OpenFaaS - Functions call count

This project is intended to query how many times your functions where called in a period of time.

While we were monitoring the performance of our functions, some people requested reports on the number of requests we were handling, broken down by functions and by periods of time.

I tried to do it with Grafana, but it was not possible, maybe because of my inexperience. Then I found out that Prometheus allowed me to make direct queries to their API, and they answered exactly what I needed to know.

http://localhost:9090/api/v1/query_range?query=gateway_function_invocation_total&start=2018-07-30T00:00:00.000Z&&end=2018-07-31T00:00:00Z&step=1h

As they were occasional reports, I prepared a small online command program to perform the query and format the output.

Before you start quering

Install dependencies with npm i

If you call the program with no params it will show you some help.

$ node index.js
Usage: openfaas-function-call-count [options]

Options:

  -V, --version         output the version number
  -s --start <start>    Starting day
  -e --end <end>        End day
  -t --step <step>      Step
  -f --format <format>  Output format [table|json] (default: table)
  -h, --help            output usage information

Query

The step and format parameters are optional, but you must provide start and end values, both in YYYY-MM-DD format.

Example: bash $ node index.js -s '2018-07-30' -e '2018-07-31'

function-calls-count/200 sum=2 .---------------------------------------------.

	Day/Hour	Accum. Calls	Calls
1	2018-07-30 13:07	25
2	2018-07-30 14:07	27	2
'---------------------------------------------'

function-calls-count/500 sum=0 .---------------------------------------------.

	Day/Hour	Accum. Calls	Calls
1	2018-07-30 12:07	3
2	2018-07-30 13:07	3	0
3	2018-07-30 14:07	3	0
'---------------------------------------------'

Same than above, but in JSON format
```bash
$ node index.js -s '2018-07-30' -e '2018-07-31' -f json
[{"metric":{"__name__":"gateway_function_invocation_total","code":"200","function_name":"function-calls-count","instance":"10.0.0.6:8080","job":"gateway"},"values":[[1532970000,"25"],[1532973600,"27"]]},{"metric":{"__name__":"gateway_function_invocation_total","code":"500","function_name":"function-calls-count","instance":"10.0.0.6:8080","job":"gateway"},"values":[[1532966400,"3"],[1532970000,"3"],[1532973600,"3"]]}]

Output as ascii-table, grouped by 3 hour window

node index.js -s '2018-07-30' -e '2018-07-31' -t 3h

function1/200 sum=119
.---------------------------------------------.
|   |     Day/Hour     | Accum. Calls | Calls |
|---|------------------|--------------|-------|
| 1 | 2018-07-30 00:07 | 4534         |       |
| 2 | 2018-07-30 03:07 | 4534         |     0 |
| 3 | 2018-07-30 06:07 | 4534         |     0 |
| 4 | 2018-07-30 09:07 | 4580         |    46 |
| 5 | 2018-07-30 12:07 | 4653         |    73 |
'---------------------------------------------'

function2/200 sum=409
.---------------------------------------------.
|   |     Day/Hour     | Accum. Calls | Calls |
|---|------------------|--------------|-------|
| 1 | 2018-07-30 00:07 | 2000         |       |
| 2 | 2018-07-30 03:07 | 2000         |     0 |
| 3 | 2018-07-30 06:07 | 2001         |     1 |
| 4 | 2018-07-30 09:07 | 2140         |   139 |
| 5 | 2018-07-30 12:07 | 2409         |   269 |
'---------------------------------------------'

function1/500 sum=0
.---------------------------------------------.
|   |     Day/Hour     | Accum. Calls | Calls |
|---|------------------|--------------|-------|
| 1 | 2018-07-30 00:07 | 1            |       |
| 2 | 2018-07-30 03:07 | 1            |     0 |
| 3 | 2018-07-30 06:07 | 1            |     0 |
| 4 | 2018-07-30 09:07 | 1            |     0 |
| 5 | 2018-07-30 12:07 | 1            |     0 |
'---------------------------------------------'