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Docker Lab: Embedding the Source Code

Previously in the lab...

Question: Why? Why do I get this error? And is there no other way to access the webserver via the private IP?

Answer(s):

  1. The apache webserver does not allow to scan its own document root.
  2. There is another way, and you're going to love it.

Get the PHP App

For this lab you're going to need a small PHP app consisting of two files.

First, let's create a directory for the app's files called php-app.

Then, inside that directory, create a new file named index.php with the following content:

<?php
echo "Welcome to Docker (my young padawan)!";

Note for play-with-docker.com:

  • create directory with this shell command: mkdir php-app
  • create file with this shell command: touch index.php
  • click on the EDITOR button
  • select the folder and then the file
  • add the content and save the changes

And lastly, create another file named db.php with the following content:

<?php
$servername = "mariadb-container-with-existing-external-volume";
$username = "peter";
$password = "venkman";

// Create connection
$conn = new \mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";

That's it for the app part.

Mounting the dev environment into your Docker container

Make sure you're outside that freshly created app directory when you execute the next commands.

Now you can mount the php-app into your docker container via

$ docker run -itd --name apache-php -v php-app:/var/www/html php:7-apache

docker run -itd --name apache-php -v php-app:/var/www/html  php:7-apache

Note: Do not forget to stop/remove the existing instance of the apache-php container.

You can now check if the error is still present OR you wait until the second question is answered.

Portforwarding your Docker Container

Docker is able to forward any port you want/specify to your local machine. This is great but also has the possibility of causing port trouble. Imagine you had a local httpd service running on port 80 and you are forwarding this same port to your Docker instance.

But let's not assume this right now! Or simply use a port other than 80.

As you might have guessed it's again a parameter named -p[local]:[container] that you can set:

docker run -itd --name apache-php -v php-app:/var/www/html -p80:80 php:7-apache

Note: Do not forget to stop/remove the existing instance of the apache-php container.

If you take a look into docker container ls you'll find an interesting change for the PORT column

$ docker container ls
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                NAMES
6b0721fa6103        php:7-apache        "docker-php-entryp..."   5 seconds ago       Up 4 seconds        0.0.0.0:80->80/tcp   apache-php
50197361e87b        mariadb             "docker-entrypoint..."   2 hours ago         Up 2 hours          3306/tcp             mariadb-container-with-existing-external-volume
6f08ac657320        mariadb             "docker-entrypoint..."   5 hours ago         Up 2 hours          3306/tcp             mariadb-container

You see that every request coming to port 80 on your local machine is forwarded to your Docker instance's port 80. If you now type http://localhost/index.php in your browser you should get the message: "Welcome to Docker...".

Note for play-with-docker.com: To access the frontend app, you have to use a special url.

  • copy the ssh connection command (ssh ip172-18-0-30-bcvhrp0abk8g00cnf9jg@direct.labs.play-with-docker.com)
  • remove ssh and replace the @ with a .
  • with that url you will see the app page: ip172-18-0-30-bcvhrp0abk8g00cnf9jg.direct.labs.play-with-docker.com

Question: Can I somehow link the containers together so they can talk to each other?

The answer lies in the next lab.

← Frontend Container | Linking Frontend and Backend →