#7-Docker Container Networking

Each container should serve a single purpose, such as running one application like a web server. Containers can be powerful by themselves, but when connected together, they are far more useful.

For example, a web server container can be connected to a database container to provide application storage. Docker provides multiple options for networking containers.

In this blog, I should explore a few of the common types of networks that Docker supports, and learn how containers within those networks interact.

Explore the Default Network

List the default networks:
```
docker network ls
```
Run an httpd container named web1, without specifying a network, and see which network it uses:
```
ocker run -d --name web1 httpd:2.4
docker inspect web1
```
Take note of the IPAddress.
Run a container using the busybox image, and see if you can connect to the web1 server:
```
docker run --rm -it busybox
```
Check the container's networking, and verify it is in the same IP range as web1:
```
ip addr
```
Ping the web1 container using the IP address:
```
ping <WEB1_IP_ADDRESS>
```
Attempt to ping the web1 container by name:
```
ping web1
```
Attempt to access web1 using wget:
```
wget <WEB1_IP_ADDRESS>
```
Exit the container:
```
exit
```

Explore Bridge Networks

Create a new bridge network named test_application:
```
docker network create test_application
```

Run an httpd container named web2, in the test_application network:

docker run -d --name web2 --network test_application httpd:2.4

Check the status of the container:
```
docker ps -a
```
Verify that web2 was added to the test_application network:
```
docker inspect web2
```
Run a container using the busybox image, and see if you can connect to the web2 server, within the test_application network:
```
docker run --rm -it --network test_application busybox
```
Check the container's networking, and verify it is in the same IP range as web2:
```
ip addr
```
Ping the web2 container using the IP address:
```
ping <WEB2_IP_ADDRESS>
```
Attempt to ping the web2 container by name:
```
ping web2
```
Using wget, attempt to access web2 with the hostname:
```
wget web2
```
Attempt to ping web1:
```
ping <WEB1_IP_ADDRESS>
```
Attempt to access web1 using wget:
```
wget <WEB1_IP_ADDRESS>
```
Exit the container:
```
exit
```

Explore the Host Network

Run an httpd container named web3 on the host network:

docker run -d --name web3 --network host httpd:2.4

Check the status of the container:
```
docker ps -a
```
Attempt to connect to web3 directly from the server:
```
wget localhost
```
Stop web3:
```
docker stop web3
```
Attempt to connect to web3 directly from the server again:
```
wget localhost
```
Start web3:
```
docker start web3
```
Run a container using the busybox image, and see if you can connect to the web3 server:
```
docker run --rm -it --network host busybox
ping web3
```
Using wget, attempt to access localhost within the busybox image:
```
wget localhost
```
Attempt to ping web2:
```
ping <WEB2_IP_ADDRESS>
```
Attempt to ping web1:
```
ping <WEB1_IP_ADDRESS>
```

END