what is docker?
a tool that enables you to create, deploy and run applications by using containers
What is a Dockerfile?
a file containing information (series of commands) on how to build a docker image
what is a docker image and what does it contain?
an unchangeable file that contains - source code - libraries - dependencies - tools - other files needed for an application to run.
what is a container?
a virtualized environment where users can isolate applications from the underlying system
difference between image and container
containers depend on docker images and use them to create the virtualized environment
difference between container and VM
- containers are specific for a technology
- containers can be disposed of easier
- container virtualizes operating system
- VM virtualizes hardware
- VM have a host OS in general => much bigger
- if you use containers you don’t need to have an OS for every app
what is the container registry?
store manage and secure container images
what is a microservice and what are the benefits?
an architectural style that structures an application as a collection of services that are:
- Highly maintainable and testable
- Loosely coupled
- Independently deployable
- Continuous refactoring
docker build
creates an image from a Dockerfile
-t
specifies the repository and a tag
docker tag
create a tag that refers to an image
docker create
create a container from an image
docker run
docker create + docker start
docker push
push image to a registry
docker pull
pull image from a registry
What is Kubernetes and what is it used for?
Open source system for:
- automating deployment
- scaling
- management of containerized apps
What are Kubernetes namespaces?
virtual clusters backed by the same physical cluster
What is a pod?
- smallest deployable units of computing that you can create and manage in Kubernetes
- group of containers with shared network/storage
- have a specification on how to run the containers
What is a replica set?
ensures how many replicas of a pod should be running
