Initial version of user documentation of container registry

doc/README.md

@@ -13,6 +13,7 @@
 - [Profile Settings](profile/README.md)
 - [Project Services](project_services/project_services.md) Integrate a project with external services, such as CI and chat.
 - [Public access](public_access/public_access.md) Learn how you can allow public and internal access to projects.
+- [Container Registry](container-registry/README.md) Learn how to use GitLab Container Registry.
 - [SSH](ssh/README.md) Setup your ssh keys and deploy keys for secure access to your projects.
 - [Webhooks](web_hooks/web_hooks.md) Let GitLab notify you when new code has been pushed to your project.
 - [Workflow](workflow/README.md) Using GitLab functionality and importing projects from GitHub and SVN.

doc/container_registry/README.md

+# GitLab Container Registry
+
+> **Note:**
+This feature was [introduced][ce-4040] in GitLab 8.8.
+
+With the Docker Container Registry integrated into GitLab, every project can
+have its own space to store its Docker images.
+
+You can read more about Docker Registry at https://docs.docker.com/registry/introduction/.
+
+You can read more about administering GitLab Container Registry on [GitLab Container Registry Administration](../administration/container_registry.md)
+
+---
+
+## Start using Container Registry
+
+1. First ask your system administrator to enable GitLab Container Registry following the [administration documentation](../administration/container_registry.md).
+
+2. Go to project settings and enable `Container Registry` feature on your project:
+
+![](project_feature.png)
+
+3. Login to Container Registry with your credentials:
+
+```
+docker login registry.example.com
+```
+
+## Build and push images
+
+Your registry is accessible under address configured via `registry_external_url`.
+To start using it you need to first build and publish images:
+
+```
+docker build -t registry.example.com/group/project .
+docker push registry.example.com/group/project
+```
+
+## Use images from GitLab Container Registry
+
+To download and run container from images hosted in GitLab Container Registry use `docker run`:
+
+```
+docker run [options] registry.example.com/group/project [arguments]
+```
+
+## Control Container Registry from GitLab
+
+GitLab offers simple Container Registry management. Go to your project and click **Container Registry**.
+This view will show you all tags in your repository and will easily allow you to delete them.
+
+![](container_registry.png)
+
+## Build and push images using GitLab CI
+
+> **Note:**
+This feature requires GitLab 8.8 and GitLab Runner 1.2.
+
+Make sure that your GitLab Runner is configured to allow building docker images.
+You have to check the [Using Docker Build](../../ci/docker/using_docker_build.md).
+
+You can use [docker:dind](https://hub.docker.com/_/docker/) to build your images. 
+This is how the `.gitlab-ci.yml` looks like:
+
+```
+ build_image:
+   image: docker:git
+   services:
+   - docker:dind
+   stage: build
+   script:
+     - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN registry.gitlab.com
+     - docker build -t registry.gitlab.com/group/project:latest .
+     - docker push registry.gitlab.com/group/project:latest
+```
+
+You have to use special credentials `gitlab-ci-token` with password stored in `$CI_BUILD_TOKEN` in order to push to registry connected to your project.
+This allows you to automated building and deployment of your images.
+
+## Limitations
+
+In order to use container image from private project as an `image:` in your `.gitlab-ci.yml` you have to follow
+[Using a private Docker Registry](https://gitlab.com/gitlab-org/gitlab-ci-multi-runner/blob/master/docs/configuration/advanced-configuration.md#using-a-private-docker-registry).
+This workflow will be simplified in the future.