How To Run Nginx Using Docker

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NGINX is a popular open-source software used for web serving, reverse proxying, caching, load balancing, media streaming, and more. It can also function as a proxy server for email (IMAP, POP3, and SMTP) and a reverse proxy and load balancer for HTTP, TCP, and UDP servers. Nginx is quite popular and used on many high traffic websites today. In this tutorial, we’ll learn how to run Nginx in a container using Docker. We’ll tackle how to download and run the image, create several containers from that image, learn about foreground vs background tasks, and see how to inspect the logs.

Image Vs Container

An Image is an application you want to run
A Container is an instance of the image running as a process
There can be many containers running via the same image
Docker Hub is the main registry for images at hub.docker.com

Launch A Container

We can launch a new container using the following command.

docker container run --publish 80:80 nginx

You may see some output in the terminal similar to this.

$ docker container run --publish 80:80 nginx
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Configuration complete; ready for start up

Docker Dashboard will also show the container running.

nginx docker container running

Open a browser to visit http://localhost and we should see an Nginx web server happily offering the default web page.

nginx web page via docker

In the terminal, we will also see some logging of the browser making requests from the webserver.

172.17.0.1 - - [28/Sep/2020:15:10:03 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36" "-"

How It Works

docker container run –publish 80:80 nginx

When the command above is triggered, the Docker engine takes a series of steps.

Download the Nginx image from Docker Hub, if not already in local cache
Started a new Container from the Nginx image
Opened port 80 on the host IP
Routes host traffic port 80 to Container IP port 80

Running In Detached Mode

The reason why we were able to see the log output of the container straight away, is because the container is running in the foreground. Many times you just want the container to run in the background. This is what is known as Detached Mode. First, we need to stop the running container. We can do this by first finding the container id or name with docker ps, then using the docker stop command to stop it.

$ docker ps
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                NAMES
902affce585b        nginx               "/docker-entrypoint.ΓÇª"   2 hours ago         Up 2 hours          0.0.0.0:80->80/tcp   sharp_hoover

Based on the above output, we can stop the container with either of the following two:

docker stop sharp_hoover

docker stop 902affce585b

Now let’s run the image again, creating a brand new container that runs in detached mode. Note the use of the –detach flag.

$ docker container run --publish 80:80 --detach nginx

Detach tells Docker to run the container in the background, and the only output to the terminal, in this case, is the unique container id. Every time you run a new container, you get a new unique id. Let’s look at the containers running again using docker container ls.

$ docker container ls
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                NAMES
d62595efbb6c        nginx               "/docker-entrypoint.ΓÇª"   4 minutes ago       Up 4 minutes        0.0.0.0:80->80/tcp   quizzical_hermann

Our new Nginx container running in the background has the name quizzical_hermann.

We can stop the container with docker container stop passing in just the first couple of characters of the container id.

$ docker container stop d62
d62

Listing Containers

In the past, you might use docker ps to display containers. The more appropriate way to list containers now is using docker container ls. When listing our containers we don’t see any.

$ docker container ls
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

This is because if a container is not running, it will not be displayed. To see all containers, even those that are not running, you need to add the -a flag.

$ docker container ls -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                      PORTS               NAMES
d62595efbb6c        nginx               "/docker-entrypoint.ΓÇª"   14 minutes ago      Exited (0) 4 minutes ago                        quizzical_hermann
902affce585b        nginx               "/docker-entrypoint.ΓÇª"   2 hours ago         Exited (0) 16 minutes ago                       sharp_hoover

Now we see both containers. Those funny names are created automatically if you don’t specify a name for the container during creation. Just like every ID is unique for containers, the name is also required to be unique. Docker randomly generates the name from an open-source list of adjectives and notable hackers of scientists. So how can we give our own name to a container? We can do this by specifying the –name flag.

$ docker container run --publish 80:80 --detach --name my_nginx_server nginx
4402b968a91567195e690ca4c5c7d79525c5823f640ff0d2cceb6ee045d2a8d6

$ docker container ls -a
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS                      PORTS                NAMES
4402b968a915        nginx               "/docker-entrypoint.ΓÇª"   8 seconds ago       Up 7 seconds                0.0.0.0:80->80/tcp   my_nginx_server
d62595efbb6c        nginx               "/docker-entrypoint.ΓÇª"   19 minutes ago      Exited (0) 10 minutes ago                        quizzical_hermann
902affce585b        nginx               "/docker-entrypoint.ΓÇª"   2 hours ago         Exited (0) 21 minutes ago                        sharp_hoover

Viewing Container Logs In Detached Mode

If a container is running in the background, we don’t see any output from the logs at the terminal. If we want to see those logs, we can do that with the docker container logs command.

$ docker container logs my_nginx_server
/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
10-listen-on-ipv6-by-default.sh: Getting the checksum of /etc/nginx/conf.d/default.conf
10-listen-on-ipv6-by-default.sh: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
/docker-entrypoint.sh: Configuration complete; ready for start up
172.17.0.1 - - [28/Sep/2020:17:18:38 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36" "-"
172.17.0.1 - - [28/Sep/2020:17:18:39 +0000] "GET / HTTP/1.1" 304 0 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.121 Safari/537.36" "-"

Working With Containers

Here are the commands you’ll want to be familiar with when working with your containers.

$ docker container

Usage:  docker container COMMAND

Manage containers

Commands:
  attach      Attach local standard input, output, and error streams to a running container
  commit      Create a new image from a container's changes
  cp          Copy files/folders between a container and the local filesystem
  create      Create a new container
  diff        Inspect changes to files or directories on a container's filesystem
  exec        Run a command in a running container
  export      Export a container's filesystem as a tar archive
  inspect     Display detailed information on one or more containers
  kill        Kill one or more running containers
  logs        Fetch the logs of a container
  ls          List containers
  pause       Pause all processes within one or more containers
  port        List port mappings or a specific mapping for the container
  prune       Remove all stopped containers
  rename      Rename a container
  restart     Restart one or more containers
  rm          Remove one or more containers
  run         Run a command in a new container
  start       Start one or more stopped containers
  stats       Display a live stream of container(s) resource usage statistics
  stop        Stop one or more running containers
  top         Display the running processes of a container
  unpause     Unpause all processes within one or more containers
  update      Update configuration of one or more containers
  wait        Block until one or more containers stop, then print their exit codes

Run 'docker container COMMAND --help' for more information on a command.

Removing Containers

At this point, we have 3 containers in total. One is running and the other two are idle. Let’s try to remove them all in one shot.

$ docker container rm 440 d62 902
d62
902
Error response from daemon: You cannot remove a running container 4402b968a91567195e690ca4c5c7d79525c5823f640ff0d2cceb6ee045d2a8d6. Stop the container before attempting removal or force remove

Two of the containers were removed, however, we can see by the error message that a running container can not be removed without stopping it first or forcing the remove. Here we use the -f flag to force the running container to be removed.

$ docker container rm 440 -f
440

Finally, we list all containers one more time, and we can see that our docker playground is clean.

$ docker container ls -a
CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               NAMES

Learn More About Docker And Nginx

How To Use The Official Nginx Docker Image (docker.com)
Nginx Admin Guide Installing Nginx Installing Nginx Docker (docs.nginx.com)
What Is The Difference Between A Docker Image And A Container (stackoverflow.com)
Docker Image Vs Container (phoenixnap.com)
Docker Image Vs Container Everything You Need To Know (stackify.com)
Docker Detached Mode Explained (freecodecamp.org)
How To List Docker Containers (linuxize.com)
Tips How To Live Tail Docker Logs (papertrail.com)
How To Remove Docker Images Containers And Volumes (digitalocean.com)

Summary

We learned about some basic commands to work with Nginx and Docker. The commands we want to be familiar with after this tutorial are listed here.

docker container run	Run a command in a new container
docker container ls	List containers
docker container stop	Stop one or more running containers
docker container start	Start one or more stopped containers
docker container logs	Fetch the logs of a container
docker container top	Display the running processes of a container
docker container rm	Remove one or more containers

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