Attaching a debugger to Sitecore in Docker

Adding a few config options to that, I ended up with something like:

param(
    [Parameter(Mandatory)]
    [string]$containerName,
    [string]$role = "cm",
    [string]$port = "4024"
)

$container = "$($containerName)_$($role)_1"
$network = "$($containerName)_default"

$json = . docker inspect $container
$obj = $json | ConvertFrom-Json  

$ip = $obj.NetworkSettings.Networks.$network.IPAddress

$debugTarget = "$($ip):$($port)"
$debugTarget | Set-Clipboard
Write-Host "Debug target $($debugTarget) sent to clipboard..."

						

This assumes that you've kept the default name for Docker's network settings in your compose file – if you don't you'd need to change how the network name is worked out above. Then you can save that as "Get-DebugTarget.ps1" and you can pop up a PowerShell window, and run that against your container:

.\Get-DebugTarget.ps1 demo

						

and see:

And you can paste that straight into your Visual Studio "attach debugger" window:

And attach to your web process. Bingo...

Note: I found I had to type a space after pasting into that dialog in VS2019, because otherwise it doesn't seem to recognise that you typed the text, and defaults to closing the dialog when I hit enter. I guess they didn't expect you to just paste into that field...

Two: What if we didn't need to know the IP address? url copied!

Well, when you browse to your Sitecore website you're able to use localhost. That's because the default compose file maps the IIS port inside your container to a specific port on your default network outside the container:

  cm:
    image: ${REGISTRY}sitecore-xp-spe-standalone:${SITECORE_VERSION}-windowsservercore-${WINDOWSSERVERCORE_VERSION}
    entrypoint: powershell.exe -Command "& C:\\tools\\entrypoints\\iis\\Development.ps1 -WatchDirectoryParameters @{ Path = 'C:\\src'; Destination = 'C:\\inetpub\\wwwroot'; ExcludeFiles = @(); }"
    volumes:
      - ${LICENSE_PATH}:C:\license
      - .\data\cm:C:\inetpub\wwwroot\App_Data\logs
      - .\code:C:\src
      - C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\Common7\IDE\Remote Debugger:C:\remote_debugger:ro
    ports:
      - "44001:80"
    links:
      - sql
      - solr

						

If we add the debug port to that mapping, then we could attach the debugger to localhost too:

  cm:
    image: ${REGISTRY}sitecore-xp-spe-standalone:${SITECORE_VERSION}-windowsservercore-${WINDOWSSERVERCORE_VERSION}
    entrypoint: powershell.exe -Command "& C:\\tools\\entrypoints\\iis\\Development.ps1 -WatchDirectoryParameters @{ Path = 'C:\\src'; Destination = 'C:\\inetpub\\wwwroot'; ExcludeFiles = @(); }"
    volumes:
      - ${LICENSE_PATH}:C:\license
      - .\data\cm:C:\inetpub\wwwroot\App_Data\logs
      - .\code:C:\src
      - C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\Common7\IDE\Remote Debugger:C:\remote_debugger:ro
    ports:
      - "44001:80"
      - "4024:4024"
    links:
      - sql
      - solr

						

Run docker-compose down, save that change and then run docker-compose up again, and now we can attach to localhost:

I've stuck with the standard port of 4024 here – but you can use whatever port mapping you like.

I'll bet there are other ways – maybe better ones – but that's investigation for another day...

Edited to add: Yes, there are other ways! On Twitter Reto Hugi pointed me at this interesting post by Rob Ahnemann, which takes another approach: Using another container to dynamically rewrite your hosts file.