Update agent ARM32/64 images to use Alpine (#6264)

Our amd64 .NET-based Docker images have always used Alpine. I _think_ our arm64 .NET images may have been Alpine to start but moved to Ubuntu to work around some temporary issue. And our arm32 images were always Ubuntu-based because .NET Core 3.1 images for arm32v7 didn't come in Alpine.

Now that our codebase has upgraded to .NET 6, we want to use Alpine in all our .NET images for the reduced size and smaller attack surface.

This change moves all our .NET images to Alpine. In many cases, the Dockerfiles for the different architectures are identical, or nearly so. We have an opportunity to consolidate in the future, but I didn't take that step here to keep things focused.

Regarding the Edge Hub module: rather than updating the scripts to build watchdog and broker for Alpine, I have removed watchdog and broker from the module. They are preview components that are being removed from the main branch of the product. See the note [here](https://docs.microsoft.com/en-us/azure/iot-edge/how-to-publish-subscribe?view=iotedge-2020-11).

This change also cherry-picks a131745 to run Arm64 end-to-end tests on a 1ES-hosted agent instead of Raspberry Pi.

To test, I ran the Build Images pipeline, then passed the results to the End-to-end and Connectivity test pipelines, and verified the tests passed on amd64, arm32v7, and arm64v8.

builds/e2e/compare-compatibility.yaml

@@ -164,10 +164,10 @@ jobs:
 ################################################################################
   - job: ubuntu_2004_arm64v8
 ################################################################################
-    displayName: Ubuntu 20.04 with arm64v8
+    displayName: Ubuntu 20.04 on arm64v8
 
     pool:
-      name: 'Azure-IoT-Edge-1ES-Hosted-Linux-Arm64'
+      name: $(pool.linux.arm.name)
       demands:
       - ImageOverride -equals agent-aziotedge-ubuntu-20.04-arm64
 
@@ -189,45 +189,7 @@ jobs:
         KeyVaultName: $(az.keyvault)
         SecretsFilter: >-
           edgebuild-service-principal-secret,
-    - bash: |
-          set -e
-          # Install PowerShell dependencies
-          sudo apt-get update
-          sudo apt-get install -y liblttng-ust0 jq
-          # Get the PowerShell tarball
-          release_id=$(curl -sSH 'Accept: application/vnd.github.v3+json' https://api.github.com/repos/powershell/powershell/releases/latest | jq '.id')
-          url=$(curl -sSH 'Accept: application/vnd.github.v3+json' https://api.github.com/repos/powershell/powershell/releases/$release_id/assets | jq -r ".[] | select(.name | contains(\"linux-arm64.tar.gz\")) | .browser_download_url")
-          echo "$release_id"
-          echo "$url"
-          file=$(basename $url)
-          curl -sSL $url -o /tmp/$file
-          # Install PowerShell
-          sudo mkdir -p /opt/microsoft/powershell/7
-          sudo tar zxf /tmp/$file -C /opt/microsoft/powershell/7
-          sudo chmod +x /opt/microsoft/powershell/7/pwsh
-          sudo ln -s /opt/microsoft/powershell/7/pwsh /usr/bin/pwsh
-      displayName: Install pwsh
-    - bash: |
-        set -e
-        # Install .NET Core dependencies
-        sudo apt-get update
-        sudo DEBIAN_FRONTEND=noninteractive apt-get install -y \
-            libc6 libgcc1 libgssapi-krb5-2 libicu66 libssl1.1 libstdc++6 zlib1g
-        # Install .NET Core
-        curl -sSL https://dot.net/v1/dotnet-install.sh | bash /dev/stdin --channel 6.0
-        sudo ln -s $HOME/.dotnet/dotnet /usr/bin/dotnet
-      displayName: Install .NET Core
-    - bash: |
-        set -e
-        # Install Moby
-        curl https://packages.microsoft.com/config/ubuntu/20.04/prod.list > ./microsoft-prod.list
-        sudo cp ./microsoft-prod.list /etc/apt/sources.list.d/
-        curl https://packages.microsoft.com/keys/microsoft.asc | gpg --dearmor > microsoft.gpg
-        sudo cp ./microsoft.gpg /etc/apt/trusted.gpg.d/
-        rm microsoft-prod.list microsoft.gpg
-        sudo apt-get update
-        sudo apt-get install -y moby-engine
-      displayName: Install moby
+    - template: ../templates/prep-arm-agent.yaml
     - template: templates/e2e-setup.yaml
     - bash: |
           set -e

builds/e2e/e2e.yaml

@@ -175,11 +175,11 @@ jobs:
 ################################################################################
   - job: ubuntu_2004_arm64v8
 ################################################################################
-    displayName: Ubuntu 20.04 with arm64v8
+    displayName: Ubuntu 20.04 on arm64v8
     pool:
-      name: $(pool.custom.name)
-      demands: 
-        - agent-group -equals rpi3-e2e-aarch64
+      name: $(pool.linux.arm.name)
+      demands:
+      - ImageOverride -equals agent-aziotedge-ubuntu-20.04-arm64
 
     variables:
       os: linux
@@ -191,6 +191,7 @@ jobs:
     timeoutInMinutes: 120
 
     steps:
+    - template: ../templates/prep-arm-agent.yaml
     - template: templates/e2e-clean-directory.yaml
     - template: templates/e2e-setup.yaml
     - template: templates/e2e-clear-docker-cached-images.yaml

builds/e2e/templates/e2e-run-base-image-update.yaml

@@ -13,7 +13,6 @@ parameters:
 #   NestedEdgeOnly: Only applies to nested edge cases
 #   NestedEdgeAmqpOnly: Only applies to nested edge cases using amqp upstream protocol
 #   LegacyMqttRequired: Only applies to cases with the edgehub legacy mqtt protocol head
-#   BrokerRequired: Only applies to cases with the broker enabled
 steps:
 - pwsh: |
     $testFile = '$(binDir)/Microsoft.Azure.Devices.Edge.Test.dll'
@@ -47,7 +46,6 @@ steps:
     elseif ($test_type -eq 'nestededge_amqp')
     {
       $filter += '&Category!=SingleNodeOnly'
-      $filter += '&Category!=BrokerRequired'
       $filter += '&Category!=FlakyOnNested'
       # Below tests were disabled and marked for re-enable when a blocking item was resolved.
       # When it was resolved the tests were never enabled. We need to re-enable these.

builds/e2e/templates/e2e-run.yaml

@@ -12,7 +12,6 @@ parameters:
 #   NestedEdgeOnly: Only applies to nested edge cases
 #   NestedEdgeAmqpOnly: Only applies to nested edge cases using amqp upstream protocol
 #   LegacyMqttRequired: Only applies to cases with the edgehub legacy mqtt protocol head
-#   BrokerRequired: Only applies to cases with the broker enabled
 #   SkipManifestTrust: Only applies to manifest/content trust tests
 steps:
 - pwsh: |
@@ -48,7 +47,6 @@ steps:
     elseif ($test_type -eq 'nestededge_amqp')
     {
       $filter += '&Category!=SingleNodeOnly'
-      $filter += '&Category!=BrokerRequired'
       $filter += '&Category!=FlakyOnNested'
       # Below tests were disabled and marked for re-enable when a blocking item was resolved.
       # When it was resolved the tests were never enabled. We need to re-enable these.