kapow/doc

Installing Kapow!

Kapow! has a reference implementation in Go that is under active develpment right now. If you want to start using kapow you can:

• Download a binary (linux, at this moment) from our releases section
• Install the package with the get command (you need the Go runtime installed and configured)

    go get -u github.com/BBVA/kapow

Examples

Below are some examples on how to define and invoke routes in Kapow!

As you can see Kapow! binary is a server and a CLI that you can use to configure a running server. The server exposes an API that you can invoke directly if you want.

In order to get information from the request that fired the scrip execution and to help you in composing the response, the server exposes some resources to interact with from the script.

The mandatory Hello World (for WWW fans)

First you create a pow file named greet.pow with the following contents:

    kapow route add /greet -c 'name=$(kapow get /request/params/name); echo Hello ${name:-World} | kapow set /response/body'

note you have to escape as the command will run on a shell itself. Then, you execute:

    kapow server greet.pow

to start a Kapow! server exposing your service. Now you can check that it works as intended with good ole' curl:

    curl localhost:8080/greet
    Hello World

    curl localhost:8080/greet?name=friend
    Hello friend

If you want to work with JSON you can use this version of the pow greet-json.pow

  kapow route add -X POST /greet -c 'kapow route add -X POST /greet -c 'who=$(kapow get /request/body | jq -r .name); kapow set /response/status 201; jq --arg value "${who:-World}" -n \{name:\$value\} | kapow set /response/body''

that uses jq to allow you working with json from the command line. Check that it works with

  curl -X POST -H "Content-Type: application/json" -d '{"name": "friend"}' localhost:8080/greet
  {"name": "friend" }

  curl -X POST -H "Content-Type: application/json" -d '' localhost:8080/greet
  {"name": "World"}

The mandatory Echo (for UNIX fans)

First you create a pow file named echo.pow with the following contents:

    kapow route add -X POST /echo -c 'kapow get /request/body | kapow set /response/body'

then, you execute:

    kapow server echo.pow

and you can check that it works as intended with good ole' curl:

    curl -X POST -d '1,2,3... testing' localhost:8080/echo
    1, 2, 3, 4, 5, 6, 7, 8, 9, testing

If you send a big file and want to see the content back as a real-time stream you can use this version echo-stream.pow

    kapow route add -X POST /echo -c 'kapow get /request/body | kapow set /response/stream'

The multiline fun

Unless you're a hardcore Perl hacker, you'll probably need to write your stuff over more than one line in order to avoid the mess we saw on our json greet version.

Don't worry, we need to write several lines, too. Bash, in its magnificent UNIX® style, provides us with the here-documents mechanism that we can leverage precisely for this purpose.

Imagine we want to return both the standard output and a generated file from a command execution. Let's write a log-and-stuff.pow file with the following content:

  kapow route add /log_and_stuff - <<- 'EOF'
    echo this is a quite long sentence and other stuff | tee log.txt | kapow set /response/body
    cat log.txt | kapow set /response/body
  EOF

then we serve it with kapow:

    kapow server log-and-stuff.pow

Yup. As simple as that. You can check it.

    curl localhost:8080/log_and_stuff
    this is a quite long sentence and other stuff
    this is a quite long sentence and other stuff

Interact with other systems

You can leverage all the power of the shell in your scripts and interact with other systems by using all the available tools. Write a log-and-stuff-callback.pow file with the following content:

  kapow route add /log_and_stuff - <<- 'EOF'
    callback_url=$(kapow get /request/params/callback)
    echo this is a quite long sentence and other stuff | tee log.txt | kapow set /response/body
    echo sending to $callback_url | kapow set /response/body
    curl -X POST --data-binary @log.txt $callback_url | kapow set /response/body
  EOF

serve it with kapow:

    kapow server log-and-stuff-callback.pow

and finally check it.

    curl localhost:8080/log_and_stuff?callback=nowhere.com
    this is a quite long sentence and other stuff
    sending to nowhere.com
    <html>
    <head><title>405 Not Allowed</title></head>
    <body>
    <center><h1>405 Not Allowed</h1></center>
    <hr><center>nginx</center>
    </body>
    </html>

You must be aware that you must have all the dependencies you use in your scripts installed in the host that will run the Kapow! server.

In addition, a pow file can contain as much routes as you like so you can start a server with several routes configured in one shoot.

Sample Docker usage

Clone the project

    git clone https://github.com/BBVA/kapow.git

Build the kapow! docker image

    make docker

Now you have a container image with all the above pow files copied in /tmp so you can start each example by running

    docker run --rm -p 8080:8080 docker server example.pow

Build a docker image for running the nmap example

    cd /path/to/kapow/poc/examples/nmap; docker build -t kapow-nmap .

Run kapow

    docker run \
            -d \
            -p 8080:8080 \
            kapow-nmap

which will output something like this:

   e7da20c7d9a39624b5c56157176764671e5d2d8f1bf306b3ede898d66fe3f4bf

Test /list endpoint

In another terminal, try running:

    curl http://localhost:8080/list/github.com

which will respond something like:

    Starting Nmap 7.70 ( https://nmap.org ) at 2019-05-10 14:01 UTC
    Nmap scan report for github.com (140.82.118.3)
    rDNS record for 140.82.118.3: lb-140-82-118-3-ams.github.com
    Nmap done: 1 IP address (0 hosts up) scanned in 0.04 seconds

et voilà !

License

This project is distributed under the Apache License 2.0.