why soft link is not saved in docker container-CodePudding

I have created a python link from python3, but it is not saved when I log in to container image. Why?

FROM    ubuntu:latest
RUN     apt-get update
RUN     apt-get install -y libxml2-dev xmlsec1
RUN     apt-get install -y python3-pip python3-dev
RUN     cd /usr/local/bin
RUN     ln -s /usr/bin/python3 python
RUN     pip3 --no-cache-dir install --upgrade pip
RUN     rm -rf /var/lib/apt/lists/*
COPY    .  /app
WORKDIR /app
RUN     pip install -r requirements.txt
CMD     python3 app.py

CodePudding user response：

Command RUN launches a new shell every time. As a result, working directory is not preserved between dockerfile steps, so

RUN     cd /usr/local/bin

won't affect the following ln command. You can combine both commands in one step:

RUN     cd /usr/local/bin && ln -s /usr/bin/python3 python

Alternatively, use WORKDIR or provide the full link path to ln.