Google Cloud: Metrics Explorer: "Aggregator" vs "Aligner" - Whats the difference?

Question

Trying to understand the difference between the two: Aggregator vs Aligner. Docs was not helpful for me.

What I'm trying to achieve is to get the bytes of logs generated within a week per each namespace and container combination. For example, I want to see that container C in namespace N generated 10Gb of logs during the last 7 days.

This is how far I got:

Resource type = Kubernetes Container
Metric = Log bytes
Group by = namespace_name and container_name
Aggregator = sum(?) mean(?)
Minimum alignment period = 1(?) 7(?) days
Aligner = sum(?) mean(?)

Answer 1

I was confused with this until I realized that a single metric, such as kubernetes.io/container/cpu/core_usage_time is available in multiple different resources in my cluster.

So when you search for that metric, you'll get a whole lot of different resources that emit that metric. Aggregation is adding up all the data from those different resources WITH THAT SAME METRIC.

This all combines into one "time series" for that metric, an aggregation of all the individual time series from each of those different resources.

Now, alignment is the process of using that time series and putting all the data points through a function (over a period of time, known as the alignment period) which results in one single data point (per alignment period).

So aggregation combines the same metric across multiple resources, while alignment combines multiple data points in the same time series into one data point (per alignment period, which is why that field is required when using alignment).