Azure backend: support snapshots/versioning

[evenh]

Rebased PR with some small fixes. Originally by @pmarques (2018) and @rahdjoudj (2019).

Fixes #18284
Closes #18512
Closes #21888

[hashicorp-cla]

All committers have signed the CLA.

[Bessonov]

Just mess up my state. @tombuildsstuff please, don't let this MR rotten in 2020. If you have not enough time, who can help out?

[WebSpider]

Really looking forward to this!
(Just spent a few hr rolling back a failed provider update, rewriting statefile by hand)

[landro]

Hi @tombuildsstuff , any chance we can get this merged any time soon? We urgently need this in order to prevent incidents like the one @WebSpider experienced. Thanks!

[WascawyWabbit]

Really looking forward to this, any news on when it will be released?

[Bowbaq]

@tombuildsstuff I just messed my state, thought I was just going to restore a previous version & came to find out that versioning is not only not enabled by default but not even possible. This would have likely saved me a few hours of work

[WascawyWabbit]

Any update on this one please? I can see that review requests are pending From Feb 10th, which is > 2 months ago now.

[doubletr]

@tombuildsstuff, Could you please help to review this RP? It's pending for about 3 months. Thanks for your help in advance.

[tombuildsstuff]

Dependent on #24669

[codecov]

Codecov Report

Merging #24069 into master will decrease coverage by 0.00%.
The diff coverage is 50.00%.

Impacted Files	Coverage Δ
backend/remote-state/azure/backend_state.go	0.00% <0.00%> (ø)
backend/remote-state/azure/client.go	0.00% <0.00%> (ø)
backend/remote-state/azure/backend.go	96.10% <100.00%> (+0.18%)	⬆️
terraform/node_resource_plan.go	91.80% <0.00%> (-1.64%)	⬇️
dag/walk.go	92.54% <0.00%> (-0.63%)	⬇️
terraform/evaluate.go	53.15% <0.00%> (+0.45%)	⬆️

[evenh]

I have squashed the commits and rebased after #24669 was merged in. Could you please review @tombuildsstuff, especially since you are very familiar with Giovanni ;)

[tombuildsstuff]

hey @evenh

Thanks for this PR - apologies for the delay reviewing this - as mentioned previously we've been waiting to move off the deprecated Storage SDK in the Azure SDK for Go in favour of Giovanni.

Taking a look through this mostly LGTM - the main issue being switching to use the terminology that Azure uses instead of what Amazon uses ("snapshot" instead of "versioning") - but if we can fix that up then we should be able to take another look and kick off the tests :)

Thanks!

[landro]

Hi there, just wanted to let you know that if you enable soft delete on the storage account, you actually get new snapshots of the state every time you run terraform. See this for details: https://docs.microsoft.com/en-us/azure/storage/blobs/soft-delete-overview (Put operation)

[tombuildsstuff]

LGTM - thanks for this @evenh

[tombuildsstuff]

Ran the tests for this and they pass - thanks for this @evenh / sorry for the delay getting this merged 👍

PASS
ok  	github.com/hashicorp/terraform/backend/remote-state/azure	1468.780s

[evenh]

Hooray, thanks :-)

[ghost]

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