What is Docker and Docker-Compose?
Q What is Docker? Docker is a tool which is used by developer and operation teams to create and automate the deployment of applications in lightweight containers so that applications can work efficiently in different environments Note Container is a software package that consists of all the dependencies required to run an application Q How are Docker container created? Docker File creates a Docker Image using the buildmand A Docker Image contains all the project code Using Docker Image any user can run the code in order to create Docker Containers Once a Docker Image is built it uploaded in a registry or a Docker Hub From the Docker Hub users can get the Docker Image and build new containers Q What is Dockerpose? Docker Compose is used for running multiple containers as a single service Here containers run in isolation but can interact with each other All Docker Compose files are YAML files In Docker Compose a user can start all the services (containers) using a singlemand For example If you have an application which requires NGINX server and Redis database you can create a Docker Compose file which can run both the containers as a service without the need to start each one separately
What's the difference between Docker Swarm, Docker Compose and Docker Networks?
Docker Compose is a tool to define and run multi-container applications. Multi-container applications are applications where multiple containers work together to provide the required functionality. You define your application in the Compose file. You can run your application with the `dockerpose`mand. The `dockerpose`mand takes your Compose file as input and makes sure that your application state is what you described in the Compose file (we call this the desired state). Docker Compose can run your multi-container application on a SINGLE HOST ONLY it cannot run your application on aputer cluster. If you want to run your application on a COMPUTER CLUSTER then you need Docker Swarm. italic Docker Swarm runs multi-container applications just like Compose does. The key difference is that Swarm schedules and manages your containers across multiple machines while Compose schedules and manages containers on a single host only. italic You can use a standard Compose file to deploy your application to the Swarm. It the same Compose file that you use with Compose but some options are limited to either Swarm or Compose in the Compose file. These are described in the documentation Compose file version 3 reference s . Docker Networks is a toolset to define how your containers connect to each other. It is an architecture design decision to specify which containers talk to each other on the same network how many networks your application has to separate concerns and what technologies you use to create gateways between these networks. You define your network configuration in the Compose file. (You can create and manage Docker networks with the `docker network`mand but it better to define you configuration in the form of code in the Compose file.) You usually define your own networks these are called user defined networks. You can read more here Overview s . Compose and Swarm have different default network s. The default network in the Compose scenario is a bridge network. Bridge is a build-in network in Docker it separates your containers from the rest of the host machine. When you start you multi container application with `dockerpose` then your user defined networks will be created as bridge networks. The default network in Swarm mode is the overlay network. An overlay network is a network that routes requests across multiple machines in the Swarm cluster. When you start up your application using the Compose file in Swam mode (themand to do so is `docker stack deploy`) then your user defined networks will be created as overlay networks. There are many important details in the background. Feel free to read more in my free tutorials. Dockerpose tutorial for beginners by example all you need to know s and Docker Swarm Tutorial | Code Along | Zero to Hero under 1 Hour s .
Why doesn't Docker compose work with Kubernetes?
Short answer they have a different architecture. Long(er) answer. Dockerpose provides the metadata required to take a docker s) and run them as containers while talking either directly to the Docker engine itself Swarm or Universal Control Plane (UCP). Thepose file contains the directives in the form of key pairs to perform quite a few operations including building container images deploying containers or app services pose v3) and defining how the containers and services should be instantiated together. This ispleted through the Docker Engine API s . Kubernetes on the other hand provides abstraction on top of a container runtime. While Kube leverages the docker engine as the container runtime you (as the dev or operator) do not interact directly with the engine itself. The folks at Google and themunity building Kube have designed the tool as multipleponents which interact through a set of APIs. These APIs each manage a Kubernetes . More info here Understanding Kubernetes s s . With Kube when you address the API to instantiate a Pod the Kube API interprets your configuration and in turn interacts with the docker engine API to run the containers making up your pod. In addition the Kube API also manages the kubernetes-specific objects (like replication controllers).
Is Docker Compose enough to handle a production system?
Docker Compose alone no. Docker Compose on a Swarm s ? Youre closer to yes. Docker Swarm includes many of the self-healing properties that made containers an important tool to run applications in production. I use Swarm at home for my production services mainly because Swarm is super simple to set up. However things may be harder for more advanced use cases. Swarm has a lot going for it right now (in light ofpetition with Kubernetes). Here some of the highlights I consider critical to running my production systems citation target s title Swarm mode overview index 1 unique_id sDDFQ Desired state reconciliation Along with a declarative service model this means if any containers crash or be unhealthy then it will self-heal and start more containers to recover. Multi-host networking Automatically takes care of container-to-container networking across different nodes. Without a good shared network everything would be harder. Service discovery balancing To send network traffic to a service containers all you need is the service name. This is great for setting up an HTTP router or simply connecting a back-end app to its database. No hard-coding IP addresses or standing up your own load balancers. Rolling updates Absolutely essential to ensure zero downtime for your applications. Volume & Network plugins Extensibility should be a requirement of any container orchestration platform. Shared file storage plugins are required to properly distribute containers across multiple nodes. Advanced networking plugins are pretty important for power users too. With all of that said you may have much bigger needs than simply keeping your apps running. If you need Advanced orchestration (e.g. state management deployment strategy container placement) Extensible and accessible APIs Access control at the API layer (not just on by mounting the Docker socket) Then Kubernetes or Docker EE are probably for you.
Are there good alternatives to Docker Compose?
It depends what youre trying to aplish. If youre trying to run multiple containers on a single host Dockerpose if your friend. If youre trying to run multiple containers but have them spread across a bunch of different machines all of which are running the Docker engine then Docker Swarm is the tool that does that. but an alternative worth looking at is Kubernetes Or if you are looking to marshal a bunch of Docker instances on an Amazon platform you could look at Amazon ECS.
What are the main features of Docker-compose?
Going by the definition provided by Docker for dockerpose s - Compose is a tool for defining and running multi-container Docker applications. With Compose you use a Compose file to configure your application services. The site also mentions the most important features - Multiple isolated environments on a single host s#Multiple-isolated-environments-on-a-single-host Preserve volume data when containers are created s#preserve-volume-data-when-containers-are-created Only recreate containers that have changed s#only-recreate-containers-that-have-changed Variables and moving aposition between environments s#variables-and-moving-aposition-between-environments While Dockerfile is a pretty good way of defining various behavioral aspects of your container - volumes network interfaces ip address etc but it does not help if you want to deploy a stack e.g. when you have a Web tier Message queue App Tier and DB tier involved you will have to write separate Dockerfile for each of them and then handle the deployment and access among them. Docker Compose (or the docker stack deploy for Swarm mode) aims at solving the problem of running multiple containers as a stack. It basically allows you to incorporate all the dependencies for deploying a stack in one single file. For starters you can specify- What is the base using a container built from a Dockerfile. Similarly you can build the whole stack and ship it.
Is Kubernetes significantly more difficult to master than Docker-Compose?
Not necessarily Kubernetes in itself is easy to grasp and makes sense there are lots of free material online. the question is should I learn and start using kubernetes? and my answer Yes definitely yes. Kubernetes is bing the platform for the Data Center workloads its ecosystem the cloud-native ecosystem s is expanding day by day and if you catch up with it today it would be easier to get along with its growth and its extensions. most people find installing and managing kubernetes in production s difficult however that is changing with managed services in public cloud and on-premise. e.g. Red Hat Openshift s Pivotal PKS s and Rancher s among others. to master any technology you need to start using it reach its limits push it and put it in production. I would say all technologies are easy to learn if you put your heart on them and understand the mindset behind them. start here introduction-to-kubernetes s by edx. also did you try minishift s or minikube s in your laptop? or even better start using online labs from katacoda s
Dockerpose helps you run multiple containers for your application. It uses a configuration file like code In this file you can define how each container will run like name of container image for the container (mongo4.) environmental variables volumes etc. Once defined you can execute dockerpose -f up code to start all containers inside. If you want to see a practical example of how to create and use dockerpose I have created a video where I use dockerpose in developing a nodejs app s