Blob enumerator

Lists the blobs of an Azure Storage container, optionally filtered by a name prefix and skipping blobs with a given index tag, and emits one file info record per blob. Use it with Blob reader to process the files of a container.

Pins

Pin	Kind	Types	Description
Input	input	any	Starts the enumeration (for example a timer).
Output	output	Viaducta.TypeSystem.Metadata.ViaFileInfo	Called once per blob.
Continue	continue output	same as input	Called with the input record after the last blob.

Configuration

Field	Type	Default	Description
Authentication	dropdown: 0 ConnectionString, 1 EntraId, 2 ServicePrincipal, 3 SasToken	0	How to sign in to the storage account.
ConnectionString	string		Storage connection string (DefaultEndpointsProtocol=https;AccountName=...;AccountKey=... or a SAS connection string). Required when Authentication is 0.
AccountUrl	string		Blob endpoint, for example https://myaccount.blob.core.windows.net, no query. Required when Authentication is 1, 2 or 3.
TenantId	string		Entra ID tenant id. Required for 2, optional for 1.
ClientId	string		2: client id of the app registration (required). 1: client id of a user-assigned managed identity (optional).
ClientSecret	password		Client secret of the app registration. Required for 2.
SasToken	password		Account or container SAS token (sv=...&sig=..., a leading ? is ignored). Required for 3.
ContainerName	string		Required. Container to list.
Prefix	string		Optional blob name prefix, for example incoming/2026/. Empty lists all blobs.
SkipTag	string		Blob index tag name; blobs that have this tag are not listed (for example viaducta-processed, set by Blob reader post-processing 3 Tag). Empty lists all.
TopLevelOnly	boolean	false	true lists only the blobs directly under Prefix (end it with /), not those in deeper virtual folders.
NamePattern	string	*	Only blobs whose name after the last / matches; * and ? as wildcards, case-insensitive, for example *.csv.
MinAgeMinutes	integer	0	Only blobs not modified for at least this many minutes, so blobs still being written are skipped. 0 lists all.
OrderBy	dropdown: 0 Name, 1 LastModified, 2 CreateTime	0	Emit order: by name (ordinal), or oldest modification / creation first.
MaxBlobs	integer	0	Emit at most this many blobs per run, the first ones in OrderBy order. 0 emits all.

Behaviour

• The storage client is created at flow start. 1 EntraId uses the default Azure credential: the managed identity of the host (system-assigned, or the user-assigned one of ClientId), workload identity, environment variables or the Azure CLI sign-in. The identity needs the Storage Blob Data Reader role (Storage Blob Data Owner to read tags with SkipTag).
• Per input the whole listing is read first (flat: virtual folders are part of the name and all levels are returned; with TopLevelOnly only the blobs directly under Prefix), filtered by SkipTag, NamePattern and MinAgeMinutes, ordered by OrderBy and cut to MaxBlobs; then the blobs are emitted. Changes downstream components make in the container during the run (for example Blob reader moving blobs) don't change the list.
• Each blob is emitted as ViaFileInfo: FileName = blob name (including virtual folders), FilePath = blob URL <container URL>/<blob name> (URL-escaped, without query string or SAS token), Size = content length, CreateDateTime = creation time (UTC), LastAccessDateTime = last access time (UTC; DateTime.MinValue when access tracking is off).
• The progress bar shows <emitted>/<total> blobs (while a large container is listed: listing, <n> blobs); the run ends with the status <emitted>/<total> blobs listed.
• After the last blob Continue is called with the input record.

Notes

• Connect Output to Blob reader to read each listed blob: the reader takes container and blob from FilePath (leave its ContainerName/BlobName empty). With post-processing in the reader (delete, move, tag + SkipTag) a timer-driven flow processes each blob once.
• The listing is kept in memory for the run; use Prefix to narrow very large containers. MaxBlobs limits what is emitted, not what is listed.
• MaxBlobs with OrderBy 1 and reader post-processing processes a backlog oldest first in slices, one slice per timer run.
• The container is part of FilePath (the blob URL); Blob reader and Blob operation take it from there.
• Store secrets as expression settings and reference them (=Secrets.AzureStorage) instead of typing keys into the flow.

Example

{ "Authentication": 1, "AccountUrl": "https://myaccount.blob.core.windows.net", "ContainerName": "imports", "Prefix": "daily/", "SkipTag": "viaducta-processed", "NamePattern": "*.csv", "MinAgeMinutes": 5, "OrderBy": 1, "MaxBlobs": 100 }

Timer → Blob enumerator → Blob reader → CSV decoder → ...