Very simple Compile Daemon for Go

Watches your .go files in a directory and invokes go build if a file changed. Nothing more.

Usage:

$ ./CompileDaemon -directory=yourproject/

Installation

You can use the go tool to install CompileDaemon:

go get github.com/githubnemo/CompileDaemon

Development

You need to use Go 1.16 or higher to build Compile Daemon, and you need to set the env var GO111MODULE=on, which enables you to develop outside of $GOPATH/src.

Command Line Options

Option	Default	Description
		actions
-build=…	go build	Specify the command to run when rebuilding is required.
-command=…	none	Specify the command to run after a succesful build. The default is to run nothing. This command is issued with the working directory set to -directory.
		file selection
-directory=…	.	Which directory to watch.
-recursive=…	true	Recurse down the specified directory
-exclude-dir=…	none	Do not watch directories matching this glob pattern, e.g. ".git". You may have multiples of this flag.
-exclude=…	none	Exclude files matching this glob pattern, e.g. ".#*" ignores emacs temporary files. You may have multiples of this flag.
-include=…	none	Include files whose last path component matches this glob pattern. You may have multiples of this flag.
-pattern=…	(.+\.go|.+\.c)$	A regular expression which matches the files to watch. The default watches .go and .c files.
		file watch
-polling=…	false	Use polling instead of FS notifications to detect changes. Default is false
-polling-interval=…	100	Milliseconds of interval between polling file changes when polling option is selected
		misc
-color=_	false	Colorize the output of the daemon's status messages.
-log-prefix=_	true	Prefix all child process output with stdout/stderr labels and log timestamps.
-graceful-kill=_	false	On supported platforms, send the child process a SIGTERM to allow it to exit gracefully if possible.

Examples

In its simplest form, the defaults will do. With the current working directory set to the source directory you can simply…

$ CompileDaemon

… and it will recompile your code whenever you save a source file.

If you want it to also run your program each time it builds you might add…

$ CompileDaemon -command="./MyProgram -my-options"

… and it will also keep a copy of your program running. Killing the old one and starting a new one each time you build.

You may find that you need to exclude some directories and files from monitoring, such as a .git repository or emacs temporary files…

$ CompileDaemon -exclude-dir=.git -exclude=".#*" …

If you want to monitor files other than .go and .c files you might…

$ CompileDaemon -include=Makefile -include="*.less" -include="*.tmpl"

Security Considerations

Beware that, in case you are using CompileDaemon in production to rebuild a binary (please explain to me why you would do this, but carry on), an attacker with write access is able to insert arbitrary code into your binary. So make sure that you secure write access to the file system appropriately.

Common Issues

Too many open files

If you get an error for too many open files, you might wish to exclude your .git, .hg, or similar VCS directories using -exclude-dir=…. This is common on OS X and BSD platforms where each watched file consumes a file descriptor.

If you still have too many open files, then you need to raise your process's file limit using the ulimit command. Something like ulimit -n 1024 will probably take care of it. There is also a sysctl based limit which you may reach and need to adjust.

filepath.Walk() no space left on device

As described in this issue it might happen that you run out of inotify watchers which are limited by your system configuration. Please consider increasing them as is documented here.

Docker + Mac OS X

Some issues (here and here) report that changes on Docker volumes under Mac OS X are not reported.

There seem to be issues with either the implementation of the bind file system mount between Mac OS X hosts and Docker containers or in fsnotify/fsnotify or a combination of both. As long as this is not resolved, a possible workaround is to use polling:

CompileDaemon -polling

This will actively watch for changes, so it naturally uses more CPU resources. You can tune the polling interval to your liking using the -polling-interval=N parameter but be advised: you should never use this in production as it is simply too wasteful.

Project Details

Credits

CompileDaemon was written by githubnemo.

Code and documentation was contributed by jimstudt.

Repository

CompileDaemon is kept at https://github.com/githubnemo/CompileDaemon

License

CompileDaemon is licensed under the BSD Two Clause License