storage: make Azure blobID chunk delimiter configurable (#5777)

* Make Azure chunk delimiter configurable

* Changelog: #5777

* doc update

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## Main
 * [5780](https://github.com/grafana/loki/pull/5780) **simonswine**: Update alpine image to 3.15.4.
+* [5777](https://github.com/grafana/loki/pull/5777) **tatchiuleung** storage: make Azure blobID chunk delimiter configurable.
 * [5715](https://github.com/grafana/loki/pull/5715) **chaudum** Add option to push RFC5424 syslog messages from Promtail in syslog scrape target.
 * [5696](https://github.com/grafana/loki/pull/5696) **paullryan** don't block scraping of new logs from cloudflare within promtail if an error is received from cloudflare about too early logs.
 * [5685](https://github.com/grafana/loki/pull/5625) **chaudum** Fix bug in push request parser that allowed users to send arbitrary non-string data as "log line".

docs/sources/configuration/_index.md

@@ -743,6 +743,10 @@ The `azure_storage_config` configures Azure as a general storage for different d
 # CLI flag: -<prefix>.azure.account-key
 [account_key: <string> | default = ""]
 
+# Chunk delimiter to build the blobID
+# CLI flag: -<prefix>.azure.chunk-delimiter
+[chunk_delimiter: <string> | default = "-"]
+
 # Preallocated buffer size for downloads.
 # CLI flag: -<prefix>.azure.download-buffer-size
 [download_buffer_size: <int> | default = 512000]

pkg/storage/chunk/azure/blob_storage_client.go

@@ -85,6 +85,7 @@ type BlobStorageConfig struct {
 	Environment        string         `yaml:"environment"`
 	ContainerName      string         `yaml:"container_name"`
 	AccountName        string         `yaml:"account_name"`
+	ChunkDelimiter     string         `yaml:"chunk_delimiter"`
 	AccountKey         flagext.Secret `yaml:"account_key"`
 	DownloadBufferSize int            `yaml:"download_buffer_size"`
 	UploadBufferSize   int            `yaml:"upload_buffer_size"`
@@ -106,6 +107,7 @@ func (c *BlobStorageConfig) RegisterFlagsWithPrefix(prefix string, f *flag.FlagS
 	f.StringVar(&c.Environment, prefix+"azure.environment", azureGlobal, fmt.Sprintf("Azure Cloud environment. Supported values are: %s.", strings.Join(supportedEnvironments, ", ")))
 	f.StringVar(&c.ContainerName, prefix+"azure.container-name", "cortex", "Name of the blob container used to store chunks. This container must be created before running cortex.")
 	f.StringVar(&c.AccountName, prefix+"azure.account-name", "", "The Microsoft Azure account name to be used")
+	f.StringVar(&c.ChunkDelimiter, prefix+"azure.chunk-delimiter", "-", "Chunk delimiter for blob ID to be used")
 	f.Var(&c.AccountKey, prefix+"azure.account-key", "The Microsoft Azure account key to use.")
 	f.DurationVar(&c.RequestTimeout, prefix+"azure.request-timeout", 30*time.Second, "Timeout for requests made against azure blob storage.")
 	f.IntVar(&c.DownloadBufferSize, prefix+"azure.download-buffer-size", 512000, "Preallocated buffer size for downloads.")
@@ -251,7 +253,7 @@ func (b *BlobStorage) PutObject(ctx context.Context, objectKey string, object io
 }
 
 func (b *BlobStorage) getBlobURL(blobID string, hedging bool) (azblob.BlockBlobURL, error) {
-	blobID = strings.Replace(blobID, ":", "-", -1)
+	blobID = strings.Replace(blobID, ":", b.cfg.ChunkDelimiter, -1)
 
 	// generate url for new chunk blob
 	u, err := url.Parse(fmt.Sprintf(b.selectBlobURLFmt(), b.cfg.AccountName, b.cfg.ContainerName, blobID))