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Example: vCenter Tagging Function

Pre-reqs:

  • OpenFaaS running on a local or remote Kubernetes cluster (e.g. kind)
  • An installation of vCenter (tested against 6.5) or the vCenter simulator vcsim
  • A vCenter user/service account with sufficient rights to perform the (tagging) action of the example function
  • docker to run tools like govc if not installed on your machine already
  • git to clone the function example
  • faas-cli to deploy the function
  • kubectl to deploy the connector

Note: Make sure that your OpenFaaS environment can reach vCenter as the tagging function performs API calls against vCenter.

How it works:

Functions can subscribe to events in vCenter through the "topic" annotations applied through your stack.yml file. Based on these events a function can take action, e.g. tag a VM, run post-processing scripts, audit to an external system, etc.

For example, a VmPoweredOnEvent from vCenter would have a function annotation vm.powered.on.

Get started with the vCenter Tagging Function example

In the following example we will subscribe to the VmPoweredOnEvent by adding an annotation to our function of vm.powered.on. The function will then add a specific tag to any VM when it is powered on.

Note: In a DRS-enabled cluster the annotation would be drs.vm.powered.on.

  1. Create a category/tag to be attached to a VM when it is powered on. Since we need the unique tag ID (i.e. vSphere URN) we will use govc for this job. You can also use vSphere APIs (REST/SOAP) to retrieve the URN.
# Run pre-built govc Docker image if you don't have govc already installed on your machine
docker run --rm -it embano1/govc:0ee42d3 sh

# Test connection to vCenter, ignore TLS warnings
export GOVC_INSECURE=true
export GOVC_URL='https://vcuser:[email protected]' 
./govc tags.ls

# If the connection is successful create a demo category/tag to be used by the function
./govc tags.category.create democat1
urn:...
./govc tags.create -c democat1 demotag1
urn:vmomi:InventoryServiceTag:019c0a9e-0672-48f5-ac2a-e394669e2916:GLOBAL
  1. Take a note of the urn:... for demotag1 as we will need it for the next steps
  2. In a separate terminal download the example function
git clone https://github.com/embano1/pytagfn
cd pytagfn
  1. Configure the Python tagging function stack.yaml.
environment:
    # FQDN/IP<:PORT>, must be reachable/resolvable from OpenFaaS. If port is != 443 please specify (e.g. "vcsim.openfaas:8989")
    VC: vcenter.ip                      
    VC_USERNAME: VCUSER                  # WIP: migration to secrets
    VC_PASSWORD: VCPASSWORD              # WIP: migration to secrets
    
    # Replace TAG_URN example below with the one you created with govc above
    TAG_URN: urn:vmomi:InventoryServiceTag:019c0a9e-0672-48f5-ac2a-e394669e2916:GLOBAL 
    TAG_ACTION: attach                   # alternatively, this Python function also supports detach
    
    # Enable debugging in case something goes wrong
    write_debug: true
    read_debug: true

annotations:
    topic: vm.powered.on
  1. Deploy the function
faas-cli template pull
faas-cli deploy
Deploying: pytag-fn.

Deployed. 202 Accepted.
URL: http://127.0.0.1:8080/function/pytag-fn
  1. Download and deploy the OpenFaaS vCenter Connector

Note: The deployment assumes you have basic authentication configured for OpenFaaS on Kubernetes as per this guide. Thus, the deployment requires a secret gateway-basic-auth to be available (volumes section in the YAML).

If you don't use authentication for the gateway, edit yaml/kubernetes/connector-dep.yml as per instructions in the file.

git clone https://github.com/openfaas-incubator/vcenter-connector
cd vcenter-connector

# In yaml/kubernetes/connector-dep.yml modify the container args "-vcenter" (incl. protocol, i.e. "https://"), "-vc-user" and "-vc-pass" accordingly. If vCenter port != 443, please specify (e.g. "https://vcsim.openfaas:8989").

# Deploy the connector to Kubernetes
kubectl -n openfaas create -f yaml/kubernetes/connector-dep.yml

# Check the logs of the pod whether it connected successfully to vCenter and OpenFaaS
kubectl -n openfaas logs deploy/vcenter-connector -f

Note: If you are not running your vCenter connector in the same cluster as OpenFaaS also edit the -gateway flag in the connector deployment manifest accordingly (default: http://gateway.openfaas:8080, i.e. OpenFaaS in a Kubernetes namespace openfaas).

  1. Generate a "Power On" event

In the next step we will power on a VM to trigger an event in vCenter ("VM powered on..."). This event will be received by the connector and forwarded to the OpenFaaS function(s) subscribed to the corresponding event type (vm.powered.on). The function will then add the tag we created above (demotag1) to the VM.

# Note: This can be done in vCenter UI or via govc
# Pick a VM that is powered off and does not have already "demotag1", then in the running govc container power on the VM
./govc vm.power -on /Datacenter-North/vm/Nested-Pod/vesxi67-2

# Verify that the tag was correctly attached
./govc tags.attached.ls demotag1
VirtualMachine:vm-267

Troubleshooting

If your VM did not get the tag attached, verify:

  • vCenter IP/username/password
  • Permissions of the vCenter user
  • Whether the components can talk to each other (connector to vCenter and OpenFaaS, function to vCenter)
  • Check the logs:
kubectl -n openfaas logs deploy/vcenter-connector -f

# Successful log message in the OpenFaaS vCenter connector
2019/01/25 23:39:09 Message on topic: vm.powered.on
2019/01/25 23:39:09 Invoke function: pytag-fn
2019/01/25 23:39:10 Response [200] from pytag-fn
kubectl -n openfaas-fn logs deploy/pytag-fn -f

# Successful log message in the OpenFaaS tagging function
2019/01/25 23:48:55 Forking fprocess.
2019/01/25 23:48:55 Query
2019/01/25 23:48:55 Path  /

{"status": "200", "message": "successfully attached tag on VM: vm-267"}
2019/01/25 23:48:56 Duration: 1.551482 seconds