Migrate Redmine issues to TFS (Azure DevOps) work items

CreateTFSItems.ps1

param(
    $user, # "TFS username - doesn't need @domain suffix"
    $token, # TFS personal access token
    $fileToImport, # path to the .json file
    $redmineIssueUrl # URL to legacy redmine server. eg. https://redmine/issues
)

# The following command gets the open issues through the Redmine API:
# For reference check: http://www.redmine.org/projects/redmine/wiki/Rest_Issues
# Sample call
# http://redmine/issues.json?offset=0&limit=100&sort=id

# Set these according to your instance:
$serverUrl = 'http://desktop-9a6epju'
$collectionName = 'DefaultCollection'
$projectName = 'MyProject'
$apiVersion = '4.1' #check: https://docs.microsoft.com/en-us/azure/devops/integrate/concepts/rest-api-versioning?view=azure-devops

$ErrorActionPreference = "Stop"

$base64AuthInfo = [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f $user,$token)))

$headers = @{Authorization=("Basic {0}" -f $base64AuthInfo)}

# Get users (if you need to map between usernames)
# $result=Invoke-RestMethod -Method GET -Uri "https://$($vstsAccountName).vsaex.visualstudio.com/_apis/userentitlements?api-version=5.0-preview.1" -Headers $headers
#
# $userMap = @{
# }
#
# $result.value | ForEach-Object {
#     $userMap.Add($_.user.displayName, $_.user.displayName)
# }

$priorityMap = @{
    'High' = '1'
    'Normal' = '2'
    'Low' = '3'
}


$jsonText = Get-Content $fileToImport -Encoding UTF8 | Out-String
$json = $jsonText | ConvertFrom-Json

$issues = $json.issues

foreach ($item in $issues) {
    switch ($item.tracker.name) {
        "Bug" { 
            $workItemType = "Bug"
            $descriptionField = "Microsoft.VSTS.TCM.ReproSteps"
        }
        "Enhancement" { 
            $workItemType = "Product Backlog Item" 
            $descriptionField = "System.Description"
        }
        "Feature" { 
            $workItemType = "Product Backlog Item" 
            $descriptionField = "System.Description"
        }
        "New request" {
            $workItemType = "Product Backlog Item" 
            $descriptionField = "System.Description"
        }
        Default {
            $workItemType = "Product Backlog Item" 
            $descriptionField = "System.Description"

            #Write-Warning "Skipping $($item.Tracker)"
            #continue;
        }
    }

    $itemsubject = $item.subject
    $subject = '{0} (#{1})' -f $itemSubject, $item.id
    $description = '{0}' -f $item.description -replace '\r\n', '<br>' -replace "\t", " - "
    $description = $description -replace '•', ''

    $bodyArray = @(
        @{
            op    = "add"
            path  = "/fields/System.Title"
            value = $subject
        }
        @{
            op    = "add"
            path  = "/fields/$descriptionField"
            value = $description
        }
        @{
            op    = "add"
            path  = "/relations/-"
            value = @{
                rel = "Hyperlink"
                url = "$($redmineIssueUrl)/$($item.id)"
                attributes = @{
                    comment = "Link to original ticket"
                }
            }
        }
        @{
            op    = "add"
            path  = "/fields/System.CreatedDate"
            value = $item.created_on
        }
        #@{        
        #    op    = "add"
        #    path  = "/fields/System.State"
        #    value = $item.status.name
        #}
    )

    if ($item.assigned_to.name -ne "") {
        $name = '{0}' -f $item.assigned_to.name
        $bodyArray += @{
            op    = "add"
            path  = "/fields/System.AssignedTo"
            value = $name
        }
    }
    
    $body = $bodyArray | ConvertTo-Json -Depth 3
    $uri = "$serverUrl/$collectionName/$projectName/_apis/wit/workitems/`$$($workItemType)?api-version=$apiVersion&bypassRules=true"
    $body = [System.Text.Encoding]::UTF8.GetBytes($body)

    Write-Host $uri
    #Write-Host $body

    $result = Invoke-RestMethod -Method POST -Uri $uri -Headers $headers -ContentType "application/json-patch+json" -Body $body

    Write-Host "Created item $($result.id) from legacy ticket $($item.ID)"
}

I've mode a more extended version of this script (it also migrated attachments, parent-child relations, etc) at https://github.com/wpoely86/redmine-azure-devops-migrate