Use Azure Pipelines for Windows instead of AppVeyor

This removes the AppVeyor configuration and adapts it for use on Azure
Pipelines. For deployment, the maintainer must create a `docker-creds`
variable group containing `DockerUsername` and `DockerPassword`.
`DockerPassword` should be secret.  This variable group must be linked
to the particular build.

Secrets are not visible to PR builds by default, which mitigates some of
the security risks here. Still, it would be better to opt in to
deployment as opposed to opting out of it with a `condition`.

Author: ecstatic-morse

appveyor.yml

@@ -0,0 +1,18 @@
+jobs:
+- job: Windows
+  pool:
+    vmImage: win1803
+  variables:
+    group: docker-creds
+    IMAGE_NAME: 'crates-build-env-windows'
+  steps:
+    - pwsh: ./windows/ci/build.ps1
+      displayName: Build Docker image
+    - pwsh: ./windows/ci/publish.ps1
+      displayName: Publish image to Docker Hub
+      # FIXME: Using condition for this seems brittle, maybe there's a better way?
+      condition: |
+        and(succeeded(), eq(variables['Build.SourceBranch'], 'refs/heads/master'), ne(variables['Build.Reason'], 'PullRequest'))
+      env:
+        DOCKER_PASSWORD: $(DockerPassword)
+        DOCKER_USERNAME: $(DockerUsername)

azure-pipelines.yml

@@ -1,8 +1,6 @@
-$ErrorActionPreference = "Stop"
-
-$ContainerBase = '@sha256:c06b4bfaf634215ea194e6005450740f3a230b27c510cf8facab1e9c678f3a99'
+$ContainerBase = ':1803'
 
 docker build                                    `
-    -t "$env:PUSH_IMAGE"                        `
+    -t "$env:IMAGE_NAME"                        `
     --build-arg "BASE_IMAGE_VER=$ContainerBase" `
     windows

windows/ci/build.ps1

@@ -1,17 +1,11 @@
-$ErrorActionPreference = "Stop"
-
-# Build the image
-./windows/ci/build.ps1
-
 foreach ($var in "DOCKER_USERNAME", "DOCKER_PASSWORD") {
     if (-not (Test-Path "env:$var")) {
         echo "Environment variable \"$var\" not set"
         exit 22
     }
 }
 
-# Log in to dockerhub
-[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($Env:DOCKER_PASSWORD)).Trim() `
-    | docker login --username "$Env:DOCKER_USERNAME" --password-stdin
-
-docker push "$env:PUSH_IMAGE"
+Write-Host "Publishing to hub.docker.com/$env:DOCKER_USERNAME"
+docker login --username "$env:DOCKER_USERNAME" --password "$env:DOCKER_PASSWORD"
+docker tag "$env:IMAGE_NAME" "$env:DOCKER_USERNAME/$env:IMAGE_NAME"
+docker push "$env:DOCKER_USERNAME/$env:IMAGE_NAME"