# independency of layers
! Base principle : each command within a Dockerfile (as in an image) is an INDEPENDENT LAYER !
This implies that each LAYER has its own environment.
! Example :
CMD cd /tmp
COPY ./* . # <= copy into img's root (not /tmp !) If you do need to have several cmds executed, solutions are : - launch a script containing several instructions - chain on same line : CMD cd /tmp && copy ./* . - special cmds allow to bypass this limit : * WORKDIR * ENV (can also be set via RUN cmd line : -e )
Indicates which folder within a container are writable (in case the container has been launched in read-only mode)