mirror of https://github.com/docker/docs.git
Merge pull request #870 from mstanleyjones/720_whalesay_too_unixy
Add Windows info to Getting Started topics
This commit is contained in:
Misty Stanley-Jones
GitHub
commit
6801369fbc
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@ -9,131 +9,183 @@ title: Build your own image
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---
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The `whalesay` image could be improved. It would be nice if you didn't have to
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think of something to say. And you type a lot to get `whalesay` to talk.
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think of something to say and you didn't need to type as much to get `whalesay`
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to talk.
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docker run docker/whalesay cowsay boo-boo
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```bash
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docker run docker/whalesay cowsay boo-boo
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```
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In this next section, you will improve the `whalesay` image by building a new version that "talks on its own" and requires fewer words to run.
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In this next section, you will improve the `whalesay` image by building a new
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version that "talks on its own" and requires fewer words to run.
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## Step 1: Write a Dockerfile
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In this step, you use your favorite text editor to write a short Dockerfile. A
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Dockerfile describes the software that is "baked" into an image. It isn't just
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ingredients though, it can tell the software what environment to use or what
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commands to run. Your recipe is going to be very short.
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In this step, you use a text editor to write a short Dockerfile. A Dockerfile
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is a recipe which describes the files, environment, and commands that make up an
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image. Your recipe is going to be very short.
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1. Go back to your command terminal window.
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You run these steps in a terminal window on Linux or macOS, or a command prompt
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on Windows. Remember that if you are using macOS or Windows, you are still
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creating an image which runs on Linux.
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2. Make a new directory by typing `mkdir mydockerbuild` and pressing RETURN.
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1. Make a new directory. If you're on Windows, use `md` instead of `mkdir`.
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$ mkdir mydockerbuild
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```bash
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$ mkdir mydockerbuild
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```
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This directory serves as the "context" for your build. The context just means it contains all the things you need to build your image.
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This directory will contain all the things you need to build your image.
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Right now, it's empty.
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3. Change to your new directory.
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2. Change to your new directory. Whether you're on Linux, macOS, or Windows,
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the `cd` command is the same.
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$ cd mydockerbuild
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```bash
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$ cd mydockerbuild
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```
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Right now the directory is empty.
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3. Edit a new text file named `Dockerfile` in the current directory, using a
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text editor such as `nano` or `vi` on Linux or Mac, or `notepad` on Windows.
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4. Create a Dockerfile in the directory by typing `touch Dockerfile` and pressing RETURN.
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**Linux or Mac**:
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$ touch Dockerfile
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```bash
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$ nano Dockerfile
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```
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The command appears to do nothing but it actually creates the Dockerfile in the current directory. Just type `ls` to see it.
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**Windows**:
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$ ls
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Dockerfile
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```none
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C:\> notepad Dockerfile
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```
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5. Open the `Dockerfile` in a visual text editor like <a href="https://atom.io/" target="_blank">Atom</a> or <a href="https://www.sublimetext.com/" target="_blank">Sublime</a>, or a text based editor like <a href="http://ex-vi.sourceforge.net/" target="_blank">vi</a>, or <a href="https://www.nano-editor.org/" target="_blank">nano</a>.
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4. Add a `FROM` statement by copying the following line into the file:
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6. Add a line to the file like this:
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```Dockerfile
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FROM docker/whalesay:latest
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```
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FROM docker/whalesay:latest
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The `FROM` keyword tells Docker which image your image is based on.
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Whalesay is cute and has the `cowsay` program already, so we'll start
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there.
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The `FROM` keyword tells Docker which image your image is based on. Whalesay is cute and has the `cowsay` program already, so we'll start there.
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5. Add a `RUN` statement which will install the `fortunes` program into the
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image.
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7. Now, add the `fortunes` program to the image.
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```Dockerfile
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RUN apt-get -y update && apt-get install -y fortunes
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```
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RUN apt-get -y update && apt-get install -y fortunes
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The `whalesay` image is based on Ubuntu, which uses `apt-get` to install
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packages. These two commands refresh the list of packages available to the
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image and install the `fortunes` program into it. The `fortunes` program has
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prints out wise sayings for our whale to say.
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The `fortunes` program has a command that prints out wise sayings for our whale to say. So, the first step is to install it. This line installs the software into the image.
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6. Add a `CMD` statement, which tells the image the final command to run after
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its environment is set up. This command runs `fortune -a` and sends its
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output to the `cowsay` command.
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8. Once the image has the software it needs, you instruct the software to run
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when the image is loaded.
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```Dockerfile
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CMD /usr/games/fortune -a | cowsay
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```
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CMD /usr/games/fortune -a | cowsay
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7. Check your work. Your file should look just like this:
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This line tells the `fortune` program to pass a nifty quote to the `cowsay` program.
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```Dockerfile
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FROM docker/whalesay:latest
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RUN apt-get -y update && apt-get install -y fortunes
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CMD /usr/games/fortune -a | cowsay
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```
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9. Check your work, your file should look like this:
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FROM docker/whalesay:latest
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RUN apt-get -y update && apt-get install -y fortunes
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CMD /usr/games/fortune -a | cowsay
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10. Save and close your Dockerfile.
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At this point, you have all your software ingredients and behaviors described in a Dockerfile. You are ready to build a new image.
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8. Save the file and close the text editor. At this point, your software recipe
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is described in the `Dockerfile` file. You are ready to build a new image.
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## Step 2: Build an image from your Dockerfile
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1. At the command line, make sure the Dockerfile is in the current directory by typing `cat Dockerfile`
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While you are in the `mydockerbuild` directory, build the image using the
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`docker build` image. The `-t` parameter gives your image a tag, so you can
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run it more easily later. Don't forget the `.` command, which tells the
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`docker build` command to look in the current directory for a file called
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`Dockerfile`. This command works the same in Linux, macOS, or Windows.
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$ cat Dockerfile
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FROM docker/whalesay:latest
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```bash
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$ docker build -t docker-whale .
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RUN apt-get -y update && apt-get install -y fortunes
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Sending build context to Docker daemon 2.048 kB
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...snip...
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Removing intermediate container cb53c9d09f3b
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Successfully built c2c3152907b5
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```
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CMD /usr/games/fortune -a | cowsay
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2. Now, build your new image by typing the `docker build -t docker-whale .` command in your terminal (don't forget the . period).
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$ docker build -t docker-whale .
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Sending build context to Docker daemon 2.048 kB
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...snip...
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Removing intermediate container a8e6faa88df3
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Successfully built 7d9495d03763
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The command takes several seconds to run and reports its outcome. Before
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you do anything with the new image, take a minute to learn about the
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Dockerfile build process.
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The command takes several seconds to run and reports its outcome. Keep reading
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to learn a little more about what the output means and what happens when you
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build an image.
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## Step 3: Learn about the build process
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The `docker build -t docker-whale .` command takes the `Dockerfile` in the
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current directory, and builds an image called `docker-whale` on your local
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machine. The command takes about a minute and its output looks really long and
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complex. In this section, you learn what each message means.
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The `docker build -t docker-whale .` command reads the `Dockerfile` in the
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current directory and processes its instructions one by one to build an image
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called `docker-whale` on your local machine. The command takes about a minute
|
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and its output looks really long and complex. In this section, you learn what
|
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each message means.
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First Docker checks to make sure it has everything it needs to build.
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1. Docker checks to make sure it has everything it needs to build. This
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generates this message:
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|
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```none
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Sending build context to Docker daemon 2.048 kB
|
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```
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Then, Docker loads with the `whalesay` image. It already has this image
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locally as you might recall from the last page. So, Docker doesn't need to
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download it.
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2. Docker checks to see whether it already has the `whalesay` image locally and
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pulls it from Docker hub if not. In this case, the image already exists
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locally because you pulled it in a previous task. This corresponds to `FROM`
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statement in the Dockerfile, and generates this message:
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|
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```none
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Step 1 : FROM docker/whalesay:latest
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---> fb434121fc77
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---> 6b362a9f73eb
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```
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Docker moves onto the next step which is to update the `apt-get` package
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manager. This takes a lot of lines, no need to list them all again here.
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At the end of each step, an ID is printed. This is the ID of the layer that
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was created by this step. Each line in a Dockerfile corresponds to a layer
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in the image. Your ID will be different.
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3. Docker starts up temporary container running the `whalesay` image (the
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`Running in` line below). In the temporary container, Docker runs the next
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command in the Dockerfile, which is the `RUN` command, which installs the
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`fortune` command. This generates a lot of lines of output, just like you
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would see if you were manually running the `apt-get` commands on an Ubuntu
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host.
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```none
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Step 2 : RUN apt-get -y update && apt-get install -y fortunes
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---> Running in 27d224dfa5b2
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---> Running in 05d4eda04526
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Ign http://archive.ubuntu.com trusty InRelease
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Ign http://archive.ubuntu.com trusty-updates InRelease
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Ign http://archive.ubuntu.com trusty-security InRelease
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Get:1 http://archive.ubuntu.com trusty-updates InRelease [65.9 kB]
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Get:2 http://archive.ubuntu.com trusty-security InRelease [65.9 kB]
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Hit http://archive.ubuntu.com trusty Release.gpg
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....snip...
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Get:15 http://archive.ubuntu.com trusty-security/restricted amd64 Packages [14.8 kB]
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Get:16 http://archive.ubuntu.com trusty-security/universe amd64 Packages [134 kB]
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Hit http://archive.ubuntu.com trusty Release
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Get:3 http://archive.ubuntu.com trusty-updates/main Sources [480 kB]
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||||
Get:4 http://archive.ubuntu.com trusty-updates/restricted Sources [5921 B]
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||||
Get:5 http://archive.ubuntu.com trusty-updates/universe Sources [214 kB]
|
||||
Get:6 http://archive.ubuntu.com trusty-updates/main amd64 Packages [1160 kB]
|
||||
Get:7 http://archive.ubuntu.com trusty-updates/restricted amd64 Packages [20.4 kB]
|
||||
Get:8 http://archive.ubuntu.com trusty-updates/universe amd64 Packages [505 kB]
|
||||
Get:9 http://archive.ubuntu.com trusty-security/main Sources [157 kB]
|
||||
Get:10 http://archive.ubuntu.com trusty-security/restricted Sources [4621 B]
|
||||
Get:11 http://archive.ubuntu.com trusty-security/universe Sources [54.5 kB]
|
||||
Get:12 http://archive.ubuntu.com trusty-security/main amd64 Packages [700 kB]
|
||||
Get:13 http://archive.ubuntu.com trusty-security/restricted amd64 Packages [17.0 kB]
|
||||
Get:14 http://archive.ubuntu.com trusty-security/universe amd64 Packages [191 kB]
|
||||
Hit http://archive.ubuntu.com trusty/main Sources
|
||||
Hit http://archive.ubuntu.com trusty/restricted Sources
|
||||
Hit http://archive.ubuntu.com trusty/universe Sources
|
||||
Hit http://archive.ubuntu.com trusty/main amd64 Packages
|
||||
Hit http://archive.ubuntu.com trusty/restricted amd64 Packages
|
||||
Hit http://archive.ubuntu.com trusty/universe amd64 Packages
|
||||
Fetched 3640 kB in 11s (329 kB/s)
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||||
Reading package lists...
|
||||
---> eb06e47a01d2
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|
||||
Then, Docker installs the new `fortunes` software.
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Reading package lists...
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Building dependency tree...
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Reading state information...
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|
@ -143,69 +195,129 @@ Then, Docker installs the new `fortunes` software.
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x11-utils bsdmainutils
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The following NEW packages will be installed:
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fortune-mod fortunes fortunes-min librecode0
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0 upgraded, 4 newly installed, 0 to remove and 3 not upgraded.
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0 upgraded, 4 newly installed, 0 to remove and 92 not upgraded.
|
||||
Need to get 1961 kB of archives.
|
||||
After this operation, 4817 kB of additional disk space will be used.
|
||||
Get:1 http://archive.ubuntu.com/ubuntu/ trusty/main librecode0 amd64 3.6-21 [771 kB]
|
||||
...snip......
|
||||
Get:2 http://archive.ubuntu.com/ubuntu/ trusty/universe fortune-mod amd64 1:1.99.1-7 [39.5 kB]
|
||||
Get:3 http://archive.ubuntu.com/ubuntu/ trusty/universe fortunes-min all 1:1.99.1-7 [61.8 kB]
|
||||
Get:4 http://archive.ubuntu.com/ubuntu/ trusty/universe fortunes all 1:1.99.1-7 [1089 kB]
|
||||
debconf: unable to initialize frontend: Dialog
|
||||
debconf: (TERM is not set, so the dialog frontend is not usable.)
|
||||
debconf: falling back to frontend: Readline
|
||||
debconf: unable to initialize frontend: Readline
|
||||
debconf: (This frontend requires a controlling tty.)
|
||||
debconf: falling back to frontend: Teletype
|
||||
dpkg-preconfigure: unable to re-open stdin:
|
||||
Fetched 1961 kB in 19s (101 kB/s)
|
||||
Selecting previously unselected package librecode0:amd64.
|
||||
(Reading database ... 13116 files and directories currently installed.)
|
||||
Preparing to unpack .../librecode0_3.6-21_amd64.deb ...
|
||||
Unpacking librecode0:amd64 (3.6-21) ...
|
||||
Selecting previously unselected package fortune-mod.
|
||||
Preparing to unpack .../fortune-mod_1%3a1.99.1-7_amd64.deb ...
|
||||
Unpacking fortune-mod (1:1.99.1-7) ...
|
||||
Selecting previously unselected package fortunes-min.
|
||||
Preparing to unpack .../fortunes-min_1%3a1.99.1-7_all.deb ...
|
||||
Unpacking fortunes-min (1:1.99.1-7) ...
|
||||
Selecting previously unselected package fortunes.
|
||||
Preparing to unpack .../fortunes_1%3a1.99.1-7_all.deb ...
|
||||
Unpacking fortunes (1:1.99.1-7) ...
|
||||
Setting up librecode0:amd64 (3.6-21) ...
|
||||
Setting up fortune-mod (1:1.99.1-7) ...
|
||||
Setting up fortunes-min (1:1.99.1-7) ...
|
||||
Setting up fortunes (1:1.99.1-7) ...
|
||||
Processing triggers for libc-bin (2.19-0ubuntu6.6) ...
|
||||
---> c81071adeeb5
|
||||
Removing intermediate container 23aa52c1897c
|
||||
---> dfaf993d4a2e
|
||||
Removing intermediate container 05d4eda04526
|
||||
```
|
||||
|
||||
Finally, Docker finishes the build and reports its outcome.
|
||||
When the `RUN` command finishes, a new layer is created and the imtermediate
|
||||
container is removed.
|
||||
|
||||
4. A new intermediate container is created, and Docker adds a layer for the
|
||||
`CMD` line in the Dockerfile, and removes the intermediate container.
|
||||
|
||||
```none
|
||||
Step 3 : CMD /usr/games/fortune -a | cowsay
|
||||
---> Running in a8e6faa88df3
|
||||
---> 7d9495d03763
|
||||
Removing intermediate container a8e6faa88df3
|
||||
Successfully built 7d9495d03763
|
||||
```
|
||||
|
||||
You have now built an image called `docker-whale`.
|
||||
|
||||
|
||||
## Step 4: Run your new docker-whale
|
||||
|
||||
In this step, you verify the new images is on your computer and then you run your new image.
|
||||
Now you can verify that the new image is on your computer and you can run it.
|
||||
|
||||
1. Open a command line terminal.
|
||||
1. In a terminal window or command prompt, type `docker images`, which lists
|
||||
the images you have locally.
|
||||
|
||||
2. Type `docker images` and press RETURN.
|
||||
```bash
|
||||
$ docker images
|
||||
|
||||
This command, you might remember, lists the images you have locally.
|
||||
REPOSITORY TAG IMAGE ID CREATED SIZE
|
||||
docker-whale latest c2c3152907b5 4 minutes ago 275.1 MB
|
||||
docker/whalesay latest fb434121fc77 4 hours ago 247 MB
|
||||
hello-world latest 91c95931e552 5 weeks ago 910 B
|
||||
```
|
||||
|
||||
$ docker images
|
||||
REPOSITORY TAG IMAGE ID CREATED SIZE
|
||||
docker-whale latest 7d9495d03763 4 minutes ago 273.7 MB
|
||||
docker/whalesay latest fb434121fc77 4 hours ago 247 MB
|
||||
hello-world latest 91c95931e552 5 weeks ago 910 B
|
||||
2. Run your new image by typing `docker run docker-whale`.
|
||||
|
||||
3. Run your new image by typing `docker run docker-whale` and pressing RETURN.
|
||||
```bash
|
||||
|
||||
$ docker run docker-whale
|
||||
_________________________________________
|
||||
/ "He was a modest, good-humored boy. It \
|
||||
\ was Oxford that made him insufferable." /
|
||||
-----------------------------------------
|
||||
\
|
||||
\
|
||||
\
|
||||
## .
|
||||
## ## ## ==
|
||||
## ## ## ## ===
|
||||
/""""""""""""""""___/ ===
|
||||
~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ / ===- ~~~
|
||||
\______ o __/
|
||||
\ \ __/
|
||||
\____\______/
|
||||
$ docker run docker-whale
|
||||
|
||||
______________________________________
|
||||
< You will be successful in your work. >
|
||||
--------------------------------------
|
||||
\
|
||||
\
|
||||
\
|
||||
## .
|
||||
## ## ## ==
|
||||
## ## ## ## ===
|
||||
/""""""""""""""""___/ ===
|
||||
~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ / ===- ~~~
|
||||
\______ o __/
|
||||
\ \ __/
|
||||
\____\______/
|
||||
```
|
||||
|
||||
The whale is now a lot smarter. It comes up with its own thoughts and it takes
|
||||
less typing to run. You may also notice that Docker didn't have to download
|
||||
anything, because you built the image locally.
|
||||
|
||||
3. Just for fun, run it again.
|
||||
|
||||
```bash
|
||||
_______________________________________
|
||||
/ If everything seems to be going well, \
|
||||
| you have obviously overlooked |
|
||||
\ something. /
|
||||
---------------------------------------
|
||||
\
|
||||
\
|
||||
\
|
||||
## .
|
||||
## ## ## ==
|
||||
## ## ## ## ===
|
||||
/""""""""""""""""___/ ===
|
||||
~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ / ===- ~~~
|
||||
\______ o __/
|
||||
\ \ __/
|
||||
\____\______/
|
||||
|
||||
```
|
||||
|
||||
Your whale now has a mind of its own, but if you don't like what it says,
|
||||
just run it again!
|
||||
|
||||
As you can see, you've made the whale a lot smarter. It finds its own
|
||||
things to say and the command line is a lot shorter! You may also notice
|
||||
that Docker didn't have to download anything. That is because the image was
|
||||
built locally and is already available.
|
||||
|
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## Where to go next
|
||||
|
||||
On this page, you learned to build an image by writing your own Dockerfile.
|
||||
You ran your image in a container. You also just used Linux from your Mac yet
|
||||
again. In the next section, you take the first step in sharing your image by
|
||||
[creating a Docker Hub account](step_five.md).
|
||||
|
||||
Now that you have learned to build an image and run it, you can learn to share
|
||||
the image by [creating a Docker Hub account](step_five.md).
|
||||
|
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Reference in New Issue