Overcast is a terminal-focused cloud management tool that was designed to make it easy to spin up and manage clusters of servers in a consistent, scriptable way. Inspired by Packer.
Define clusters using the command line or manually by editing a JSON file.
$ overcast cluster create db
$ overcast cluster create app
Spin up new instances on DigitalOcean. Once finished these are automatically added to clusters.
$ overcast instance create db.01 --cluster=db --host=digitalocean
$ overcast instance create db.02 --cluster=db --host=digitalocean
Import existing instances located anywhere to a cluster.
$ overcast instance import app.01 --cluster=app --ip=127.0.0.2 \
--ssh-port=22222 --ssh-key=$HOME/.ssh/id_rsa
$ overcast instance import app.02 --cluster=app --ip=127.0.0.3 \
--ssh-port=22222 --ssh-key=$HOME/.ssh/id_rsa
Run commands or script files on an instance, a cluster, or all clusters, sequentially or in parallel.
$ overcast run db install/core install/redis
$ overcast run all uptime "free-m" "df -h" --parallel
Push and pull files between your local machine and an instance, a cluster, or all clusters. Dynamically rewrite file paths to include the instance name.
$ overcast push app nginx/myapp.conf /etc/nginx/sites-enabled/myapp.conf
$ overcast pull all /etc/nginx/sites-enabled/myapp.conf nginx/{instance}.myapp.conf
Overcast is a thin wrapper around your native SSH client, and doesn't install or leave anything on the servers you communicate with.
A script library is included to make it easy to install common software components in a modular fashion. The library is tailored to Ubuntu 12.04, but could easily be extended to include other distributions/versions.
There are a number of server management frameworks out there already (Chef, Puppet, Ansible, Salt), but all involve either a complicated server/client implementation, a steep learning curve or a giant, monolithic conceptual framework.
I wanted something that is conceptually simple and easy to use, that is only concerned with programmatic communication with clusters of servers, that leaves problems like process/state management and monitoring to other tools.
Install Node.js if not already installed.
Install Overcast using npm.
$ npm -g install overcast
You can now use Overcast from any directory.
$ overcast help
overcast cluster create [name]
Creates a new cluster.
Example:
$ overcast cluster create db
overcast cluster remove [name]
Removes a cluster from the index. If the cluster has any instances
attached to it, they will be moved to the "orphaned" cluster.
Example:
$ overcast cluster remove db
overcast expose [instance|cluster|all] [port...]
Reset the exposed ports on the instance or cluster using iptables.
This will fail if you don't include the current SSH port.
Expects an Ubuntu server, untested on other distributions.
Examples:
$ overcast expose redis 22 6379
$ overcast expose mysql 22 3306
$ overcast expose app 22 80 443
overcast exposed [instance|cluster|all]
List the exposed ports on the instance or cluster.
Expects an Ubuntu server, untested on other distributions.
Usage:
overcast [command] [options...]
Help:
overcast help
overcast help [command]
Commands:
overcast cluster list
overcast cluster create [name]
overcast cluster remove [name]
overcast expose [instance|cluster|all] [port...]
overcast exposed [instance|cluster|all]
overcast info
overcast init
overcast instance create [name] [options]
overcast instance import [name] [options]
overcast instance remove [name]
overcast list
overcast ping [instance|cluster|all]
overcast port [instance|cluster|all] [port]
overcast pull [instance|cluster|all] [source] [dest]
overcast push [instance|cluster|all] [source] [dest]
overcast run [instance|cluster|all] [command...]
overcast run [instance|cluster|all] [file...]
overcast ssh [instance]
Config directory:
/path/to/.overcast
overcast info
Pretty-prints the complete clusters.json file, stored here:
/path/to/.overcast/clusters.json
overcast init
Create an .overcast config directory in the current working directory.
No action taken if one already exists.
overcast instance create [name] [options]
Creates a new instance on a hosting provider. You'll need to add your API
credentials to the .overcast/variables.json file for this to work.
See the .overcast/example.variables.json file for reference.
The instance will start out using the auto-generated SSH key found here:
/path/to/.overcast/keys/overcast.key.pub
Option | Default
--cluster=CLUSTER |
--provider=NAME | digitalocean
--region=NAME | nyc2
--image=NAME | ubuntu-12-04-x64
--size=NAME | 512mb
Example:
$ overcast instance create db.01 --cluster=db --host=digitalocean
overcast instance import [name] [options]
Imports an existing instance to a cluster.
Option | Default
--cluster=CLUSTER |
--ip=IP |
--ssh-port=PORT | 22
--ssh-key=PATH | .overcast/keys/overcast.key
--user=USERNAME | root
Example:
$ overcast instance import app.01 --cluster=app --ip=127.0.0.1 \
--ssh-port=22222 --ssh-key=$HOME/.ssh/id_rsa
overcast instance remove [name]
Removes an instance from the index.
The server itself is not affected by this action.
Example:
$ overcast instance remove app.01
overcast list
Short list of your cluster and instance definitions, stored here:
/path/to/.overcast/clusters.json
overcast ping [instance|cluster|all]
Ping an instance or cluster.
Option | Default
--count=N | 3
Examples:
$ overcast ping app.01
$ overcast ping db --count=5
overcast port [instance|cluster|all] [port]
Change the SSH port for an instance or a cluster.
Careful, this port should already be open!
Examples:
$ overcast port app.01 22222
$ overcast port db 22222
overcast pull [instance|cluster|all] [source] [dest]
Pull a file or directory from an instance or cluster using scp. Source is absolute.
Destination can be absolute or relative to the .overcast/files directory.
Any reference to {instance} in the destination will be replaced with the instance name.
Example:
Assuming instances "app.01" and "app.02", this will expand to:
- .overcast/files/nginx/app.01.myapp.conf
- .overcast/files/nginx/app.02.myapp.conf
$ overcast pull app /etc/nginx/sites-enabled/myapp.conf nginx/{instance}.myapp.conf
overcast push [instance|cluster|all] [source] [dest]
Push a file or directory to an instance or cluster using scp. Source can be
absolute, or relative to the .overcast/files directory. Destination is absolute.
Any reference to {instance} in the source will be replaced with the instance name.
Example:
Assuming instances "app.01" and "app.02", this will expand to:
- .overcast/files/nginx/app.01.myapp.conf
- .overcast/files/nginx/app.02.myapp.conf
$ overcast push app nginx/{instance}.myapp.conf /etc/nginx/sites-enabled/myapp.conf
overcast run [instance|cluster|all] [command...]
Runs a command or series of commands on an instance or cluster.
Commands will run sequentially unless you use the --parallel flag,
in which case each command will run on all instances simultanously.
Option
--env="KEY=VAL KEY='1 2 3'"
--parallel -p
Examples:
$ overcast run app --env="foo='bar bar' testing=123" env
$ overcast run all uptime "free -m" "df -h"
overcast run [instance|cluster|all] [file...]
Executes a script file or files on an instance or cluster.
Script files can be either absolute or relative path.
Script files will run sequentially unless you use the --parallel flag,
in which case each file will execute on all instances simultanously.
Option
--env="KEY=VAL KEY='1 2 3'"
--parallel -p
Relative paths are relative to this directory:
/path/to/.overcast/scripts
Example:
$ overcast run db install/core install/redis
overcast ssh [instance]
Opens an SSH connection to an instance.
Overcast looks for an .overcast directory in the current directory, or in some parent directory, otherwise falling back to $HOME/.overcast.
This allows you to have multiple configurations, and to check your cluster definitions and scripts into a repo, like source code.
The config directory looks like this:
.overcast
/files # Files to be copied to instances
/keys # SSH keys. Can be your own or auto-generated by overcast
/scripts # Scripts to be run on instances
/clusters.json # Cluster/instance definitions
/variables.json # API keys, etc
npm install
npm test
MIT. Copyright © 2014 Andrew Childs.
FAQs
A simple command line program that makes it easy to spin up, configure, and manage virtual machines over SSH.
The npm package overcast receives a total of 23 weekly downloads. As such, overcast popularity was classified as not popular.
We found that overcast demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
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