Initial attempt at fixing issues-2994

docs/install/docker-registry-and-cache-server.md

+# Prepare the Docker Registry and Cache Server
+
+To speedup the builds we advise to setup a personal Docker registry server
+working in proxy mode. A cache server is also recommended.
+
+## Install Docker Registry
+
+>**Note:**
+Read more in [Distributed registry mirroring][registry].
+
+1. Login to a dedicated machine where Docker registry proxy will be running
+2. Make sure that Docker Engine is installed on this machine
+3. Create a new Docker registry:
+
+    ```bash
+    docker run -d -p 6000:5000 \
+        -e REGISTRY_PROXY_REMOTEURL=https://registry-1.docker.io \
+        --restart always \
+        --name registry registry:2
+    ```
+
+    You can modify the port number (`6000`) to expose Docker registry on a
+    different port.
+
+4. Check the IP address of the server:
+
+    ```bash
+    hostname --ip-address
+    ```
+
+    You should preferably choose the private networking IP address. The private
+    networking is usually the fastest solution for internal communication
+    between machines of a single provider (DigitalOcean, AWS, Azure, etc,)
+    Usually the private networking is also not accounted to your monthly
+    bandwidth limit.
+
+5. Docker registry will be accessible under `MY_REGISTRY_IP:6000`.
+
+## Install the cache server
+
+>**Note:**
+You can use any other S3-compatible server, including [Amazon S3][S3]. Read
+more in [Distributed runners caching][caching].
+
+1. Login to a dedicated machine where the cache server will be running
+1. Make sure that Docker Engine is installed on that machine
+1. Start [minio], a simple S3-compatible server written in Go:
+
+    ```bash
+    docker run -it --restart always -p 9005:9000 \
+            -v /.minio:/root/.minio -v /export:/export \
+            --name minio \
+            minio/minio:latest server /export
+    ```
+
+    You can modify the port `9005` to expose the cache server on different port.
+
+1. Check the IP address of the server:
+
+    ```bash
+    hostname --ip-address
+    ```
+
+1. Your cache server will be available at `MY_CACHE_IP:9005`
+1. Read the Access and Secret Key of minio with: `sudo cat /.minio/config.json`
+1. Create a bucket that will be used by the Runner: `sudo mkdir /export/runner`.
+   `runner` is the name of the bucket in that case. If you choose a different
+   bucket then it will be different
+1. All caches will be stored in the `/export` directory
+
+[caching]: ../configuration/autoscale.md#distributed-runners-caching
+[registry]: ../configuration/autoscale.md#distributed-docker-registry-mirroring