Ensuring the metadata's persisted for the AzureRM backend

[tombuildsstuff]

After looking into this, it appears if we don't request the current Metadata before putting the Blob Contents - the Metadata is lost; which means that all information needed to unlock the blob is lost. This PR ensures we retrieve the metadata (e.g. lock information) before pushing the file to blob storage - and adds a test to ensure that the metadata is set correctly when altering.

• Upgrading to v10.3.0-beta of the Azure SDK for Go
• Upgrading to v8.3.1 beta of AutoRest
• Loading the Blob MetaData before persisting it

Fixes #16012

Running this test without this fix:

$ TF_ACC=1 envchain azurerm go test ./backend/remote-state/azure/ -v -run=TestPutMaintainsMetaData
=== RUN   TestPutMaintainsMetaData
--- FAIL: TestPutMaintainsMetaData (121.72s)
	backend_test.go:119: creating resource group terraform-backend-testing-4890229005814052142
	backend_test.go:125: creating storage account tfbackendtestingjrxr
	backend_test.go:139: fetching access key for storage account
	backend_test.go:156: creating container terraform
	client_test.go:127: "acceptancetest" was not set to "f3b56bad-33ad-4b93-a600-7a66e9cbd1eb" in the MetaData: map[]
	backend_test.go:173: destroying created resources
	backend_test.go:183: Azure resources destroyed
FAIL
exit status 1
FAIL	github.com/hashicorp/terraform/backend/remote-state/azure	121.746s

after this fix:

$ TF_ACC=1 envchain azurerm go test ./backend/remote-state/azure/ -v -run=TestPutMaintainsMetaData
=== RUN   TestPutMaintainsMetaData
--- PASS: TestPutMaintainsMetaData (137.13s)
	backend_test.go:119: creating resource group terraform-backend-testing-41068478022798168
	backend_test.go:125: creating storage account tfbackendtestingscbr
	backend_test.go:139: fetching access key for storage account
	backend_test.go:156: creating container terraform
	backend_test.go:173: destroying created resources
	backend_test.go:183: Azure resources destroyed
PASS
ok  	github.com/hashicorp/terraform/backend/remote-state/azure	137.153s

[jbardin]

LGTM.
Can we get a full TF_ACC test run output documented here before merging?

acceptance test failure

[jbardin]

nevermind, Azure ACC tests just need a longer timeout

=== RUN   TestBackend_impl
--- PASS: TestBackend_impl (0.00s)
=== RUN   TestBackendConfig
--- PASS: TestBackendConfig (0.00s)
=== RUN   TestBackend
--- PASS: TestBackend (136.78s)
	backend_test.go:119: creating resource group terraform-backend-testing-4720723530017762978
	backend_test.go:125: creating storage account tfbackendtestingrgut
	backend_test.go:139: fetching access key for storage account
	backend_test.go:156: creating container terraform
	backend_test.go:173: destroying created resources
	backend_test.go:183: Azure resources destroyed
=== RUN   TestBackendLocked
--- PASS: TestBackendLocked (138.23s)
	backend_test.go:119: creating resource group terraform-backend-testing-7551546351769012132
	backend_test.go:125: creating storage account tfbackendtestingtjw3
	backend_test.go:139: fetching access key for storage account
	backend_test.go:156: creating container terraform
	backend_test.go:91: TestBackend: testing state locking for *azure.Backend
	backend_test.go:173: destroying created resources
	backend_test.go:183: Azure resources destroyed
=== RUN   TestRemoteClient_impl
--- PASS: TestRemoteClient_impl (0.00s)
=== RUN   TestRemoteClient
--- PASS: TestRemoteClient (115.10s)
	backend_test.go:119: creating resource group terraform-backend-testing-7006787121995469946
	backend_test.go:125: creating storage account tfbackendtestinga698
	backend_test.go:139: fetching access key for storage account
	backend_test.go:156: creating container terraform
	backend_test.go:173: destroying created resources
	backend_test.go:183: Azure resources destroyed
=== RUN   TestRemoteClientLocks
--- PASS: TestRemoteClientLocks (130.95s)
	backend_test.go:119: creating resource group terraform-backend-testing-5580027579435905588
	backend_test.go:125: creating storage account tfbackendtestingbf9c
	backend_test.go:139: fetching access key for storage account
	backend_test.go:156: creating container terraform
	backend_test.go:173: destroying created resources
	backend_test.go:183: Azure resources destroyed
=== RUN   TestPutMaintainsMetaData
--- PASS: TestPutMaintainsMetaData (129.40s)
	backend_test.go:119: creating resource group terraform-backend-testing-3850395580908544072
	backend_test.go:125: creating storage account tfbackendtestingcp2j
	backend_test.go:139: fetching access key for storage account
	backend_test.go:156: creating container terraform
	backend_test.go:173: destroying created resources
	backend_test.go:183: Azure resources destroyed
PASS

[apparentlymart]

Merging this on behalf of @tombuildsstuff so we can include it in the next release.

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

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