As @rexposadas said, images include all the layers and each layer includes all the dependencies for what you installed. It is also important to note that the base images (like fedora:latest
tend to be very bare-bones. You may be surprised by the number of dependencies your installed software has.
I was able to make your installation significantly smaller by adding yum -y clean all
to each line:
FROM fedora:latest
RUN yum -y install nano && yum -y clean all
RUN yum -y install git && yum -y clean all
It is important to do that for each RUN, before the layer gets committed, or else deletes don’t actually remove data. That is, in a union/copy-on-write file system, cleaning at the end doesn’t really reduce file system usage because the real data is already committed to lower layers. To get around this you must clean at each layer.
$ docker history bf5260c6651d
IMAGE CREATED CREATED BY SIZE
bf5260c6651d 4 days ago /bin/sh -c yum -y install git; yum -y clean a 260.7 MB
172743bd5d60 4 days ago /bin/sh -c yum -y install nano; yum -y clean 12.39 MB
3f2fed40e4b0 2 weeks ago /bin/sh -c #(nop) ADD file:cee1a4fcfcd00d18da 372.7 MB
fd241224e9cf 2 weeks ago /bin/sh -c #(nop) MAINTAINER Lokesh Mandvekar 0 B
511136ea3c5a 12 months ago 0 B