moby/docs/sources/concepts/manifesto.rst

:title: Manifesto
:description: An overview of Docker and standard containers
:keywords: containers, lxc, concepts, explanation

.. _dockermanifesto:

Docker Manifesto
----------------

Docker complements LXC with a high-level API which operates at the
process level. It runs unix processes with strong guarantees of
isolation and repeatability across servers.

Docker is a great building block for automating distributed systems:
large-scale web deployments, database clusters, continuous deployment
systems, private PaaS, service-oriented architectures, etc.

- **Heterogeneous payloads** Any combination of binaries, libraries,
  configuration files, scripts, virtualenvs, jars, gems, tarballs, you
  name it. No more juggling between domain-specific tools. Docker can
  deploy and run them all.
- **Any server** Docker can run on any x64 machine with a modern linux
  kernel - whether it's a laptop, a bare metal server or a VM. This
  makes it perfect for multi-cloud deployments.
- **Isolation** docker isolates processes from each other and from the
  underlying host, using lightweight containers.
- **Repeatability** Because containers are isolated in their own
  filesystem, they behave the same regardless of where, when, and
  alongside what they run.

.. image:: images/lego_docker.jpg
   :target: http://bricks.argz.com/ins/7823-1/12

What is a Standard Container?
.............................

Docker defines a unit of software delivery called a Standard
Container. The goal of a Standard Container is to encapsulate a
software component and all its dependencies in a format that is
self-describing and portable, so that any compliant runtime can run it
without extra dependency, regardless of the underlying machine and the
contents of the container.

The spec for Standard Containers is currently work in progress, but it
is very straightforward. It mostly defines 1) an image format, 2) a
set of standard operations, and 3) an execution environment.

A great analogy for this is the shipping container. Just like Standard
Containers are a fundamental unit of software delivery, shipping
containers are a fundamental unit of physical delivery.

Standard operations
~~~~~~~~~~~~~~~~~~~

Just like shipping containers, Standard Containers define a set of
STANDARD OPERATIONS. Shipping containers can be lifted, stacked,
locked, loaded, unloaded and labelled. Similarly, standard containers
can be started, stopped, copied, snapshotted, downloaded, uploaded and
tagged.


Content-agnostic
~~~~~~~~~~~~~~~~~~~

Just like shipping containers, Standard Containers are
CONTENT-AGNOSTIC: all standard operations have the same effect
regardless of the contents. A shipping container will be stacked in
exactly the same way whether it contains Vietnamese powder coffee or
spare Maserati parts. Similarly, Standard Containers are started or
uploaded in the same way whether they contain a postgres database, a
php application with its dependencies and application server, or Java
build artifacts.

Infrastructure-agnostic
~~~~~~~~~~~~~~~~~~~~~~~~~~

Both types of containers are INFRASTRUCTURE-AGNOSTIC: they can be
transported to thousands of facilities around the world, and
manipulated by a wide variety of equipment. A shipping container can
be packed in a factory in Ukraine, transported by truck to the nearest
routing center, stacked onto a train, loaded into a German boat by an
Australian-built crane, stored in a warehouse at a US facility,
etc. Similarly, a standard container can be bundled on my laptop,
uploaded to S3, downloaded, run and snapshotted by a build server at
Equinix in Virginia, uploaded to 10 staging servers in a home-made
Openstack cluster, then sent to 30 production instances across 3 EC2
regions.


Designed for automation
~~~~~~~~~~~~~~~~~~~~~~~

Because they offer the same standard operations regardless of content
and infrastructure, Standard Containers, just like their physical
counterpart, are extremely well-suited for automation. In fact, you
could say automation is their secret weapon.

Many things that once required time-consuming and error-prone human
effort can now be programmed. Before shipping containers, a bag of
powder coffee was hauled, dragged, dropped, rolled and stacked by 10
different people in 10 different locations by the time it reached its
destination. 1 out of 50 disappeared. 1 out of 20 was damaged. The
process was slow, inefficient and cost a fortune - and was entirely
different depending on the facility and the type of goods.

Similarly, before Standard Containers, by the time a software
component ran in production, it had been individually built,
configured, bundled, documented, patched, vendored, templated, tweaked
and instrumented by 10 different people on 10 different
computers. Builds failed, libraries conflicted, mirrors crashed,
post-it notes were lost, logs were misplaced, cluster updates were
half-broken. The process was slow, inefficient and cost a fortune -
and was entirely different depending on the language and
infrastructure provider.

Industrial-grade delivery
~~~~~~~~~~~~~~~~~~~~~~~~~

There are 17 million shipping containers in existence, packed with
every physical good imaginable. Every single one of them can be loaded
on the same boats, by the same cranes, in the same facilities, and
sent anywhere in the World with incredible efficiency. It is
embarrassing to think that a 30 ton shipment of coffee can safely
travel half-way across the World in *less time* than it takes a
software team to deliver its code from one datacenter to another
sitting 10 miles away.

With Standard Containers we can put an end to that embarrassment, by
making INDUSTRIAL-GRADE DELIVERY of software a reality.