Jq is a lightweight and flexible command-line JSON processor. This means that it allows us to filter, map and edit json data from the command line.
Installing
First, we need to install jq via the installer available at https://stedolan.github.io/jq/.
Purpose
When running k6 tests through the command:
k6 run --out json=results.json script.js
A report in json format is generated. As the tests run, results are generated that we can only read from inside the file. There are thousands of them, which makes them difficult to read. In our tests, we use the rule that a tag is set for each request. An example request could look like the following.
const statusData = http.get("https://k6.io", {
tags: { myTag: "staticStatusContent" }
});
With the above tagged, we will be able to distinguish the results in the .json file based on the tag set. There is ample room for automation here, as we can also filter the results based on the group to which the requests belong. We, however, will focus on the tags themselves for now.
Let’s move on to the commands we will use. Let’s add that in each of the examples we care about getting the times of the requests. In case we want to get other data, we will use, for example, http_req_connecting or http_req_failed. For more on the metrics we can use, see https://k6.io/docs/using-k6/metrics/.
Checking all the tags used
jq '. | select(.type=="Point" and .metric == "http_req_duration" and .data.tags.myTag) | .data.tags.myTag' FILE_NAME
Checking the times of requests with the indicated tag
jq '. | select(.type=="Point" and .metric == "http_req_duration" and .data.tags.myTag == "TAG_NAME") | .data.value' FILE_NAME
The result is returned in milliseconds.
The average time of requests with the given tag
jq '. | select(.type=="Point" and .metric == "http_req_duration" and .data.tags.myTag == "TAG_NAME") | .data.value' FILE_NAME | jq -s 'add/length'
Minimum request time with the given tag
jq '. | select(.type=="Point" and .metric == "http_req_duration" and .data.tags.myTag == "TAG_NAME") | .data.value' FILE_NAME | jq -s min
Maximum request time with the given tag
jq '. | select(.type=="Point" and .metric == "http_req_duration" and .data.tags.myTag == "TAG_NAME") | .data.value' FILE_NAME | jq -s max
All of the above data can be automated. We use a bash script for this, the code for which is below.
#!/bin/bash
echo -e "Usage: \`$ bash getMetrics.sh resultsFile.json\`"
echo -e "Checking the results in the $1 file\n"
fileName=$1
# results checking all http_req_duration tags
tagsInFile=`jq '. | select(.type=="Point" and .metric == "http_req_duration" and .data.tags.myTag) | .data.tags.myTag' $fileName`
# clearing tags of quotation marks
clearedTags="${tagsInFile//\"}"
# create an array based on the newline character
IFS=$'\n' tags=($clearedTags)
for tag in "${tags[@]}"; do
# checking all data for each tag
data="jq '. | select(.type==\"Point\" and .metric == \"http_req_duration\" and .data.tags.myTag == \"$tag\") | .data.value' $fileName"
# specific data
avg=$(eval "$data | jq -s 'add/length'";)
min=$(eval "$data | jq -s min";)
max=$(eval "$data | jq -s max";)
# outputting data in the console
echo "tag...: $tag"
echo -e "data..: avg: ${avg}ms; min: ${min}ms; max: ${max}ms; avg: ${avg}ms;" "\n"
done
echo "Done!"
Sample Usage
We run the created script (named getMetrics.sh) with the code above as follows.
$ bash getMetrics.sh resultsFile.json
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