Cloudwatch Flashcards
What is the product called that allows you to query CW?
Cloudwatch Metrics Insights
What is the Namespace component for CW?
A namespace is a container for CloudWatch metrics. Metrics in different namespaces are isolated from each other, so that metrics from different applications are not mistakenly aggregated into the same statistics.
There is no default namespace. You must specify a namespace for each data point you publish to CloudWatch. You can specify a namespace name when you create a metric. These names must contain valid XML characters, and be fewer than 256 characters in length. Possible characters are: alphanumeric characters (0-9A-Za-z), period (.), hyphen (-), underscore (_), forward slash (/), hash (#), and colon (:).
The AWS namespaces typically use the following naming convention: AWS/service. For example, Amazon EC2 uses the AWS/EC2 namespace. For the list of AWS namespaces
What are Metrics in CW?
Metrics are the fundamental concept in CloudWatch. A metric represents a time-ordered set of data points that are published to CloudWatch. Think of a metric as a variable to monitor, and the data points as representing the values of that variable over time. For example, the CPU usage of a particular EC2 instance is one metric provided by Amazon EC2. The data points themselves can come from any application or business activity from which you collect data.
Metrics are uniquely defined by a name, a namespace, and zero or more dimensions. Each data point in a metric has a time stamp, and (optionally) a unit of measure. You can retrieve statistics from CloudWatch for any metric.
What are the limitations of Metrics in CW?
Metrics exist only in the Region in which they are created. Metrics cannot be deleted, but they automatically expire after 15 months if no new data is published to them. Data points older than 15 months expire on a rolling basis; as new data points come in, data older than 15 months is dropped.
What is the metric data retention?
Metrics retention
CloudWatch retains metric data as follows:
Data points with a period of less than 60 seconds are available for 3 hours. These data points are high-resolution custom metrics. Data points with a period of 60 seconds (1 minute) are available for 15 days Data points with a period of 300 seconds (5 minute) are available for 63 days Data points with a period of 3600 seconds (1 hour) are available for 455 days (15 months)
Data points that are initially published with a shorter period are aggregated together for long-term storage. For example, if you collect data using a period of 1 minute, the data remains available for 15 days with 1-minute resolution. After 15 days this data is still available, but is aggregated and is retrievable only with a resolution of 5 minutes. After 63 days, the data is further aggregated and is available with a resolution of 1 hour.
What are Dimensions in Metrics?
A dimension is a name/value pair that is part of the identity of a metric. You can assign up to 10 dimensions to a metric.
Every metric has specific characteristics that describe it, and you can think of dimensions as categories for those characteristics. Dimensions help you design a structure for your statistics plan. Because dimensions are part of the unique identifier for a metric, whenever you add a unique name/value pair to one of your metrics, you are creating a new variation of that metric.
AWS services that send data to CloudWatch attach dimensions to each metric. You can use dimensions to filter the results that CloudWatch returns. For example, you can get statistics for a specific EC2 instance by specifying the InstanceId dimension when you search for metrics.
For metrics produced by certain AWS services, such as Amazon EC2, CloudWatch can aggregate data across dimensions. For example, if you search for metrics in the AWS/EC2 namespace but do not specify any dimensions, CloudWatch aggregates all data for the specified metric to create the statistic that you requested. CloudWatch does not aggregate across dimensions for your custom metrics.
How are Dimensions used?
If you publish only those four metrics, you can retrieve statistics for these combinations of dimensions:
Server=Prod,Domain=Frankfurt Server=Prod,Domain=Rio Server=Beta,Domain=Frankfurt Server=Beta,Domain=Rio
What would it look like if you posted a custom metric?
aws cloudwatch put-metric-data –metric-name PageViewCount –namespace MyService –value 2 –timestamp 2016-10-20T12:00:00.000Z
What can the CW Agent do?
Collect internal system-level metrics from Amazon EC2 instances across operating systems. The metrics can include in-guest metrics, in addition to the metrics for EC2 instances. The additional metrics that can be collected are listed in Metrics collected by the CloudWatch agent.
Collect system-level metrics from on-premises servers. These can include servers in a hybrid environment as well as servers not managed by AWS.
Retrieve custom metrics from your applications or services using the StatsD and collectd protocols. StatsD is supported on both Linux servers and servers running Windows Server. collectd is supported only on Linux servers.
Collect logs from Amazon EC2 instances and on-premises servers, running either Linux or Windows Server.
What is StatsD and collectd?
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What is the CW Agent Config File?
Before running the CloudWatch agent on any servers, you must create a CloudWatch agent configuration file.
The agent configuration file is a JSON file that specifies the metrics and logs that the agent is to collect, including custom metrics. You can create it by using the wizard or by creating it yourself from scratch.
