Add count param, minor refactoring and update docs

Author: davideschiera

examples/list_hosts.py

@@ -1,69 +1,93 @@
 #!/usr/bin/env python
 #
-## This script shows how to leverage sysdig's data query API to obtain the list
-# of the instrumented hosts that have been seen in the last hour (`duration` variable).
-# The output will show the container count (`container.count` metric) in addition to the hostnames (`host.hostName` tag) in a from like this:
+# This script shows how to leverage Sysdig data query API to obtain the list of the instrumented
+# hosts that have been seen in your infrastructure.
+# The output will show the container count (`container.count` metric) in addition to the
+# hostnames (`host.hostName` tag) in a format like this:
 #
 # host-1    12
 # host-2     4
 #
-# host-1    12
-# host-2     4
-#his: host.name 12
-# Where 12 is the container count and host.name is the host
+# where the first column is the hostname and the second column is the number of containers running
+# in each host.
 #
 import getopt
 import json
 import os
 import sys
 sys.path.insert(0, os.path.join(os.path.dirname(os.path.realpath(sys.argv[0])), '..'))
 from sdcclient import SdcClient
+
 #
 # Parse arguments
 #
 def usage():
-    print 'usage: %s [-j|--json] [-d|--duration <secs>] <sysdig-token>' % sys.argv[0]
-    print '-d|--duration: List hosts seen in the last <secs> seconds'
+    print 'usage: %s [-j|--json] [-d|--duration <secs>] [-c|--count <number>] <sysdig-token>' % sys.argv[0]
+    print '-d|--duration: List hosts seen in the last <secs> seconds (default: 3600, ie. last hour)'
+    print '-c|--count: Number of hosts to print (default: 100)'
     print '-j|--json: Print output as json'
     print 'You can find your token at https://app.sysdigcloud.com/#/settings/user'
     sys.exit(1)
 try:
-    opts, args = getopt.getopt(sys.argv[1:],"jd:",["json", "duration="])
+    opts, args = getopt.getopt(sys.argv[1:],"jd:c:",["json", "duration=", "count="])
 except getopt.GetoptError:
     usage()
+
 duration = 3600
+count = 100
 print_json = False
 for opt, arg in opts:
+    print opt
+    print arg
     if opt in ("-d", "--duration"):
         duration = int(arg)
+    elif opt in ("-c", "--count"):
+        count = int(arg)
     elif opt in ("-j", "--json"):
         print_json = True
 sdc_token = args[0]
-#
+
+# Instantiate the SDC client
+sdclient = SdcClient(sdc_token)
+
 #
 # Prepare the query's metrics list.
-# In this case, we have one tag (used for segmentation) and one metric::
-# host.hostName. This is a tag, to identify each item of the output.
-# container.count: This is the metric
+# In this case, we have one tag (used for segmentation) and one metric:
+# - host.hostName. This is a tag, to identify each item of the output
+# - container.count: This is the metric
 #
-# Instantiate the SDC client
-sdclient = SdcClient(sdc_token)
-metrics = [{"id": "host.hostName"}, {"id": "container.count","aggregations":{"time":"avg","group":"avg"}}]
+metrics = [
+    { "id": "host.hostName" },
+    { "id": "container.count", "aggregations": { "time": "avg", "group": "avg" } }
+]
+
 res = sdclient.get_data(
-    metrics, -duration, 0, duration, paging={
+    metrics,  # list of metrics
+    -duration,  # start time: either a unix timestamp, or a difference from "now"
+    0,  # end time: either a unix timestamp, or a difference from "now" (0 means you need "last X seconds")
+    duration,  # sampling time, ie. data granularity;
+               # if equal to the time window span then the result will contain a single sample
+    paging = {
         "from": 0,
-        "to": 999
+        "to": count - 1
     })
+
 if res[0]:
-    output = []
-    data = res[1]['data']
-    for i in range(0, len(data)):
-        sample = data[i]
-        metrics = sample['d']
-        hostName = metrics[0]
-        count = metrics[1]
-        output.append('%s\t%d' % (hostName, count))
-    print '\n'.join(output)
+    # data fetched successfully
+    if print_json:
+        print json.dumps(res[1])
+    else:
+        data = res[1]['data']
+        output = []
+        for i in range(0, len(data)):
+            sample = data[i]
+            metrics = sample['d']
+            hostName = metrics[0]
+            count = metrics[1]
+            output.append('%s\t%d' % (hostName, count))
+
+        print '\n'.join(output)
 else:
+    # data fetch failed
     print res[1]
     sys.exit(1)