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https://github.com/denisbuserski/docker-k8s-demo

Demo projects regarding my first touch to Docker and K8s
https://github.com/denisbuserski/docker-k8s-demo

docker java kubernetes mariadb mariadb-docker spring-boot

Last synced: about 2 months ago
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Demo projects regarding my first touch to Docker and K8s

Host: GitHub
URL: https://github.com/denisbuserski/docker-k8s-demo
Owner: DenisBuserski
Created: 2024-07-04T09:38:34.000Z (7 months ago)
Default Branch: main
Last Pushed: 2024-12-17T17:48:46.000Z (about 2 months ago)
Last Synced: 2024-12-26T02:24:17.777Z (about 2 months ago)
Topics: docker, java, kubernetes, mariadb, mariadb-docker, spring-boot
Language: Java
Homepage:
Size: 4.7 MB
Stars: 0
Watchers: 2
Forks: 0
Open Issues: 0
Metadata Files:
- Readme: README.md

Awesome Lists containing this project

README

# Docker & K8s

![docker-and-k8s-logo](docker-and-k8s.jpeg)

Docker

Build the Docker image from a Dockerfile
```
docker build -t [IMAGE_NAME]:[VERSION] .

docker build -t hello-docker:1.0 .
```
`-t` - Flag used to tag the image with a name and optionally a version or tag. Name - `hello-docker`, tag - `1.0`

`.` - Specifies the build context. The build context is the set of files located in the specified directory, which Docker
will use for the build process. The `.` refers to the current directory, meaning Docker will look for a Dockerfile in the
current directory and use the files in the current directory as the context for building the image.

| `docker run` | `docker start` | `docker stop` |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------|------------------------------|
| Creates and starts a new container from an image | Starts an existing stopped container | Stop the Docker container |
| `docker run --name [CONTAINER_NAME] [IMAGE_NAME]:[VERSION]` | `docker start [CONTAINER_ID]` | `docker stop [CONTAINER_ID]` |
| `docker run --name MyDockerApp hello-docker:1.0` | | |
| `docker run -d --rm --name MyDockerApp hello-docker:1.0` | | |
| `docker run -d -p 8080:80 --name MyDockerApp hello-docker:1.0` | | |
| `--name` - Assign a custom name to the container being created | | |
| `-d` - Detached mode. This allows you to continue using the terminal for other commands while the container runs in the background. | Starts the container in detached mode by default. | |
| `docker attach [CONTAINER_NAME]` - Connect your terminal to a running Docker container's standard input, output, and error streams. | | |
| `-rm` - Automatically remove the container when it exits. | | |
| `-p 8080:80` - Publish a container's port(s) to the host. Allows you to make services running inside the container accessible from the host machine or network. Maps port 8080 on the host to port 80 in the container. | | |

| Check all RUNNING Docker containers | Check all Docker containers | Check Docker images | Follow the logs of a container in realtime use |
|-------------------------------------|------------------------------|----------------------|------------------------------------------------|
| `docker ps` | `docker ps -a` | `docker images` | `docker logs -f [CONTAINER_NAME]` |

| Description | Command | | Addition |
|-------------------------------------------------|--------------------------------------------|--------------------------------------|------------------------------------------------------------|
| Delete container | `docker container rm [CONTAINER_ID]` | | |
| Delete image | `docker image rm [IMAGE_ID]` | `docker rmi [IMAGE_ID]` | Before deleting an image delete the container that uses it |
| Remove all unused images and containers | `docker system prune -a` | | |
| Remove volume | `docker volume rm` | `docker volume prune` | |

`_TO_DO_`
Docker has 2 options for containers to store files on the host machine, so that the files are persisted even after the
container stops:

| Volumes | Bind mounts(Host volume) |
|-------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Completely handled by Docker. | When you use a bind mount in Docker, you are linking a directory on the host filesystem to a directory in the container. |
| | If you modify, create, or delete files in the directory on the host, these changes will be immediately visible inside the container in the corresponding directory. |
| | If you modify, create, or delete files from within the container in the mounted directory, these changes will be reflected on the host filesystem. |
| One container writes to the storage while another reads from it. | Allows for real-time collaboration between the host and the container, which is particularly useful for development environments where code changes need to be tested immediately without rebuilding the container image. |
| Named volume - Have specific name assigned to it. | `docker run -v host_dir:container_dir` |
| `docker run -v name:container_dir` | |
| Anonymous volume - Not given a specific name. Docker assigns them an unique ID automatically. | |
| `docker run -v container_dir` | |
| | |

Start multiple containers `docker-compose.yml`:
```
docker-compose up
```

Stop the containers:
```
docker-compose down
```

K8s

### Features:
- High availability - No downtime
- Scalability - High performance
- Disaster recovery - Backup and restore

### Kubernetes architecture
![kubernetes-architecture](kubernetes-architecture.png)

`K8s cluster`
- Cluster - Set of nodes
- Consists of a `Master node` and 1 or more `Worker nodes`.
- `Node` is a worker machine in K8s.
- Its components run on every node, maintaining running pods and providing the K8s runtime environment.
- Can be either a physical or virtual machine.
- Has multiple pods on it.
- `kubelet` - Ensures that the containers defined in a Pod are running and healthy.
- `kube-proxy`
- Implements the networking aspects of the `Service` concept.
- `Service` - Abstract way to expose an application running on a set of pods as a network service.
- Provides a virtual IP(known as the ClusterIP), which enables communication with any pod in the set without worrying about individual pod IP changes.
- As pods are created and destroyed, services provide a stable endpoint, allowing other pods to discover and connect to the appropriate IP addresses, even as individual pods come and go.
- Uses a simple round-robin load balancing approach to distribute traffic across the pods.
- `Ingress` - Manages external access to the services in a K8s cluster(HTTP/HTTPS traffic). When external traffic comes
to the cluster, it first passes through the Ingress, which routes it to the appropriate Service based on defined rules.
- Maintains network rules on nodes, which allow internal and external communication to the pods.
- `Container runtime`- Software responsible for running containers.
- `Worker node`
- Every cluster needs at least 1 worker node in order to run pods.
- Does the actual work, runs the containers that make up the application, managed by the `kubelet`.
- Controlled by the Master node.
- Hosts the pods that are the components of the application workload.
- `Pod`
- Smallest unit in K8s.
- Holds 1 or more containers.
- Represents a set of running containers in the cluster.
- Usually 1 application per pod.
- Each pod gets its own unique IP address, which changes if the pod is recreated.
- Can die very easily.
- The lifecycle of a `Pod` and a `Service` are independent of each other.
- `Master node`
- Hosts the K8s `Control plane` components.
- Need less resources than `Worker nodes`.
- Control plane components make global decisions about the cluster, as well as detecting and responding to cluster events.
- `kube-apiserver`
- Exposes an HTTP API that serves as the primary communication hub for end users, cluster components, and external systems.
- If you want to deploy a new application in a K8s cluster you interact with the API server using UI(K8s Dashboard)
or CLI(`kubectl`).
- Cluster gateway.
- Acts as a gatekeeper for authentication.
- Good for security, because there is only 1 entry point into the cluster.
- `kube-scheduler`
- Watches for newly created Pods that have no assigned Node, and selects an appropriate Node for them to run on
based on resource availability and other scheduling constraints.
- Only decides on which Node a new Pod should be scheduled, the actual the process of running the Pod is handled by the `kublet`.
- `kube-controller-manager`
- Detects and manages changes in the cluster's desired state.
- If a pod dies or becomes unhealthy, the Controller manager is responsible for ensuring that the desired state is
restored. It does this by creating a new pod to replace the missing pod, and the `kube-scheduler` will then
schedule the new pod onto an appropriate node.
- `etcd`
- Store all cluster state data.
- The cluster brain.
- Key value store.
- How does the `kube-scheduler` know what resources are available?
- How does the `kube-contrller-manager` know that the cluster state change?
- Does not store Application data.
- `cloud-contrller-manager` - Interacts with the underlying cloud provider's API to manage cloud-specific resources,
such as load balancers, storage, and networking.

K8s objects
- `Pod`
- `Deployment`
- Describe the desired state of your application(Example - Which images to use, Number of pod replicas).
- Blueprint for app pods.
- Controls multiple pods.
- Manages a `ReplicaSet`(Ensures the desired number of pod replicas are running in the cluster at all times).
- `Services`
- `Volumes` - attaches a physical hard drive can be local or cloud

`Minikube` - 1 node K8s cluster. `Master node` and `Worker node` run on 1 node. Useful for local test.

`Configmap` - Used to store non-sensitive, external configuration data for an application (Example - DB_URL).

`Secret` - Similar to `Configmap`, but is used to store sensitive data such as passwords, API keys, or tokens(Example - DB_USER / DB_PASSWORD).

`Helm` - Package manager for K8s. `Helm chart` - bundle of yaml files, can be pusshed to repo
`ArgoCd`
`Vault`

K8s doesn't manage data persistence
DBs cant be replicated via Deployment, because it has a state
`StatefulSet` - for statefull apps or dbs
DBs are ofter hosted outside the K8s cluster

The configuration file has 3 parts:
- Metadata - `metadata:`
- Contains identifying information about the resource, such as its name, `Namespace`, and `Labels`.
- `Namespace` - Help isolate workloads, making it easier to apply resource quotas, access controls, and policies specific to each namespace
- `kube-system`
- `kube-public`
- `kube-node-lease`
- `default`
- `Labels`
- Specification - `spec:`
- Describes the desired state of the resource.
- Attributes are specific to the kind.
- Status
- Automatically generated and updated by K8s.
- K8s continuously compares the Desired state(From the `spec`) with the Actual state(Stored in `etcd`) and takes actions to reconcile any differences.

`deployment.yml`
```yaml
apiVersion: apps/v1 #For each component there is a different apiVersion
kind: Deployment
metadata:
name: java-deployment
namespace: my-namespace
labels:
app: java
spec:
replicas: 1
selector:
matchLabels:
app: java
template:
metadata:
labels:
app: java
spec:
containers:
- name: java
image: java
ports:
- containerPort: 8080
env:
- name: JAVA_ROOT_USERNAME
valueFrom:
secretKeyRef:
name: java-secret
key: java-root-username
- name: JAVA_ROOT_PASSWORD
valueFrom:
secretKeyRef:
name: java-secret
key: java-root-password

```

Learning materials

### Udemy course
- [Docker & Kubernetes: The Practical Guide [2024 Edition]](https://www.udemy.com/course/docker-kubernetes-the-practical-guide/?couponCode=LETSLEARNNOWPP)

### Docker
#### Videos
- [Intro to Docker [with Java Examples]](https://www.youtube.com/watch?v=FzwIs2jMESM)
- [Docker in IntelliJ IDEA](https://www.youtube.com/watch?v=FzwIs2jMESM)
- [100+ Docker Concepts you Need to Know](https://www.youtube.com/watch?v=rIrNIzy6U_g)
- [Docker in 100 Seconds](https://www.youtube.com/watch?v=Gjnup-PuquQ)
- [Learn Docker in 7 Easy Steps - Full Beginner's Tutorial](https://www.youtube.com/watch?v=gAkwW2tuIqE)
- [How to dockerize your Spring Boot API | Docker Tutorial](https://www.youtube.com/watch?v=3SNKdr3f9Io)
- [you need to learn Docker RIGHT NOW!! // Docker Containers 101](https://www.youtube.com/watch?v=eGz9DS-aIeY)
- [Why Use Docker: Real-life Use Cases](https://www.youtube.com/watch?v=rcYswUg0J5k)
- [Multi Container Docker Applications | A real-world example](https://www.youtube.com/watch?v=bX_tFv0YCqg)
- [Docker Crash Course Tutorial](https://www.youtube.com/playlist?list=PL4cUxeGkcC9hxjeEtdHFNYMtCpjNBm3h7)
- [Docker Tutorial for Beginners | Full Course [2021]](https://www.youtube.com/watch?v=p28piYY_wv8&t=3763s)
- [Docker Volumes explained in 6 minutes](https://www.youtube.com/watch?v=p2PH_YPCsis)
- [Docker Volumes Explained](https://www.youtube.com/watch?v=n4LRpnqsXIo)
- [How to create and use a Docker volume](https://www.youtube.com/watch?v=_MlSdlP6nwc)
- [Docker Volumes Explained (PostgreSQL example)](https://www.youtube.com/watch?v=G-5c25DYnfI)
- [Docker Volumes Demo || Docker Tutorial 13](https://www.youtube.com/watch?v=SBUCYJgg4Mk)
- [Docker Crash Course #10 - Volumes](https://www.youtube.com/watch?v=Wh4BcFFr6Fc)
- [What is Docker Volume | How to create Volumes | What is Bind Mount | Docker Storage](https://www.youtube.com/watch?v=VOK06Q4QqvE)
- [Docker Compose will BLOW your MIND!! (a tutorial)](https://www.youtube.com/watch?v=DM65_JyGxCo)
- [Docker Compose & Docker Volumes | Docker](https://www.youtube.com/watch?v=41o4RJxfCZM)
- [Docker Crash Course #11 - Docker Compose](https://www.youtube.com/watch?v=TSySwrQcevM)
- [Docker Compose Tutorial](https://www.youtube.com/watch?v=HG6yIjZapSA)
- [When would you want to use docker and docker-compose on your projects?](https://www.youtube.com/watch?v=m3To85qMOuA&list=WL&index=94)

### K8s
#### Videos
- [What is Kubernetes?](https://www.youtube.com/watch?v=IMOZCDhH7do&list=PLN_xGGp_EzELV3J2Bp-kNkmI2Vor338NI&index=9)
- [Kubernetes Explained in 100 Seconds](https://www.youtube.com/watch?v=PziYflu8cB8)
- [Kubernetes Explained in 6 Minutes | k8s Architecture](https://www.youtube.com/watch?v=TlHvYWVUZyc&list=WL&index=51)
- [Docker vs Kubernetes vs Docker Swarm | Comparison in 5 mins](https://www.youtube.com/watch?v=9_s3h_GVzZc)
- [What is Kubernetes | Kubernetes explained in 15 mins](https://www.youtube.com/watch?v=VnvRFRk_51k)
- [Kubernetes Tutorial For Beginners - Learn Kubernetes](https://www.youtube.com/watch?v=yznvWW_L7AA&list=WL&index=104)
- [Kubernetes Tutorial - Kubernetes Architecture Explained](https://www.youtube.com/watch?v=1vnA13v8PcA&list=WL&index=83)
- [Първи стъпки с Kubernetes - Димитър Захариев](https://www.youtube.com/watch?v=-zu7qioThP4)
- [you need to learn Kubernetes RIGHT NOW!!](https://www.youtube.com/watch?v=7bA0gTroJjw&list=WL)
- [Intro to Kubernetes | Container Tools For Beginners | Orchestration Tools | Great Learning](https://www.youtube.com/watch?v=WUU85wXv4mA&list=WL&index=75&t=673s)
- [Kubernetes Crash Course for Absolute Beginners [NEW]](https://www.youtube.com/watch?v=s_o8dwzRlu4&list=WL&index=63&t=290s)
- [Deploying Java Applications with Docker and Kubernetes | DevOps Project](https://www.youtube.com/watch?v=0GgBi8yNQT4&list=WL&index=67&t=433s)
- [Kubernetes Roadmap - Complete Step-by-Step Learning Path](https://www.youtube.com/watch?v=S8eX0MxfnB4&list=WL&index=83)
- [Do NOT Learn Kubernetes Without Knowing These Concepts...](https://www.youtube.com/watch?v=wXuSqFJVNQA&list=WL&index=18&t=1s)
- [Kubernetes Tutorial for Beginners [FULL COURSE in 4 Hours]](https://www.youtube.com/watch?v=X48VuDVv0do&list=WL&index=12&t=1s)

#### Read
- [What is Kubernetes?](https://www.redhat.com/en/topics/containers/what-is-kubernetes)
- [What is Kubernetes?](https://cloud.google.com/learn/what-is-kubernetes)
- [How to explain Kubernetes in plain English](https://enterprisersproject.com/article/2017/10/how-explain-kubernetes-plain-english)
- [What Is Kubernetes? What You Need To Know As A Developer](https://medium.com/@rphilogene/what-is-kubernetes-what-you-need-to-know-as-a-developer-674af25e3947)
- [Overview](https://kubernetes.io/docs/concepts/overview/)
- [Kubernetes Components](https://kubernetes.io/docs/concepts/overview/components/)
- [Objects In Kubernetes](https://kubernetes.io/docs/concepts/overview/working-with-objects/)
- [The Kubernetes API](https://kubernetes.io/docs/concepts/overview/kubernetes-api/)
- [Cluster Architecture](https://kubernetes.io/docs/concepts/architecture/)