Docker vs Kubernetes — Erreurs de Configuration dans les Applications Java

 Beaucoup d’applications Java fonctionnent parfaitement en Docker local…

mais échouent dès le passage à Kubernetes.

Beaucoup pensent :

Kubernetes = Docker à grande échelle ❌

Faux.

Kubernetes change le réseau, le cycle de vie, la configuration et la gestion mémoire.
La majorité des pannes viennent de la configuration, pas du code.

1) Utiliser localhost pour communiquer entre services

Fonctionne en Docker Compose
Échoue en Kubernetes

Pourquoi ?

Chaque pod possède son propre réseau.

Solution

Utiliser le DNS du service :

payment.service.url=http://payment-service:8080

2) Configuration codée en dur

Local :

application-prod.yml dans le jar

Kubernetes utilise ConfigMaps et Secrets.

Solution

Ne jamais intégrer la config d’environnement dans l’image.

3) Mauvaise configuration mémoire JVM

Erreur classique :

OOMKilled
Container restarting

Solution

Configurer la JVM :

-XX:+UseContainerSupport
-XX:MaxRAMPercentage=75

4) Absence de Health Probes

Docker :
Container running = OK

Kubernetes :
Running ≠ Ready

Solution

Activer :

management.endpoint.health.probes.enabled=true

5) Écriture sur disque local

Les pods Kubernetes sont éphémères.
Les données disparaissent au redémarrage.

Solution

Utiliser Persistent Volume ou stockage objet.

6) Temps de démarrage trop long

Kubernetes tue les applications lentes à démarrer.

Spring Boot peut prendre 60s → pod redémarre.

Solution

Augmenter timeout ou optimiser démarrage.

Différence d’Architecture

DockerKubernetes
Lance un containerOrchestre un système distribué
StatiqueDynamique
Restart manuelAuto-heal
Machine uniqueCluster

Checklist Production

✔ pas de localhost
✔ configuration externalisée
✔ mémoire JVM adaptée
✔ probes santé
✔ pas de disque local
✔ démarrage rapide

📚 Lectures recommandées

Pour améliorer la stabilité :

👉 https://shikhanirankari.blogspot.com/search/label/French

À lire :

Conseil Final

Docker prouve que votre application fonctionne
Kubernetes prouve que votre architecture fonctionne

Concevez pour l’échec, pas pour localhost.

💼 Support professionnel disponible

Si vous rencontrez des problèmes sur des projets réels liés au développement backend d’entreprise ou à l’automatisation des workflows, je propose des services de conseil payants, de débogage en production, de support projet et de formations ciblées.

Les technologies couvertes incluent Java, Spring Boot, PL/SQL, Azure, CMS, ainsi que l’automatisation des workflows (jBPM, Camunda BPM, RHPAM, Flowable), DMN/Drools.

📧 Contact: ishikhanirankari@gmail.com | info@realtechnologiesindia.com

🌐 Website: IT Trainings | Digital lectern | Digital rostrum | Digital metal podium     


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