Add BaremetalHost annotation-based fencing

This commit adds one more way of fencing a compute node,
using baremetal apis (metal3).

It works by adding a reboot annotation, see:
https://book.metal3.io/bmo/reboot_annotation.html

{"annotations":{"reboot.metal3.io/iha":"{\"mode\": \"hard\"}"}}

After the evacuation is completed this annotation is removed and
the compute host powered back on.

fencing.yaml should contain something like:

  FencingConfig:
    edpm-compute-1:
      agent: bmh
      token: <long-token>
      host: edpm-compute-1

The token is obtained with something like the following:

kubectl create serviceaccount k8sadmin -n kube-system
kubectl create clusterrolebinding k8sadmin --clusterrole=cluster-admin --serviceaccount=kube-system:k8sadmin
kubectl -n kube-system describe secret $(sudo kubectl -n kube-system get secret | (grep k8sadmin || echo "$_") | awk '{print $1}') | grep token: | awk '{print $2}'

Customers should create a serviceaccount that has enough rights to
perform operations on the baremetalhost resources instead of using
a cluster-admin.

templates/instanceha/bin/instanceha.py

@@ -498,6 +498,21 @@ def _redfish_reset(url, user, passwd, timeout, action):
     r = requests.post(url, data=json.dumps(payload), headers=headers, auth=(user, passwd), verify=False, timeout=timeout)
     return r
 
+def _bmh_fence(token, host, action):
+
+    url = "https://kubernetes.default.svc/apis/metal3.io/v1alpha1/namespaces/openstack/baremetalhosts/%s?fieldManager=kubectl-patch" % host
+    headers={'Authorization': 'Bearer '+token, 'Content-Type': 'application/merge-patch+json'}
+    cacert = '/var/run/secrets/kubernetes.io/serviceaccount/ca.crt'
+
+    if action == 'off':
+        ann={"metadata":{"annotations":{"reboot.metal3.io/iha":"{\"mode\": \"hard\"}"}}}
+        r = requests.patch(url, headers=headers, verify=cacert, data=json.dumps(ann))
+        return r
+
+    else:
+        ann={"metadata":{"annotations":{"reboot.metal3.io/iha":None}}}
+        r = requests.patch(url, headers=headers, verify=cacert, data=json.dumps(ann))
+        return r
 
 def _host_fence(host, action):
     logging.info('Fencing host %s %s' % (host, action))
@@ -589,6 +604,26 @@ def _host_fence(host, action):
                 logging.warning('Could not power on %s' % host)
                 #return True
 
+    elif 'bmh' in fencing_data["agent"]:
+
+        token = str(fencing_data["token"])
+        host = str(fencing_data["host"])
+
+        if action == 'off':
+            r = _bmh_fence(token, host, "off")
+            if r.status_code == 200:
+                logging.info('Power off of %s ok' % host)
+                return True
+            else:
+                logging.error('Could not power off %s' % host)
+                return False
+        else:
+            r = _bmh_fence(token, host, "on")
+            if r.status_code == 200:
+                logging.info('Power on of %s ok' % host)
+            else:
+                logging.warning('Could not power on %s' % host)
+
     else:
         logging.error('No valid fencing method detected for %s' % host)
         return False