Mariio

Human | Lifelong learner 📖 | | Sysadmin 💻 | Devops | @LABTIC_CI 's padawan

[Dhanian 🗯️ @e_opore]

DOCKER IMAGES & LAYERS
A STEP-BY-STEP TUTORIAL

WHAT IS A DOCKER IMAGE

-> A Docker image is a read-only template used to create containers
-> It contains application code, runtime, libraries, and dependencies
-> Images are portable and can run consistently across environments
-> Built using a Dockerfile

WHAT ARE DOCKER LAYERS

-> Docker images are composed of multiple layers
-> Each layer represents a change or instruction
-> Layers are stacked to form the final image
-> All layers are immutable once created

HOW DOCKER IMAGES ARE BUILT

-> Docker reads the Dockerfile
-> Executes instructions one by one
-> Each instruction creates a new layer
-> Layers are combined into a final image

COMMON DOCKERFILE INSTRUCTIONS AND LAYERS

-> FROM
-> Defines the base image
-> Creates the first layer

-> RUN
-> Executes commands
-> Adds a new layer with changes

-> COPY / ADD
-> Transfers files into the image
-> Creates a new layer

-> ENV
-> Sets environment variables
-> Adds metadata layer

-> WORKDIR
-> Sets working directory
-> Affects subsequent instructions

-> CMD / ENTRYPOINT
-> Defines container startup behavior
-> Final layer configuration

LAYERED FILESYSTEM EXPLAINED

-> Each layer is read-only
-> Layers are stacked on top of each other
-> Docker merges them into a single unified filesystem
-> Containers add a writable layer on top

WRITABLE CONTAINER LAYER

-> Created when a container starts
-> Stores runtime changes
-> Includes logs, temporary files, and modifications
-> Removed when the container is deleted

DOCKER LAYER CACHING

-> Docker caches each layer during build
-> If nothing changes, cached layers are reused
-> Improves build performance
-> Changing one layer invalidates subsequent layers

LAYER REUSE AND SHARING

-> Multiple images can share common layers
-> Saves disk space and bandwidth
-> Faster image pulls and builds
-> Encourages reuse of base images

WHY DOCKER LAYERS MATTER

-> Efficient storage management
-> Faster build times
-> Faster deployment and scaling
-> Easy updates by rebuilding only changed layers

BEST PRACTICES FOR USING LAYERS

-> Use minimal base images
-> Combine RUN instructions where possible
-> Order instructions for optimal caching
-> Avoid unnecessary files in the image
-> Use multi-stage builds for cleaner images

FINAL SUMMARY

-> Docker images are built from layered instructions
-> Each layer is immutable and reusable
-> Containers run on top of these layers with a writable layer
-> Efficient layering improves speed, storage, and scalability

LEARN DOCKER IN DEPTH
-> Grab the Docker Mastery eBook
-> https://t.co/sC9bTrAJWt

[AI_Explorer @ai_explorer25]

Learn Coding by playing games

1. Kubernetes
https://t.co/asmX2e63Va

2. DevOps
https://t.co/5d9UZmCLKm

3. Linux
https://t.co/5lykebIy4w

4. Git
https://t.co/ffznxkA17X

5. Python
https://t.co/2nprnaayRU

6. CSS & HTML
https://t.co/1hOf8oa8Kk

7. Cybersecurity
https://t.co/kD2US36n4R

8. Mobile Coding (like Duolingo)
https://t.co/aXsdDAR7PR

9. For Complete Beginners
https://t.co/XoxpHQwCZM

10. 25+ Programming Languages
https://t.co/c5uulSTTeW

[Mariio @mxdjo]

@Awdalit @Idontgive2u Essayez de quitter un pays de la zone CEDEAO pour un pays d'Afrique Centrale, vous verrez ce qu'on demande pour le visa.

[Mariio @mxdjo]

@AureeNguessan Mettez ça sur UCAEVD.
Ils vont réagir rapidement

[Tom Dörr @tom_doerr]

Local AWS emulator alternative

https://t.co/jkRY0GqV8N

[Rohit Ghumare @ghumare64]

If you use k8s, you'll love reading this.

[Tom Dörr @tom_doerr]

Generates architecture diagrams from Terraform code

https://t.co/YW8krQ4zjo

[AfriBourse & Startup @AfriBourseStart]

like retweet pour avoir accès a notre Dashboard analytique du titre uniwax ! 🙂

[Ramón 👑 @byramonade]

If the Algorithm shows you my Art, kindly support by sharing

[jeune_goural_ @miloud_lionnel]

BRVM : Une école de discipline personnelle ⬇️👇🏽⤵️

[Mariio @mxdjo]

@Emmvnuelw @miloud_lionnel 34 actuellement

[Jonathan 🇧🇯 @jonkounou]

Vous négociez bientôt votre salaire au Bénin, en CIV ou au Sénégal ? J’ai soumis les données de salaire minimum de TOUTE l’Afrique à une IA et 30 min plus tard → un calculateur gratuit qui vous dit EN 5 SECONDES si vous gagnez ce que vous méritez.
🔗 https://t.co/wDP8A7Blx1

[Mariio @mxdjo]

@youngstar2679 @hdrewxxl On avait aussi Felix Kouadjo comme préparateur physique et analyste vidéo

[Mariio @mxdjo]

@FatimaNdiathie @GothamCitizen11 Montrez-nous plutôt la communication officielle de la CAF. C'est trop facile de s’appuyer sur un article provenant d’un site web gambien comme preuve, d’autant plus que des fact-checkers ont indiqué que cette information était fausse.

[Mariio @mxdjo]

@Mnu_Mpofana @Fimiii06 Officiellement c'est la Côte d'Ivoire indépendamment de la langue.

[Mariio @mxdjo]

@ohmygodwoah @Fimiii06 Since 1985, it's Côte d'Ivoire in all languages.

[Mariio @mxdjo]

@Fimiii06 🤣🤣🤣

[Mariio @mxdjo]

@FRMFXtra @grok est ce vrai ?

[Mariio @mxdjo]

@GunnerPuls Baros & Koller

[Mariio @mxdjo]

@_tea_anna Hello
Can you please share with me as well?