mirror of
https://github.com/docker/compose.git
synced 2025-10-31 03:03:49 +01:00
e6797e1166
docs update per Mary's comments on the PR Signed-off-by: Victoria Bialas <victoria.bialas@docker.com>
192 lines
6.2 KiB
Markdown
192 lines
6.2 KiB
Markdown
<!--[metadata]>
|
|
+++
|
|
title = "Getting Started"
|
|
description = "Getting started with Docker Compose"
|
|
keywords = ["documentation, docs, docker, compose, orchestration, containers"]
|
|
[menu.main]
|
|
parent="workw_compose"
|
|
weight=-85
|
|
+++
|
|
<![end-metadata]-->
|
|
|
|
|
|
# Getting Started
|
|
|
|
On this page you build a simple Python web application running on Docker Compose. The
|
|
application uses the Flask framework and increments a value in Redis. While the
|
|
sample uses Python, the concepts demonstrated here should be understandable even
|
|
if you're not familiar with it.
|
|
|
|
## Prerequisites
|
|
|
|
Make sure you have already
|
|
[installed both Docker Engine and Docker Compose](install.md). You
|
|
don't need to install Python, it is provided by a Docker image.
|
|
|
|
## Step 1: Setup
|
|
|
|
1. Create a directory for the project:
|
|
|
|
$ mkdir composetest
|
|
$ cd composetest
|
|
|
|
2. With your favorite text editor create a file called `app.py` in your project
|
|
directory.
|
|
|
|
from flask import Flask
|
|
from redis import Redis
|
|
|
|
app = Flask(__name__)
|
|
redis = Redis(host='redis', port=6379)
|
|
|
|
@app.route('/')
|
|
def hello():
|
|
redis.incr('hits')
|
|
return 'Hello World! I have been seen %s times.' % redis.get('hits')
|
|
|
|
if __name__ == "__main__":
|
|
app.run(host="0.0.0.0", debug=True)
|
|
|
|
3. Create another file called `requirements.txt` in your project directory and
|
|
add the following:
|
|
|
|
flask
|
|
redis
|
|
|
|
These define the applications dependencies.
|
|
|
|
## Step 2: Create a Docker image
|
|
|
|
In this step, you build a new Docker image. The image contains all the
|
|
dependencies the Python application requires, including Python itself.
|
|
|
|
1. In your project directory create a file named `Dockerfile` and add the
|
|
following:
|
|
|
|
FROM python:2.7
|
|
ADD . /code
|
|
WORKDIR /code
|
|
RUN pip install -r requirements.txt
|
|
CMD python app.py
|
|
|
|
This tells Docker to:
|
|
|
|
* Build an image starting with the Python 2.7 image.
|
|
* Add the current directory `.` into the path `/code` in the image.
|
|
* Set the working directory to `/code`.
|
|
* Install the Python dependencies.
|
|
* Set the default command for the container to `python app.py`
|
|
|
|
For more information on how to write Dockerfiles, see the [Docker user guide](https://docs.docker.com/engine/userguide/dockerimages/#building-an-image-from-a-dockerfile) and the [Dockerfile reference](http://docs.docker.com/reference/builder/).
|
|
|
|
2. Build the image.
|
|
|
|
$ docker build -t web .
|
|
|
|
This command builds an image named `web` from the contents of the current
|
|
directory. The command automatically locates the `Dockerfile`, `app.py`, and
|
|
`requirements.txt` files.
|
|
|
|
|
|
## Step 3: Define services
|
|
|
|
Define a set of services using `docker-compose.yml`:
|
|
|
|
1. Create a file called docker-compose.yml in your project directory and add
|
|
the following:
|
|
|
|
|
|
version: '2'
|
|
services:
|
|
web:
|
|
build: .
|
|
ports:
|
|
- "5000:5000"
|
|
volumes:
|
|
- .:/code
|
|
depends_on:
|
|
- redis
|
|
redis:
|
|
image: redis
|
|
|
|
This Compose file defines two services, `web` and `redis`. The web service:
|
|
|
|
* Builds from the `Dockerfile` in the current directory.
|
|
* Forwards the exposed port 5000 on the container to port 5000 on the host machine.
|
|
* Mounts the project directory on the host to `/code` inside the container allowing you to modify the code without having to rebuild the image.
|
|
* Links the web service to the Redis service.
|
|
|
|
The `redis` service uses the latest public [Redis](https://registry.hub.docker.com/_/redis/) image pulled from the Docker Hub registry.
|
|
|
|
## Step 4: Build and run your app with Compose
|
|
|
|
1. From your project directory, start up your application.
|
|
|
|
$ docker-compose up
|
|
Pulling image redis...
|
|
Building web...
|
|
Starting composetest_redis_1...
|
|
Starting composetest_web_1...
|
|
redis_1 | [8] 02 Jan 18:43:35.576 # Server started, Redis version 2.8.3
|
|
web_1 | * Running on http://0.0.0.0:5000/
|
|
web_1 | * Restarting with stat
|
|
|
|
Compose pulls a Redis image, builds an image for your code, and start the
|
|
services you defined.
|
|
|
|
2. Enter `http://0.0.0.0:5000/` in a browser to see the application running.
|
|
|
|
If you're using Docker on Linux natively, then the web app should now be
|
|
listening on port 5000 on your Docker daemon host. If http://0.0.0.0:5000
|
|
doesn't resolve, you can also try http://localhost:5000.
|
|
|
|
If you're using Docker Machine on a Mac, use `docker-machine ip MACHINE_VM` to get
|
|
the IP address of your Docker host. Then, `open http://MACHINE_VM_IP:5000` in a
|
|
browser.
|
|
|
|
You should see a message in your browser saying:
|
|
|
|
`Hello World! I have been seen 1 times.`
|
|
|
|
3. Refresh the page.
|
|
|
|
The number should increment.
|
|
|
|
## Step 5: Experiment with some other commands
|
|
|
|
If you want to run your services in the background, you can pass the `-d` flag
|
|
(for "detached" mode) to `docker-compose up` and use `docker-compose ps` to
|
|
see what is currently running:
|
|
|
|
$ docker-compose up -d
|
|
Starting composetest_redis_1...
|
|
Starting composetest_web_1...
|
|
$ docker-compose ps
|
|
Name Command State Ports
|
|
-------------------------------------------------------------------
|
|
composetest_redis_1 /usr/local/bin/run Up
|
|
composetest_web_1 /bin/sh -c python app.py Up 5000->5000/tcp
|
|
|
|
The `docker-compose run` command allows you to run one-off commands for your
|
|
services. For example, to see what environment variables are available to the
|
|
`web` service:
|
|
|
|
$ docker-compose run web env
|
|
|
|
See `docker-compose --help` to see other available commands. You can also install [command completion](completion.md) for the bash and zsh shell, which will also show you available commands.
|
|
|
|
If you started Compose with `docker-compose up -d`, you'll probably want to stop
|
|
your services once you've finished with them:
|
|
|
|
$ docker-compose stop
|
|
|
|
At this point, you have seen the basics of how Compose works.
|
|
|
|
|
|
## Where to go next
|
|
|
|
- Next, try the quick start guide for [Django](django.md),
|
|
[Rails](rails.md), or [WordPress](wordpress.md).
|
|
- [Explore the full list of Compose commands](./reference/index.md)
|
|
- [Compose configuration file reference](compose-file.md)
|