# Dockerfile Instructions

## Working with Instructions

* FROM: Initializes a new build stage and sets the Base Image
* RUN: Will execute any commands in a new layer
* CMD: Provides a default for an executing container. There can only be one CMD instruction in a Dockerfile
* LABEL: Adds metadata to an image
* EXPOSE: Informs Docker that the container listens on the specified network ports at runtime
* ENV: Sets the environment variable to the value
* ADD: Copies new files, directories or remote file URLs from and adds them to the filesystem of the image at the path .
* COPY: Copies new files or directories from and adds them to the filesystem of the container at the path .
* ENTRYPOINT: Allows for configuring a container that will run as an executable
* VOLUME: Creates a mount point with the specified name and marks it as holding externally mounted volumes from native host or other containers
* USER: Sets the user name (or UID) and optionally the user group (or GID) to use when running the image and for any RUN, CMD, and ENTRYPOINT instructions that follow it in the Dockerfile
* WORKDIR: Sets the working directory for any RUN, CMD, ENTRYPOINT, COPY, and ADD instructions that follow it in the Dockerfile
* ARG: Defines a variable that users can pass at build-time to the builder with the docker build command, using the --build-arg = flag
* ONBUILD: Adds a trigger instruction to the image that will be executed at a later time, when the image is used as the base for another build
* HEALTHCHECK: Tells Docker how to test a container to check that it is still working
* SHELL: Allows the default shell used for the shell form of commands to be overridden

## To set up the environment:

```bash
sudo apt install git -y
```

```bash
mkdir weather-app
```

```bash
cd weather-app
```

```bash
git clone https://github.com/nishanthkumarpathi/content-weather-app src
```

## Create the Dockerfile:

```bash
vi Dockerfile
```

## Dockerfile contents:

Create an image for the weather-app

```bash
FROM node
LABEL org.label-schema.version=v1.1
RUN mkdir -p /var/node
ADD src/ /var/node/
WORKDIR /var/node
RUN npm install
EXPOSE 3000
CMD ./bin/www
```

## Build the weather-app image:

```bash
docker image build -t nishanthkp/weather-app:v1 .
```

List the images:

```bash
docker image ls
```

## Create the weather-app container:

```bash
docker container run -d --name weather-app1 -p 8081:3000 nishanthkp/weather-app:v1
```

## List all running containers:

```bash
docker container ls
```