class MCollective::RPC::ActionRunner

A helper used by RPC::Agent#implemented_by to delegate an action to an external script. At present only JSON based serialization is supported in future ones based on key=val pairs etc will be added

It serializes the request object into an input file and creates an empty output file. It then calls the external command reading the output file at the end.

any STDERR gets logged at error level and any STDOUT gets logged at info level.

It will interpret the exit code from the application the same way MCollective::RPC::Reply#fail! and fail handles their codes creating a consistent interface, the message part of the fail message will come from STDERR

Generally externals should just exit with code 1 on failure and print to STDERR, this is exactly what Perl die() does and translates perfectly to our model

It uses the MCollective::Shell wrapper to call the external application

Attributes

action[R]
agent[R]
command[R]
format[R]
request[R]
stderr[R]
stdout[R]

Public Class Methods

new(command, request, format=:json) click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 26
def initialize(command, request, format=:json)
    @command = command
    @agent = request.agent
    @action = request.action
    @format = format
    @request = request
    @stdout = ""
    @stderr = ""
end

Public Instance Methods

canrun?(command) click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 117
def canrun?(command)
    File.executable?(command)
end
load_json_results(file) click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 91
def load_json_results(file)
    return {} unless File.readable?(file)

    JSON.load(File.read(file))
rescue JSON::ParserError
    {}
end
load_results(file) click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 73
def load_results(file)
    Log.debug("Attempting to load results in #{format} format from #{file}")

    data = {}

    if respond_to?("load_#{format}_results")
        tempdata = send("load_#{format}_results", file)

        tempdata.each_pair do |k,v|
            data[k.to_sym] = v
        end
    end

    data
rescue Exception => e
    {}
end
run() click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 36
def run
    unless canrun?(command)
        Log.warn("Cannot run #{to_s}")
        raise RPCAborted, "Cannot execute #{to_s}"
    end

    Log.debug("Running #{to_s}")

    request_file = saverequest(request)
    reply_file = tempfile("reply")
    reply_file.close

    runner = shell(command, request_file.path, reply_file.path)

    runner.runcommand

    Log.debug("#{command} exited with #{runner.status.exitstatus}")

    stderr.each_line {|l| Log.error("#{to_s}: #{l.chomp}")} unless stderr.empty?
    stdout.each_line {|l| Log.info("#{to_s}: #{l.chomp}")} unless stdout.empty?

    {:exitstatus => runner.status.exitstatus,
     :stdout     => runner.stdout,
     :stderr     => runner.stderr,
     :data       => load_results(reply_file.path)}
ensure
    request_file.close! if request_file.respond_to?("close!")
    reply_file.close! if reply_file.respond_to?("close")
end
save_json_request(req) click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 113
def save_json_request(req)
    req.to_json
end
saverequest(req) click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 99
def saverequest(req)
    Log.debug("Attempting to save request in #{format} format")

    if respond_to?("save_#{format}_request")
        data = send("save_#{format}_request", req)

        request_file = tempfile("request")
        request_file.puts data
        request_file.close
    end

    request_file
end
shell(command, infile, outfile) click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 66
def shell(command, infile, outfile)
    env = {"MCOLLECTIVE_REQUEST_FILE" => infile,
           "MCOLLECTIVE_REPLY_FILE"   => outfile}

    Shell.new("#{command} #{infile} #{outfile}", :cwd => "/tmp", :stdout => stdout, :stderr => stderr, :environment => env)
end
tempfile(prefix) click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 125
def tempfile(prefix)
    Tempfile.new("mcollective_#{prefix}", "/tmp")
end
to_s() click to toggle source
# File lib/mcollective/rpc/actionrunner.rb, line 121
def to_s
    "#{agent}##{action} command: #{command}"
end