learn/docker/dFile.md

Keywords

FROM (module)

• gives instructions about the base platform to use (node, fedora, etc)

• FROM node:20

WORKDIR (path)

• like when you cd into a directory
• makes sure any commands executed will be in this directory

• WORKDIR /app

COPY (src) (dest)

• copies files from src to dest
• I THINK it's like a symbolic link? Maybe?

• COPY package*.json ./

Note: you can get docker to ignore files by creating a .dockerignore file

RUN (commands)

• like running a command in the terminal!
• RUN npm install

ENV ((varName=varVal) (varName2=varVal2) ...)

• sets env vars (like doing it from the command line)

• ENV PORT=3000

EXPOSE (PORT)

• this will expose a port to the network

• EXPOSE 3000

CMD (args[])

• only ONE per dockerfile
• will tell the container how to run the application
• same as nodejs spawn args

• CMD ["npm", "start"]

Notes

every step/instruction in docker is it's own layer

• docker attempts to cache layers if nothing is changes
• this means we want to install dependancies first so they aren't re-installed every time (i.e. are cached)