HTTP server inside a docker container

Introduction

This article mainly focuses on how to run an HTTP server inside a Docker container. The key point is port mapping.

Basic setup

I skipped installation of Docker on Ubuntu here. Please refer to my last Docker note.

For server example, I have some in my github.

C version

Python flask

Rust version

Here I choose Rust version for example.

Run Rust docker

# pull rust official image to local
docker pull rust

# run a container
docker run -itd -p 8080:5000 --name httpserver rust

Here -itd means interactive, TTY, and detached, which are running options for the container. -p sets the port mapping. 8080 is the host port and 5000 is the container port.

So we need the server inside the container to listen for HTTP requests on port 5000.

Because we run the container in detached mode, we first need to attach to the container.

# httpserver is our container name
docker attach httpserver

Inside the container we can use Ctrl-P then Ctrl-Q to detach again.

Another way to go into the container is to open another shell.

# -it has same meaning as 'docker run'
docker exec -it httpserver bash

Since we have one more shell now, it is OK to close the other one.

Setup server

Now assume we are already in the container. Vim and Git might be needed, but I skip their installation here.

To fetch and run the server:

# clone source code from my github
git clone https://github.com/ysmiles/ServerClientExamples-Rust

# compile and run
cd tcptime/
cargo run

It might be necessary to change main.rs from TcpListener::bind("127.0.0.1:8000") to TcpListener::bind("0.0.0.0:5000") before compiling. That lets the server accept connections from outside the container after the port mapping.

Now detach from the container and test at server local to see the result.

# curl can give a http request to a specific address
curl http://0.0.0.0:8080

The output should be something like below:

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="utf-8">
  <title>Hello!</title>
</head>

<body>
  <h1>Hello!</h1>
  <p>Hi from Rust</p>
  <p>Current server time is:</p>
  <p>2017-12-06 11:20:17</p>
</body>

</html>

Then test remotely. The original post embedded a live external server here, but that demo endpoint is no longer reliable and the old http:// embed was not appropriate to keep in the migrated site.

If you want to verify your own setup instead, open the mapped port in a browser or use curl from another machine on the same network.