Docker best practices. Docker file best practices.

2. Docker development Best Practices
1.CI/CD for Testing and Deployment: Experts recommend using Docker Hub or any other CI/CD
pipeline to build and tag a Docker image whenever a pull request is created. Furthermore, the images
should be signed by the development, security, and testing teams before they are pushed to production
so that it is constantly tested for quality by the desired teams.
2.Use Different Environments for Development and Testing: One of the best practices while using
Docker for development is creating different testing and development environments. Doing so will allow
the developer to keep the Docker files isolated and execute them without influencing the final build after
testing.
3.Update Docker to the Latest Version: Before you begin working on a Docker project, you need to
ensure that you update the Docker to the latest version. Even though it will not directly impact the
project, it will provide you with the latest features that Docker has to offer. New updates also have
certain security features, safeguarding the project from potential attacks

3. Docker container Best Practices
1.Frequently Backup a Single Manager Node: A common Docker container practice is to back a
single managed node frequently, which helps admins in restoration. Docker Swarm and Universal
Control Plane data are part of every node, so backing up a single manager node can get the job done
for the admins.
2.Cloud Deployment of a Docker Container: When deploying a Docker container to a cloud, both
Amazon Web Services and Microsoft Azure do not have integrated hosts optimized for Docker. They
use the Kubernetes cluster for deployment. A standard virtual machine should be created by the admins
who prefer to deploy a single container. Apart from that, securing the secure socket shell and installing
Docker is the next step. Admins can now deploy the application on a cloud after installing Docker.
3.Control Docker Containers through a Load Balancer: A load balancer helps admins get good
control over Docker containers which helps them in making containers highly available and scalable.
The most commonly used load balancer is NGINX which can easily be installed on Docker. This load
balancer supports multiple balancing methods, static and dynamic caching, rate limiting, and multiple
distinct applications.

4. 1. Beware of inheritance and dependencies
Your containers inherit a parent image that generally includes its base
operating system and dependencies—things like dependent packages,
default users, etc. Those inherited attributes and dependencies might
expose your containers to unnecessary risk. Make sure you’re aware of
the inherited attributes and take any additional steps necessary to further
isolate and protect your containers.
2. Limit container interaction
Container security has emerged as a serious concern for many
organizations—specifically how containers interact with one another and
with the outside world. Your containers should not accept connections on
exposed ports through any network interface. You should take steps both
to control how—and how much—containers interact with each other
internally, and limit the number of containers that have contact with the
outside world so you can minimize exposure to external risks.

5. 3. Monitor containers for vulnerabilities
One of the challenges of using a code repository like Docker Hub is that
once a container image is uploaded to the repository nobody takes
responsibility for keeping it patched and secure. It might be fine when
originally created, but over time new vulnerabilities and exploits are
discovered and you need to scan for those before using containers in
production. A tool like Twistlock can help you monitor for and identify
vulnerabilities in your container images.
4. Run containers as read only where possible
One of the best and simplest ways to limit exposure to risk for container is
to run them in read-only mode. That obviously won’t work for all
containers—there will be containers that must accept input of some sort in
order for apps to work, but containers that can be run in read-only mode
should be. You should also never run containers in privileged mode.

6. Docker Logging best practices
1.Logging from Application: Logging directly from the application is a method where applications within
the container manage the logging through a framework. The developers will have the utmost control over
the logging event when using this method.
2.Logging Drivers: Logging drivers is a unique feature of Docker that helps read data by the stderr or
stdout streams of the container as they are specifically configured to accomplish this task. Once done, the
host machine stores log files that include the prior data.
3. Dedicated Container for Logging: Having a dedicated container for logging helps in eradicating
dependencies on host machines. This container will be responsible for log file management within the
Docker environment.
4.Sidecar Method: The Sidecar method is undoubtedly among the best if you want to manage
microservices architecture. Here, the sidecars run simultaneously with the parent application, where they
share the same network and volume. These shared resources allow you to expand the app functionalities
and eradicate the need to install any extra configurations.

8. Dockerfile
When using containers to deploy your applications, one of the most important things
that you must get right is your Dockerfiles. Dockerfiles are how you tell Docker how to
build and deploy your containers. If they aren’t well-written or optimized for your
needs, that can significantly impact how quickly and efficiently you can get new
versions of your application up and running.

9. Dockerfile Best Practices
- Do not use your Dockerfile as a build script:
A Dockerfile is a set of instructions that can be used to create a custom image.
It should never be used as a build script because it will make your builds
unnecessarily long. When you must compile or bundle software in your
Dockerfile, you should use the ADD instruction. This will copy the files
necessary for compilation into the image before it starts running commands.
This will let you keep the Dockerfile short and manage any dependencies
required for compilation separately from the Dockerfile.
- Use ENV to define environment variables:
Setting environment variables is a best practice for Dockerfiles. Although it
might seem like a small detail, defining your environment variables will make
your containers more portable. This is because your environment variables are
the only thing that can change from one execution to the next. If you have a
variable that must be different both inside and outside of your container, then
you must define it using ENV.

10. Dockerfile Best Practices
- Commit your Dockerfile to the repository:
One of the best practices of Dockerfiles is committing them to your repository.
This lets you easily and quickly reference it later without remembering all of the
commands that you used or what their order was.
- Be mindful of your base image and its size:
One of the most important things to consider when creating your Dockerfile is
the base image that you’re using. It will increase your Docker image's size if you
have a lot of extraneous code. This will make it much slower for your container
to start up or, even worse, prevent it from starting at all. The best way to avoid
this is by being mindful of which packages and scripts you use. If it doesn’t
seem necessary to include it in the base image, try and find a way to install it
when the container starts up instead. This will save space on your container,
thus making it run more quickly and efficiently.

11. Dockerfile Best Practices
- Do not expose secrets:
Never share or copy the application credentials or any sensitive information in
the Dockerfile. Instead, use the .dockerignore file to prevent copying files that
might contain sensitive information. The .dockerignore file acts as equivalent to
the .gitignore file, and it lets you specify the files that you want the build process
to ignore.
- Be mindful of which ports are exposed:
When designing your Dockerfile, make sure that you know which ports are
exposed. By default, Docker will expose all of the containers to a range of
random internal ports. This is problematic, as it can expose critical services to
the outside world and leave them open for attack. If you’re using a service that
must be exposed to the public internet, then you must create an entry in the
Dockerfile. This is done by adding 'EXPOSE' in your Dockerfile.

12. Docker image building Best Practices
Version Docker Images:A common practice among Docker users is using the
latest tag for images which is also the default tag for images. Using this tag will
eradicate the possibility of identifying the running version code based on the image
tag. Not only does it become easier to overwrite it, but it also leads to extreme
complications while doing rollbacks. Make sure to avoid using the latest tag,
especially for base images, as it could unintentionally lead to the deployment of a
new version. Rather than using the default tag, the best practice is to use
descriptors like semantic version, timestamps, or Docker image IDs as a tag. With
the practice of having a relevant tagging scheme, it becomes easier to tie the tag to
the code.

13. Docker image building Best Practices
Avoid Storing Secrets in Images: Undeniably, confidential data or secrets like SSH keys,
passwords, and TLS certificates are highly sensitive for an organization. Storing such data in
images without encryption can make it easier for anyone to extract and exploit it. This situation is
extremely common when images are pushed into a public registry. Rather than that, injecting
these through build-time arguments, environment variables, and an orchestration tool is the best
practice. In addition, sensitive data can also be added to the .dockerignore file. Another practice
to accomplish this goal is by being specific about the files that should be copied over the image.
Environment Variables:Environment variables are primarily used to keep the application flexible
and secure. These can also be used to pass on sensitive information or secrets. However, these
will still be visible in the logs, child processes, linked containers, and docker inspect. The
following is a frequently used approach for managing secrets.

14. Docker image building Best Practices
Using a .dockerignore File: The .dockerignore file is used to define the required build context. Before
an image is built, the user has to specify the files and folders that should be excluded from the initial
build context sent to the Docker daemon which is done with the help of the .dockerignore file. Prior to
evaluating the COPY or ADD commands, the entire project’s root is sent to the Docker daemon, making
it a hefty deal. Apart from that, there can be stances when the daemon and the Docker CLI are on
different machines. In that case, the .dockerignore file should be added to local secrets, temporary files,
local development files, or build logs. Doing so can boost the build process, avoid secret leaks, and
reduce the Docker image size.
Image Linting and Scanning: Inspecting the source code for any stylistic or programmatic error that
can cause issues is called lining. Linting can help ensure that the Dockerfiles comply with the right
practice and can be maintained. This process can also be followed in images to determine any
underlying vulnerabilities or issues.

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