Azure storage needs the endpoint suffix after v1.15.0

[friedrichg]

Describe the bug
After da2ad99
all the containers that depend on block storage resources hang on authorization failing to start.
There is no message.

it's necessary to specify the endpoint suffix for all values,
In my case I had to specify blob.core.windows.net
the empty value is no longer valid.

  # Azure storage endpoint suffix without schema. The account name will be
  # prefixed to this value to create the FQDN
  # CLI flag: -ruler-storage.azure.endpoint-suffix
  [endpoint_suffix: <string> | default = ""]

Expected behavior
Cortex should now fail to start if the suffix value is not provided

Additional Context

One can see the problem with

$ cat alertmanager.yaml
alertmanager:
  data_dir: /data
  enable_api: true
alertmanager_storage:
  azure:
    account_key: dmFsaWRhY2NvdW50a2V5 # validstoragekey encoded with base64
    account_name: validstorageaccountname
    container_name: validcontainername
    # endpoint_suffix: blob.core.windows.net
  backend: azure
server:
  log_level: debug
target: alertmanager

$ docker run -e AZURE_SDK_GO_LOGGING=all -v $PWD/alertmanager.yaml:/alertmanager.yaml cortexproject/cortex:master-da2ad99 -config.file=/alertmanager.yaml
...
Get "https://validstorageaccountname./validcontainername?restype=container": dial tcp: lookup validstorageaccountname. on 192.168.5.3:53: no such host
...

[alanprot]

Seems related to thanos-io/thanos#6175

[moki1202]

@friedrichg @alanprot here's my approach to this, I can add a validate function in pkg/storage/bucket/azure/config.go which checks whether endpoint_suffix is empty or not, and execute the function right after parsing the command line flags. If error occurs then I can just do os.Exit(1). Is this approach correct?

[friedrichg]

@moki1202 fixing in thanos should be more appropriate