Docker

Dockerfile - Multiple RUN commands v. single chained RUN command

Docker best practice:

In your Dockerfile, combine commands to minimize the number of layers and therefore reduce the image size.

# 2 commands
RUN apt-get update
RUN apt-get install -y netcat


# single command
RUN apt-get update && apt-get install -y netcat

Results:

# docker history to see layers

$ docker images
REPOSITORY   TAG       IMAGE ID       CREATED          SIZE
dockerfile   latest    180f98132d02   51 seconds ago   259MB

$ docker history 180f98132d02

IMAGE          CREATED              CREATED BY                                      SIZE      COMMENT
180f98132d02   58 seconds ago       COPY . . # buildkit                             6.71kB    buildkit.dockerfile.v0
<missing>      58 seconds ago       RUN /bin/sh -c pip install -r requirements.t…   35.5MB    buildkit.dockerfile.v0
<missing>      About a minute ago   COPY requirements.txt . # buildkit              58B       buildkit.dockerfile.v0
<missing>      About a minute ago   WORKDIR /app
...