Overmind
Overmind is a process manager for Procfile-based applications and tmux. With Overmind, you can easily run several processes from your Procfile in a single terminal.
Procfile is a simple format to specify types of processes your application provides (such as web application server, background queue process, front-end builder) and commands to run those processes. It can significantly simplify process management for developers and is used by popular hosting platforms, such as Heroku and Deis. You can learn more about the Procfile format here.
There are some good Procfile-based process management tools, including foreman by David Dollar, which started it all. The problem with most of those tools is that processes you want to manage start to think they are logging their output into a file, and that can lead to all sorts of problems: severe lagging, losing or breaking colored output. Tools can also add vanity information (unneeded timestamps in logs). Overmind was created to fix those problems once and for all.
See this article for a good intro and all the juicy details! Introducing Overmind and Hivemind
Overmind features
You may know several Procfile process management tools, but Overmind has some unique, extraterrestrial powers others don't:
- Overmind starts processes in a tmux session, so you can easily connect to any process and gain control over it;
- Overmind can restart a single process on the fly — you don't need to restart the whole stack;
- Overmind allows a specified process to die without interrupting all of the other ones;
- Overmind can restart a specified processes automatically when they die;
- Overmind uses tmux's control mode to capture process output — so it won't be clipped, delayed, and it won't break colored output;
- Overmind can read environment variables from a file and use them as parameters so that you can configure Overmind behavior globally and/or per directory.
If a lot of those features seem like overkill for you, especially the tmux integration, you should take a look at Overmind's little sister — Hivemind!
Installation
Note: At the moment, Overmind supports Linux, *BSD, and macOS only.
Overmind works with tmux, so you need to install it first:
# on macOS (with homebrew)
$ brew install tmux
# on Ubuntu
$ apt-get install tmux
Note: You can find installation manual for other systems here: https://github.com/tmux/tmux
There are three ways to install Overmind:
With Homebrew (macOS)
brew install overmind
Download the latest Overmind release binary
You can download the latest release here.
Build Overmind from source
You need Go 1.12 or later to build the project.
$ GO111MODULE=on go get -u github.com/DarthSim/overmind/v2
Note: You can update Overmind the same way.
Usage
In short: You can get help by running overmind -h and overmind help [command].
Running processes
Overmind reads the list of processes you want to manage from a file named Procfile. It may look like this:
web: bin/rails server
worker: bundle exec sidekiq
assets: gulp watch
To get started, you just need to run Overmind from your working directory containing a Procfile:
$ overmind start
You can also use the short alias:
$ overmind s
Specifying a Procfile
If a Procfile isn't located in your working directory, you can specify the exact path:
$ overmind start -f path/to/your/Procfile
$ OVERMIND_PROCFILE=path/to/your/Procfile overmind start
Specifying the ports
Overmind sets environment variable PORT for each process in your Procfile so that you can do things like this:
web: bin/rails server -p $PORT
Overmind assigns the port base (5000 by default) to PORT for the first process and increases PORT by port step (100 by default) for the each next one. You can specify port base and port step like this:
$ overmind start -p 3000 -P 10
$ OVERMIND_PORT=3000 OVERMIND_PORT_STEP=10 overmind start
Disabling PORT variable
If you don't want Overmind to set PORT variable, you can disable it:
$ overmind start -N
$ OVERMIND_NO_PORT=1 overmind start
Running only the specified processes
You can specify the names of processes you want to run:
$ overmind start -l web,sidekiq
$ OVERMIND_PROCESSES=web,sidekiq overmind start
Not running the specified processes
Similar to the above, if there are some processes in the Procfile that you do not want to run:
$ overmind start -x web,sidekiq
$ OVERMIND_IGNORED_PROCESSES=web,sidekiq overmind start
This takes precedence over the previous -l flag. i.e. if you:
$ overmind start -l web -x web
$ OVERMIND_IGNORED_PROCESSES=web OVERMIND_PROCESSES=web overmind start
Nothing will start.
Scaling processes (formation)
By default, Overmind starts one instance of each process, but you can set the number of each process instances to run:
$ overmind start -m web=2,worker=5
$ OVERMIND_FORMATION=web=2,worker=5 overmind start
There is a special name all that you can use to scale all processes at once:
$ overmind start -m all=2,worker=5
$ OVERMIND_FORMATION=all=2,worker=5 overmind start
If you set instances number of some process to zero, this process won't be run:
$ overmind start -m some_production_task=0
$ OVERMIND_FORMATION=some_production_task=0 overmind start
Processes that can die
Usually, when a process dies, Overmind will interrupt all other processes. However, you can specify processes that can die without interrupting all other ones:
$ overmind start -c assets,npm_install
$ OVERMIND_CAN_DIE=assets,npm_install overmind start
Auto-restarting processes
If some of your processes tend to randomly crash, you can tell Overmind to restart them automatically when they die:
$ overmind start -r rails,webpack
$ OVERMIND_AUTO_RESTART=rails,webpack overmind start
Specifying the colors
Overmind colorizes process names with different colors. May happen that these colors don't match well with your color scheme. In this case, you can define your own colors using xterm color codes:
$ overmind start -b 123,123,125,126,127
$ OVERMIND_COLORS=123,123,125,126,127 overmind start
If you want Overmind to always use these colors, you can specify them in the environment file located in your home directory.
Connecting to a process
If you need to gain access to process input, you can connect to its tmux window:
$ overmind connect [process_name]
You can safely disconnect from the window by hitting Ctrl b and then d.
Restarting a process
You can restart a single process without restarting all the other ones:
$ overmind restart sidekiq
You can restart multiple processes the same way:
$ overmind restart sidekiq assets
It's also possible to use wildcarded process names:
$ overmind restart 'sidekiq*'
When the command is called without any arguments, it will restart all the processes.
Stopping a process
You can stop a single process without stopping all the other ones:
$ overmind stop sidekiq
You can stop multiple processes the same way:
$ overmind stop sidekiq assets
It's also possible to use wildcarded process names:
$ overmind stop 'sidekiq*'
When the command is called without any arguments, it will stop all the processes without stopping Overmind itself.
Killing processes
If something goes wrong, you can kill all running processes:
$ overmind kill
Overmind environment
If you need to set specific environment variables before running a Procfile, you can specify them in the .overmind.env file in the current working directory, your home directory, or/and in the .env file in in the current working directory. The file should contain variable=value pairs, one per line:
PATH=$PATH:/additional/path
OVERMIND_CAN_DIE=npm_install
OVERMIND_PORT=3000
For example, if you want to use a separate Procfile.dev by default on a local environment, create .overmind.env file with OVERMIND_PROCFILE=Procfile.dev. Now, Overmind uses Procfile.dev by default.
You can specify additional env file to load with OVERMIND_ENV variable:
$ OVERMIND_ENV=path/to/env overmind s
The files will be loaded in the following order:
~/.overmind.env./.overmind.env./.env$OVERMIND_ENV
You can also opt to skip loading the .env file entirely (.overmind.env will still be read) by setting the variable OVERMIND_SKIP_ENV.
Running a command in the Overmind environment
Since you set up an environment with .env files, you may want to run a command inside this environment. You can do this using run command:
$ overmind run yarn install
Run as a daemon
Overmind can be run as a daemon:
$ overmind start -D
$ OVERMIND_DAEMONIZE=1 overmind start
Use echo command for the logs:
$ overmind echo
You can quit daemonized Overmind with quit:
$ overmind quit
Specifying a socket
Overmind receives commands via a Unix socket. Usually, it opens a socket named .overmind.sock in a working directory, but you can specify the full path:
$ overmind start -s path/to/socket
$ OVERMIND_SOCKET=path/to/socket overmind start
All other commands support the same flag:
$ overmind connect -s path/to/socket web
$ overmind restart -s path/to/socket sidekiq
$ overmind kill -s path/to/socket
Using TCP network
Overmind can bind its command center to a TCP address instead of Unix socket. It is useful when you run it on a remote machine.
$ overmind start -s "0.0.0.0:4321" -S "tcp"
$ OVERMIND_SOCKET="0.0.0.0:4321" OVERMIND_NETWORK="tcp" overmind start
You need to pass the same flags to other commands:
$ overmind connect -s "0.0.0.0:4321" -S "tcp" web
Known issues
Overmind uses system Ruby/Node/etc instead of custom-defined one
This may happen if your Ruby/Node/etc version manager isn't configured properly. Make sure that the path to your custom binaries is included in your PATH before the system binaries path.
Overmind does not stop Docker process properly
Unfortunately, this is how Docker works. When you send SIGINT to a docker run ... process, it just detaches container and exits. You can solve this by using named containers and signal traps:
mydocker: trap 'docker stop mydocker' EXIT > /dev/null; docker run --name mydocker ...
Overmind can't start because of bind: invalid argument error
All operating systems have limitations on Unix socket path length. Try to use a shorter socket path.
Overmind exits after pg_ctl --wait start and keeps PostgreSQL server running
Since version 12.0 pg_ctl --wait start exits right after starting the server. Just use postgres command directly.
Author
Sergey "DarthSim" Aleksandrovich
Highly inspired by Foreman.
Many thanks to @antiflasher for the awesome logo.
License
Overmind is licensed under the MIT license.
See LICENSE for the full license text.
