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- python 2.7.x<\/li>\n<\/ul>\n
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- boto 2.36.0<\/li>\n<\/ul>\n
In the following steps we will configure a custom metric to monitor the active sessions of a particular user using an RDS instance and create an alarm for this custom metric to terminate EC2 instance when it reaches the threshold of zero.<\/span><\/strong><\/p>\n
Creating a custom metric<\/b><\/p>\n
The following code snippet can either be run on python interactive console or the whole code can be copied and run using it as a python script.<\/p>\n
from boto.ec2.cloudwatch import connect_to_region\r\n\r\nimport MySQLdb\r\n\r\nimport boto.ec2.cloudwatch\r\n\r\ndb=MySQLdb.connect(\"ravit.rdshostname.ap-northeast-1.rds.amazonaws.com\",\"username\",\"password\",\"databasename\")\r\n\r\ncursor=db.cursor()\r\n\r\nn=cursor.execute(\"select * from GetActiveSessions\")\r\n\r\nn1=cursor.fetchone()\r\n\r\ns=str(n1)\r\n\r\ntable=string.maketrans( '', '', )\r\n\r\nnumber=s.translate(table,\"(){}<>,L\")\r\n\r\nnumbers=int(number)\r\n\r\nreg='ap-northeast-1'\r\n\r\nconn_cw=boto.ec2.cloudwatch.connect_to_region(reg,aws_access_key_id=\u2019your_access_key\u2019,aws_secret_access_key=\u2019your_secret_key\u2019)\t\t\r\n\r\nconn_cw.put_metric_data(namespace='my_namespace',name='my_metric',value=numbers,dimensions={'InstanceId':'i-a1b2c3d4'})\r\n<\/pre>\n<\/p>\n
The following code gets the active number of users in RDS running MySQL and updates the custom metric based on that value. This script can be run as a cron job to get dynamic values where for every one minute the value of the custom metric is updated.<\/span><\/p>\n
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\n Parameter<\/b><\/td>\n Input parameter type<\/b><\/td>\n Description<\/b><\/td>\n<\/tr>\n \n namespace<\/td>\n string<\/td>\n The namespace of the alarm to tag.<\/td>\n<\/tr>\n \n name<\/td>\n list or string<\/td>\n The list of names to add the alarms or a string name to add a single alarm name.<\/td>\n<\/tr>\n \n value<\/td>\n int, float or list<\/td>\n The list or a single int value to add to the alarm.<\/td>\n<\/tr>\n \n dimensions<\/td>\n dictionary<\/td>\n The name-value pairs to associate with the metric.The dimensions can either be InstanceId key-value pairs or InstanceName key-value-pair.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n <\/p>\n
Note:<\/b>\u00a0For values like \u00a0CPUUtilization, AWS\/EC2 cannot be used in the namespace and name field because they are pre-defined values and cannot be overridden. These values can be accessed by using the function:<\/p>\n
metrics=boto.ec2.cloudwatch.CloudWatchConnection(aws_access_key_id=\u2019your_access_key\u2019,aws_secret_access_key=\u2019your_secret_key\u2019).list_metrics()\r\n\r\nfor metric in metrics:\r\n\tprint metric.name +\u201d\\t\u201d+ metric.namespace\r\n<\/pre>\n
The above code prints a list of metric name and metric namespace values which cannot be used in the custom metric function.<\/p>\n
How to check whether the custom metric was created:<\/b>
\nStep 1. Navigate to CloudWatch in the \u00a0AWS Management Console. A new dropdown menu called ‘custom metrics’<\/strong> appears. Click on it.<\/p>\n![\"custom_metrics_1\"](\"https:\/\/content.cloudthat.com\/resources\/wp-content\/uploads\/2022\/11\/custom_metrics_1.png\")
<\/a><\/p>\nStep 2. Click on the drop down menu, the newly created metric\u2019s namespace \u2018my_namespace<\/strong>\u2019 is displayed, click on it.<\/p>\n
![\"custom_metrics_3\"](\"https:\/\/content.cloudthat.com\/resources\/wp-content\/uploads\/2022\/11\/custom_metrics_3.png\")
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- boto 2.36.0<\/li>\n<\/ul>\n