Command as service

This application is intended to be an easy way to automate running commands as an HTTP service.

Installation

• Install ruby 2.x and install bundler gem
• Clone this repo: git clone https://github.com/chrodriguez/cmd_as_service.git
• Run: bundle install

Configuration

This service is entirely configured based on environment variables. The complete list of variables is:

• CMD_AS: command to execute. Argument to this command can be set as POST argument
• CACHE_TIMEOUT: time a generated token will be valid. Default: 300 seconds.
• MAIL_TO: recipient mail address to send validation and notification emails.
• MAIL_FROM: sender mail address to send mails from.
• MAIL_SUBJECT: mail subject text to send for initial validation emails. Defualt: Command as a service
• MAIL_HOST: mail server to use as SMTP server
• MAIL_PORT: mail server port. Default: 25
• MAIL_USER: mail server authentication user if needed
• MAIL_PASS: mail server authentication password
• MAIL_AUTH: mail server authentication method. Valid values are: plain, login, cram_md5. If empty means no authentication.
• MAIL_STARTTLS: mail server uses starttls?

HTTP Services

The application exposes only two entry points that must be used as a state machine:

POST /

This command is the main entry point. It will accept the following arguments:

• args: string with arguments to send as parameters to configured $CMD
• force:: force token regeneration. Valid values are true and 1. Other values will be considered as false

When a requirement arrives, the application will send a confirmation email to configured recipients. This email will give recipients the confirmation URL to be accessed for accepting command execution.

GET /:token

This entry point is a validation URI. Token must be a valid token previously generated with a POST method. If token is valid (valid hash and is still within configured timeout threshold), command is executed using a thread. When command finishes, a resulting email will be send to configured recipients with command status and output

Sample usage

Start server

MAIL_HOST=smtp.example.net MAIL_TO=user@example.net RACK_ENV=production ruby serve.rb

Start server specifying other port

RACK_ENV=production puma -w 1 -t 2:4 -p 4567

Sample client usage

Ask to run command as a service

curl -d 'force=1&args=Hello world' http://localhost:4567

Docker

You can play with this application using a provided image that can be used as template o used as base image for your own docker images. Dockerfile is provided in docker/ directory.

Run a sample echo container

The following example uses gmail as server

docker run --rm -it \
  -e CMD_AS=/bin/echo \
  -e MAIL_TO=user@gmail.com \
  -e MAIL_FROM=user@gmail.com \
  -e MAIL_HOST=smtp.gmail.com \
  -e MAIL_PORT=587 \
  -e MAIL_USER=user@gmail.com \
  -e MAIL_PASS=**** \
  -e MAIL_AUTH=plain \
  -e MAIL_STARTTLS=true \
  -p 9292:9292 chrodriguez/cmd_as_service

Then use curl to play with this demo:

curl -d 'args=Hello world' localhost:9292

An email will be sent with instructions to follow. Finally, after command execution an email with subject SUCCESS... will be sent with a body similar to the following example. Any output produced by the command (via stderr and/or stdout) will be attached to the email.

Command finished in 0.06 seconds
-------------------------------------------------------------------------------

Please refer to the attached file(s) for the standard and error output produced
by the command, if any.

[attachment stdout.txt contains "Hello world"]