Merge branch '22864-kubernetes-deploy-with-terminal' into 'master'

Add online terminal support for Kubernetes

## What does this MR do?

Gives terminal access to kubernetes-deployed environments  via the deployment service

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?

Part of idea to production

## Screenshots (if relevant)

### `/root/reviewing/environments`

![Screen_Shot_2016-12-15_at_19.10.40](/uploads/bd2c54c07b6c85dec3328a20cd185b64/Screen_Shot_2016-12-15_at_19.10.40.png)

### `/root/reviewing/environments/10013`

![Screen_Shot_2016-12-19_at_12.52.39](/uploads/db4e4e06cda88437e8727433d65898b9/Screen_Shot_2016-12-19_at_12.52.39.png)

### `/root/reviewing/enviroments/10013/terminal`

![Screen_Shot_2016-12-15_at_02.35.52](/uploads/1bb77b7e2de2c657ae3bda62dc4f0970/Screen_Shot_2016-12-15_at_02.35.52.png)

## Does this MR meet the acceptance criteria?

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- Tests
  - [X] Added for this feature/bug
  - [x] All builds are passing
- [X] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [X] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

## What are the relevant issue numbers?

* Closes #22864 #22958
* Alternative to, and somewhat based on,  !6770 
* Depends on https://gitlab.com/gitlab-org/gitlab-workhorse/merge_requests/83

See merge request !7690

2 files changed, 93 insertions, 0 deletions

diff --git a/lib/gitlab/kubernetes.rb b/lib/gitlab/kubernetes.rb
new file mode 100644
index 00000000000..288771c1c12
--- /dev/null
+++ b/lib/gitlab/kubernetes.rb
@@ -0,0 +1,80 @@
+module Gitlab
+  # Helper methods to do with Kubernetes network services & resources
+  module Kubernetes
+    # This is the comand that is run to start a terminal session. Kubernetes
+    # expects `command=foo&command=bar, not `command[]=foo&command[]=bar`
+    EXEC_COMMAND = URI.encode_www_form(
+      ['sh', '-c', 'bash || sh'].map { |value| ['command', value] }
+    )
+
+    # Filters an array of pods (as returned by the kubernetes API) by their labels
+    def filter_pods(pods, labels = {})
+      pods.select do |pod|
+        metadata = pod.fetch("metadata", {})
+        pod_labels = metadata.fetch("labels", nil)
+        next unless pod_labels
+
+        labels.all? { |k, v| pod_labels[k.to_s] == v }
+      end
+    end
+
+    # Converts a pod (as returned by the kubernetes API) into a terminal
+    def terminals_for_pod(api_url, namespace, pod)
+      metadata = pod.fetch("metadata", {})
+      status   = pod.fetch("status", {})
+      spec     = pod.fetch("spec", {})
+
+      containers = spec["containers"]
+      pod_name   = metadata["name"]
+      phase      = status["phase"]
+
+      return unless containers.present? && pod_name.present? && phase == "Running"
+
+      created_at = DateTime.parse(metadata["creationTimestamp"]) rescue nil
+
+      containers.map do |container|
+        {
+          selectors:    { pod: pod_name, container: container["name"] },
+          url:          container_exec_url(api_url, namespace, pod_name, container["name"]),
+          subprotocols: ['channel.k8s.io'],
+          headers:      Hash.new { |h, k| h[k] = [] },
+          created_at:   created_at,
+        }
+      end
+    end
+
+    def add_terminal_auth(terminal, token, ca_pem = nil)
+      terminal[:headers]['Authorization'] << "Bearer #{token}"
+      terminal[:ca_pem] = ca_pem if ca_pem.present?
+      terminal
+    end
+
+    def container_exec_url(api_url, namespace, pod_name, container_name)
+      url = URI.parse(api_url)
+      url.path = [
+        url.path.sub(%r{/+\z}, ''),
+        'api', 'v1',
+        'namespaces', ERB::Util.url_encode(namespace),
+        'pods', ERB::Util.url_encode(pod_name),
+        'exec'
+      ].join('/')
+
+      url.query = {
+        container: container_name,
+        tty: true,
+        stdin: true,
+        stdout: true,
+        stderr: true,
+      }.to_query + '&' + EXEC_COMMAND
+
+      case url.scheme
+      when 'http'
+        url.scheme = 'ws'
+      when 'https'
+        url.scheme = 'wss'
+      end
+
+      url.to_s
+    end
+  end
+end
diff --git a/lib/gitlab/workhorse.rb b/lib/gitlab/workhorse.rb
index aeb1a26e1ba..d28bb583fe7 100644
--- a/lib/gitlab/workhorse.rb
+++ b/lib/gitlab/workhorse.rb
@@ -95,6 +95,19 @@ module Gitlab
         ]
       end
 
+      def terminal_websocket(terminal)
+        details = {
+          'Terminal' => {
+            'Subprotocols' => terminal[:subprotocols],
+            'Url' => terminal[:url],
+            'Header' => terminal[:headers]
+          }
+        }
+        details['Terminal']['CAPem'] = terminal[:ca_pem] if terminal.has_key?(:ca_pem)
+
+        details
+      end
+
       def version
         path = Rails.root.join(VERSION_FILE)
         path.readable? ? path.read.chomp : 'unknown'