rbuild: Edit locally, build remotely

rbuild is a script to support the workflow of editing C source code on a local machine (e.g. a macOS laptop with MacVim), and syncing the source code to a remote build machine with full development environment (e.g. a Linux server). It can also be used to sync the generated binaries to a third machine lacking a development environment.

In the normal rbuild workflow, the developer edits locally, and runs rbuild -s to stage the source code to the build machine and rbuild -b to perform a remote build. These can be combined into rbuild -sb, which are also the default options when running rbuild without any arguments. rbuild requires a configuration file found in $HOME/.rbuild.conf or provided using the -C option. This file needs to include at the very least a BUILD_HOST variable with the name of the build machine.

rbuild -s stages the source code from LOCAL_DIR to BUILD_HOST:STAGING_DIR using rsync. Unless overriden in the config file, STAGING_DIR defaults to RBUILD_DIR\BASENAME. RBUILD_DIR and BASENAME can be overriden too, but by default RBUILD_DIR is rbuild and BASENAME is the basename of LOCAL_DIR. LOCAL_DIR can be overriden but by default is based on the current dir or its first parent that contains one fo the files specified in the space-separated list in LOCAL_DIR_ANCHORS, which can be overriden itself, but defaults to .hg .git .configure.ac. This helps an rbuild command issued from inside a subdirectory of the project, to find the project root directory (the LOCAL_DIR).

autoconf-based projects require a one-time setup before building. This can be performed on the build server by hand after rbuild -s and before the first rbuild -b. Typically this requires running autoreconf --install in the remote staging directory STAGING_DIR, and configure --prefix $INSTALL_DIR in the remote build dir, as specified by BUILD_DIR described later.

The following shortcuts can be used instead of the manual method:

• rbuild -A runs autoreconf --install in the remote source directory.
• rbuild -a runs configure --prefix=$INSTALL_DIR in the remote build directory.

The only environment variable passed to autoreconf by default is ACLOCAL_PATH. You can point ACLOCAL_PATH in .rbuild.conf to directories with custom m4 macros. To pass additional variables through .rbuild.conf, use:

EXTRA_AUTORECONF_VARS="..."

The environment variables passed to configure by default are CC, CFLAGS, CXX, CXXFLAGS and PKG_CONFIG_PATH. To pass additional variables through .rbuild.conf:

EXTRA_CONFIGURE_VARS="LDFLAGS=-L/usr/local/lib LIBS=\'-lm -lpcap\'"

To pass additional command line options to configure:

EXTRA_CONFIGURE_ARGS='--enable-optimizations'

To set environment variables for make use BUILD_VARS, for example:

BUILD_VARS="GIT_REVISION=$(git rev-parse HEAD)"

The remote build directory on BUILD_HOST is BUILD_DIR. It could be specified in the config file, but the default of RBUILD_DIR/BASENAME.BUILD_ENV can be used too. BUILD_ENV defaults to debug but can be specified on the rbuild command line using -e. The value of BUILD_ENV can be used inside .rbuild.conf to customize the build, as can be seen in the provided sample.rbuild.conf.

INSTALL_DIR defaults to '$HOME/.local'. Note that $HOME on the local machine and the remote build host may differ. Using single quotes ensures that the $HOME variable is evaluated on the remote machine.

rbuild -b performs make install in BUILD_DIR on the BUILD_HOST.

Other command line options include:

• -c to run make clean in the build dir
• -t to run make check in the build dir
• -r to completely remove the build dir
• -j to control the -j argument of make
• -o is a shortcut to -e optimized
• -S copies the source code to the DEPLOY_HOST (useful for remote GDB)
• -R removes the source code from the DEPLOY_HOST
• -x dump the built-in rsync exclude list and exit
• -B build a specific makefile target

Multiple flags can be combined, e.g. rbuild -sAabod. Any operation specified in the command line is executed in this order independently of its position:

1. Stage
2. Clean
3. Autoreconf
4. Configure
5. Make
6. Deploy
7. Deploy source

rsync exclude list

If autoreconf has been run on the remote source directory, its generated files would be clobbered by a subsequent rbuild -s. To avoid this, rbuild supports an rsync exclude list passed to rsync via its --exclude-file option. rbuild will look for this list with this order:

1. $LOCAL_DIR/.rbuild_exclude
2. $HOME/.rbuild.exclude
3. Use a built-in list which can be inspected by running rbuild -x

If autoreconf is not required, or if it is performed on the local machine, use of the exclude list is not required and can be disabled using an empty exclusion list file.

Vim integration

rbuild arranges for the filenames in the build output to use relative paths, so that they can be used by a local editor. For example, with Vim we can specify set makeprg=rbuild to invoke rbuild using :make and use Vim to navigate the results. Vim plugins that are useful in combination with rbuild include vim-dispatch that can allows background build with tmux, and vim-addon-local-vimrc for per-project .vimrc files.

Deploying to a third machine

rbuild can be used to deploy the built binaries from the remote build host to another remote host that lacks a development environment. The command rbuild -d runs rsync on the build host to sync INSTALL_DIR to the machine specified in DEPLOY_HOST. INSTALL_DIR must be valid on the deploy host (any missing directories will be created) and DEPLOY_HOST must be usable as an SSH host on BUILD_HOST. The transfer is performed between the two remote machines, using rsync.