text: # Docker Builds for he-transformer with a _Reference-OS_
  
  ## Introduction
  
  This directory contains a basic build system for creating docker images of the _reference-OS_ on which he-transformer builds and unit tests are run.  The purpose is to provide reference builds for _Continuous Integration_ used in developing and testing he-transformer.
  
  The `Makefile` provides targets for:
  
  * Building the _reference-OS_ into a docker image
  * Building he-transformer and running unit tests in this cloned repo, mounted into the docker image of the _reference-OS_
  * Starting an interactive shell in the _reference-OS_ docker image, with the cloned repo available for manual builds and unit testing
  
  The _make_ targets are designed to handle all aspects of building the _reference-OS_ docker image, running he-transformer builds and unit testing in it, and opening up a session in the docker image for interactive use.  You should not need to issue any manual commands (unless you want to).  In addition the `Dockerfile.he-transformer.*` files provide a description of how each _reference-OS_ environment is built, should you want to build your own server or docker image.
  
  ## Prerequisites
  
  In order to use the _make_ targets, you will need to do the following:
  
  * Have *docker* installed on your computer with the docker daemon running.
  * These scripts assume that you are able to run the `docker` command without using `sudo`.  You will need to add your account to the `docker` group so this is possible.
  * If your computer (running docker) sits behind a firewall, you will need to have the docker daemon properly configured to use proxies to get through the firewall, so that public docker registries and git repositories can be accessed.
  * You should _not_ run `make check_*` targets from a directory in an NFS filesystem, if that NFS filesystem uses _root squash_ (see **Notes** section below).  Instead, run `make check_*` targets from a cloned repo in a local filesystem.
  
  ## Make Targets
  
  The _make_ targets are designed to provide easy commands to run actions using the docker image.  All _make_ targets should be issued on the host OS, and _not_ in a docker image.
  
  Most _make_ targets are structured in the form `<action>_<compiler>`.  The `<action>` indicates what you want to do (e.g. build, check), while the `<compiler>` indicates what you want to build with (i.e. gcc or clang).
  
  * In general, you simply need to run the command **`make check_all`**.  This first makes the `build_docker_image` target as a dependency.  Then it makes the `build_*` and `check_*` targets, which will build he-transformer using _cmake_ and _make_ and then run unit testing.  Please keep in mind that `make check_*` targets do not work when your working directory is in an NFS filesystem that uses _root squash_ (see **Notes** section below).
  
  * Two builds types are supported: building with `gcc` and `clang`.  Targets are named `*_gcc` and `*_clang` when they refer to building with a specific compiler, and the `*_all` targets are available to build with both compilers.  Output directories are BUILD-GCC and BUILD-CLANG, at the top level.
  
  * You can also run the command **`make shell`** to start an interactive bash shell inside the docker image.  While this is not required for normal builds and unit testing, it allows you to run interactively within the docker image with the cloned repo mounted.  Again, `build_docker_image` is made first as a dependency.  Please keep in mind that `make shell` does not work when your working directory is in an NFS filesystem that uses _root squash_ (see **Notes** section below).
  
  * Running the command **`make build_docker_image`** is also available, if you simply want to build the docker image.  This target does work properly when your working directory is in an NFS filesystem.
  
  * **`make clean`** is available to clean up the BUILD-* and docker build directories.
  
  Note that all operations performed inside the docker image are run as a regular user, using the `run-as-user.sh` script.  This is done to avoid writing root-owned files in mounted filesystems.
  
  * Additionally, the `RM_CONTAINER` flag may be used to persist the docker containers. By default `RM_CONTAINER=true`, and the docker containers are removed after building. Setting `RM_CONTAINER=false` will keep the containers, enabling an easy way to build he-transformer without installing the required software dependencies.
  
  ## Examples/Hints
  
  * To build an Ubuntu 16.04 docker container, compile with gcc 7.4, and run unit tests:
  
  ```
  cd contrib/docker
  make check_gcc
  ```
  
  * To build an Ubuntu 16.04 docker container, compile with clang 6.0 , and run unit tests:
  
  ```
  cd contrib/docker
  make check_clang
  ```
  
  * To build a Ubuntu 18.04 docker container, compile with gcc 7, and run unit tests:
  
  ```
  cd contrib/docker
  make check_gcc OS=ubuntu1804
  ```
  
  * To build an Ubuntu 16.04 docker container with persistent builds, compile with gcc 7.4, and run unit tests:
  
  ```
  cd contrib/docker
  make build_gcc RM_CONTAINER=false
  ```
  
  To launch the shell with the persistent docker image, run
  ```bash
  make shell
  ```
  Then, `/home/dockuser/he-transformer-test` will contain the he-transformer repository with the build files.
  
  ## Helper Scripts
  
  These helper scripts are included for use in the `Makefile` and automated (Jenkins) jobs.  **These scripts should _not_ be called directly unless you understand what they do.**
  
  
  #### `build-he-transformer-and-test.sh`
  
  A helper script to simplify implementation of make targets with multiple reference OS environments with different compilers using docker images.
  
  #### `docker_cleanup.sh`
  
  A helper script for Jenkins jobs to clean up old exited docker containers and `he_transformer_*` docker images.
  
  #### `make-dimage.sh`
  
  A helper script to simplify building of docker images for multiple reference OS environments.
  
  #### `run_as_user.sh`
  
  A helper script to run as a normal user within the docker container.  This is done to avoid writing root-owned files in mounted filesystems.
  
  #### `run_as_ubuntu_user.sh`
  
  Same as `run_as_user.sh`, specifically called for _make_ targets with Ubuntu 16.04 docker containers.
  
  #### `run_as_centos_user.sh`
  
  A helper script to run as a normal user within a CentOS 7.4 docker container.
  
  ## Notes
  
  * The top-level `Makefile` in this cloned repo can be used to build and unit-test he-transformer _outside_ of docker.  This directory is only for building and running unit tests for he-transformer in the _reference-OS_ docker image.
  
  * Due to limitations in how docker mounts work, `make check_*` and `make shell` targets will fail if you try to run them while in a working directory that is in an NFS-mount that has _root squash_ enabled.  The cause results from the process in the docker container running as root.  When a file or directory is created by root in the mounted directory tree, from within the docker image, the NFS-mount (in the host OS) does not allow a root-created file, leading to a permissions error.  This is dependent on whether the host OS performs "root squash" when mounting NFS filesystems.  The fix to this is easy: run `make check_*` and `make shell` from a local filesystem.
  
  * The _make_ targets have been tested with the following docker containers on an Ubuntu 16.04 host OS with docker installed and the docker daemon properly configured.  Some adjustments may be needed to run these on other OSes.
  
  #### Ubuntu 16.04 (default)
  
  ```
  Dockerfile: Dockerfile.he-transformer.ubuntu1604
  Reference-OS: Ubuntu 16.04
  BUILD-GCC: gcc 7.4.0
  BUILD-CLANG: clang 6.0.1
  ```
  
  #### Ubuntu 18.04
  
  ```
  Dockerfile: Dockerfile.he-transformer.ubuntu1804
  Reference-OS: Ubuntu 18.04
  BUILD-GCC: gcc 7.4.0
  BUILD-CLANG: clang 6.0.1
  ```