Pablo Fischer > App-Foca-0.05 > App::Foca::Server

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NAME ^

App::Foca::Server - Foca server

DESCRIPTION ^

Foca is an application (a HTTP server using HTTP::Daemon) that allows the execution of pre-defined commands via, obviously, HTTP.

Well, lets suppose you have a log parser on all your servers and you are in need to parse all of them, the common way would be to ssh to each host (can be as simple as ssh'ing to each host or using a multiplex tool) and execute your parser, but what if your SSH keys or the keys of a user are not there? It will be a heck of pain to enter your password hundred of times or lets imagine you want to parse your logs via some automation (like doing it from an IRC bot or tied to your monitoring solution).. then the problem comes more complex with SSH and private keys. With Foca you don't need to worry about those things, the command will get executed and the output will be returned as a HTTP response.

All commands that Foca knows about it are listed in a YAML file. Foca uses a default timeout value for all commands but with this YAML file you can give a specific timeout to a specific command. All commands are executed with IPC (open3).

Now the question is.. is Foca secure? Well it depends on you. Depends if you run it as non-root user and the commands you define. Foca will try to do things to protect, for example it will reject all requests that have pipes (|), I/O redirection (>, <, <<, >>), additionally the HTTP request will be validated before it gets executed via the call of validate_request() (App::Foca::Server returns true all the time so if you want to add extra functionality please create a subclass and re-define the method).

EXAMPLE ^

    my $server = App::Foca::Server->new(
            port                => $port,
            commands_file       => $commands,
            commands_timeout    => $timeout,
            debug               => $debug);

    $server->run_server();

EXAMPLE COMMANDS FILE ^

    commands_dirs:
        - /some/path/over/there/bin

    commands:
        df_path:
            cmd: '/bin/df {%foca_args%} | tail -n1'
        uptime:
            cmd: '/usr/bin/uptime'
        'true':
            cmd: '/bin/true'

The way the example commands file work is: First it will look if there is a commands_dir key, this key should have a list of directories (that means it should be an array reference), Foca will look for all executables inside the given directories and add them into memory. Second, it will look for the commands key, this one should be a hash where each key is the name of the command and it should have at least a cmd key which value should be the real command to execute.

Please note that when you use the commands_dir, Foca will use the basename of each executable as the name of the command so if you have /usr/local/foo, the foca command will be foo while the command it will execute will be /usr/local/foo.

Also, you can override commands found in commands_dir via commands, so going back to our /usr/local/foo example, you can have this executable in your /usr/local directory but also have a foo command defined in commands, the one that is defined in commands will be the one that will be used by Foca.

Command parameters are accepted but they should be find or declared in the Foca-Cmd-Params HTTP header. App::Foca::Client takes care of preparing the header.

Commands can have place-holders, this means that you can define your command in the YAML file and the real command can be a combination of pipes. If your command needs some parameters then you can use {%foca_args%} and it will be replaced with whatever parameters are found in the HTTP header Foca-Cmd-Params.

There are two ways to update the list of commands once the server started: One is by obviously restarting it and the other one is via localhost send a HTTP request to localhost:yourport/reload.

VERSION ^

Version 0.05

Attributes ^

commands_file

YAML file with the supported commands.

commands

Hash reference with a list of supported commands. Basically the content of commands_file.

port

Where to listen for requests?

commands_timeout

Global timeout for all commands. Default to 1min (60 seconds).

tmp_dir

Temporary directory, for cache.

debug

Debug/verbose mode, turned off by default.

server

App::Foca::Server::HTTP object.

cache

For mmap cache (so we can share cache across processes).

Methods ^

run_server()

Runs the HTTP::Daemon server. it forks on each request.

prepare_status_response()

Prepares a response (HTTP::Response) for the /status request. /status requests returns some stats about Foca server, such as: number of active connections, number of closed/zombie connections (user connected and left the connection open with a process that is no longer needed).

prepare_foca_response($connection, $request)

Prepares a response (HTTP::Response) for a given foca request (HTTP::Request).

build_response($code, $body)

Builds a HTTP response (HTTP::Response) based on the given HTTP status code and optionally adds a body.

Returns a HTTP::Response so it can be send via the opened connection.

validate_request($command, $request)

re-define this method if you want to add some extra security. By default all requests are valid at this point.

run_cmd($connection, $name, $cmd, $params)

Runs whatever the command is and sets a timeout to it. If it takes too long then it will try to kill the process.

Depending on the settings given to the command it will return the STDOUT or STDERR or even both. The rules are:

1. On success it will look for STDOUT, if nothing is there then it looks in STDERR. If nothing is foudn in STDERR and STDOUT then an empty string is returned.
2. On error it will look for STDERR first, if nothing is there then it looks in STDOUT. If nothing is there then it returns an empty string.

Both STDOUT and STDERR can be returned if the command is defined as follows:

    server_uptime:
        cmd: '/usr/bin/uptime'
        capture_all: 'y'

load_commands()

Load the commands YAML file and stores it in memory with Cache::FastMnap

COPYRIGHT ^

Copyright (c) 2010-2012 Yahoo! Inc. All rights reserved.

LICENSE ^

This program is free software. You may copy or redistribute it under the same terms as Perl itself. Please see the LICENSE file included with this project for the terms of the Artistic License under which this project is licensed.

AUTHORS ^

Pablo Fischer (pablo@pablo.com.mx)

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