Azure DevOps yaml pipeline, downloaded artifact is empty - azure-devops

Question

Converting a pipeline from classic to YAML (so I know it works).
I build and my publish artifact task looks like this:
- task: PublishPipelineArtifact#1
displayName: 'Publish Pipeline Artifact'
inputs:
targetPath: '$(Build.ArtifactStagingDirectory)/MyArtifact'
artifact: MyArtifact
The result when build looks like this:
I then want to deploy this to a webapp
YAML:
- stage: Dev
jobs:
- job: DeployApp
displayName: Deploy Web App
pool:
name: myPrivate
demands: msbuild
steps:
- task: DownloadPipelineArtifact#2
inputs:
artifact: MyArtifact
- task: AzureRmWebAppDeployment#4
displayName: 'Deploy App'
inputs:
WebAppKind: 'Web App On Windows'
azureSubscription: 'edited out...'
WebAppName: webAppName
package: '$(System.ArtifactsDirectory)'
enableXmlTransform: true
Which results in this output in Azure DevOps:
A difference in chunks but since size match very exactly I'm happy.
I then get error on the deployment so I started look in Kudo and can see that in SitePackages all my packages are 1 kb (or empty...). I expected 61.2 MB.
I took my working classic deployment, and there i had this row:
packageForLinux:'$(System.DefaultWorkingDirectory)/_MyArtifact/MyArtifact/MyApplication.zip'
But that path wasn't even found. And packageForLinux felt wrong but doesn't matter as I understand it.
So can someone please me in the right direction how to deploy a web app (on windows) using YAML?

Answer 1

The folder that's used is $(Pipeline.Workspace), not $(System.DefaultWorkingDirectory), the default folder is different for each task type, so you can't always trust they extract to the default working directory.

Answer 2

I've wasted a lot of time deciphering these folder paths. I'm adding this info to help anyone else with this issue. Obviously my artifact was empty because my staging folder was empty.
After a few hours of digging I discovered that $(Build.SourcesDirectory) represents the root of where my dacpac files are built to
In my case I'm using the CopyFiles task as it supports wildcards. So whatever dacpac files are generated under the bin subfolder will be picked up and copied to the artifacts staging directory
# Build and publish the database solution
trigger:
- master
# this builds on a self hosted pool rather than the MS cloud agent
pool:
name: MySelfHostedPool
demands:
- MSBuild
- SqlPackage
steps:
- task: MSBuild#1
displayName: Build DB solution
inputs:
solution: MemberDB.sln
logFileVerbosity: diagnostic
# Copy build output to artifact staging directory so they can be published as artifacts in the next step
- task: CopyFiles#2
displayName: Copy dacpac to artifacts staging
inputs:
SourceFolder: '$(Build.SourcesDirectory)'
flattenFolders: true
Contents: '**\bin\**\*.dacpac'
TargetFolder: '$(Build.ArtifactStagingDirectory)'
- task: PublishPipelineArtifact#1
displayName: Publish dacpac
inputs:
artifactname: 'drop'
targetPath: $(Build.ArtifactStagingDirectory)