Create Readme.md

docker/Readme.md

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+#  Docker Cmd
+
+> **login** : docker login
+
+> **Index** : https://app.eraser.io/workspace/yTPql82lXyOpbyX63Xgn
+
+##  Links:
+
+- **All docker images are available at** : [hub.docker.com](hub.docker.com)
+
+## Attribute:
+
+- **-it**: interactive, connect the main cmd to container cmd , and don't disconnect
+
+- **-t**: tag
+
+
+
+##  Main Line cmd:
+
+- **to make image/container** : install any image that will automatically make a container. **Cmd** : docker run -it ubuntu
+- **to go inside any container** : docker start -i thanos(container_name)
+- **to go inside if container is already running**: docker exec -it thanos bash
+- **to run any cmd inside container** : docker exec *container_name* ls. **eg:** docker exec pendatic_mendel ls
+- **to see images** : docker image ls
+
+- **Port mapping** : docker run -it p 1025:1025 container_name
+
+- **Port mapping with evn set** : docker run -it -p 1025:1025(my_machine_Port:docker_port) -e key=value -e key=value continer_name. **eg** docker run -it -e PORT=4000 -p 4000:4000 first-nodejs
+
+- **to build dockerfile** : docker build -t -image name you want to give- . (path)
+
+
+##  Container cmd:
+
+- **to see active** : docker container ls
+
+- **to see all active** : docker container ls -a
+
+- **to start container** : docker start -container name- , eg: docker start pedantic_mendel
+
+- **to stop container** : docker stop pendatic_mendel
+
+
+
+##  Dockerfile
+
+save the file with name : "dockerfile" where package.json is present
+
+    FROM ubuntu
+
+    RUN apt-get update
+
+    RUN apt-get install -y curl
+
+    RUN apt-get upgrade -y
+
+    RUN curl -sL https://deb.nodesource.com/setup_18.x | bash -
+
+    RUN apt-get upgrade -y
+
+    RUN apt-get install -y nodejs
+
+
+
+    WORKDIR /usr/app
+
+    COPY package.json package.json
+
+    COPY package-lock.json package-lock.json
+
+    COPY index.js index.js
+
+
+
+    RUN npm install
+
+
+
+
+Now run : docker build -t first-nodejs .
+
+
+
+## Layer Caching
+
+>inside dockerfile if any line execute every time when building dockerfile then docker cache it and start building again from line where changes happened.
+
+1. **Layered Architecture**: Each command in a Dockerfile (like `COPY`, `RUN`, etc.) creates a new layer on top of the previous one. These layers build up the final image.
+
+2. **Cache Reuse**: Docker caches these layers, so when you rebuild an image, it reuses unchanged layers instead of rebuilding everything from scratch.
+
+3. **Faster Builds**: By using cached layers, Docker significantly speeds up the build process for parts that haven't changed.
+
+4. **Cache Invalidated by Changes**: If a layer changes (e.g., the content of a `COPY` command), all subsequent layers need to be rebuilt, starting from that point.
+
+
+## Docker Compose
+
+1. **Multiple Containers**: Docker Compose allows you to define and run multiple containers as a single application using a `docker-compose.yml` file.
+
+2. **Service Definition**: Each container is defined as a "service" in the YAML file, specifying its image, volumes, networks, and other configurations.
+
+3. **Simplified Management**: You can manage all containers together (start, stop, build) with a single command like `docker-compose up` and `docker-compose down`.
+
+4. **Environment Configuration**: Easily manage environment variables, networks, and volumes between multiple services, making development and deployment consistent.
+
+5. **Isolation and Orchestration**: Compose helps isolate environments and orchestrate container interactions, making it easy to spin up complex multi-container environments.
+
+
+##  Docker network
+> Three main types of network:
+> 1.bridge
+> 2.host
+> 3.none
+
+> *we use it to connect two container under same network*
+
+- **To show networks** : docker network ls
+
+- **To inspect specific network**: docker network inspect milkyway
+
+- **To create own network**: docker network create -d bridge -network_name- (eg: youtube)
+
+- **To run on specific network**: docker run -it --network=milkyway --name wanda busybox