I have a dockerfile that download and builds GTK from source, but the following line is not updating my image's environment variable:
RUN PATH="/opt/gtk/bin:$PATH"
RUN export PATH
I read that that I should be using ENV to set environment values, but the following instruction doesn't seem to work either:
ENV PATH /opt/gtk/bin:$PATH
This is my entire Dockerfile:
FROM ubuntu
RUN apt-get update
RUN apt-get install -y golang gcc make wget git libxml2-utils libwebkit2gtk-3.0-dev libcairo2 libcairo2-dev libcairo-gobject2 shared-mime-info libgdk-pixbuf2.0-* libglib2-* libatk1.0-* libpango1.0-* xserver-xorg xvfb
# Downloading GTKcd
RUN wget http://ftp.gnome.org/pub/gnome/sources/gtk+/3.12/gtk+-3.12.2.tar.xz
RUN tar xf gtk+-3.12.2.tar.xz
RUN cd gtk+-3.12.2
# Setting environment variables before running configure
RUN CPPFLAGS="-I/opt/gtk/include"
RUN LDFLAGS="-L/opt/gtk/lib"
RUN PKG_CONFIG_PATH="/opt/gtk/lib/pkgconfig"
RUN export CPPFLAGS LDFLAGS PKG_CONFIG_PATH
RUN ./configure --prefix=/opt/gtk
RUN make
RUN make install
# running ldconfig after make install so that the newly installed libraries are found.
RUN ldconfig
# Setting the LD_LIBRARY_PATH environment variable so the systems dynamic linker can find the newly installed libraries.
RUN LD_LIBRARY_PATH="/opt/gtk/lib"
# Updating PATH environment program so that utility binaries installed by the various libraries will be found.
RUN PATH="/opt/gtk/bin:$PATH"
RUN export LD_LIBRARY_PATH PATH
# Collecting garbage
RUN rm -rf gtk+-3.12.2.tar.xz
# creating go code root
RUN mkdir gocode
RUN mkdir gocode/src
RUN mkdir gocode/bin
RUN mkdir gocode/pkg
# Setting the GOROOT and GOPATH enviornment variables, any commands created are automatically added to PATH
RUN GOROOT=/usr/lib/go
RUN GOPATH=/root/gocode
RUN PATH=$GOPATH/bin:$PATH
RUN export GOROOT GOPATH PATH
Although the answer that Gunter posted was correct, it is not different than what I already had posted. The problem was not the ENV directive, but the subsequent instruction RUN export $PATH
There's no need to export the environment variables, once you have declared them via ENV in your Dockerfile.
As soon as the RUN export ... lines were removed, my image was built successfully
RUN A=B, RUN export A, and RUN export A=B, are valid shell commands, but affect the environment only of commands that follow in that same RUN directive (but none are given). Similarly, if you had RUN export PATH=/foo; prog1; prog2; (in the same RUN), the PATH modification would affect prog1 and prog2. So, RUN export $PATH is a noop (because no program uses that modified environment) and it should make no difference if that directive is there or not. By "Gunter", do you mean this answer?
[I mentioned this in response to the selected answer, but it was suggested to make it more prominent as an answer of its own]
It should be noted that
ENV PATH="/opt/gtk/bin:${PATH}"
may not be the same as
ENV PATH="/opt/gtk/bin:$PATH"
The former, with curly brackets, might provide you with the host's PATH. The documentation doesn't suggest this would be the case, but I have observed that it is. This is simple to check just do RUN echo $PATH and compare it to RUN echo ${PATH}
This is discouraged (if you want to create/distribute a clean Docker image), since the PATH variable is set by /etc/profile script, the value can be overridden.
head /etc/profile:
if [ "`id -u`" -eq 0 ]; then
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
else
PATH="/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games"
fi
export PATH
At the end of the Dockerfile, you could add:
RUN echo "export PATH=$PATH" > /etc/environment
So PATH is set for all users.
/etc/environment is a list of assignment expressions, not a script, and does not support variable expansion, so it is unlikely that the RUN syntax would work.
export PATH=<some path> will be written to /etc/environment, which is still incorrect because that file is not a script but a list of <var name>=<value>. export will likely make it fail unless your system supports some black magic outside the spec.
/etc/profile or /etc/environment, so changing these scripts is usually ineffective.
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=equals sign necessary?=it needs to be without spaces. If you add spaces next to=like thisENV PATH = "/opt/gtk/bin:${PATH}"WILL CRASH YOUR $PATH$PATHappended?ENV PATH="/opt/gtk/bin:${PATH}"may not be the same asENV PATH="/opt/gtk/bin:$PATH"The former, with curly brackets, might provide you with the host's PATH. The documentation doesn't suggest this would be the case, but I have observed that it is. This is simple to check just doRUN echo $PATHand compare it toRUN echo ${PATH}