DEV Community: Ragu

Docker Networking

Ragu — Sat, 19 Nov 2022 07:43:30 +0000

Source from Zeal Vora,KPLABS Course(Premium Instructor at Udemy)
Udemy

Zeal is one of my favorite author for docker. Please try to yourself 💖

(Tip: HE is ready to give some discount for students 😜)

Hi buddy, this is all are intermediate points. if you need to basic understanding please look at my previous docker beginner blog otherwise please ignore

-----------------Table of content-----------------

Networking
Type of networks in docker
Publish the argument
Legacy approach
Docker networking commands

Networking

Communication between the container or securely make the communication so we using the networking.

Container security
Purpose of public and private containers

Type of networks in docker

Based on microservice application need networking configuration was changed (private and public communication).

Docker0 interface is a default network card for docker.Inside of all network related activity based on docker0 virtual network card

Bridge network
User define bridge network
Host network
NAT network
None network
overlay
macvlan

Bridge network

A bridge network uses a software bridge that allows containers connected to the same bridge network to communicate while providing isolation from containers which are not connected to that bridge network

Bridge is default network for docker.Its easy to make the communication between inside and across the host.simply mention the diagram. its a two way communication

If we do not specify a driver, this is the type of network you are creating.

When you start Docker, a default bridge network (also called a bridge) is created automatically, and newly-started containers connect to it unless otherwise specified.

We also can create a User-Defined Bridge Network which is superior to the default bridge.

User define bridge network

User-defined bridges provide automatic DNS resolution between containers.
Containers on the default bridge network can only access each other by IP addresses, unless you use the --link option, which is considered legacy.
On a user-defined bridge network, containers can resolve each other by name or alias.

Host network

Connection establish the with-in the host its called host network.

NAT network(Network address translation)

It's kind of bridge network but one way transaction.some time database containers is a private network but update some necessary package via internet so in this case use this NAT.no one can ping the inside of container.

None network

If you want to completely disable the networking stack on a container, you can use the none network.

This mode will not configure any IP for the container and doesn’t have any access to the external network as well as for other containers.

3.Publish the argument

We were discussing an approach to publishing container port to host.

docker container run -dt --name webserver -p 80:80 nginx

This is also referred to as a publish list as it publishes the only a list of the port specified.

There is also a second approach to publish all the exposed ports of the container.

docker container run -dt --name webserver -P nginx
This is also referred to as a publish all.

In this approach, all exposed ports are published to random ports of the host.

4.Legacy approach

Before the Docker networks feature, you could use the Docker link feature to allow containers to discover each other and securely transfer information about one container to another container.

The --link flag is a legacy feature of Docker. It may eventually be removed. Unless you absolutely need to continue using it, we recommend that you use user-defined networks to facilitate communication between two containers instead of using --link

Docker networking commands

See the available docker network interface

docker network ls

See the available system network interface

ifconfig

Docker Intermediate

Ragu — Tue, 15 Nov 2022 17:52:28 +0000

Source from Zeal Vora,KPLABS Course(Premium Instructor at Udemy)
Udemy

Zeal is one of my favorite author for docker. Please try to yourself 💖

(Tip: HE is ready to give some discount for students 😜)

Hi buddy, this is all are intermediate points. if you need to basic understanding please look at my previous docker beginner blog otherwise please ignore

-----------------Table of content-----------------

Docker file
COPY VS ADD
EXPOSE
HEALTH CHECK
ENTRY POINT
WORKDIR
ENV
TAG
Docker commit
layer of docker images
Inspect
Prune
Flattening image
Docker registry
Apply the filters

16.Moving the image across the host

17.Build cache

1.Docker file

Every docker container based on images. Images based on docker files.

Docker files contain the set of commands and microservice procedures. Docker file start FROM instructions its is a base image

FROM busybox
ENV NGINX 1.2
RUN touch web-$NGINX.txt
CMD ["/bin/sh"]

** 2. COPY VS ADD **

Both command are copy the file from local to inside the container but depends on need it will change.

COPY = copy the files from local to inside the container
ADD = get the files from website like application zip files then
unzip the exact destination

COPY src dest

** 3. EXPOSE **

Expose command used for port documentation. Its helps to where we are going to run the port.so clear about the port mapping

EXPOSE port-no

4. HEALTH CHECK

Health check is testing our application healthy or not. Its check some argument and true or false condition.
Condition is true application is healthy whether condition is false application is un-healthy

HEALTHCHECK --interval=35s --timeout=4s CMD curl -f https://localhost/ || exit 1

5. ENTRY POINT

In Docker files, an ENTRYPOINT instruction is used to set executables that will always run when the container is initiated. Unlike CMD commands, ENTRYPOINT commands cannot be ignored or overridden—even when the container runs with command line arguments stated

Once container is start we will give the dynamic command options in entry point section

ENV name Darwin
ENTRYPOINT ["/bin/echo", "Welcome, $name"]

6. WORKDIR

Containers default working directory is called WORKDIR. once execute the container we launch directly in which one we mention the WORKDIR argument.

WORKDIR destination

7. ENV

ENV is a similar like system environment variable. Its works like key and value pair options inside of the container. We pass the dynamic value instead of ENV.

ENV command

8. TAG

Tag the image for reference. Help to improve the image information and maintenance

tag image-id tag-name

9. Docker commit

clone the running docker container for version maintenance and reusability.

docker commit container-id

10. layer of docker images

Docker is the layer architecture so each docker file line represent the layer.Layer have a unique information

*11. Inspect *

Docker image have a lot of information include date,command,size and os architect see the all info associate with the docker image.

docker inspect

12. Prune

Clean-up the dangling and unused images with prune.It's helps to reduce the unused images and increase the system memory.

docker prune

12. Flattening image

Use to create the single layer image.Its helps to manage the storage.single layer of image and fulfill the all requirement

FROM debian:wheezy WORKDIR /tmp RUN wget -nv http://centurylinklabs.com/someutility-v1.0.0.tar.gz && \ tar -xvf someutility-v1.0.0.tar.gz && \ mv /tmp/someutility-v1.0.0/someutil /usr/bin/someutil && \ rm -rf /tmp/someutility-v1.0.0 && \ rm /tmp/someutility-v1.0.0.tar.gz

13. Docker registry

Its help to maintain the image version in repository.similar to github method.we have two option private and public repository. push pull and tag in options are available with repository.

15. Apply the filters

Public repository have a so many options in images.official and unofficial image options are available so filiter help to getting the exact image option.

docker search image name

--filter , -f       Filter output based on conditions provided
--format        Pretty-print search using a Go template
--limit number          Max number of search results
--no-trunc      Don't truncate output

16.Moving the image across the host

It helps to move the image one environment to another one.
first archive and load the file then move the tar file.

docker save myapp > myapp.tar
docker load < myapp.tar

17.Build cache

Already we discuss docker is the layer architecture so each and every layer have a individual build structure .

Rebuild the same images multiple times that time docker refer to the cache. its save the build time.rather than we add the new step for same docker image that time only docker build again.

Docker for Beginner's

Ragu — Mon, 07 Nov 2022 19:32:19 +0000

Source from Zeal Vora,KPLABS Course(Premium Instructor at Udemy)
Udemy

Zeal is one of my favorite author for docker. Please try to yourself 💖

(Tip: HE is ready to give some discount for students 😜)

-----------------Table of content-----------------

What is docker and why we need ?
Docker Installation and pre-requisite
Image VS. Containers
Basic commands
port binding
Attached and detached mode
Restart policy
Disk usage

1.Container and purpose

Docker is the set of alone process and container tool. Its easy to deploy the microservice with running application using the containers.

Weightless
Movable
Compact

2. Docker Installation and pre-requisite

Docker available in variety of operating systems, this includes:

Windows
Linux
MAC

The installation of Docker is pretty straight forward in each one of them.

Docker installation

3. Image VS. Containers

Microservice application (Recipe of microservice) procedural code is called image

Running docker image is called container.

4. Basic commands

docker images - List the docker images

docker pull image-name i Pull the image from docker hub
docker ps - List the container
docker stop container-ID - Stop the container
docker start container-ID - Start the container
docker rm -f image name - Remove the docker image
netstat -ntlp - See the running port
docker exec -it container-id /bin/bash - Goto inside the container
docker run -dt -p containerport:actualport --name=anyname conatainer id - Port mapping with container
docker container stop $(docker container ls -aq) - Stop the all container

docker container rm $(docker container ls -aq) - Remove the all container

5. port binding

Goto inside the container

docker exec -it container-id /bin/bash

Port mapping with container

docker run -dt -p 80:81 --name=anyname conatainer id

6. Attached and detached mode

docker run -dt

d - detached mode
t - terminal tty

When we start a docker container, we need to decide if we want to run in a default foreground mode or the detached mode.

You may want to use this if you want a container to run but do not want to view and follow all its output

7. Restart policy

when docker daemon is stopped that time entire container goes
down. we avoid that situation so we using the restart policy

no - Do not automatically restart the container
on-failure - Restart the container if its exists due to an error
unless-stopped - Restart the container unless it is explicitly stopped
always - Always restart the container if it stops

8. Disk usage

docker system df