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Docker packages apps into a single unit, called an image. When these images are run via Docker, they're called containers, where a single container is an instance of an image. It's possible to run many containers based on a single image.
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Docker packages apps into
a single unit called an image.
0:00
When these images are run via
Docker they're called containers.
0:04
Where a single container
is an instance of an image,
0:08
it's possible to run many
containers based on a single image.
0:11
You can think of a container as a shipping
container, just like you'd see on ships.
0:15
Within each shipping container could
be many different kinds of contents.
0:20
But because they're all uniform in shape,
0:24
they can all be handled the same way
even though their content is different.
0:26
Usually the contents of a container
are related in some way and
0:31
will be delivered to the same location.
0:34
In Docker, the contents of a container
come together to form a singular unit
0:36
that represents an app, service,
website or any single piece of software.
0:41
Docker packages the programs, services,
and libraries your app depends on in to
0:46
an image along with your
instructions on how to run it.
0:50
And the environment it should run in.
0:54
This all gets taken by docker and
run on the host machine as a container.
0:56
An image is a mutable file that
essentially a snapshot of a container.
1:00
They're created with the build command.
1:05
And they produce a container when
started with the run command.
1:07
Images can be stored in the Docker
registry, which is like a GitHub for
1:11
Docker images.
1:15
Then they could be retrieved later on
the system where you wanna deploy them.
1:16
Because images can become pretty large,
1:20
they're designed to be composed
of layers of other images.
1:22
That means, we only have to send small
amounts of data over the network
1:26
when transferring images.
1:29
To make all this magic happen,
Docker uses three major components.
1:31
The Docker daemon, which is
a process running on your host OS.
1:35
Docker registries,
1:39
which are servers daemons connect to
in order to retrieve images they need.
1:41
And the Docker client, which issues
commands to the Docker daemon.
1:45
The Docker daemon coordinates running
containers, packaging images and
1:50
transferring images to and
from registries.
1:54
The Docker command line interface or
client is what you see.
1:56
The client is where you run
commands on the host machine.
2:00
To spin up new Docker containers,
build Docker files into images,
2:03
monitor running containers and
many other tasks.
2:07
Docker registries store Docker images.
2:10
We talked about Docker hub earlier which
is the public registry anyone can use.
2:13
The Docker tools are configured
to talk to Docker hub by default.
2:18
But that's just one of
the available registries.
2:22
Docker cloud is another one.
2:24
And you can run a private registry on
your company's own servers if you want.
2:26
If you run a Docker pull command
using the Docker client,
2:30
the Docker daemon will connect to
a Docker registry, retrieve an image, and
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store it on the Docker host machine.
2:38
When you use the Docker run command,
2:40
the Docker daemon launches a copy of
a locally stored image as a new container.
2:42
You can even run your own private
registry within your organization.
2:47
Which allows you to manage your company's
images without pushing them to the public
2:50
Docker registry.
2:54
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