docker-build.md

@@ -28,4 +28,15 @@ docker run --rm -w /host/ShellB3 --name shellb3_centos6_build -v /path/to/ShellB
 
 Where `/path/to/ShellB3` is the absolute path to the ShellB3 repository you cloned in Step 1. In this example `mk_polar2grid` is the ShellB3 trim being built, this can be changed to whatever you'd like. The `clean` command should be included if you plan to build for multiple operating systems (other docker images) so that the previous build is removed from the working directory. The final tarball generated with be in `/path/to/ShellB3`
 
-You can also replace `mk_polar2grid bin_dist clean` with any `shallbethree.sh` arguments. Note that each call to `docker run` will create a new docker container that will automatically be deleted with the `--rm` argument.
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+You can also replace `mk_polar2grid bin_dist clean` with any `shallbethree.sh` arguments. Note that each call to `docker run` will create a new docker container that will automatically be deleted with the `--rm` argument.
+
+Build for CentOS 6 Target - GCC 7
+---------------------------------
+
+Currently in the `geo2grid` branch the docker image made from the above instructions includes the gcc 7 compiler, but it must be sourced specially. This branch has also been tested with multiple workers when processing Make files.
+
+```
+docker run --rm -w /host/ShellB3 -h "geo2grid_build" -e MAKEFLAGS='-j8' --name shellb3_centos6_build -v /data/docker_volume/repos/git/ShellB3:/host shellb3_centos6_gcc7 scl enable devtoolset-7 "./copied_mount.sh mk_polar2grid bin_dist"
+```
+
+This method of calling ShellB3 building also uses a new `copied_mount.sh` script to link source tarballs and build directories from the host machine to the docker container to avoid file system and timing errors while building. The successful tarball is copied back to the host after success. A failed build is copied to the host as a `build_YYYYMMDD_HHMMSS` directory.
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