changed the way sccache is started

containers/agent-windows-jenkins/Dockerfile

@@ -23,4 +23,4 @@ VOLUME C:\Temp
 
 # start swarm plugin
 COPY start_agent.ps1 c:\jenkins
-ENTRYPOINT ["C:\\BuildTools\\Common7\\Tools\\VsDevCmd.bat", "-arch=amd64", "-host_arch=amd64", "&&", "powershell.exe", "-NoLogo", "-ExecutionPolicy", "Bypass", "C:\\jenkins\\start_agent.ps1"]
+CMD ["C:\\jenkins\\start_agent.ps1"]

containers/agent-windows-jenkins/start_agent.ps1

@@ -25,9 +25,24 @@ Copy-Item "C:\credentials\.boto" "C:\Users\ContainerAdministrator\.boto"
 $env:TEMP="${$AGENT_ROOT}\TEMP"
 $env:TMP="${env:TEMP}"
 
+# set local cache folder for sccache
+$env:SCCACHE_DIR="C:\ws\sccache"
+# Start sccache server and keep it running to avoid problems with Jenkins
+# https://github.com/mozilla/sccache/blob/master/docs/Jenkins.md
+$env:SCCACHE_IDLE_TIMEOUT="0"
+
+# wipe cache at startup, otherwise it will time out
+Remove-Item -Recurse -Force $env:SCCACHE_DIR
+sccache --start-server
+if ($lastexitcode -ne 0) {
+    Write-Error "Failed to start sccache server."
+    exit $lastexitcode
+}
+
+# start Jenkins agent
 java -jar ${env:SWARM_PLUGIN_JAR} `
     -master http://${JENKINS_SERVER}:8080 `
     -executors 1 `
     -fsroot ${AGENT_ROOT} `
-    -labels "windows vs2019" `
+    -labels "windows vs2019 cores_${env:NUMBER_OF_PROCESSORS}" `
     -name ${env:PARENT_HOSTNAME} 

containers/agent-windows-vs2019/Dockerfile

@@ -38,8 +38,6 @@ RUN choco install -y cmake --version 3.15.4
 RUN choco install -y python3
 RUN choco install -y gnuwin
 RUN choco install -y sccache
-# set local cache folder for sccache
-ENV SCCACHE_DIR=C:\ws\sccache
 RUN pip install psutil
 
 # install python dependencies for the scripts