mirror of https://github.com/docker/docs.git
Getting started python fixes (#12217)
* Fix CMD arguments The previous CMD command doesn't actually start the service. * Simplify (and fix) curl command Previously it was specifying a lot of parameters that in our case are optional and IMO don't help with understanding what's going on. Furthermore the previous command was asking for a `/test` page which we do not serve. And finally it was using POST which is not supported in our app created in the previous step. * Fix typo
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uigctaw
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@ -108,10 +108,10 @@ At this point, we have an image that is based on Python version 3.8 and we have
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COPY . .
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```
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This `COPY` command takes all the files located in the current directory and copies them into the image. Now, all we have to do is to tell Docker what command we want to run when our image is executed inside a container. We do this using the `CMD` command.
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This `COPY` command takes all the files located in the current directory and copies them into the image. Now, all we have to do is to tell Docker what command we want to run when our image is executed inside a container. We do this using the `CMD` command. Note that we need to make the application externally visible (i.e. from outside the container) by specifying `--host=0.0.0.0`.
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```dockerfile
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CMD [ "python3", "app.py" ]
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CMD [ "python3", "-m" , "flask", "run", "--host=0.0.0.0"]
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```
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Here's the complete Dockerfile.
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@ -126,7 +126,7 @@ RUN pip3 install -r requirements.txt
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COPY . .
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CMD [ "python3", "app.py" ]
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CMD [ "python3", "-m" , "flask", "run", "--host=0.0.0.0"]
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```
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### Directory structure
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@ -156,13 +156,14 @@ $ docker build --tag python-docker .
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=> [internal] load .dockerignore
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=> => transferring context: 2B
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=> [internal] load metadata for docker.io/library/python:3.8-slim-buster
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=> [1/5] FROM docker.io/library/python:3.8-slim-buster
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=> [1/6] FROM docker.io/library/python:3.8-slim-buster
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=> [internal] load build context
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=> => transferring context: 953B
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=> CACHED [2/5] WORKDIR /app
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=> [3/5] COPY requirements.txt requirements.txt
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=> [4/5] RUN pip3 install -r requirements.txt
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=> [5/5] COPY . .
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=> CACHED [2/6] WORKDIR /app
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=> [3/6] COPY requirements.txt requirements.txt
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=> [4/6] RUN pip3 install -r requirements.txt
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=> [5/6] COPY . .
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=> [6/6] CMD [ "python3", "-m", "flask", "run", "--host=0.0.0.0"]
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=> exporting to image
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=> => exporting layers
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=> => writing image sha256:8cae92a8fbd6d091ce687b71b31252056944b09760438905b726625831564c4c
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@ -27,12 +27,7 @@ After running this command, you’ll notice that you were not returned to the co
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Let’s make a `GET` request to the server using the `curl` command.
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```shell
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$ curl --request POST \
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--url http://localhost:8000/test \
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--header 'content-type: application/json' \
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--data '{
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"msg": "testing"
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}'
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$ curl localhost:8000
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curl: (7) Failed to connect to localhost port 8000: Connection refused
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```
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@ -42,28 +37,23 @@ To stop the container, press ctrl-c. This will return you to the terminal prompt
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To publish a port for our container, we’ll use the `--publish flag` (`-p` for short) on the `docker run` command. The format of the `--publish` command is `[host port]:[container port]`. So, if we wanted to expose port 8000 inside the container to port 3000 outside the container, we would pass `3000:8000` to the `--publish` flag.
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Start the container and expose port 8000 to port 8000 on the host:
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We did not specify a port when running the flask application in the container and the default is 5000. If we want our previous request going to port 8000 to work we can map the host's port 8000 to the container's port 5000:
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```shell
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$ docker run --publish 8000:8000 python-docker
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$ docker run --publish 8000:5000 python-docker
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```
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Now, let’s rerun the curl command from above:
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```shell
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$ curl --request POST \
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--url http://localhost:8000/test \
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--header 'content-type: application/json' \
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--data '{
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"msg": "testing"
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}'
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{"code":"success","payload":[{"msg":"testing","id":"dc0e2c2b-793d-433c-8645-b3a553ea26de","createDate":"2020-09-01T17:36:09.897Z"}]}
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$ curl localhost:8000
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Hello, Docker!
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```
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Success! We were able to connect to the application running inside of our container on port 8000. Switch back to the terminal where your container is running and you should see the POST request logged to the console.
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```shell
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2020-09-01T17:36:09:8770 INFO: POST /test
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[31/Jan/2021 23:39:31] "GET / HTTP/1.1" 200 -
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```
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Press ctrl-c to stop the container.
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@ -73,7 +63,7 @@ Press ctrl-c to stop the container.
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This is great so far, but our sample application is a web server and we don't have to be connected to the container. Docker can run your container in detached mode or in the background. To do this, we can use the `--detach` or `-d` for short. Docker starts your container the same as before but this time will “detach” from the container and return you to the terminal prompt.
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```shell
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$ docker run -d -p 8000:8000 python-docker
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$ docker run -d -p 8000:5000 python-docker
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ce02b3179f0f10085db9edfccd731101868f58631bdf918ca490ff6fd223a93b
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```
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@ -82,13 +72,8 @@ Docker started our container in the background and printed the Container ID on t
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Again, let’s make sure that our container is running properly. Run the same curl command from above.
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```shell
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$ curl --request POST \
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--url http://localhost:8000/test \
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--header 'content-type: application/json' \
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--data '{
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"msg": "testing"
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}'
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{"code":"success","payload":[{"msg":"testing","id":"dc0e2c2b-793d-433c-8645-b3a553ea26de","createDate":"2020-09-01T17:36:09.897Z"}]}
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$ curl localhost:8000
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Hello, Docker!
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```
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## List containers
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@ -98,7 +83,7 @@ Since we ran our container in the background, how do we know if our container is
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```shell
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$ docker ps
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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ce02b3179f0f python-docker "docker-entrypoint.s…" 6 minutes ago Up 6 minutes 0.0.0.0:8000->8000/tcp wonderful_kalam
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ce02b3179f0f python-docker "docker-entrypoint.s…" 6 minutes ago Up 6 minutes 0.0.0.0:8000->5000/tcp wonderful_kalam
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```
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The `docker ps` command provides a bunch of information about our running containers. We can see the container ID, The image running inside the container, the command that was used to start the container, when it was created, the status, ports that exposed and the name of the container.
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@ -161,7 +146,7 @@ Now that all of our containers are stopped, let’s remove them. When you remove
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```shell
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$ docker ps --all
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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ce02b3179f0f python-docker "docker-entrypoint.s…" 19 minutes ago Up 8 seconds 0.0.0.0:8000->8000/tcp wonderful_kalam
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ce02b3179f0f python-docker "docker-entrypoint.s…" 19 minutes ago Up 8 seconds 0.0.0.0:8000->5000/tcp wonderful_kalam
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ec45285c456d python-docker "docker-entrypoint.s…" 31 minutes ago Exited (0) 23 minutes ago agitated_moser
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fb7a41809e5d python-docker "docker-entrypoint.s…" 40 minutes ago Exited (0) 39 minutes ago goofy_khayyam
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```
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@ -182,11 +167,11 @@ Now, let’s address the random naming issue. Standard practice is to name your
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To name a container, we just need to pass the `--name` flag to the `docker run` command.
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```shell
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$ docker run -d -p 8000:8000 --name rest-server python-docker
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$ docker run -d -p 8000:5000 --name rest-server python-docker
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1aa5d46418a68705c81782a58456a4ccdb56a309cb5e6bd399478d01eaa5cdda
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$ docker ps
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CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
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1aa5d46418a6 python-docker "docker-entrypoint.s…" 3 seconds ago Up 3 seconds 0.0.0.0:8000->8000/tcp rest-server
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1aa5d46418a6 python-docker "docker-entrypoint.s…" 3 seconds ago Up 3 seconds 0.0.0.0:8000->5000/tcp rest-server
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```
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That’s better! We can now easily identify our container based on the name.
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@ -201,4 +186,4 @@ In this module, we took a look at running containers, publishing ports, and runn
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Help us improve this topic by providing your feedback. Let us know what you think by creating an issue in the [Docker Docs](https://github.com/docker/docker.github.io/issues/new?title=[Python%20docs%20feedback]){:target="_blank" rel="noopener" class="_"} GitHub repository. Alternatively, [create a PR](https://github.com/docker/docker.github.io/pulls){:target="_blank" rel="noopener" class="_"} to suggest updates.
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<br />
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<br />
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