From 6d4d7d0a9b19027d9e1b928832cb2d22aa084710 Mon Sep 17 00:00:00 2001 From: Misty Stanley-Jones Date: Wed, 18 Jan 2017 12:38:55 -0800 Subject: [PATCH] Update 'usingdocker' tutorial to name the container Do some clean-up while I'm in there --- engine/tutorials/usingdocker.md | 247 ++++++++++++++++++-------------- 1 file changed, 140 insertions(+), 107 deletions(-) diff --git a/engine/tutorials/usingdocker.md b/engine/tutorials/usingdocker.md index cfec30a00f..aac4f049d8 100644 --- a/engine/tutorials/usingdocker.md +++ b/engine/tutorials/usingdocker.md @@ -3,10 +3,6 @@ redirect_from: - /engine/userguide/containers/usingdocker/ description: Learn how to manage and operate Docker containers. keywords: docker, the docker guide, documentation, docker.io, monitoring containers, docker top, docker inspect, docker port, ports, docker logs, log, logs -menu: - main: - parent: engine_learn_menu - weight: -5 title: Run a simple application --- @@ -21,59 +17,68 @@ background. In the process you learned about several Docker commands: ## Learn about the Docker client -The `docker` program is called the Docker client. Each action you can take with -the client is a command and each command can take a series of flags and arguments. +The `docker` program is called the Docker client. To control Docker using the +client, you use commands, flags, and arguments. Have a look at the following +example, which uses the `run` command, the `-i` and `-t` flags, and the `ubuntu` +and `/bin/bash` arguments. - # Usage: [sudo] docker [subcommand] [flags] [arguments] .. - # Example: - $ docker run -i -t ubuntu /bin/bash +```bash +$ docker run -i -t ubuntu /bin/bash +``` -You can see this in action by using the `docker version` command to return -version information on the currently installed Docker client and daemon. +The `docker version` command shows information about the version of Docker the +client is using, as well as other version-specific information. - $ docker version +```bash +$ docker version -This command will not only provide you the version of Docker client and -daemon you are using, but also the version of Go (the programming -language powering Docker). +Client: + Version: 1.12.5 + API version: 1.24 + Go version: go1.6.4 + Git commit: 7392c3b + Built: Fri Dec 16 02:42:17 2016 + OS/Arch: windows/amd64 - Client: - Version: 1.12.5 - API version: 1.24 - Go version: go1.6.4 - Git commit: 7392c3b - Built: Fri Dec 16 02:42:17 2016 - OS/Arch: windows/amd64 - - Server: - Version: 1.12.5 - API version: 1.24 - Go version: go1.6.4 - Git commit: 7392c3b - Built: Fri Dec 16 02:42:17 2016 - OS/Arch: linux/amd64 +Server: + Version: 1.12.5 + API version: 1.24 + Go version: go1.6.4 + Git commit: 7392c3b + Built: Fri Dec 16 02:42:17 2016 + OS/Arch: linux/amd64 +``` ## Get Docker command help -You can display the help for specific Docker commands. The help details the -options and their usage. To see a list of all the possible commands, use the -following: +Each Docker command has associated usage information, which you can see when you +use the `--help` flag. You can use `--help` for the `docker` command itself, or +for its sub-commands. - $ docker --help +To see usage information for the entire `docker` command, including a list of +all the possible commands, use `docker --help`. -To see usage for a specific command, specify the command with the `--help` flag: +```bash +$ docker --help +``` - $ docker attach --help +To see usage for a specific command, add the `--help` flag after that specific +command. For instance, the following command shows the help text for the +`docker attach` command. - Usage: docker attach [OPTIONS] CONTAINER +```bash +$ docker attach --help - Attach to a running container +Usage: docker attach [OPTIONS] CONTAINER - Options: - --detach-keys string Override the key sequence for detaching a container - --help Print usage - --no-stdin Do not attach STDIN - --sig-proxy Proxy all received signals to the process (default true) +Attach to a running container + +Options: + --detach-keys string Override the key sequence for detaching a container + --help Print usage + --no-stdin Do not attach STDIN + --sig-proxy Proxy all received signals to the process (default true) +``` > **Note:** > For further details and examples of each command, see the @@ -82,18 +87,20 @@ To see usage for a specific command, specify the command with the `--help` flag: ## Run a web application in Docker Now that you've learned a bit more about the Docker client, you can move onto -the important stuff: running more containers. So far none of the -containers you've run did anything particularly useful, so you can -change that by running an example web application in Docker. +the important stuff: running more containers. First, run an example Python Flask +web application as a Docker container. -For the web application you're going to run a Python Flask application. -Start with a `docker run` command. - - $ docker run -d -P training/webapp python app.py +```bash +$ docker run -d -P --name my_webapp training/webapp python app.py +``` This command consists of the following parts: * The `-d` flag runs the container in the background (as a so-called daemon). +* The `--name my_webapp` flag names the container `my_webapp`. If you do not + specify a name, Docker creates a random (and sometimes amusing) name for the + container. This name is guaranteed to be unique among all the containers + running on a given Docker host. * The `-P` flag maps any required network ports inside the container to your host. This lets you view the web application. * The `training/webapp` image is a pre-built image that contains a simple Python @@ -108,12 +115,14 @@ This command consists of the following parts: ## View the web application container -Now you can see your running container using the `docker ps` command. +To see information about your running container, use the `docker ps` command. - $ docker ps -l +```bash +$ docker ps -l - CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES - bc533791f3f5 training/webapp:latest python app.py 5 seconds ago Up 2 seconds 0.0.0.0:49155->5000/tcp nostalgic_morse +CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES +bc533791f3f5 training/webapp:latest python app.py 5 seconds ago Up 2 seconds 0.0.0.0:49155->5000/tcp my_webapp +``` The `-l` flag shows only the details of the *last* container started. @@ -121,30 +130,31 @@ The `-l` flag shows only the details of the *last* container started. > By default, the `docker ps` command only shows information about running > containers. If you want to see stopped containers too, use the `-a` flag. -You can see the same details you saw [when you first dockerized a -container](dockerizing.md), with one important addition in the `PORTS` -column. +In particular, have a look at the `PORTS` column. - PORTS - 0.0.0.0:49155->5000/tcp +```none +PORTS +0.0.0.0:49155->5000/tcp +``` -When you passed the `-P` flag to the `docker run` command, -Docker mapped any ports exposed in the container to your host. +When you passed the `-P` flag to the `docker run` command, Docker mapped any +ports exposed in the container to ports on your host machine. In this case, +port 5000 (the default port for Python Flask) is mapped to port 49155 on the +Docker host. > **Note:** > You'll learn more about how to expose ports in Docker images when > [you learn how to build images](dockerimages.md). -In this case Docker has exposed port 5000 (the default Python Flask -port) on port 49155. - Network port bindings are very configurable in Docker. In the last example the `-P` flag is a shortcut for `-p 5000` that maps port 5000 inside the container to a high port (from *ephemeral port range* which typically ranges from 32768 to 61000) on the local Docker host. You can also bind Docker containers to specific ports using the `-p` flag, for example: - $ docker run -d -p 80:5000 training/webapp python app.py +```bash +$ docker run -d --name my_other_webapp -p 80:5000 training/webapp python app.py +``` This would map port 5000 inside your container to port 80 on your local host. You might be asking about now: why wouldn't we just want to always @@ -179,9 +189,11 @@ so Docker has a useful shortcut you can use: `docker port`. To use `docker port`, specify the ID or name of your container and then the port for which you need the corresponding public-facing port. - $ docker port nostalgic_morse 5000 +```bash +$ docker port my_webapp 5000 - 0.0.0.0:49155 +0.0.0.0:49155 +``` In this case you've looked up what port is mapped externally to port 5000 inside the container. @@ -191,11 +203,13 @@ the container. You can also find out a bit more about what's happening with your application and use another of the commands you've learned, `docker logs`. - $ docker logs -f nostalgic_morse +```basg +$ docker logs -f my_webapp - * Running on http://0.0.0.0:5000/ - 10.0.2.2 - - [06/Nov/2016 20:16:31] "GET / HTTP/1.1" 200 - - 10.0.2.2 - - [06/Nov/2016 20:16:31] "GET /favicon.ico HTTP/1.1" 404 - +* Running on http://0.0.0.0:5000/ +10.0.2.2 - - [06/Nov/2016 20:16:31] "GET / HTTP/1.1" 200 - +10.0.2.2 - - [06/Nov/2016 20:16:31] "GET /favicon.ico HTTP/1.1" 404 - +``` The `-f` flag causes the `docker logs` command to act like the `tail -f` command and watch the container's standard output. You can see here the logs from Flask @@ -206,10 +220,12 @@ showing the application running on port 5000 and the access log entries for it. In addition to the container's logs you can also examine the processes running inside it using the `docker top` command. - $ docker top nostalgic_morse +```bash +$ docker top my_webapp - PID USER COMMAND - 854 root python app.py +PID USER COMMAND +854 root python app.py +``` Here you can see that the `python app.py` command is the only process running inside the container. @@ -220,45 +236,56 @@ Lastly, you can take a low-level dive into the Docker container using the `docker inspect` command. It returns a JSON document containing useful configuration and status information for the specified container. - $ docker inspect nostalgic_morse +```bash +$ docker inspect my_webapp +``` You can see a sample of that JSON output. - [{ - "ID": "bc533791f3f500b280a9626688bc79e342e3ea0d528efe3a86a51ecb28ea20", - "Created": "2014-05-26T05:52:40.808952951Z", - "Path": "python", - "Args": [ - "app.py" - ], - "Config": { - "Hostname": "bc533791f3f5", - "Domainname": "", - "User": "", - . . . +```none +[{ + "ID": "bc533791f3f500b280a9626688bc79e342e3ea0d528efe3a86a51ecb28ea20", + "Created": "2014-05-26T05:52:40.808952951Z", + "Path": "python", + "Args": [ + "app.py" + ], + "Config": { + "Hostname": "bc533791f3f5", + "Domainname": "", + "User": "", + ... +}] +``` You can also narrow down the information you want to return by requesting a specific element, for example to return the container's IP address, you would: - {% raw %} - $ docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' nostalgic_morse - {% endraw %} +```bash +{% raw %} +$ docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' my_webapp - 172.17.0.5 +172.17.0.5 +{% endraw %} +``` ## Stop the web application container The web application is still running inside the container. You can stop it using -the `docker stop` command and the name of the container: `nostalgic_morse`. +the `docker stop` command and the name of the container: `my_webapp`. - $ docker stop nostalgic_morse +```bash +$ docker stop my_webapp - nostalgic_morse +my_webapp +``` You can now use the `docker ps` command to check if the container has been stopped. - $ docker ps -l +```bash +$ docker ps -l +``` ## Restart the web application container @@ -267,41 +294,47 @@ developer needs the container back. From here you have two choices: you can create a new container or restart the old one. Look at starting your previous container back up. - $ docker start nostalgic_morse +```bash +$ docker start my_webapp - nostalgic_morse +my_webapp +``` Now quickly run `docker ps -l` again to see the running container is back up or browse to the container's URL to see if the application responds. > **Note:** -> Also available is the `docker restart` command that runs a stop and -> then start on the container. +> The `docker restart` command is also available. It is the equivalent of +> running `docker stop` followed by `docker start`. ## Remove the web application container Your colleague has let you know that they've now finished with the container and won't need it again. Now, you can remove it using the `docker rm` command. - $ docker rm nostalgic_morse +```bash +$ docker rm my_webapp - Error: Impossible to remove a running container, please stop it first or use -f - 2014/05/24 08:12:56 Error: failed to remove one or more containers +Error: Impossible to remove a running container, please stop it first or use -f +2014/05/24 08:12:56 Error: failed to remove one or more containers +``` What happened? You can't actually remove a running container. This protects you from accidentally removing a running container you might need. You can try this again by stopping the container first. - $ docker stop nostalgic_morse +```bash +$ docker stop my_webapp - nostalgic_morse +my_webapp - $ docker rm nostalgic_morse +$ docker rm my_webapp - nostalgic_morse +my_webapp +``` -And now the container is stopped and deleted. +Now the container is stopped and deleted. > **Note:** > Always remember that removing a container is final!