Added some docker information

DOCKER-CHEATSHEET.md

@@ -0,0 +1,321 @@
+# Docker Cheat Sheet
+
+### Lifecycle
+
+* [`docker run`](http://docs.docker.io/reference/commandline/cli/#run) creates a container.
+* [`docker stop`](http://docs.docker.io/reference/commandline/cli/#stop) stops it.
+* [`docker start`](http://docs.docker.io/reference/commandline/cli/#start) will start it again.
+* [`docker restart`](http://docs.docker.io/reference/commandline/cli/#restart) restarts a container.
+* [`docker rm`](http://docs.docker.io/reference/commandline/cli/#rm) deletes a container.
+* [`docker kill`](http://docs.docker.io/reference/commandline/cli/#kill) sends a SIGKILL to a container.  [Has issues](https://github.com/dotcloud/docker/issues/197).
+* [`docker attach`](http://docs.docker.io/reference/commandline/cli/#attach) will connect to a running container.
+* [`docker wait`](http://docs.docker.io/reference/commandline/cli/#wait) blocks until container stops.
+
+If you want to run and then interact with a container, `docker start` then `docker attach` or, as of 0.9, `nsenter`.
+
+You can find a copy of [nsenter here](https://github.com/jpetazzo/nsenter)
+
+# Using nsenter
+
+This is a small Docker recipe to build `nsenter` easily and install it in your
+system.
+
+### Entering a Docker Container
+
+The "official" way to enter a docker container while it's running is to use `nsenter`, which uses [libcontainer under the hood](http://jpetazzo.github.io/2014/03/23/lxc-attach-nsinit-nsenter-docker-0-9/).  Using an `sshd` daemon is [considered evil](http://jpetazzo.github.io/2014/06/23/docker-ssh-considered-evil/).  
+
+Unfortunately, nsenter requires some configuration and installation. If your operating system does not include nsenter (usually in a package named util-linux or similar, although it has to be quite a recent version), the easiest way is probably to install it through docker, as described in the first of the following links:
+
+* [Installing nsenter using docker](https://github.com/jpetazzo/nsenter)
+* [How to enter a Docker container](https://blog.codecentric.de/en/2014/07/enter-docker-container/)
+* [Docker debug with nsenter on boot2docker](http://blog.sequenceiq.com/blog/2014/07/05/docker-debug-with-nsenter-on-boot2docker/)
+
+`nsenter` allows you to run any command (e.g. a shell) inside a container that's already running another command (e.g. your database or webserver). This allows you to see all mounted volumes, check on processes, log files etc. inside a running container.
+
+The first installation method described above also installs a small wrapper script wrapping `nsenter` named `docker-enter` that makes executing a shell inside a running container as easy as `docker-enter CONTAINER` and any other command via `docker-enter CONTAINER COMMAND`.
+
+
+### What is `nsenter`?
+
+It is a small tool allowing to `enter` into `n`ame`s`paces. Technically,
+it can enter existing namespaces, or spawn a process into a new set of
+namespaces. "What are those namespaces you're blabbering about?"
+We are talking about [container namespaces].
+
+`nsenter` can do many useful things, but the main reason why I'm so
+excited about it is because it lets you [enter into a Docker container].
+
+
+### Why build `nsenter` in a container?
+
+This is because my preferred distros (Debian and Ubuntu) ship with an
+outdated version of `util-linux` (the package that should contain `nsenter`).
+Therefore, if you need `nsenter` on those distros, you have to juggle with
+APT repository, or compile from source, or… Ain't nobody got time for that.
+
+I'm going to make a very bold assumption: if you landed here, it's because
+you want to enter a Docker container. Therefore, you won't mind if my
+method to build `nsenter` uses Docker itself.
+
+
+### How do I install `nsenter` with this?
+
+If you want to install `nsenter` into `/usr/local/bin`, just do this:
+
+    docker run --rm -v /usr/local/bin:/target jpetazzo/nsenter
+
+The `jpetazzo/nsenter` container will detect that `/target` is a
+mountpoint, and it will copy the `nsenter` binary into it.
+
+If you don't trust me, and prefer to extract the `nsenter` binary,
+rather than allowing my container to potentially wreak havoc into
+your system's `$PATH`, you can also do this:
+
+    docker run --rm jpetazzo/nsenter cat /nsenter > /tmp/nsenter && chmod +x /tmp/nsenter
+
+Then do whatever you want with the binary in `/tmp/nsenter`.
+
+
+###  `nsenter` inner workings.
+
+First, figure out the PID of the container you want to enter:
+
+    PID=$(docker inspect --format {{.State.Pid}} <container_name_or_ID>)
+
+Then enter the container:
+
+    nsenter --target $PID --mount --uts --ipc --net --pid
+
+
+### What's that docker-enter thing?
+
+It's just a small shell script that wraps up the steps described above into
+a tiny helper. It takes the name or ID of a container and optionally the name
+of a program to execute inside the namespace. If no command is specified a
+shell will be invoked instead.
+  `NOTE:` you have to be root to use it this way. 
+
+    # list the root filesystem
+    docker-enter my_awesome_container ls -la
+
+
+If you want to expose container ports through the host, see the [exposing ports](https://github.com/wsargent/docker-cheat-sheet#exposing-ports) section.
+
+### Info
+
+* [`docker ps`](http://docs.docker.io/reference/commandline/cli/#ps) shows running containers.
+* [`docker inspect`](http://docs.docker.io/reference/commandline/cli/#inspect) looks at all the info on a container (including IP address).
+* [`docker logs`](http://docs.docker.io/reference/commandline/cli/#logs) gets logs from container.
+* [`docker events`](http://docs.docker.io/reference/commandline/cli/#events) gets events from container.
+* [`docker port`](http://docs.docker.io/reference/commandline/cli/#port) shows public facing port of container.
+* [`docker top`](http://docs.docker.io/reference/commandline/cli/#top) shows running processes in container.
+* [`docker diff`](http://docs.docker.io/reference/commandline/cli/#diff) shows changed files in the container's FS.
+
+`docker ps -a` shows running and stopped containers.
+
+### Import / Export
+
+There doesn't seem to be a way to use docker directly to import files into a container's filesystem.  The closest thing is to mount a host file or directory as a data volume and copy it from inside the container.
+
+* [`docker cp`](http://docs.docker.io/reference/commandline/cli/#cp) copies files or folders out of a container's filesystem.
+* [`docker export`](http://docs.docker.io/reference/commandline/cli/#export) turns container filesystem into tarball.
+
+
+### Images
+
+Images are just [templates for docker containers](http://docker.readthedocs.org/reference/terms/image/).
+
+
+
+Docker.io hosts its own [index](https://index.docker.io/) to a central registry which contains a large number of repositories.
+
+* [`docker login`](http://docs.docker.io/reference/commandline/cli/#login) to login to a registry.
+* [`docker search`](http://docs.docker.io/reference/commandline/cli/#search) searches registry for image.
+* [`docker pull`](http://docs.docker.io/reference/commandline/cli/#pull) pulls an image from registry to local machine.
+* [`docker push`](http://docs.docker.io/reference/commandline/cli/#push) pushes an image to the registry from local machine.
+
+### Dockerfile
+
+[The configuration file](http://docs.docker.io/introduction/working-with-docker/#working-with-the-dockerfile). Sets up a Docker container when you run `docker build` on it.  Vastly preferable to `docker commit`.
+
+### Instructions
+
+* [FROM](http://docs.docker.io/reference/builder/#from)
+* [MAINTAINER](http://docs.docker.io/reference/builder/#maintainer)
+* [RUN](http://docs.docker.io/reference/builder/#run)
+* [CMD](http://docs.docker.io/reference/builder/#cmd)
+* [EXPOSE](http://docs.docker.io/reference/builder/#expose)
+* [ENV](http://docs.docker.io/reference/builder/#env)
+* [ADD](http://docs.docker.io/reference/builder/#add)
+* [ENTRYPOINT](http://docs.docker.io/reference/builder/#entrypoint)
+* [VOLUME](http://docs.docker.io/reference/builder/#volume)
+* [USER](http://docs.docker.io/reference/builder/#user)
+* [WORKDIR](http://docs.docker.io/reference/builder/#workdir)
+* [ONBUILD](http://docs.docker.io/reference/builder/#onbuild)
+
+### Tutorial
+
+* [Flux7's Dockerfile Tutorial](http://flux7.com/blogs/docker/docker-tutorial-series-part-3-automation-is-the-word-using-dockerfile/)
+
+### Examples
+
+* [Examples](http://docs.docker.io/reference/builder/#dockerfile-examples)
+
+### Best Practices
+
+Best to look at [http://github.com/wsargent/docker-devenv](http://github.com/wsargent/docker-devenv) and the [best practices](http://crosbymichael.com/dockerfile-best-practices.html) / [take 2](http://crosbymichael.com/dockerfile-best-practices-take-2.html) for more details.
+
+If you use [jEdit](http://jedit.org), I've put up a syntax highlighting module for [Dockerfile](https://github.com/wsargent/jedit-docker-mode) you can use.
+
+## Layers
+
+The [versioned filesystem](http://en.wikipedia.org/wiki/Aufs) in Docker is based on layers.  They're like [git commits or changesets for filesystems](http://docker.readthedocs.org/reference/terms/layer/).
+
+## Links
+
+Links are how Docker containers talk to each other [through TCP/IP ports](http://docs.docker.io/use/working_with_links_names/).  [Linking into Redis](http://docs.docker.io/use/working_with_links_names/#links-service-discovery-for-docker) and [Atlassian](http://blogs.atlassian.com/2013/11/docker-all-the-things-at-atlassian-automation-and-wiring/) show worked examples.  You can also (in 0.11) resolve [links by hostname](http://docs.docker.io/use/working_with_links_names/#resolving-links-by-name).
+
+NOTE: If you want containers to ONLY communicate with each other through links, start the docker daemon with `-icc=false` to disable inter process communication.
+
+If you have a container with the name CONTAINER (specified by `docker run --name CONTAINER`) and in the Dockerfile, it has an exposed port:
+
+```
+EXPOSE 1337
+```
+
+Then if we create another container called LINKED like so:
+
+```
+docker run -d --link CONTAINER:ALIAS --name LINKED user/wordpress
+```
+
+Then the exposed ports and aliases of CONTAINER will show up in LINKED with the following environment variables:
+
+```
+$ALIAS_PORT_1337_TCP_PORT
+$ALIAS_PORT_1337_TCP_ADDR
+```
+
+And you can connect to it that way.
+
+To delete links, use `docker rm --link `.
+
+## Volumes
+
+Docker volumes are [free-floating filesystems](http://docs.docker.com/userguide/dockervolumes/).  They don't have to be connected to a particular container.
+
+Volumes are useful in situations where you can't use links (which are TCP/IP only).  For instance, if you need to have two docker instances communicate by leaving stuff on the filesystem.
+
+You can mount them in several docker containers at once, using `docker run -volume-from`
+
+Because volumes are isolated filesystems, they are often used to store state from computations between transient containers.  That is, you can have a stateless and transient container run from a recipe, blow it away, and then have a second instance of the transient container pick up from where the last one left off.
+
+See [advanced volumes](http://crosbymichael.com/advanced-docker-volumes.html) for more details.
+
+## Exposing ports
+
+Exposing ports through the host container is [fiddly but doable](http://docs.docker.io/use/port_redirection/#binding-a-port-to-an-host-interface).
+
+First expose the port in your Dockerfile:
+
+```
+EXPOSE <CONTAINERPORT>
+```
+
+Then map the container port to the host port (only using localhost interface):
+
+```
+docker run -p 127.0.0.1:$HOSTPORT:$CONTAINERPORT --name CONTAINER -t someimage
+```
+
+If you're running Docker in Virtualbox, you then need to forward the port there as well.  It can be useful to define something in Vagrantfile to expose a range of ports so that you can dynamically map them:
+
+```
+Vagrant.configure(VAGRANTFILE_API_VERSION) do |config|
+  ...
+
+  (49000..49900).each do |port|
+    config.vm.network :forwarded_port, :host => port, :guest => port
+  end
+
+  ...
+end
+```
+
+If you forget what you mapped the port to on the host container, use `docker port` to show it:
+
+```
+docker port CONTAINER $CONTAINERPORT
+```
+
+## Tips
+
+Sources:
+
+* [15 Docker Tips in 5 minutes](http://sssslide.com/speakerdeck.com/bmorearty/15-docker-tips-in-5-minutes)
+
+### Last Ids
+
+```
+alias dl='docker ps -l -q'
+docker run ubuntu echo hello world
+docker commit `dl` helloworld
+```
+
+### Commit with command (needs Dockerfile)
+
+```
+docker commit -run='{"Cmd":["postgres", "-too -many -opts"]}' `dl` postgres
+```
+
+### Get IP address
+
+```
+docker inspect `dl` | grep IPAddress | cut -d '"' -f 4
+```
+
+or
+
+```
+wget http://stedolan.github.io/jq/download/source/jq-1.3.tar.gz
+tar xzvf jq-1.3.tar.gz
+cd jq-1.3
+./configure && make && sudo make install
+docker inspect `dl` | jq -r '.[0].NetworkSettings.IPAddress'
+```
+
+or (this is unverified)
+
+```
+docker inspect -f '{{ .NetworkSettings.IPAddress }}' <container_name>
+```
+
+### Get port mapping
+
+```
+docker inspect -f '{{range $p, $conf := .NetworkSettings.Ports}} {{$p}} -> {{(index $conf 0).HostPort}} {{end}}' <containername>
+```
+
+### Get Environment Settings
+
+```
+docker run --rm ubuntu env
+```
+
+### Delete old containers
+
+```
+docker ps -a | grep 'weeks ago' | awk '{print $1}' | xargs docker rm
+```
+
+### Delete stopped containers
+
+```
+docker rm `docker ps -a -q`
+```
+
+### Show image dependencies
+
+```
+docker images -viz | dot -Tpng -o docker.png
+```

README.md

@@ -17,7 +17,30 @@ Refer : https://github.com/Eugeny/ajenti-v
 * Allow Web w SSL/Domain aliasing/DNS/Emailing/Database in a single setup 
 * Very easy to move around/scale/create dev environments
 
-##How to use?
+##Docker Installation
+* Install Docker on CentOS or Fedora
+* To install Docker on CentOS, first enable EPEL repository, and then use yum command:
+```
+$ sudo yum install docker-io
+$ sudo service docker start
+$ sudo chkconfig docker on
+```
+* To install Docker on Fedora, use the following commands:
+```
+$ sudo yum install docker-io
+$ sudo systemctl start docker.service
+$ sudo systemctl enable docker.service
+```
+* After installing Docker on CentOS or Fedora, you need to add yourself to docker group to be able to run Docker as a non-root * user. Use this command for that:
+```
+$ sudo usermod -a -G docker $USER
+```
+###Log out, and log back in to activate the group change.
+
+#At this point, you should be able to run docker command as a unprivileged user
+
+
+###How to use?
 
 Follow this tutorial if you like step by step instructions 
 #### http://greenycloud.com/hosting-on-whatpanel/
@@ -60,6 +83,9 @@ on the docker-run command you can use different external ports than defaults for
 ex  -p 7090:8000 , -p 2345:22  so it wont be obvious target for the attacker/viruses to try and hit your server.
 
 
+### See DOCKER-CHEATSHEET.md for nsenter information
+
+
 ##Why Centos Image ?
 
 I would have loved to use the Ubuntu image / phusion baseimage however the ubuntu repositories are not suited for web hosting/ecommerce environments.