While recently updating my Automating Active Directory Domain Join in ESX(i) Kickstart article, it reminded me an old blog post by Justin Guidroz who initially identified a way to add an ESXi host to vCenter using python and the vSphere MOB. The approach was very neat but was not 100% automated as it required some user interaction with the vSphere MOB to identify certain API properties before one could potentially script it within a kickstart installation.

I decided to revisit this problem as it was something I had investigated awhile back. There are numerous ways on getting something like this to work in your environment, but it all boils down to your constraints, naming convention and provisioning process. If you have a well defined environment and utilizing a good naming structure and can easily identify which vCenter a given ESX(i) host should be managed from, then this can easily be integrated into your existing kickstart with minor tweaks. This script was tested on vCenter 4.1 Update 1 and ESXi 4.1 and 4.1 Update1.

UPDATE (03/29/2011): Updated the IP Address extraction to use gethostbyname and added proper logout logic after joining vCenter.

UPDATE (02/01/2013): I have provided a download link to the joinvCenter.py script below as there have been some funky formatting issues when displaying the script. For ESXi 5.x hosts, you will need to ensure httpClient is enabled (disabled by default) on the ESXi firewall else it will not be able to connect to your vCenter Server. Please refer below for the instructions.

There are a few steps that are necessary before we get started and a recommended one for those that have security concerns around this solution.

Step 1 - You will need to extract some information from the vCenter server in which you would like your ESX(i) hosts to join. You will need to generate an inventory path to the vCenter cluster which will take the form of: [datacenter-name]/host/[cluster-name], this will automatically locate the managed object ID of your vCenter cluster which is required as part of the host add process. This was a manual process in Justin's original solution.

In this example, I have a datacenter called "Primp-Skunkworks" and a cluster under that datacenter called "Primp-Skunkworks-Cluster", the inventory path will look like the following:  


You will need this value to populate a variable in the script which will be described a little bit later

Step 2 - As you may have guessed, to add an ESX(i) host to vCenter, you will need to connect to vCenter server and use an account that has the permission to add a host. It is recommended that you do not use or expose any administrative accounts for this as the credentials are stored within the script unencrypted. A work around is to create a service account whether that is a local account or an Active Directory account with only the permission to add an ESX(i) host to a vCenter cluster. You will create a new role, in this example I call it "JoinvCenter" and you just need to provide the Host->Inventory->Add host to cluster privilege.

Once you have created the role, you will need to assign this role to the service account user either globally in vCenter if you want to add to multiple cluster or a given datacenter/cluster.

Now that we have the pre-requisites satisfied, we will need to populate a few variables within the script which will be used in your %post section of ESX(i) kickstart configuration file.

This variable defines the name of your vCenter server, please provide the FQDN:

This variable define the vCenter cluster path which was generated earlier:

These variables define the server account credentials used to add an ESX(i) host to vCenter. You will need to run the following command to encode the selected password. You will need access to a system with python interpreter to run the following command:

python -c "import base64; 
print base64.b64encode('MySuperDuperSecretPasswordYo')"

Note: This does not encrypt your password but obfuscate it slightly so that you are not storing the password in plain text. If a user has access to the encoded hash, it is trivial to decode it.

These variables define the ESX(i) root credentials which is required as part of the vCenter add process. If you do not want to store these in plain text, you will also need to encode them using the command in previous section:

We are now all done and ready to move forward with the actual script which will be included in your kickstart configuration. As a sanity check, you can run this script manually on an existing ESX(i) host to ensure that the process works before testing in kickstart. For ESXi 5.x hosts, ensure httpClient firewall ruleset is enabled by following ESXCLI command:

esxcli network firewall ruleset set -e true -r httpClient

 You should also ensure this is the very last script to execute as I ran into a race condition while the root password was being updated automatically from the default 999.* scripts. To ensure this is the very last script, set the --level to something like 9999 in your %firstboot stanza

Download: joinvCenter.py

To aide in troubleshooting, the script also outputs the details to syslog and on ESX(i), it will be stored in /var/log/messages and you can just search for the string "GHETTO-JOIN-VC". If everything is successful, after %firstboot section has completed, you should be able to see an ESX(i) host join vCenter and the following in the logs.

Tips: You should only see "Success" messages, if you see any "Failed" messages, something went wrong. If you are still running into issues, make sure your ESX(i) host has it's hostname configured with FQDN and you should see an error on your vCenter server if it fails to whether it's due to hostname and/or credentials. You can also redirect the output of the script to local VMFS volume for post-troubleshooting.

Depending on your provision process and how you determine which ESX(i) host should join which vCenter/cluster, you can easily add logic in the main kickstart configuration file to automatically determine or extract from a configuration file and dynamically update joinvCenter.py script prior to execution.

I would like to thank Justin Guidroz and VMTN user klich for their contributions on the python snippets that were used in the script. 

FYI - I am sure the python code could be cleaner but I will leave that as an exercise for those more adept to python. My python-fu is not very strong 😉

54 thoughts on “How to automatically add ESX(i) host to vCenter in Kickstart

  1. Funny that you post this today. Over the weekend I did some automation around PXE installation with kickstart and was thinking that connecting to VC was the one missing piece.

    I really like the idea of a bare bones user account. Instead of the somewhat hacky python script I was thinking about using ‘wget’ to for example download ruby and rbvmomi to do this ‘the proper way’.
    Alternatively I was thinking of just posting an event on a RabbitMQ server using a small python script where the ESX announces its IP. A proper (and more powerful) rbvmomi script could then pick the rest up from there.

  2. @Christian,

    You may be able to get ruby/rbvmomi running on classic ESX, but with ESXi, it probably won’t work in the Busybox Console. At a minimum you’ll probably need a statically linked ruby binary to encapsulate all it’s dependencies.

    The latter solution is probably the best option and it’s actually one that VMware uses with it’s Auto Deploy appliance which does exactly that after pre-provision. It does “call back” to Auto Deploy and from there the system uses the APIs to join it to specific vCenter & apply a host profile. ESXi has netcat starting with 4.1 which you can build a dumb client to periodically call back to a server and then perform advanced operations using any SDK available whether that is VI Java, Perl, PowerCLI, etc. on any platform (Windows/Linux)

    The possibilities are pretty much endless

  3. One thing I’ve found is that you can use urllib2.HTTPCookieProcessor() in your opener to handle cookies instead of having to capture it after the first page and pass it with each subsequent request.

    opener = urllib2.build_opener(authhandler,urllib2.HTTPCookieProcessor())

  4. Hi there, got this configured and running on ESXi 4.1.0 build 348481.

    All looks good, logs success etc but never appears in the vcenter console. Any ideas?
    Thanks Ed

  5. @Rucking,

    Can you manually run the script from the ESXi host and see if you get any errors? While debugging this, I’ve seen that though the successful message is thrown, it may have had an error in processing the request. Also, did you see any failed tasks in your vCenter server about this host trying to join?

  6. Yep, running it manually logs success with no errors. Not seeing any events in VCenter at all, was expecting to but see nothing. Checked the cluster variable, vcenter variables, authentication etc etc by changing them to be deliberately wrong, changing any of these causes an error. So my ‘good’ config is definately good. It’s obviously jumping out somewhere but it’s doing it silently, any more points for debug?

  7. Found the errors – The tags on this line are case sensitive in our environment so hostname /hostName don’t match, same with sslThumbprint. Sorting/matching these cases fixed the issues. Not sure why our environment is case sensitive and yours isn’t but there you go. Cheers

    # Code to create ConnectHostSpecxml = ‘%hostname%sha%user%pass1’

  8. Hello William,

    Amazing post! I’m trying to run this script manually from an ESXi 4.1u1 host to test it out and make sure it’s working before putting it into a kickstart script. I keep getting “Failed to retrieve MOB data” error message from the error log. When I go to the MOB listed from a browser https://VCENTER/mob/?moid=SearchIndex&method=findByInventoryPath and use the AD account created and assigned the permissions from above I can access the URL just fine. I’m not sure where to go from here.

    I’ve worked with your Active Directory connection script and that one works swimmingly.



  9. @Jim

    When you encoded your password, do you see any weird characters? It’s possible you may have characters that may need to be escaped using “\”. On easy way to validate this is instead of using double-quotes, try single quotes around the vc_encodedpassword

  10. @William

    that worked 🙂 I’m able to get the script to run through with out an error now. The only issue now is it doesn’t actually join vCenter. I get a silent failure. I see the AD account I created log into the vCenter server and then log out but the ESXi host never joins my cluster. I’ve verified the Cluster name is correct as DataCentername/host/Clustername. Do you have anymore advice? Thanks again

  11. @Jim,

    Check that the account has the correct permission and that you can manually add the ESXi host to the particular cluster. Since this credentials related, it’s outside of the script.

  12. @William,

    Thanks for the advice yet again! There are no issues with adding the ESXi host to the cluster under the AD account I specfied. I logged into the vSphere Client with the account in question and added the ESXi host directly into the cluster. It added with out any issues.

  13. Hey guys, i am in the middle of my Bachelor-Thesis and i write about die virtualization. By that, i want to show some automaziation. So i scriptet a little bit with pxe-boot, webserver, … and finally realized the installation of an esxi-host.

    install url
    rootpw VMware208
    clearpart –overwritevmfs –firstdisk=local
    autopart –firstdisk=local –overwritevmfs

    #network –bootproto=dhcp –device=vmnic6
    network –bootproto=static –device=vmnic6 –ip= –gateway= –netmask= –hostname=esx208 –nameserver=”,″
    keyboard German

    So now I want the add the host to my Vcenter. So i edit my script like this:

    install url
    rootpw VMware208
    clearpart –overwritevmfs –firstdisk=local
    autopart –firstdisk=local –overwritevmfs

    #network –bootproto=dhcp –device=vmnic6
    network –bootproto=static –device=vmnic6 –ip= –gateway= –netmask= –hostname=esx208 –nameserver=”,″
    keyboard German

    %firstboot –unsupported –interpreter=busybox

    #enable TechSupportModes
    vim-cmd hostsvc/enable_remote_tsm
    vim-cmd hostsvc/start_remote_tsm
    vim-cmd hostsvc/enable_local_tsm
    vim-cmd hostsvc/start_local_tsm
    vim-cmd hostsvc/net/refresh

    #Add Host to Vcenter

    import re,os,urllib,urllib2
    url = “”
    username = “administrator”
    password = “administratorpassword”
    passman = urllib2.HTTPPasswordMgrWithDefaultRealm()
    authhandler = urllib2.HTTPBasicAuthHandler(passman)
    opener = urllib2.build_opener(authhandler)
    cmd = “openssl x509 -sha1 -in /etc/vmware/ssl/rui.crt -noout -fingerprint”
    tmp = os.popen(cmd)
    #tmp_sha1 = tmp.readline()
    s1 = re.split(‘=’,tmp_sha1)
    s2 = s1[1]
    s3 = re.split(‘\n’, s2)
    sha1 = s3[0]

    xml = ‘’
    xml = xml.replace(sha1)

    params = {‘spec’:xml,’asConnected’:’1′,’resourcePool’:”,’license’:”}
    e_params = urllib.urlencode(params)
    req = urllib2.Request(url,e_params)
    page = urllib2.urlopen(req).read()


    I have to say, that for this test i did disable the ssl function.

    The Installation runs but the password is now default and not VMware208 and the Server is also not in my Vcenter.
    What went wrong??? There were no errors!

    Could you please help me?

  14. Great site! I am having issues running this script. Its failing with the error:

    Failed to find cluster “ESX 4 – Devlab/Host/Test-Cluster-01”!

    If i browse to the MOB FindByInventoryPath screen I can search for the datacenter “ESX 4 – Devlab” and I get a result, but if I add /Host or /Host/Test-Cluster-01 it does not return a result.

    If I use the direct access method in Justin’s script I can browse to the unique ID as well (https://devvcenter02/mob/?moid=domain%2dc11994).

  15. Great write up, I’m hitting an issue where I get the following returned.

    Method Invocation: InvalidRequest

    There are no errors with the script it logs in and gets the correct moid etc. I’ve tried doing it manually through the website as well but get the same response. Do you have any ideas or tips on where the underlying issue may be? I’ve modified the role as well.


  16. @chris,

    Hm, it almost sounds like a permission issue if you can’t perform the operation using the MOB. Are you able to join the host to the very same cluster using the vSphere Client connecting to vCenter?

  17. Awesome script Wiliam!
    Unfortunately I’m getting “AttributeError” and hope you can guide me in the right direction. BTW, in our production vCenter there are couples of folders between Datacenter and Cluster. Will that be a problem?

    /tmp # python /tmp/joinvCenter.py
    Traceback (most recent call last):
    File “/tmp/joinvCenter.py”, line 61, in
    nonce = reg.search(page_content).group(1)
    AttributeError: ‘NoneType’ object has no attribute ‘group’

  18. @chris,@Nasir

    If you have folders, between your Datacenter + Clusters, then you just need to properly append those.

    Here is one example and what the path string would look like:

    Datacenter: Primp-Skunkworks
    Folder: Primp-Folder
    Cluster: Skunkworks-Cluster

    Inventory Path:

    Notice, the “Folders” name still goes after the “host” key.

    I would recommend using the vSphere MOB – http://www.virtuallyghetto.com/2010/07/whats-new-in-vsphere-41-mob.html to help you find the inventory path

  19. I had the same issue with matching case in the xml. All lowercase in the opening tag wouldn’t work. Changing the opening tag to match the closing tag did. I had to change these three tags to match:

    I also figured out how to add the host at the root level rather than in a cluster by changing these three lines:

    clusterMoRef = re.search(‘domain-c[0-9]*’,page)
    url = “https://” + vcenter_server + “/mob/?moid=” + clusterMoRef.group() + “&method=addHost”
    params = {‘vmware-session-nonce’:nonce,’spec’:xml,’asConnected’:’1′,’resourcePool’:”,’license’:”}

    To these:

    clusterMoRef = re.search(‘group-h[0-9]*’,page)
    url = “https://” + vcenter_server + “/mob/?moid=” + clusterMoRef.group() + “&method=addStandaloneHost”
    params = {‘vmware-session-nonce’:nonce,’spec’:xml,’compResSpec’:”,’addConnected’:’1′,’license’:”}

    And then changing the ‘cluster=’ variable like so:

    cluster = “Primp-Skunkworks/host”

    Hope it helps save others some time!


  20. Lol, the xml tags show up invisible in my post…let’s try again:


  21. Having the exact same problem as Nasir.
    I am using ESXi 4.1.0 build 348481
    Any progress on the solution?

    /tmp # python joinvCenter.py
    Traceback (most recent call last):
    File “joinvCenter.py”, line 62, in
    nonce = reg.search(page_content).group(1)
    AttributeError: ‘NoneType’ object has no attribute ‘group’

  22. I am trying to setup an automated install of ESXi hosts using the kickstart script and the jointovCenter python script from here.

    Everything works great and ESXi auto-installs with the kickstart script and then after %firstboot it runs this script, or if i run it manually with # python joinvCenter.py from the service console. In the logs it lists out all of the syslog messages generated from the script saying it successfully joined vCenter but it does not actually join and I see no signs of life from vCenter or in the vCenter logs. vCenter does not appear to do anything, like sending out the agent etc.

    Does anyone know why it would not be joining the host to the vCenter cluster? I am at a dead end here since all of the logs show success when running the script.

  23. William/Others:

    Related to this part of the text above:
    These variables define the ESX(i) root credentials which is required as part of the vCenter add process.

    Does it really absolutely HAVE to be the root account?
    Can I create another local account with certain privledges and just use that?

  24. hi!

    does this script also works with vsphere5?
    i got the syslog message:

    2012-05-03T08:42:55Z python: GHETTO-JOIN-VC Succesfully joined vCenter!
    2012-05-03T08:42:55Z python: GHETTO-JOIN-VC Logging off vCenter

    but the host doesn’t appear in vcenter.
    any suggestions? thanks for help!

    • @Mike,

      I had some free time and took a look at this. There were a few things that would cause some issues which hopefully is now all resolved:

      1) There were some odd formatting issues on the blog, I’ve uploaded the script to vGhetto Repository so you can just download it (link above)

      2) Starting with ESXi 5.x, you need to enable httpClient ruleset on the ESXi Firewall, this is what most folks have ran into from what I can tell. Once the rule is enabled, it’ll be able to connect to your vCenter Server.

      Go ahead and give it another try

  25. getting error:

    :not founder.py: line 151:

    ?what’s the meaning? line 151 is empty per default



  26. I am trying to run this directly on a host prior to moving it into the the kickstart. The host is ESXi 5 update 1. I am seeing the same error posted by jimpeluso (MOB DATA). I verifed that I’m able to get the MOB data outside the script without issue and changed the quotes to single ticks for the password to eliminate any special charaters.. Is there anything else I can be missing here?



    • @Mike44,

      I had some free time and took a look at this. There were a few things that would cause some issues which hopefully is now all resolved:

      1) There were some odd formatting issues on the blog, I’ve uploaded the script to vGhetto Repository so you can just download it (link above)

      2) Starting with ESXi 5.x, you need to enable httpClient ruleset on the ESXi Firewall, this is what most folks have ran into from what I can tell. Once the rule is enabled, it’ll be able to connect to your vCenter Server.

      Go ahead and give it another try

    • I too am trying to run this in a test environment the script is running through fine and the logs say everything has completed sucessfully, but I still dont get any hosts added to my cluster, I dont see any jobs in the vCenter client when the script is running. Any ideas as what is going wrong and where to look for pointers?

    • Thanks William, I tried disabling the firewall, but still didnt manage to complete sucessfully. However I did change the VC user account to a Windows Domain Admin and it did work correctly. It looks like some has gone wrong with the JoinVC user account I was using.

      Thanks for the help though.

  27. Hi William,

    I’m having the same error like the others (“Failed to retrieve MOB data”). The host is not added to the vCenter Server.
    I’ve used credentials with the correct permissions, an easy password without special chars, and http client is allowed.

    The version is 5.0 U2 (HP, build 914586)
    Any other idea?


    • FYI: The problem were indeed the permissions. The user I used had the correct permissions through a userGROUP, but not assigned to the user itself.
      When using a user which has the permissions assigned only to the user and not to a usergroup, everything works fine.

    • Well the script itself works fine.
      I’ve put it in the %firstboot stanza, but it seems that it doesn’t get executed.
      As the –level option is no longer supported in vSphere 5, I don’t see any other option to ensure it is really the last script.

      Everything in the Kickstart works, except for this part.
      In the logs I see: Failed to retrieve MOB data
      When executing the script manually, it works…
      Any idea why?

  28. I am trying to add this script to my kickstart process and am not having much luck. I am having similar issues to Rucking and Christoph but my tags all seem to be in the proper case for the xml argument. When I check the log everything states that is worked successfully but I don’t see the host add in vcenter. I see the user account connect to vcenter for a second and then it disconnets but nothing even shows up in the tasks. If I change any parameters I can see that it fails in the log and if I use the MOB web interface I can add the host with no problems. Any thoughts?

  29. I am getting this error message:

    Traceback (most recent call last):
    File “/tmp/joinvcenter.py”, line 102, in
    hostip = socket.gethostbyname(socket.gethostname())
    socket.gaierror: [Errno -2] Name or service not known

  30. Unlike many, I have the script working as coded to add host to cluster. I’m having issues with Loren’s 3 line change to add the host at the root level. All logs indicate success but host is never joined. If I change the modified 3 lines back to the original script I can add host to cluster. Anyone else able to add standalone host to the root level of the datacenter?

  31. Great script. But what if I don’t want to add it to a cluster? I just want it added to the DC root.

    • Ok I have experimented a little bit with this.

      It will work if you simple give it as cluster name “YourDatacenterName/host” with no cluster name beyond that

      But you will have to change the code to look for “group-h”, not “domain-c”

      Then you need to change the method used to call Vcenter from “addHost” to “addStandaloneHost”

      Last but not least, the parameter “asConnected” does not exist in that function; you have to use “addConnected” instead.

      In fact you can quite easily find this info by going to
      using your browser.

      Then input your DC name and navigate from there.

      Tested and working on ESXi 5.5U2 with latest VCSA.

  32. Hai …. I use to execute this code in my nested esxi ….. I had enabled httpclient ruleset … After that while I executing the code I got an error that
    …… Warning; can’t open config file : /usr/SSL/openssl.conf ……..,. So what should I do. To proceed the execution ……

      • You are running this on the host, right? /usr/SSL/openssl.conf seems like a very strange path to me. Not sure where it gets it from. But I guess it’s a warning that can also be ignored. This script should work with ESXi 5.5, not sure about nested though. But why not if networking is configured correctly (can reach vcenter).

  33. Any update to this script for vSphere 6.0? The log from the script shows that host was added to vCenter but it hasn’t. From vCenter I do see a successful login then immediate log off from python with no task for adding the host. I double checked that vCenter can resolve the hosts DNS name.

Thanks for the comment!