05243104fc
This lets you specify custom client TLS certificates and CA root for a
specific registry hostname. Docker will then verify the registry
against the CA and present the client cert when talking to that
registry. This allows the registry to verify that the client has a
proper key, indicating that the client is allowed to access the
images.
A custom cert is configured by creating a directory in
/etc/docker/certs.d with the same name as the registry hostname. Inside
this directory all *.crt files are added as CA Roots (if none exists,
the system default is used) and pair of files <filename>.key and
<filename>.cert indicate a custom certificate to present to the registry.
If there are multiple certificates each one will be tried in
alphabetical order, proceeding to the next if we get a 403 of 5xx
response.
So, an example setup would be:
/etc/docker/certs.d/
└── localhost
├── client.cert
├── client.key
└── localhost.crt
A simple way to test this setup is to use an apache server to host a
registry. Just copy a registry tree into the apache root, here is an
example one containing the busybox image:
http://people.gnome.org/~alexl/v1.tar.gz
Then add this conf file as /etc/httpd/conf.d/registry.conf:
# This must be in the root context, otherwise it causes a re-negotiation
# which is not supported by the tls implementation in go
SSLVerifyClient optional_no_ca
<Location /v1>
Action cert-protected /cgi-bin/cert.cgi
SetHandler cert-protected
Header set x-docker-registry-version "0.6.2"
SetEnvIf Host (.*) custom_host=$1
Header set X-Docker-Endpoints "%{custom_host}e"
</Location>
And this as /var/www/cgi-bin/cert.cgi
#!/bin/bash
if [ "$HTTPS" != "on" ]; then
echo "Status: 403 Not using SSL"
echo "x-docker-registry-version: 0.6.2"
echo
exit 0
fi
if [ "$SSL_CLIENT_VERIFY" == "NONE" ]; then
echo "Status: 403 Client certificate invalid"
echo "x-docker-registry-version: 0.6.2"
echo
exit 0
fi
echo "Content-length: $(stat --printf='%s' $PATH_TRANSLATED)"
echo "x-docker-registry-version: 0.6.2"
echo "X-Docker-Endpoints: $SERVER_NAME"
echo "X-Docker-Size: 0"
echo
cat $PATH_TRANSLATED
This will return 403 for all accessed to /v1 unless *any* client cert
is presented. Obviously a real implementation would verify more details
about the certificate.
Example client certs can be generated with:
openssl genrsa -out client.key 1024
openssl req -new -x509 -text -key client.key -out client.cert
Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
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| api | ||
| archive | ||
| builtins | ||
| contrib | ||
| daemon | ||
| daemonconfig | ||
| docker | ||
| dockerinit | ||
| dockerversion | ||
| docs | ||
| engine | ||
| graph | ||
| hack | ||
| image | ||
| integration | ||
| integration-cli | ||
| links | ||
| nat | ||
| opts | ||
| pkg | ||
| registry | ||
| runconfig | ||
| server | ||
| sysinit | ||
| utils | ||
| vendor | ||
| .gitignore | ||
| .mailmap | ||
| .travis.yml | ||
| AUTHORS | ||
| CHANGELOG.md | ||
| CONTRIBUTING.md | ||
| Dockerfile | ||
| FIXME | ||
| LICENSE | ||
| MAINTAINERS | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| VERSION | ||
Docker: the Linux container engine
Docker is an open source project to pack, ship and run any application as a lightweight container
Docker containers are both hardware-agnostic and platform-agnostic. This means that they can run anywhere, from your laptop to the largest EC2 compute instance and everything in between - and they don't require that you use a particular language, framework or packaging system. That makes them great building blocks for deploying and scaling web apps, databases and backend services without depending on a particular stack or provider.
Docker is an open-source implementation of the deployment engine which powers dotCloud, a popular Platform-as-a-Service. It benefits directly from the experience accumulated over several years of large-scale operation and support of hundreds of thousands of applications and databases.
Better than VMs
A common method for distributing applications and sandboxing their execution is to use virtual machines, or VMs. Typical VM formats are VMWare's vmdk, Oracle Virtualbox's vdi, and Amazon EC2's ami. In theory these formats should allow every developer to automatically package their application into a "machine" for easy distribution and deployment. In practice, that almost never happens, for a few reasons:
- Size: VMs are very large which makes them impractical to store and transfer.
- Performance: running VMs consumes significant CPU and memory, which makes them impractical in many scenarios, for example local development of multi-tier applications, and large-scale deployment of cpu and memory-intensive applications on large numbers of machines.
- Portability: competing VM environments don't play well with each other. Although conversion tools do exist, they are limited and add even more overhead.
- Hardware-centric: VMs were designed with machine operators in mind, not software developers. As a result, they offer very limited tooling for what developers need most: building, testing and running their software. For example, VMs offer no facilities for application versioning, monitoring, configuration, logging or service discovery.
By contrast, Docker relies on a different sandboxing method known as containerization. Unlike traditional virtualization, containerization takes place at the kernel level. Most modern operating system kernels now support the primitives necessary for containerization, including Linux with openvz, vserver and more recently lxc, Solaris with zones and FreeBSD with Jails.
Docker builds on top of these low-level primitives to offer developers a portable format and runtime environment that solves all 4 problems. Docker containers are small (and their transfer can be optimized with layers), they have basically zero memory and cpu overhead, they are completely portable and are designed from the ground up with an application-centric design.
The best part: because Docker operates at the OS level, it can still be run inside a VM!
Plays well with others
Docker does not require that you buy into a particular programming language, framework, packaging system or configuration language.
Is your application a Unix process? Does it use files, tcp connections, environment variables, standard Unix streams and command-line arguments as inputs and outputs? Then Docker can run it.
Can your application's build be expressed as a sequence of such commands? Then Docker can build it.
Escape dependency hell
A common problem for developers is the difficulty of managing all their application's dependencies in a simple and automated way.
This is usually difficult for several reasons:
-
Cross-platform dependencies. Modern applications often depend on a combination of system libraries and binaries, language-specific packages, framework-specific modules, internal components developed for another project, etc. These dependencies live in different "worlds" and require different tools - these tools typically don't work well with each other, requiring awkward custom integrations.
-
Conflicting dependencies. Different applications may depend on different versions of the same dependency. Packaging tools handle these situations with various degrees of ease - but they all handle them in different and incompatible ways, which again forces the developer to do extra work.
-
Custom dependencies. A developer may need to prepare a custom version of their application's dependency. Some packaging systems can handle custom versions of a dependency, others can't - and all of them handle it differently.
Docker solves dependency hell by giving the developer a simple way to express all their application's dependencies in one place, and streamline the process of assembling them. If this makes you think of XKCD 927, don't worry. Docker doesn't replace your favorite packaging systems. It simply orchestrates their use in a simple and repeatable way. How does it do that? With layers.
Docker defines a build as running a sequence of Unix commands, one after the other, in the same container. Build commands modify the contents of the container (usually by installing new files on the filesystem), the next command modifies it some more, etc. Since each build command inherits the result of the previous commands, the order in which the commands are executed expresses dependencies.
Here's a typical Docker build process:
FROM ubuntu:12.04
RUN apt-get update
RUN apt-get install -q -y python python-pip curl
RUN curl -L https://github.com/shykes/helloflask/archive/master.tar.gz | tar -xzv
RUN cd helloflask-master && pip install -r requirements.txt
Note that Docker doesn't care how dependencies are built - as long as they can be built by running a Unix command in a container.
Getting started
Docker can be installed on your local machine as well as servers - both bare metal and virtualized. It is available as a binary on most modern Linux systems, or as a VM on Windows, Mac and other systems.
We also offer an interactive tutorial for quickly learning the basics of using Docker.
For up-to-date install instructions and online tutorials, see the Getting Started page.
Usage examples
Docker can be used to run short-lived commands, long-running daemons (app servers, databases etc.), interactive shell sessions, etc.
You can find a list of real-world examples in the documentation.
Under the hood
Under the hood, Docker is built on the following components:
- The cgroup and namespacing capabilities of the Linux kernel;
- The Go programming language.
Contributing to Docker
Want to hack on Docker? Awesome! There are instructions to get you started here.
They are probably not perfect, please let us know if anything feels wrong or incomplete.
Legal
Brought to you courtesy of our legal counsel. For more context, please see the Notice document.
Use and transfer of Docker may be subject to certain restrictions by the
United States and other governments.
It is your responsibility to ensure that your use and/or transfer does not
violate applicable laws.
For more information, please see http://www.bis.doc.gov
Licensing
Docker is licensed under the Apache License, Version 2.0. See LICENSE for full license text.