing build
 
     PUT /ci/builds/:id
diff --git a/lib/ci/api/builds.rb b/lib/ci/api/builds.rb
index fb87637b94f..690bbf97a89 100644
--- a/lib/ci/api/builds.rb
+++ b/lib/ci/api/builds.rb
@@ -20,7 +20,7 @@ module Ci
 
           if build
             update_runner_info
-            present build, with: Entities::Build
+            present build, with: Entities::BuildDetails
           else
             not_found!
           end
@@ -111,7 +111,7 @@ module Ci
           build.artifacts_metadata = metadata
 
           if build.save
-            present(build, with: Entities::Build)
+            present(build, with: Entities::BuildDetails)
           else
             render_validation_error!(build)
           end
diff --git a/lib/ci/api/entities.rb b/lib/ci/api/entities.rb
index e4ac0545ea2..b25e0e573a8 100644
--- a/lib/ci/api/entities.rb
+++ b/lib/ci/api/entities.rb
@@ -16,10 +16,19 @@ module Ci
       end
 
       class Build < Grape::Entity
-        expose :id, :commands, :ref, :sha, :status, :project_id, :repo_url,
-          :before_sha, :allow_git_fetch, :project_name
-
+        expose :id, :ref, :tag, :sha, :status
         expose :name, :token, :stage
+        expose :project_id
+        expose :project_name
+        expose :artifacts_file, using: ArtifactFile, if: lambda { |build, opts| build.artifacts? }
+      end
+
+      class BuildDetails < Build
+        expose :commands
+        expose :repo_url
+        expose :before_sha
+        expose :allow_git_fetch
+        expose :token
 
         expose :options do |model|
           model.options
@@ -30,7 +39,7 @@ module Ci
         end
 
         expose :variables
-        expose :artifacts_file, using: ArtifactFile
+        expose :depends_on_builds, using: Build
       end
 
       class Runner < Grape::Entity
diff --git a/spec/models/build_spec.rb b/spec/models/build_spec.rb
index 0e13456723d..d12b9e65c82 100644
--- a/spec/models/build_spec.rb
+++ b/spec/models/build_spec.rb
@@ -426,6 +426,30 @@ describe Ci::Build, models: true do
     it { is_expected.to include(project.web_url[7..-1]) }
   end
 
+  describe :depends_on_builds do
+    let!(:build) { FactoryGirl.create :ci_build, commit: commit, name: 'build', stage_idx: 0, stage: 'build' }
+    let!(:rspec_test) { FactoryGirl.create :ci_build, commit: commit, name: 'rspec', stage_idx: 1, stage: 'test' }
+    let!(:rubocop_test) { FactoryGirl.create :ci_build, commit: commit, name: 'rubocop', stage_idx: 1, stage: 'test' }
+    let!(:staging) { FactoryGirl.create :ci_build, commit: commit, name: 'staging', stage_idx: 2, stage: 'deploy' }
+
+    it 'to have no dependents if this is first build' do
+      expect(build.depends_on_builds).to be_empty
+    end
+
+    it 'to have one dependent if this is test' do
+      expect(rspec_test.depends_on_builds.map(&:id)).to contain_exactly(build.id)
+    end
+
+    it 'to have all builds from build and test stage if this is last' do
+      expect(staging.depends_on_builds.map(&:id)).to contain_exactly(build.id, rspec_test.id, rubocop_test.id)
+    end
+
+    it 'to have retried builds instead the original ones' do
+      retried_rspec = Ci::Build.retry(rspec_test)
+      expect(staging.depends_on_builds.map(&:id)).to contain_exactly(build.id, retried_rspec.id, rubocop_test.id)
+    end
+  end
+
   def create_mr(build, commit, factory: :merge_request, created_at: Time.now)
     FactoryGirl.create(factory,
                        source_project_id: commit.gl_project_id,
diff --git a/spec/requests/ci/api/builds_spec.rb b/spec/requests/ci/api/builds_spec.rb
index 648ea0d5f50..eec927102aa 100644
--- a/spec/requests/ci/api/builds_spec.rb
+++ b/spec/requests/ci/api/builds_spec.rb
@@ -101,6 +101,18 @@ describe Ci::API::API do
           { "key" => "TRIGGER_KEY", "value" => "TRIGGER_VALUE", "public" => false },
         ])
       end
+
+      it "returns dependent builds" do
+        commit = FactoryGirl.create(:ci_commit, project: project)
+        commit.create_builds('master', false, nil, nil)
+        commit.builds.where(stage: 'test').each(&:success)
+
+        post ci_api("/builds/register"), token: runner.token, info: { platform: :darwin }
+
+        expect(response.status).to eq(201)
+        expect(json_response["depends_on_builds"].count).to eq(2)
+        expect(json_response["depends_on_builds"][0]["name"]).to eq("rspec")
+      end
     end
 
     describe "PUT /builds/:id" do
diff --git a/spec/support/gitlab_stubs/gitlab_ci.yml b/spec/support/gitlab_stubs/gitlab_ci.yml
index 3482145404e..a5b256bd3ec 100644
--- a/spec/support/gitlab_stubs/gitlab_ci.yml
+++ b/spec/support/gitlab_stubs/gitlab_ci.yml
@@ -36,8 +36,8 @@ staging:
   script: "cap deploy stating"
   type: deploy
   tags: 
-    - capistrano
-    - debian
+    - ruby
+    - mysql
   except:
     - stable
 
@@ -47,8 +47,8 @@ production:
     - cap deploy production
     - cap notify
   tags: 
-    - capistrano
-    - debian
+    - ruby
+    - mysql
   only:
     - master
     - /^deploy-.*$/