Results Output

Overview

By default, k6 will print runtime information and general results to stdout while the test is running, and a summary after the test has ended.

Runtime output to stdout

By default, k6 sends its output to stdout only. When started up, it will display a very tasteful ASCII splash screen with the k6 logo and version information, plus details about the test and options active. We will go through the things one by one here:

• execution: local k6 is not being used to control another k6 instance (distributed execution).
• output: - Output is sent to stdout only.
• script: group.js (js) Shows what script we are running. The (js) at the end indicates that k6 thinks this file contains JavaScript code (that should be executed by the VUs).
• duration: 0s, iterations: 1 The VUs in the test will only perform one single script iteration (calling the default function once) each, and there is no time limit set.
• vus: 1, max: 1 Simulate 1 VU (virtual user), allocate resources for a "max" of 1 VU (meaning we can't scale up the load level in this case).
• done [==============] 800ms / 800ms This is the progress bar that updates while the test is running, to indicate how far the test has come and how much time has passed.
• █ my user scenario is the name of a group we have created in our JS script.
• █ front page is the name of a sub-group that was created inside the previously mentioned group ("my user scenario").
• ✓ 100.00% - status code is 200 is the result from a check() that was executed inside the "front page" group. Note how this check result is indented, to indicate that it belongs to the "front page" group. The "front page" group name, in turn, is indented to indicate it belongs to its parent group ("my user scenario").
• █ features page is another group that belongs to the parent group "my user scenario".
• ✓ 100.00% - status code is 200 and ✓ 100.00% - h1 message is correct are two more checks that belong to the "features page" group.
• checks................: 100.00% tells us the percentage of our checks that passed.

And then comes the HTTP timing information. There are several metrics being reported here, and percentiles etc. for each of them:

• http_req_blocked The time VUs spent waiting to be allocated a TCP connection from the connection pool.
• http_req_connecting The time VUs spent performing TCP handshakes (setting up TCP connections to the remote host).
• http_req_looking_up The time spent performing DNS lookups.
• http_req_sending The time spent transmitting HTTP requests to the remote host.
• http_req_waiting The time spent waiting for a response to come back from the remote host (after having sent a request).
• http_req_receiving The time spent receiving a reply from the remote host.
• http_req_duration Total time for the request. It's equal to http_req_sending + http_req_waiting + http_req_receiving (i.e. how long did the remote server take to process the request and respond, without the initial DNS lookup/connection times).

All of these are metrics of the Trend type, which means you can extract max, min, percentile, average values from them. On stdout they are printed like this:

http_req_duration.....: avg=46.32ms, max=46.32ms, med=46.32ms, min=46.32ms, p90=46.32ms, p95=46.32ms

After the HTTP timing metrics, there will be a few final lines of output:

• http_reqs........: 2 The total number of HTTP requests made during the whole load test.
• iterations........: 1 The total number of times all VUs in the test managed to run through the default() function.
• vus.................: 1 How many VUs the test was configured to simulate.
• vus_max........: 1 The number of pre-allocated VU slots the test was configured for (vus_max allows you to scale up the number of VUs in the test to max that number).

Output result data

k6 may also output more granular result data using special output plugins. Currently, there are a few plugins that can output data:

• JSON plugin that writes data in JSON format to a file

• Plugins that push the metrics to:

  • Apache Kafka
  • Datadog
  • InfluxDB
  • StatsD
• Cloud plugin that streams your test results to the k6 Cloud platform

To know more about the metrics k6 collects, please see the Metrics management page

Multiple outputs

You can simultaneously send the emitted metrics to several outputs by using the CLI --out flag multiple times, for example:

$ k6 run --out json=test.json --out influxdb=http://localhost:8086/k6

Summary export

New in v0.26.0

It's also possible to export the end-of-test summary report to a JSON file that includes data for all test metrics, checks and thresholds. This is useful to get the aggregated test results in a machine-readable format, for integration with dashboards, external alerts, etc.

Example

Running k6 run --summary-export=export.json github.com/loadimpact/k6/samples/stages.js would generate the following file:

{
  "metrics": {
    "checks": {
      "fails": 0,
      "passes": 434,
      "value": 0
    },
    "data_received": {
      "count": 4267088,
      "rate": 213353.42114517145
    },
    "data_sent": {
      "count": 33726,
      "rate": 1686.2922633754104
    },
    "http_req_blocked": {
      "avg": 2.2303510806451645,
      "max": 466.009823,
      "med": 0.006873000000000001,
      "min": 0.001265,
      "p(90)": 0.0093969,
      "p(95)": 0.01104339999999999
    },
    "http_req_connecting": {
      "avg": 1.4719108986175116,
      "max": 176.017402,
      "med": 0,
      "min": 0,
      "p(90)": 0,
      "p(95)": 0
    },
    "http_req_duration": {
      "avg": 146.13434929493093,
      "max": 663.812323,
      "med": 115.237707,
      "min": 104.336176,
      "p(90)": 204.6849077,
      "p(95)": 205.27533795
    },
    "http_req_receiving": {
      "avg": 0.32699811981566856,
      "max": 5.86652,
      "med": 0.135682,
      "min": 0.026588,
      "p(90)": 1.4118543,
      "p(95)": 1.6629313999999984
    },
    "http_req_sending": {
      "avg": 0.031275672811059876,
      "max": 0.149365,
      "med": 0.028853,
      "min": 0.006069,
      "p(90)": 0.041769099999999997,
      "p(95)": 0.05106769999999998
    },
    "http_req_tls_handshaking": {
      "avg": 0,
      "max": 0,
      "med": 0,
      "min": 0,
      "p(90)": 0,
      "p(95)": 0
    },
    "http_req_waiting": {
      "avg": 145.77607550230408,
      "max": 663.551133,
      "med": 114.90324000000001,
      "min": 103.389659,
      "p(90)": 204.4926965,
      "p(95)": 205.02902265
    },
    "http_reqs": {
      "count": 434,
      "rate": 21.699900441941768
    },
    "iteration_duration": {
      "avg": 148.59040099078345,
      "max": 671.970894,
      "med": 115.69334950000001,
      "min": 104.558313,
      "p(90)": 205.0391277,
      "p(95)": 209.87447475000002
    },
    "iterations": {
      "count": 434,
      "rate": 21.699900441941768
    },
    "vus": {
      "max": 5,
      "min": 1,
      "value": 1
    },
    "vus_max": {
      "max": 5,
      "min": 5,
      "value": 5
    }
  },
  "root_group": {
    "name": "",
    "path": "",
    "id": "d41d8cd98f00b204e9800998ecf8427e",
    "groups": {},
    "checks": {
      "status is 200": {
        "name": "status is 200",
        "path": "::status is 200",
        "id": "6210a8cd14cd70477eba5c5e4cb3fb5f",
        "passes": 435,
        "fails": 0
      }
    }
  }
}