Archives 2016

Connect to your running container

Now that we have a list of running containers, we can use this information to connect. When connecting to a container, you will have different types of interfaces depending on what software the container is running. Most base OS containers, such as Debian or CentOS, will give you a bash shell. Projects such as Asterisk or FreeSWITCH will give you access to the applications CLI, such as fs_cli or asterisk -rv.

1. You can connect to the container previously listed with the docker ps command using the follwing:

   docker attach <container id>

• You can either use the container id or container name.
• In my previous image, the container id would be 60968049d6b3 and the container name would be pedantic_varahamihira
• If you do not specify a name, docker will randomly assign one.
  • You can assign a container name when running with the --name flag.

• Once you have ran the docker attach command, you will probably need to hit enter a couple times to see a prompt.

  

1. To detach your terminal from the running container, use the follwoing key combination:

   CTRL + P and CTRL + Q

2. If you type exit while attached to the container, the container will stop running. You can also use the following command, which will send a sigterm message to the container:

   docker stop <container name>

In this tutorial we will go over how to search and pull down an existing docker image from the docker hub to run it on your server or local system.

Prerequisites

• You will need to have docker running and installed on your system.

Searching the Docker Hub

• You can search the Docker Hub for pre made images. These images are either made by the community, or official builds of different projects.

  docker search centos
  

• You will get the following response. Notice what it shows you. This will include the following:

1. A description
2. Number of stars voted by the community
3. Indication if the image is official and built by the organization in charge of the project
4. Indication if the build is automated or not

• Below is an example of what you will see when searching the Docker Hub.

• Notice the first image is marked as the official CentOS docker image.

Creating a container from a remote image

• Let’s create a container based on the official CenOS build.

  docker run -dit docker.io/centos
  

• Note, Docker will automatically download the image from the Docker Hub if the image is not installed on the host. Once completed, the image will be ran.

• Here are the what the flags used in the previous command do:

View running containers

• Validate the container is running by getting a list of all running containers:

  docker ps
  

In our next tutorial we will go over how to attach to a container.