oveits/docker-nginx-busybox repository overview

⁠docker-nginx-busybox

(~ 8 MB image size)

This is a "Hello World" example on how to build docker images (manually and automated).

As target of our hello world examle, I have chosen a tiny docker image for nginx built on top of busybox forked from https://github.com/jimmidyson/docker-nginx-busybox⁠. A successful build will result in an image of ~8 MB (i.e. a perfect hello world size).

1. We describe on how to perform a manual build from Dockerfile and how to test the image.
2. We describe on how to automatically build a Docker image from a Git repository.

If you are searching for more professional nginx images with prepared https support, check out the official nginx image on https://hub.docker.com/_/nginx/⁠, which is larger as this image (~52 MB). If it must be smaller, https://hub.docker.com/r/connexiolabs/alpine-nginx/⁠ with ~27 MB might be an alternative as well.

⁠Prerequisites

1. Sign up for Github and Docker Hub, if not already done.
2. Fork this git repository (button on the upper right), if not already done.
3. Install docker, if not already done. On Windows, I recommend to install docker via Vagrant instead of going through the hassle of following the official Docker installation procedure. On my blog Install a Docker Cluster in less than 10 Minutes⁠, I show how you can install a CoreOS minimal docker host very quickly. Here we will need only a single host, so you can skip the etcd discovery part and the change of the num_instances variable.

⁠Manually build a docker image

(Status: tested successfully)

⁠Clone and build the Image

Clone your repository to a docker host. On the host, issue the commands (but replace "oveits" by your Docker Hub username)

git clone https://github.com/oveits/docker-nginx-busybox docker-nginx-busybox
cd docker-nginx-busybox

On the docker host, perform the command:

docker build --tag=nginx-busybox:latest .

Verify that the image has been created:

docker images

should lead to an output similar to:

REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
nginx-busybox       latest              5c21ee35c67c        8 hours ago         7.898 MB

⁠Start Container from the above created Image

On the docker host, perform the command:

docker run -d -p 80:80 nginx-busybox

Verify that the container has been created and is up and running:

docker ps
CONTAINER ID        IMAGE                  COMMAND             CREATED             STATUS              PORTS                         NAMES
a8614bead979        nginx-busybox:latest   "/usr/sbin/nginx"   4 seconds ago       Up 3 seconds        0.0.0.0:80->80/tcp, 443/tcp   stoic_mestorf

⁠Connect to the NginX reverse Proxy locally

On the docker host, the commands

curl localhost

Should print the content of index.html to the screen:

<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx on busybox!</title>
...
<p><em>Thank you for using nginx.</em></p>
</body>
</html>

⁠Connect to the NginX reverse Proxy per Browser

Linux: If you start a browser on the Linux docker host, use the URL

http://localhost

Windows or iOS: On boot2docker hosts (Windows and iOS), find your docker host's IP address by issuing the command

boot2docker ip
 

on the boot2docker start commandline window. Usually, this is a Virtualbox host-only network and is reachable from the Windows or iOS host only, but not from the outside world.

On Windows or iOS using a custom Linux Virtualbox VM as docker host (as we recommend since the installation of boot2docker is a nightmare sometimes), networking can be more tricky:

On the Linux docker host, issue the command

ifconfig

The interface docker0 and eth0 with IP address 10.0.2.15 are not reachable from the Windows or iOS host. Therefore, we recommend to provision the custom Linux Virtualbox VM with an additional interface eth1 with a host-only (if it does not need to be reached from outside the Windows or iOS host) or bridged network. In this case the output of ifconfig will look something like

core@core-01 ~/docker-nginx-busybox $ ifconfig
docker0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.1.42.1  netmask 255.255.0.0  broadcast 0.0.0.0              <--- not reachable from the outside!!
        ...

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 10.0.2.15  netmask 255.255.255.0  broadcast 10.0.2.255         <--- not reachable from the outside!!
        ...

eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.17.8.101  netmask 255.255.255.0  broadcast 172.17.8.255    <--- host-only network -> only reachable from the Virtualbox host
        ...

From the Windows or iOS host, open an Internet browser and put an URL like

# just in case http_proxy and/or HTTP_PROXY are not empty, perform:
unset http_proxy
unset HTTP_PROXY
# then:
http://<IP address of eth1>

to the URL field; in the example above, this is http://172.17.8.101⁠.

⁠Automatically build a Docker Image on Docker Hub from this Repository

(Status: tested successfully)

⁠Prerequisites

1. Sign up for Github and Docker Hub, if not already done.
2. Fork this git repository (button on the upper right), if not already done.
3. Install docker (see Prerequisites above)

⁠Link Github with Docker

On the Git Hub repository project home (https://github.com/⁠/docker-nginx-busybox), goto -> Settings (on the right) -> Webhooks & Services -> Add Service -> choose Docker -> enter your Docker Hub password and confirm

⁠Set Trigger on Docker

On Docker Hub Home, left of your username -> Create -> Create Automated Build -> Choose your repository -> Enter short description (required) -> Create

⁠Test Triggered Build

Test the automatic build trigger by changing e.g. the Readme file in your Github repository. This should trigger a new Docker image build (this may take a while). Check the results on the Docker Hub Build Details tab of the newly created docker repository. After some time, it should show a build status of "done".

⁠Test the Image

Test the docker image by issuing follwoing commands (change "oveits" to your Docker Hub username)

ID=$(docker run -d -p 80:80 oveits/docker-nginx-busybox); echo $ID

Check the container status and the logs with

docker ps
docker logs $ID

And connect to the server by issuing the command

curl localhost

on the docker host. The answer should look like

<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx on busybox!</title>
...
<p><em>Thank you for using nginx.</em></p>
</body>
</html>

DONE.