Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll

Introduction to Docker

Preview

Start a free Courses trial
to watch this video

Sign up for Treehouse

Building the Image and Running the Container

3:10 with Jay McGavren and Jared Smith

Okay, we've got our app files and our Dockerfile. Let's try building an image.

Change into the directory that has your Dockerfile. Then use the docker build command, with the -t option set to node-js-app to tag the image. We'll tell it that the Dockerfile is in the current directory: ..

docker build -t node-js-app .

When the build is done, we'll be returned to our shell prompt. If we run the docker images command, we'll see our new node-js-app image in the output! You'll also see the node:7 base image in the list.

We have the image; let's try running it as a container! We'll use the docker run command. The container will have port 80 exposed, so we need to publish it as a port on our Docker host. I'll pass the -p option to publish it, and map the host port of 8080 to the exposed container port 80. I'll pass the -d flag to detach the container from the terminal, so we can run other commands. And of course, I need to specify which image to run: node-js-app.

docker run -p 8080:80 -d node-js-app

If we run docker ps, we'll see a container based on the node-js-app image in the output.

docker ps

If we take the container ID shown there, and pass it to docker logs, we can see our app's output.

docker logs ID_HERE

We can execute additional processes on the container with docker exec. If we want to open a shell on the container, we can use -it to set up an interactive terminal session, specify the container ID as the container to run on, and specify /bin/bash as the executable to run.

docker exec -it ID_HERE /bin/bash

Related Discussions

Have questions about this video? Start a discussion with the community and Treehouse staff.

Sign up

    Related Discussions

    Have questions about this video? Start a discussion with the community and Treehouse staff.

    Sign up

    Okay, we've got our app files and our Docker file. 0:00
    Let's try building an image. 0:04
    Change into the directory that has your Docker file. 0:04
    Then use the Docker build command with the -t option set to node-js-app. 0:10
    That will tag the image. 0:17
    We'll tell it that the Docker file is in the current directory. 0:20
    When we run this command, Docker will first download the node 7 image, because 0:23
    our Docker file specifies that should be used as a basis for our new image. 0:28
    Then it'll carry out the other instructions from our Docker file, setting 0:32
    a working directory, copying the app files over, running npm install, and so on. 0:37
    When the build is done, we'll be returned to our shell prompt. 0:42
    If we run the Docker images command, we'll see our node-js-app image in the output. 0:46
    There it is. 0:53
    You'll also see the node 7 base image in the list. 0:54
    We have our image. 0:58
    Let's try running it as a container. 0:59
    We'll use the Docker run command. 1:02
    The container will have port 80 exposed, so 1:04
    we need to publish it as a port on our Docker host. 1:07
    I'll pass the dash -p option to publish it. 1:10
    And I'm gonna map the host port of 8080 to the exposed container port 80. 1:12
    I'll pass the -d flag to detach the container from the terminal so 1:18
    we can run other commands. 1:23
    And, of course, I need to specify which image to run, node-js-app. 1:25
    Our container will launch, and Docker will print the container ID 1:30
    before returning us to a prompt on our Docker host. 1:34
    If we run docker ps, 1:38
    we'll see a container based on the node.js app image in the output. 1:40
    If we take the container ID shown here and pass part of it to docker logs, 1:45
    so f255, I'll just use the first part of the ID, we can see our app's output. 1:51
    We can execute additional processes on the container with docker exec. 1:57
    If we want to open a shell on the container, 2:02
    we can use -it to set up an interactive terminal session. 2:05
    Specify the container ID is the container to run on. 2:09
    So f255, we'll only use a partial ID again. 2:14
    And specify /bin/bash as the executable to run. 2:16
    That will open a shell and 2:21
    we can use it to explore the system just like we would any other LINUX system. 2:23
    So we can print the working directory, we can list the contents of client directory, 2:27
    and we can show list of running processes. 2:32
    When we're done, we can type exit to quit the shell and return to our host system. 2:35
    But perhaps most importantly, if we run docker ps we 2:39
    can confirm in the output that the exposed port 80 2:44
    has been published as port 8080 on the host. 2:49
    If we open a web browser and connect to HTTP local host port 8080, 2:54
    our request will be forwarded to port 80 on the container and 2:59
    our Node app will generate a response. 3:03
    We've successfully Dockerized a web app from scratch. 3:06

    You need to sign up for Treehouse in order to download course files.

    Sign up

      You need to sign up for Treehouse in order to set up Workspace

      Sign up