Skip to content
Open Source Blog

In our last post, Daniel Semedo and I provided an overview of how to add automated performance quality gates using a performance specification file, as defined in the open source project Keptn Pitometer.

In this post, I’ll explain the steps required to add a performance quality gate to your Azure DevOps pipelines for both DevOps “Multi-Stage” and “Classic” pipelines using Keptn Pitometer.

Step 1: Setup Keptn Pitometer

As a quick refresher, Keptn Pitometer is not an application – it’s a set of open source Node.js modules used to create your own Pitometer client. Pitometer provides the processing of a performance specification (PerfSpec). This PerfSpec file defines the metrics, evaluation thresholds, and scoring objectives that constitute the resulting pass, warning or fail status calculated by Pitometer.

The quickest way to try Pitometer is to use the Pitometer webservice. In Azure, this is as simple as starting up an Azure container instance that uses the Pitometer webservice Docker image. This way any pipeline can add a quality gate by just calling webservice with their PerfSpec file. Follow these instructions to create a new container instance through the Azure portal or Azure CLI.

After the container instance is running, go to the overview page (shown below) and copy the IP address. Use this IP within the Pitometer webservice URL: http://<Your IP>:8080/api/pitometer.

overview page image

Step 2: Create your PerfSpec file

The PerfSpec file is tailored to your quality objectives and application. You’ll need to specify the indicator metrics to capture, and the scoring for the “Pitometer” service to evaluate. See example PerfSpec file here.

Once you have your own PerfSpec file, check it into your Azure DevOps or GitHub repository. This allows you to manage artifacts the same way and keep them in-sync with code changes.

Step 3: Create a script to call Pitometer

A PowerShell script is an easy way to call and parse results from the Pitometer webservice. The example below expects the following parameters and will first read the “PerfSpec” file contents and construct the request to the Pitometer webservice.

  1. Start and stop times in UTC milliseconds for gathering metrics
  2. Pitometer webservice URL
  3. PerfSpec file location within the pipeline working directory

After the Pitometer webservice is called, the script will parse the response and pull out the status attribute. The status attribute will have a value of “pass,” “warning,” “fail,” or “error.”   If there is a failure or an “error,” the script will return “exit 1” thus stopping the pipeline.

# input variables 
$START_TIME=$env:startTime
$END_TIME=$env:endTime
$PITOMETER_WEBSERVICE_URL=$env:pitometerUrl
Set-Variable -Name "PERFSPEC_FILE" -Value "$(System.DefaultWorkingDirectory)/_Demo-App-Build/app/perfspec/perfspec.json"

# read perfspec file contents and compose the Pitometer service POST body content 
Set-Variable -Name "PERFSPEC_DIR" -Value "$($PERFSPEC_FILE)" 
$PERFSPEC_CONTENT = Get-Content -Path $PERFSPEC_DIR 
$PERFSPEC_REQUEST_BODY="{""timeStart"": $START_TIME,""timeEnd"": $END_TIME,""perfSpec"": $($PERFSPEC_CONTENT)}" 
 
# some debug output
Write-Host "==============================================================="
Write-Host "startTime: "$START_TIME
Write-Host "endTime: "$END_TIME
Write-Host "url: "$PITOMETER_WEBSERVICE_URL
Write-Host "request body: "$PERFSPEC_REQUEST_BODY
Write-Host "==============================================================="

# calling Pitometer Service 
$PERFSPEC_RESULT_BODY = Invoke-RestMethod -Uri $PITOMETER_WEBSERVICE_URL -Method Post -Body $PERFSPEC_REQUEST_BODY -ContentType "application/json"  

# more debug output
Write-Host "response body: "$PERFSPEC_RESULT_BODY
Write-Host "==============================================================="
 
# save the Pitometer service response and pull out the result status 
$PERFSPEC_JSON = $PERFSPEC_RESULT_BODY | ConvertTo-Json -Depth 5 
$PERFSPEC_RESULT = $PERFSPEC_RESULT_BODY.result 
 
# evaluate the result and pass or fail the pipeline 
if ("$PERFSPEC_RESULT" -eq "fail" -Or "$PERFSPEC_RESULT" -eq "error") { 
    Write-Host "Failed the quality gate"  
    exit 1 
} else { 
    Write-Host "Passed the quality gate"  
} 

Here is how to setup up the PowerShell script inputs.

  • The timeframe is set within two environment variables called “$env.startTime” and “$env.endTime”. One can set these variables before and after the performance task using PowerShell script such as this:
$startTime = Get-Date ((get-date).toUniversalTime()) -UFormat +%s 
Write-Host ("##vso[task.setvariable variable=startTime]$startTime")
  • The Pitometer URL is set within an environment variable called $env.pitometerURL. Set the pipeline variables as shown below:

Description of pipeline variables

Step 4: Add a performance quality gate task in your pipeline that calls Pitometer

Below is a representative build and release pipeline that includes typical tasks along with the addition of performance quality gate task described in step 6.

representative build and release pipeline

  1. PerfSpec file is checked into your source code repository.
  2. Task within the Build stage adds the PerfSpec as a built artifact.
  3. Code is deployed to the application under test.
  4. Performance test runs and monitoring metrics are collected.
  5. Deployment event is pushed to a monitoring tool to provide build context.
  6. Pitometer service is called with the PerfSpec file content. Result will be pass, warn, or fail. A fail will stop the pipeline.

Azure DevOps offers both “Classic” pipelines and the new “Multi-Stage” pipelines.

What are “Classic” Build pipelines?

Azure “Classic” has two distinct pipeline types; build and release. Build pipelines can be created using a visual editor or through YAML declarative files, as opposed to release pipelines, which can only be created visually.

A Build pipeline is meant to build, unit test, and publish a reusable build artifact. Since we checked in our “PerfSpec” file with our code, we can include it in the build artifact and reference it through the Release pipeline.

The example Build pipeline, named ”Demo-App-Build,” will make an artifact named “app” that includes the whole repo, including the PerfSpec sub-folder, which contains the perfspec.json file. The ZIP artifact will be saved with the pipeline release.

example Build pipeline

What are “Classic” Release pipelines?

A Release pipeline takes input artifacts and uses their files for task scripts such as deploying code. Tasks are grouped into stages. Below is an example release pipeline named ”Demo-App-Deploy” with two stages named “Staging” and “Production.”

A Release pipeline

Below are the tasks within the ”Staging” stage. The last one is the PowerShell “Quality gate call to Pitometer” task, which determines if the pipeline stops or continues to the “Production” stage.

Tasks within the ”Staging’ stage.

The “Quality gate call to Pitometer” task simply contains the PowerShell script we reviewed earlier as an in-line script (shown below). Recall that the script will ”exit 1” and stop the pipeline when the “PerfSpec” fails.

“Multi-Stage” pipelines

Azure DevOps “Multi-Stage” pipelines allow all the build and release tasks to be defined in a YAML file. To enable this preview feature, open the menu found within your Azure DevOps account profile as shown below.

We need to capture the test start and stop times, run a performance test so that monitoring metrics are collected, and run the quality gate step. Similar to Classic pipelines, PowerShell tasks can be run as either in-line scripts or script files.

Below is a YAML pipeline code snippet for PowerShell tasks calling scripts files.

- task: PowerShell@2 
displayName: 'Capture Load Test Start Time' 
failOnStderr: true 
inputs: 
    targetType: filePath 
    filePath: $(System.DefaultWorkingDirectory)/extract/pipeline/captureStartTime.ps1 
 
- task: Bash@3 
displayName: 'Load Test' 
inputs: 
    targetType: filePath 
    filePath: $(System.DefaultWorkingDirectory)/extract/pipeline/loadtest.sh 
    arguments: 'Staging $(azure-resource-prefix)-ubp-demo-app-staging.azurewebsites.net $(loadtest-duration-seconds)' 
 
- task: PowerShell@2 
displayName: 'Capture Load Test End Time' 
failOnStderr: true 
inputs: 
    targetType: filePath 
    filePath: $(System.DefaultWorkingDirectory)/extract/pipeline/captureEndTime.ps1 

- task: PowerShell@2 
displayName: 'Quality Gate call to Pitometer' 
inputs: 
    targetType: filePath 
    failOnStderr: true 
    filePath: $(System.DefaultWorkingDirectory)/extract/pipeline/qualitygate.ps1 
    arguments: '$(startTime) $(endTime) $(pitometer-url) /home/vsts/work/1/s/extract/$(perfspecFilePath)' 
 

Step 5: Run your pipeline

Both “Classic” and “Multi-stage” pipelines show a visualization as the pipeline runs and the logs from each task can be reviewed. Below is how the visualization looks for Multi-stage” pipelines and examples for the failed quality gate.

Passing quality gate in “Multi-stage” Pipeline.
Passing quality gate in “Multi-stage” Pipeline.
Failing quality gate in “Multi-stage” Pipeline.
Failing quality gate in “Multi-stage” Pipeline.
Task details from failing quality gate task
Task details from failing quality gate task

Recap

As with most things within software, there are often several ways to achieve a given goal. I hope these five steps will provide a starting point for implementing automated performance quality gates using Keptn Pitometer within Azure DevOps pipelines.

Questions or feedback? Let me know in the comments below.