Issue
In order to use the C++17 include <filesystem>
I need gcc-9 package in my centos 7 docker.
By default rel="noreferrer">centos:7 will install gcc 4.8.5 from the regular distro repo.
docker run --rm -it centos:7
# yum install -y gcc
# gcc --version
gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44)
Is there any way to easily install a gcc-9 (or later) package (i.e. not build it from source)
Thanks !
note: need gcc-9 to have good C++17 <filesystem>
support.
GCC 9 Release note:
Using the types and functions in
<filesystem>
does not require linking with-lstdc++fs
now.
src: https://gcc.gnu.org/gcc-9/changes.html
Solution
What I have so far:
cat Dockerfile
FROM centos:7 AS env
RUN yum update -y
RUN yum install -y centos-release-scl
RUN yum install -y devtoolset-9
RUN echo "source /opt/rh/devtoolset-9/enable" >> /etc/bashrc
SHELL ["/bin/bash", "--login", "-c"]
RUN gcc --version
So you must:
Add the source stuff in a bashrc
note: On Centos it's/etc/bashrc
while on ubuntu it's/etc/bash.bashrc
Update the docker default shell to be bash AND to "load" the bashrc using
--login
Output
docker build .
Sending build context to Docker daemon 4.096kB
Step 1/32 : FROM centos:7 AS env
---> 8652b9f0cb4c
Step 2/32 : RUN yum update -y
---> Using cache
---> a2bb269cd8dc
Step 3/32 : RUN yum install -y centos-release-scl
---> Using cache
---> 1184e26c71cf
Step 4/32 : RUN yum install -y devtoolset-9
---> Using cache
---> e678665d2a4e
Step 5/32 : RUN echo "source /opt/rh/devtoolset-9/enable" >> /etc/bashrc
---> Using cache
---> fe1745d4ca87
Step 6/32 : SHELL ["/bin/bash", "--login", "-c"]
---> Running in 2dd7955f4487
Removing intermediate container 2dd7955f4487
---> 3cf4835bf680
Step 7/32 : RUN gcc --version
---> Running in b5de3266d607
gcc (GCC) 9.3.1 20200408 (Red Hat 9.3.1-2)
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
...
What won't work
Test 1
RUN scl enable devtoolset-9 bash
RUN gcc --version | head -1
each RUN
is a new shell so the sub-bash is lost on the second line.
Test 2
RUN source /opt/rh/devtoolset-9/enable && gcc --version | head -1
RUN gcc --version | head -1
Here again the source is only for the first RUN shell command but will be lost...
Test 3
This may work but with potential unexpected behaviour
ENV PATH=/opt/rh/devtoolset-9/root/bin:$PATH
RUN gcc --version | head -1
here we only "fix" the PATH
variable but if you look at the /opt/rh/devtoolset-9/enable
script there is so more to do than only updating the PATH
...
Answered By - Mizux Answer Checked By - David Marino (WPSolving Volunteer)