Copy netapi32.dll from servercore image in nano-based Windows image (…

…#9006)

To fix the following failure:
```
panic: Failed to load netapi32.dll: The specified module could not be found.

goroutine 1 [running]:
syscall.(*LazyProc).mustFind(...)
	c:/go/src/syscall/dll_windows.go:320
syscall.(*LazyProc).Addr(...)
	c:/go/src/syscall/dll_windows.go:327
syscall.NetGetJoinInformation(0x0, 0xc00061fa48, 0xc00061fa44, 0x16, 0xc0000c96e0)
	c:/go/src/syscall/zsyscall_windows.go:1804 +0x107
os/user.isDomainJoined(0xc00061faa0, 0xf3624e, 0x0)
	c:/go/src/os/user/lookup_windows.go:18 +0x5a
os/user.lookupFullName(0xc000063b30, 0xc, 0xc000259bc0, 0x16, 0xc0000c96e0, 0x23, 0x16, 0xc0000c96e0, 0x23, 0x1)
	c:/go/src/os/user/lookup_windows.go:51 +0x2d
os/user.newUser(0xc000063ad0, 0xc, 0xc000063b10, 0xc, 0xc0000c9680, 0x1f, 0xc000259bc0, 0x16, 0xc000063b30, 0xc, ...)
	c:/go/src/os/user/lookup_windows.go:181 +0xd4
os/user.current(0x0, 0x0, 0x0)
	c:/go/src/os/user/lookup_windows.go:225 +0x2d8
os/user.Current.func1()
	c:/go/src/os/user/lookup.go:15 +0x29
sync.(*Once).doSlow(0x593ff00, 0x40b75b0)
	c:/go/src/sync/once.go:66 +0xf7
sync.(*Once).Do(...)
	c:/go/src/sync/once.go:57
os/user.Current(0xc0002599c0, 0x1b, 0x3f56005)
	c:/go/src/os/user/lookup.go:15 +0x105
github.com/golang/glog.init.1()
	C:/gomodcache/github.com/golang/[email protected]/gomodcache/github.com/golang/[email protected]/glog_file.go:63 +0x4b
```

This ugly hack is needed because the [bump of github.com/dgraph-io/ristretto from 0.0.3 to 0.1.0][1]
[introduced a new dependency to `glog`][2] which is triggering the following issue with
the Windows nano docker image: [3]

Once [3] is solved, this hack can be reverted.

[1] #8500
[2] dgraph-io/ristretto#263
[3] microsoft/Windows-Containers#72

.gitlab/image_build/docker_windows.yml

@@ -65,7 +65,7 @@
   needs: ["windows_msi_and_bosh_zip_x64-a7", "build_windows_container_entrypoint"]
   variables:
     AGENT_ZIP: "datadog-agent-7*-x86_64.zip"
-    BUILD_ARG: "--build-arg BASE_IMAGE=mcr.microsoft.com/powershell:nanoserver-${VARIANT} --build-arg WITH_JMX=${WITH_JMX} --build-arg VARIANT=${VARIANT}"
+    BUILD_ARG: "--build-arg BASE_IMAGE=mcr.microsoft.com/powershell:nanoserver-${VARIANT} --build-arg NETAPI32_IMAGE=mcr.microsoft.com/powershell:windowsservercore-${VARIANT} --build-arg WITH_JMX=${WITH_JMX} --build-arg VARIANT=${VARIANT}"
     TARGET_TAG: "${IMAGE}:v${CI_PIPELINE_ID}-${CI_COMMIT_SHORT_SHA}${TAG_SUFFIX}-win${VARIANT}-amd64"
 
 .docker_build_agent6_windows_common:
@@ -77,21 +77,21 @@
   needs: ["windows_msi_x64-a6", "build_windows_container_entrypoint"]
   variables:
     AGENT_ZIP: "datadog-agent-6*-x86_64.zip"
-    BUILD_ARG: "--build-arg BASE_IMAGE=mcr.microsoft.com/powershell:nanoserver-${VARIANT} --build-arg WITH_JMX=${WITH_JMX} --build-arg VARIANT=${VARIANT}"
+    BUILD_ARG: "--build-arg BASE_IMAGE=mcr.microsoft.com/powershell:nanoserver-${VARIANT} --build-arg NETAPI32_IMAGE=mcr.microsoft.com/powershell:windowsservercore-${VARIANT} --build-arg WITH_JMX=${WITH_JMX} --build-arg VARIANT=${VARIANT}"
     TARGET_TAG: "${IMAGE}:v${CI_PIPELINE_ID}-${CI_COMMIT_SHORT_SHA}${TAG_SUFFIX}-win${VARIANT}-amd64"
 
 .docker_build_agent6_windows_servercore_common:
   extends:
     - .docker_build_agent6_windows_common
   variables:
-    BUILD_ARG: "--build-arg BASE_IMAGE=mcr.microsoft.com/powershell:windowsservercore-${VARIANT} --build-arg WITH_JMX=${WITH_JMX} --build-arg VARIANT=${VARIANT}"
+    BUILD_ARG: "--build-arg BASE_IMAGE=mcr.microsoft.com/powershell:windowsservercore-${VARIANT} --build-arg NETAPI32_IMAGE=mcr.microsoft.com/powershell:windowsservercore-${VARIANT} --build-arg WITH_JMX=${WITH_JMX} --build-arg VARIANT=${VARIANT}"
     TARGET_TAG: "${IMAGE}:v${CI_PIPELINE_ID}-${CI_COMMIT_SHORT_SHA}${TAG_SUFFIX}-win${VARIANT}-servercore-amd64"
 
 .docker_build_agent7_windows_servercore_common:
   extends:
     - .docker_build_agent7_windows_common
   variables:
-    BUILD_ARG: "--build-arg BASE_IMAGE=mcr.microsoft.com/powershell:windowsservercore-${VARIANT} --build-arg WITH_JMX=${WITH_JMX} --build-arg VARIANT=${VARIANT}"
+    BUILD_ARG: "--build-arg BASE_IMAGE=mcr.microsoft.com/powershell:windowsservercore-${VARIANT} --build-arg NETAPI32_IMAGE=mcr.microsoft.com/powershell:windowsservercore-${VARIANT} --build-arg WITH_JMX=${WITH_JMX} --build-arg VARIANT=${VARIANT}"
     TARGET_TAG: "${IMAGE}:v${CI_PIPELINE_ID}-${CI_COMMIT_SHORT_SHA}${TAG_SUFFIX}-win${VARIANT}-servercore-amd64"
 
 include:

Dockerfiles/agent/windows/amd64/Dockerfile

@@ -1,5 +1,11 @@
 ARG BASE_IMAGE=mcr.microsoft.com/powershell:lts-windowsservercore-1809
-FROM ${BASE_IMAGE}
+ARG NETAPI32_IMAGE=mcr.microsoft.com/powershell:lts-windowsservercore-1809
+
+FROM ${NETAPI32_IMAGE} AS netapi32
+
+FROM ${BASE_IMAGE} AS final
+# This "copy netapi32.dll" hack can be reverted once https://github.com/microsoft/Windows-Containers/issues/72 is fixed.
+COPY --from=netapi32 /Windows/System32/netapi32.dll /netapi32.dll
 
 ARG WITH_JMX="false"
 ARG VARIANT="unknown"
@@ -10,6 +16,12 @@ USER ContainerAdministrator
 
 SHELL ["pwsh", "-Command", "$ErrorActionPreference = 'Stop';"]
 
+RUN if (-not (Test-Path /Windows/System32/netapi32.dll)) { \
+        Move-Item /netapi32.dll -Destination /Windows/System32/netapi32.dll \
+    } else { \
+        Remove-Item /netapi32.dll \
+    }
+
 COPY datadog-agent-latest.amd64.zip install.ps1 ./
 RUN . ./install.ps1