summaryrefslogtreecommitdiffhomepage
path: root/docker.html.markdown
diff options
context:
space:
mode:
Diffstat (limited to 'docker.html.markdown')
-rw-r--r--docker.html.markdown429
1 files changed, 281 insertions, 148 deletions
diff --git a/docker.html.markdown b/docker.html.markdown
index 1df49cc3..ec6abe7e 100644
--- a/docker.html.markdown
+++ b/docker.html.markdown
@@ -1,148 +1,281 @@
----
-category: tool
-tool: docker
-filename: docker.bat
-contributors:
- - ["Ruslan López", "http://javapro.org/"]
- - ["Michael Chen", "https://github.com/ML-Chen"]
----
-
-```bat
-:: download, install and run hello-world image
-docker run hello-world
-
-:: if this is the first time you should be able to see the message
-:: Unable to find image 'hello-world:latest' locally
-:: latest: Pulling from library/hello-world
-:: 1b930d010525: Pull complete
-:: Digest: sha256:4fe721ccc2e8dc7362278a29dc660d833570ec2682f4e4194f4ee23e415e1064
-:: Status: Downloaded newer image for hello-world:latest
-::
-:: Hello from Docker!
-:: This message shows that your installation appears to be working correctly.
-::
-:: To generate this message, Docker took the following steps:
-:: 1. The Docker client contacted the Docker daemon.
-:: 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
-:: (amd64)
-:: 3. The Docker daemon created a new container from that image which runs the
-:: executable that produces the output you are currently reading.
-:: 4. The Docker daemon streamed that output to the Docker client, which sent it
-:: to your terminal.
-::
-:: To try something more ambitious, you can run an Ubuntu container with:
-:: $ docker run -it ubuntu bash
-::
-:: Share images, automate workflows, and more with a free Docker ID:
-:: https://hub.docker.com/
-::
-:: For more examples and ideas, visit:
-:: https://docs.docker.com/get-started/
-
-:: now let's see currently running images
-docker ps
-:: CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
-:: NAMES
-
-:: let's see the images we have ran previously
-docker ps -a
-
-:: CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
-:: NAMES
-:: 4a76281f9c53 hello-world "/hello" 2 minutes ago Exited (0) 2 minutes ago
-:: happy_poincare
-:: the name part is generated automatically so it probably will be different for you
-
-:: let's remove our previously generated image
-docker rm happy_poincare
-
-:: let's test if it was really deleted
-docker ps -a
-:: CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
-:: NAMES
-
-:: specify a custom name for the container
-docker run --name test_container hello-world
-:: Hello from Docker!
-:: This message shows that your installation appears to be working correctly.
-::
-:: To generate this message, Docker took the following steps:
-:: 1. The Docker client contacted the Docker daemon.
-:: 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
-:: (amd64)
-:: 3. The Docker daemon created a new container from that image which runs the
-:: executable that produces the output you are currently reading.
-:: 4. The Docker daemon streamed that output to the Docker client, which sent it
-:: to your terminal.
-::
-:: To try something more ambitious, you can run an Ubuntu container with:
-:: $ docker run -it ubuntu bash
-::
-:: Share images, automate workflows, and more with a free Docker ID:
-:: https://hub.docker.com/
-::
-:: For more examples and ideas, visit:
-:: https://docs.docker.com/get-started/
-
-docker ps -a
-:: CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
-:: NAMES
-:: d345fe1a4f41 hello-world "/hello" About a minute ago Exited (0) About a minute ago
-:: test_container
-:: as you can see the name is now what we have specified
-
-:: retrieve logs from a named container
-docker logs test_container
-:: Hello from Docker!
-:: This message shows that your installation appears to be working correctly.
-::
-:: To generate this message, Docker took the following steps:
-:: 1. The Docker client contacted the Docker daemon.
-:: 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
-:: (amd64)
-:: 3. The Docker daemon created a new container from that image which runs the
-:: executable that produces the output you are currently reading.
-:: 4. The Docker daemon streamed that output to the Docker client, which sent it
-:: to your terminal.
-::
-:: To try something more ambitious, you can run an Ubuntu container with:
-:: $ docker run -it ubuntu bash
-::
-:: Share images, automate workflows, and more with a free Docker ID:
-:: https://hub.docker.com/
-::
-:: For more examples and ideas, visit:
-:: https://docs.docker.com/get-started/
-
-docker rm test_container
-
-docker run ubuntu
-:: Unable to find image 'ubuntu:latest' locally
-:: latest: Pulling from library/ubuntu
-:: 2746a4a261c9: Pull complete
-:: 4c1d20cdee96: Pull complete 0d3160e1d0de: Pull complete c8e37668deea: Pull complete Digest: sha256:250cc6f3f3ffc5cdaa9d8f4946ac79821aafb4d3afc93928f0de9336eba21aa4
-:: Status: Downloaded newer image for ubuntu:latest
-
-docker ps -a
-:: CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
-:: NAMES
-:: c19e9e5b000a ubuntu "/bin/bash" 5 seconds ago Exited (0) 4 seconds ago
-:: relaxed_nobel
-
-:: running a container in an interactive mode
-docker run -it ubuntu
-:: root@e2cac48323d2:/# uname
-:: Linux
-:: root@e2cac48323d2:/# exit
-:: exit
-
-docker rm relaxed_nobel
-
-docker ps -a
-:: CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
-:: NAMES
-:: e2cac48323d2 ubuntu "/bin/bash" 2 minutes ago Exited (0) About a minute ago
-:: nifty_goldwasser
-
-docker rm nifty_goldwasser
-```
+---
+category: tool
+tool: docker
+filename: docker.bat
+contributors:
+ - ["Ruslan López", "http://javapro.org/"]
+ - ["Michael Chen", "https://github.com/ML-Chen"]
+ - ["Akshita Dixit", "https://github.com/akshitadixit"]
+ - ["Marcel Ribeiro-Dantas", "https://github.com/mribeirodantas"]
+---
+
+Docker is a tool that helps you build, test, ship and run applications
+seamlessly across various machines. It replicates the environment our software
+needs on any machine. You can get Docker for your machine from
+https://docs.docker.com/get-docker/
+
+It has grown in popularity over the last decade due to being lightweight and
+fast as compared to virtual-machines that are bulky and slow. Unlike VMs, docker
+does not need a full blown OS of its own to be loaded to start and does not
+compete for resources other than what the application it is running will use.
+VMs on the other hand are pretty resource intensive on our processors, disks and
+memory hence running multiple VMs for various applications becomes a challenge
+in a limited capacity architecture.
+
+<pre>
+┌────────────────────────┐ ┌───────────────────────┐
+│ ┌───────────┐ │ │ ┌───────────┐ │
+│ │ App │ │ │ │ App │ │
+│ └───────────┘ │ │ └───────────┘ │
+│ ┌────────┐ ┌────────┐ │ │ ┌────────┐ ┌───────┐ │
+│ │ Libs │ │ Deps │ │ │ │ Libs │ │ Deps │ │
+│ └────────┘ └────────┘ │ │ └────────┘ └───────┘ │
+│ ┌───────────────────┐ │ │ ┌──────────────────┐ │
+│ │ Guest OS │ │ │ │ Guest OS │ │
+│ └───────────────────┘ │ │ └──────────────────┘ │
+│ VM1 │ │ VM2 │
+└────────────────────────┘ └───────────────────────┘
+┌──────────────────────────────────────────────────┐
+│ Hypervisor │
+└──────────────────────────────────────────────────┘
+┌──────────────────────────────────────────────────┐
+│ Host OS │
+└──────────────────────────────────────────────────┘
+┌──────────────────────────────────────────────────┐
+│ Hardware Infrastructure │
+└──────────────────────────────────────────────────┘
+ (VM based architecture)
+
+┌────────────────────────┐ ┌───────────────────────┐
+│ ┌───────────┐ │ │ ┌───────────┐ │
+│ │ App │ │ │ │ App │ │
+│ └───────────┘ │ │ └───────────┘ │
+│ ┌────────┐ ┌────────┐ │ │ ┌────────┐ ┌───────┐ │
+│ │ Libs │ │ Deps │ │ │ │ Libs │ │ Deps │ │
+│ └────────┘ └────────┘ │ │ └────────┘ └───────┘ │
+│ Container1 │ │ Container2 │
+└────────────────────────┘ └───────────────────────┘
+┌──────────────────────────────────────────────────┐
+│ Docker │
+└──────────────────────────────────────────────────┘
+┌──────────────────────────────────────────────────┐
+│ OS │
+└──────────────────────────────────────────────────┘
+┌──────────────────────────────────────────────────┐
+│ Hardware Infrastructure │
+└──────────────────────────────────────────────────┘
+ (Docker based architecture)
+
+</pre>
+
+Couple of terms we will encounter frequently are Docker Images and Docker
+Containers. Images are packages or templates of containers all stored in a
+container registry such as [Docker Hub](https://hub.docker.com/). Containers
+are standalone, executable instances of these images which include code,
+runtime, system tools, system libraries and settings - everything required to
+get the software up and running. Coming to Docker, it follows a client-server
+architecture wherein the CLI client communicates with the server component,
+which here is, the Docker Engine using RESTful API to issue commands.
+
+## The Docker CLI
+```bash
+# after installing Docker from https://docs.docker.com/get-docker/
+# To list available commands, either run `docker` with no parameters or execute
+# `docker help`
+$ docker
+
+>>> docker [OPTIONS] COMMAND [ARG...]
+ docker [ --help | -v | --version ]
+
+ A self-sufficient runtime for containers.
+
+ Options:
+ --config string Location of client config files (default "/root/.docker")
+ -c, --context string Name of the context to use to connect to the daemon (overrides DOCKER_HOST env var and default context set with "docker context use")
+ -D, --debug Enable debug mode
+ --help Print usage
+ -H, --host value Daemon socket(s) to connect to (default [])
+ -l, --log-level string Set the logging level ("debug"|"info"|"warn"|"error"|"fatal") (default "info")
+ --tls Use TLS; implied by --tlsverify
+ --tlscacert string Trust certs signed only by this CA (default "/root/.docker/ca.pem")
+ --tlscert string Path to TLS certificate file (default "/root/.docker/cert.pem")
+ --tlskey string Path to TLS key file (default "/root/.docker/key.pem")
+ --tlsverify Use TLS and verify the remote
+ -v, --version Print version information and quit
+
+ Commands:
+ attach Attach to a running container
+ # […]
+
+$ docker run hello-world
+# `docker run <container-name>` is used to run a container, it will pull the
+# images from Docker Hub if they don't already exist in your system. Here the
+# docker client connects to the daemon which in turn pulls the "hello-world"
+# image from the Docker Hub. The daemon then builds a new container from the
+# image which runs the executable that produces the output streamed back to the
+# client that we see on our terminals.
+
+$ docker run -d ubuntu sleep 60s
+# The -d (or --detach) flag is when we want to run a container in the background
+# and return back to the terminal. Here we detach an ubuntu container from the
+# terminal, the output should be the id and the command exits. If we check
+# running containers, we should still see ours there:
+# CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
+# 133261b4894a ubuntu "sleep 60s" 3 seconds ago Up 2 seconds vigorous_gould
+
+$ docker run <container-id> -p 3000:8000
+# The -p (or --publish) flag is used to expose port 8000 inside the container to
+# port 3000 outside the container. This is because the app inside the container
+# runs in isolation, hence the port 8000 where the app runs is private to the
+# container.
+
+$ docker run -i
+# or
+$ docker run -it
+# Docker runs our containers in a non-interactive mode i.e. they do not accept
+# inputs or work dynamically while running. The -i flag keeps input open to the
+# container, and the -t flag creates a pseudo-terminal that the shell can attach
+# to (can be combined as -it)
+
+$ docker ps -a
+# The `docker ps` command only shows running containers by default. To see all
+# containers, use the -a (or --all) flag
+# Running the above command should output something similar in the terminal:
+# CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
+# 82f84bf6912b hello-world "/hello" 9 minutes ago Exited (0) 9 minutes ago eloquent_sammet
+
+
+$ docker stop hello-world
+# or
+$ docker start hello-world
+# The stop command simply stops one or more containers, and the start command
+# starts the container(s) up again! `docker start -a ubuntu` will attach our
+# detached container back to the terminal i.e. runs in the foreground
+
+$ docker create alpine
+# `docker create` creates a new container for us with the image specified (here,
+# alpine), the container does not auto-start unlike `docker run`. This command
+# is used to set up a container configuration and then `docker start` to shoot
+# it up when required. Note that the status is "Created":
+# CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
+# 4c71c727c73d alpine "/bin/sh" 29 seconds ago Created naughty_ritchie
+
+$ docker rm 82f84
+# Removes one or more containers using their container ID.
+# P.S.: we can use only the first few characters of the entire ID to identify
+# containers
+
+$ docker images
+# Displays all images and their information, created here means the latest image
+# tag updated on Docker Hub:
+# REPOSITORY TAG IMAGE ID CREATED SIZE
+# ubuntu latest a8780b506fa4 9 days ago 77.8MB
+# alpine latest 9c6f07244728 3 months ago 5.54MB
+# hello-world latest feb5d9fea6a5 13 months ago 13.3kB
+
+$ docker rmi
+# Removes one or more images from your system which do not have their instances
+# (or containers as we know them) running. If the image has an attached
+# container, either delete the container first or use the -f (or --force) flag
+# to forcefully delete both the container and image.
+
+$ docker pull busybox
+# The pull command downloads the specified image on our system from Docker Hub.
+
+$ docker exec -it 7b272 bash
+# This command is used to run a command in the running container's default
+# directory. Here 7b272 was our ubuntu container and the above command would
+# help us interact with the container by opening a bash session.
+
+$ docker logs <container-id>
+# Displays the information logged by the specified container
+# root@7b27222e4bb7:/# whoami
+# root
+# root@7b27222e4bb7:/# pwd
+# /
+# root@7b27222e4bb7:/# ls
+# bin boot dev etc home lib lib32 lib64 libx3 srv sys tmp usr var
+# root@7b27222e4bb7:/# exit
+# exit
+
+# More commands can be found at https://docs.docker.com/engine/reference/commandline/docker/
+```
+## The Dockerfile
+The Dockerfile is a blueprint of a Docker image. We can mention the artifacts
+from our application along with their configurations into this file in the
+specific syntax to let anyone create a Docker image of our application.
+
+### A few things to keep in mind:
+* It is always strictly named `Dockerfile` without any extensions
+* We have to build our custom image on top of some already available Docker base
+image. (there is an empty image called `scratch` which literally lets you build
+an image from scratch)
+* All capitalised commands are part of the syntax, they are not case-sensitive
+but used like a convention
+* Below is a sample Dockerfile but you can read in depth from the [official docs](https://docs.docker.com/engine/reference/builder/).
+
+```Dockerfile
+FROM <base-image>
+# define base image
+
+ENV USERNAME='admin'\
+ PWD='****'
+# optionally define environmental variables
+
+RUN apt-get update
+# run linux commands inside container env, does not affect host env
+# This executes during the time of image creation
+
+COPY <src> <target>
+# executes on the host, copies files from src (usually on the host) to target
+# on the container
+
+ENTRYPOINT ["some-script.sh"]
+# executes an entire script as an entrypoint
+
+CMD [<args>,...]
+# always part of dockerfile, introduces entry point linux command e.g.
+# `CMD node server.js`
+# This executes after image creation only when the container from the image
+# is running.
+```
+### Build your images
+Use the `docker build` command after wrapping your application into a Docker
+image to run ( or build) it.
+
+```bash
+
+$ docker build <path-to-dockerfile>
+# used to build an image from the specified Dockerfile
+# instead of path we could also specify a URL
+# -t tag is optional and used to name and tag your images for e.g.
+# `$ docker build -t my-image:0.1 ./home/app`
+# rebuild images everytime you make changes in the dockerfile
+```
+
+## Push your image to DockerHub
+If you want your application's Docker image to be made publicly available for
+any Docker user, you might wanna push it to the [Docker Hub](https://hub.docker.com/) which is a
+registry of Docker images. Make sure you have an account with a username and
+password on Docker Hub.
+
+When pushing an image to Docker Hub, we must specify our Docker Hub username
+as part of the source image name. We need to create the target image with the
+tag name of username/image-name much like GitHub repositories.
+
+```bash
+$ docker login
+# to login to Docker Hub using your username and password
+
+$ docker tag <src-image>[:<src-tag>] <target-image>[:<target-tag>]
+# this tags a local src-image to a public target-image
+# e.g. `docker tag my-sample-app:1.0.0 akshitadixit/my-sample-app`
+# if tags are not specified, they're defaulted to `latest`
+
+$ docker push <target-image>[:<target-tag>]
+# uploads our image to Docker Hub
+# e.g. `docker push akshitadixit/my-sample-app`
+# this image will be accessible under your profile's repositories as
+# `https://hub.docker.com/r/username/image-name`
+
+```