Image Layers & Union File System

Layered Filesystem

💡 Docker, IMAGE, LAYERS, EK, PANCAKE, STACK, jaisi, hoti, HAIN — HAR, LAYER, PICHLI, LAYER, ke, UPAR, STACK, hoti hai, aur, Docker, SAARI, LAYERS, ko, EK, SINGLE, UNIFIED, FILESYSTEM, ki, TARAH, DIKHATA, hai.

Docker, IMAGE, MULTIPLE, READ-ONLY, LAYERS, se, banti hai — HAR, LAYER, Dockerfile, ki, EK, INSTRUCTION, (jaise, RUN, COPY, ADD) ko, REPRESENT, karti hai. Union, File, System, (jaise, OverlayFS) IN, SAARI, LAYERS, ko, EK, SINGLE, VIEW, mein, MERGE, kar, deta hai.

SABSE, BADA, FAYDA, hai: agar, DO, IMAGES, SAME, BASE, LAYER, (jaise, ubuntu:22.04) SHARE, karti, HAIN, TO, Docker, US, LAYER, ko, DISK, par, sirf, EK, hi, BAAR, STORE, karta hai — ISSE, SPACE, aur, BUILD, TIME, dono, BACHTE, HAIN.

# Layers dekhne ke liye:
docker history nginx

# Har RUN, COPY, ADD instruction ek nayi layer banata hai
FROM ubuntu:22.04       # Layer 1
RUN apt-get update       # Layer 2
COPY app.js /app/        # Layer 3

🥞

Docker, IMAGE, LAYERS, EK, PANCAKE, STACK, jaisi, hoti, HAIN — HAR, LAYER, PICHLI, LAYER, ke, UPAR, STACK, hoti hai, aur, Docker, SAARI, LAYERS, ko, EK, SINGLE, UNIFIED, FILESYSTEM, ki, TARAH, DIKHATA, hai.

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⚡ Quick Recap

Har Dockerfile instruction ek nayi read-only layer banata hai
Union filesystem saari layers ko ek single view mein merge karta hai
Shared base layers disk space aur build time dono bachati hain

On this page (2 subtopics)

Docker, build, ke, waqt, HAR, INSTRUCTION, ke, liye, CHECK, karta hai, ki, KYA, EK, CACHED, LAYER, ALREADY, EXIST, karti, hai (SAME, instruction, + SAME, previous, layers). Agar, HAAN, TO, WO, LAYER, DOBARA, BUILD, NAHI, hoti, sirf, CACHE, se, REUSE, ho, jaati, hai.

💡Tip: Dockerfile, mein, "COPY package.json ." aur, "RUN npm install" ko, source, code, COPY, karne, se, PEHLE, RAKHO — ISSE, sirf, package.json, CHANGE, hone, par, hi, "npm install" DOBARA, chalega, poore, code, change, par, NAHI.

"docker history <image>" command, se, HAR, LAYER, ka, SIZE, dekha, ja, sakta hai. MULTIPLE, RUN, INSTRUCTIONS, ko, "&&" se, JOIN, karke, EK, hi, LAYER, mein, COMBINE, kiya, ja, sakta, hai, ISSE, TOTAL, LAYERS, aur, IMAGE, SIZE, dono, KAM, hote, HAIN.

# Multiple RUN ko ek layer mein combine karo
RUN apt-get update && \
    apt-get install -y curl && \
    rm -rf /var/lib/apt/lists/*

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Image Layers & Union File System

Layer Caching During Build

Viewing and Reducing Layer Count