Derez Blog: oVirt UI-VDSM-Hooks Plugin

Using CGI scripts located on the host's web-server, VDSM commands (vdsClient)
can be invoked directly from the WebAdmin UI. This solution is useful for commonly
used commands, scripts that are based on vdsClient API or as a shell replacement...
Following are some screenshots and code snippets to illustrate the technique capabilities
(UI-Plugin's infrastructure and hooks examples can be fetched here).

Hooks Examples

right-click on a host

GetAllTasks

GetConnectedStoragePool

GetStorageDomainsList

VdsClient API

UI for all VdsClient API commands

VdsClient - 'list' command

VdsClient - list table

Main CGI Script

/var/www/cgi-bin/ui-vdsm-hooks/ui-vdsm-hooks.cgi

#!/usr/bin/python

import cgi
import json
import re
import subprocess as sub

def executeCommand(command):
    if command in commands:
        return commands[command]()
    return "Error: command is not supported"

def executeVdsCommand(command='', args={}):
    cmd = ['vdsClient', '0', command] + args
    output = sub.Popen(
        cmd, stdout=sub.PIPE).stdout.read().rstrip('\n')
    return cgi.escape(output)

def getConnectedStoragePoolsList():
    return executeVdsCommand("getConnectedStoragePoolsList", [])

def disconnectStoragePool():
    spID = executeCommand("getConnectedStoragePoolsList")
    return executeVdsCommand(
        "disconnectStoragePool", [ spID, '0', '0' ])

def getStorageDomainsList():
    spID = executeCommand("getConnectedStoragePoolsList")
    return executeVdsCommand("getStorageDomainsList", [ spID ])

def spmStop():
    spID = executeCommand("getConnectedStoragePoolsList")
    return executeVdsCommand("spmStop", [ spID ])

def getAllTasks():
    return executeVdsCommand("getAllTasks", [])

def stopAllTasks():
    return forEachTaskExecute("stopTask")

def clearAllTasks():
    return forEachTaskExecute("clearTask")

def forEachTaskExecute(vdsCmd):
    taskIDs = re.findall("id = [\w,-]*", getAllTasks())
    for taskID in taskIDs:
        uuid = taskID.replace("id = ", "")
        executeVdsCommand(vdsCmd, [ uuid ])
    return ""

def runScript():
    form = cgi.FieldStorage()
    scriptFile = form.getfirst("args", "")
    return sub.Popen("scripts/" + scriptFile,
                      stdout=sub.PIPE).stdout.read()

commands = {
    'runScript': runScript,
    'getAllTasks': getAllTasks,
    'stopAllTasks': stopAllTasks,
    'clearAllTasks': clearAllTasks,
    'getStorageDomainsList': getStorageDomainsList,
    'getConnectedStoragePoolsList': getConnectedStoragePoolsList,
    'disconnectStoragePool': disconnectStoragePool,
    'spmStop': spmStop,
}

def printOutput(output):
    try:
        parsedJson = json.loads(output.replace("'", '"'))
        printFormattedHTML(json.dumps(parsedJson, indent=4))
    except:
        printFormattedHTML(output)

def printFormattedHTML(str):
    print str.replace('\n', '<br/>').replace(
        '    ', ' ').replace('\t', ' ')

def main():
    # Get URL parameters
    form = cgi.FieldStorage()
    command = form.getfirst("command", "")

# Print HTML header
    print "Content-Type: text/html\n\n"
    if not command == 'runScript':
        print "<b>Output:</b><br/><br/>"

# Execute command
    output = executeCommand(command)
    printOutput(output)

try:
    main()
except:
    cgi.print_exception()

VdsClient API Script

/var/www/cgi-bin/ui-vdsm-hooks/scripts/vdsClientApi.py

#!/usr/bin/python

import cgi
import json
import os
import subprocess as sub

def executeVdsCommand(command='', args=[]):
    cmd = ['vdsClient', '0', command] + args
    return sub.Popen(cmd, stdout=sub.PIPE).stdout.read().rstrip('\n')

def getVdsClientAPI():
    output = executeVdsCommand()
    return output[output.find('Commands')+9:]

def getApiCmds(api):    
    lines = api.split('\n')
    cmds = []  
    cmd = ''

for line in lines:
        if not line.startswith('\t'):
            cmds.append(cmd)
            cmd = ''
        cmd += line + '\n'

cmds[0] = 'Select a command'

return cmds

def createForm(apiCmds, selectedIndex=0):
    scriptFile = os.path.dirname(__file__).replace(
        '/var/www', '') + '/vdsClientApi.py'
    print '<form action="' + scriptFile + '">
'
    createSelectBox(apiCmds, selectedIndex)
    createCmdDescription(apiCmds, selectedIndex)
    createTextArea(selectedIndex)
    print '</form>
'

def createSelectBox(apiCmds, selectedIndex):
    print '<select name="cmdDropDown"
           onchange="this.form.submit();">'
    for i in range(0, len(apiCmds)):
        label = apiCmds[i].split('\n')[0]
        selected = 'selected' if selectedIndex == i else ''
        print '<option value="' + str(i) + '" ' + selected + '>' +
            label + '</option>'
    print '</select>'
    print '<br/><br/>'

def createCmdDescription(apiCmds, selectedIndex):
    if selectedIndex == 0:
        return

printFormattedHTML(apiCmds[selectedIndex])
    print '<br/>'

def handleSelection(apiCmds, selectedIndex):
    print 'Content-Type: text/html\n\n'
    print '<br />'
    createForm(apiCmds, selectedIndex)

def handleExecute(apiCmds, selectedIndex, cmdArgs):
    cmd = apiCmds[selectedIndex].split('\n')[0]
    args = cmdArgs.split(' ') if cmdArgs else []
    output = executeVdsCommand(cmd, args)

print '<b>Output:</b><br />'
    
    try:
        parsedJson = json.loads(output.replace("'", '"'))
        printFormattedHTML(json.dumps(parsedJson, indent=4))
    except:
        printFormattedHTML(output)

def printFormattedHTML(str):
    escaped = cgi.escape(str)
    print escaped.replace('\n', '<br />').replace(
        '    ', ' ').replace('\t', ' ')

def getFormValue(key):
    form = cgi.FieldStorage()
    return form.getvalue(key)

def main():
    api = getVdsClientAPI()
    apiCmds = getApiCmds(api)

form = cgi.FieldStorage()
    selectedIndex = getFormValue('cmdDropDown')    
    cmdArgs = getFormValue('cmdArgs')
    cmdExecuteBtn = getFormValue('cmdExecuteBtn')
 
    if selectedIndex:
        handleSelection(apiCmds, int(selectedIndex))
    else:
        createForm(apiCmds)

if cmdExecuteBtn:
        handleExecute(apiCmds, int(selectedIndex), cmdArgs)

try:
    main()
except:
    cgi.print_exception()

Plugin's start HTML

/usr/share/ovirt-engine/ui-plugins/ui-vdsm-hooks-files/start.html

<!DOCTYPE html>
<html>
<head>
<script type='text/javascript'>
    var api = parent.pluginApi('UI-VDSM-Hooks-Plugin');
    var config = api.configObject();

api.register({
        UiInit : function() {
            addHostMainTabActionButton(
                'VdsClient API', 'runScript', 
                'vdsClientApi.py', "800px", "600px");
     addHostMainTabActionButton(
                'GetAllTasks', 'getAllTasks');
            addHostMainTabActionButton(
                'StopAllTasks', 'stopAllTasks');
            addHostMainTabActionButton(
                'ClearAllTasks', 'clearAllTasks');
            addHostMainTabActionButton(
                'GetStorageDomainsList', 'getStorageDomainsList');
            addHostMainTabActionButton(
                'GetConnectedStoragePool', 
                'getConnectedStoragePoolsList');
            addHostMainTabActionButton(
                'DisconnectStoragePool', 'disconnectStoragePool');
            addHostMainTabActionButton(
                'StopSPM', 'spmStop');
        }
    });
    api.ready();
 
    var addHostMainTabActionButton = 
      function(title, command, args, width, height) {
        api.addMainTabActionButton('Host', title, {
            onClick : function() {
                var url = getCgiUrl(arguments[0], command, args);
         var dialogToken = "hook-dialog";
         api.showDialog(
                    title, dialogToken, url, 
                    width || "500px", height || "400px",
                {
                    resizeEnabled: true,
                       }
         );
     },
     isEnabled : function() {
         return arguments.length == 1;
     },
     location: 'OnlyFromContext'   
 });
    }

// Get 'CGI' scripts URL using specified host address
    var getCgiUrl = function(selectedHost, command, args) {
        var hostAddress = selectedHost.hostname;
        var cgiUrl = 'http://' + hostAddress + config.cgiUrl + 
                     "?command=" + command + "&args=" + args;

return cgiUrl;
    }
</script>
</head>
<body>
</body>
</html>

Derez Blog

Sunday, June 9, 2013

oVirt UI-VDSM-Hooks Plugin