Blob Cross-Account Replication and Sync

Overview

This flow provides controlled, auditable, delta-aware replication for Azure Blob Storage. On an hourly schedule it scans a source container, copies only new or changed blobs to a destination storage account, and writes an auditable sync-state row to Dataverse for every blob it replicates. Each run is stamped with a unique correlation id, and a summary is posted to Microsoft Teams.

Why it matters: built-in Azure replication (GRS / object replication) is account-scoped, all-or-nothing, and offers little run-level visibility. A flow-based approach gives targeted, container-level DR or content distribution with per-blob delta detection, a Dataverse audit trail, and operational reporting - portable across tenants by changing only env-var values.

Ships Off (Stopped).

Use Case

A team needs specific containers replicated to another storage account (cross-region or cross-tenant) on a schedule, copying only what has actually changed, with a record of what was copied and when. Typical drivers: disaster-recovery staging, content distribution to a secondary region, or feeding a downstream system from a curated container.

Flow Architecture

Environment Variables

Connectors & Connections

Note — All connections are referenced as solution connection references; the flow is portable between environments as long as a connection is mapped at import time.

Customization Guide

Almost every realistic variant of this flow can be implemented by changing environment variable values. A few cases require small edits inside the flow definition — those are called out explicitly below.

Cadence

Change the hourly recurrence (e.g. daily off-hours for DR staging).

Multiple destinations

Wrap the copy/log block in a second Foreach over a comma-split destination list to fan out to several targets.

Conflict policy

Current rule is newer-ETag-wins; switch to a Last-Modified comparison instead of ETag.

Deletes

Add a second pass that lists destination blobs and tombstones/removes those no longer present at source.

Large blobs

Replace the read+write pair with a SAS-based server-side Copy Blob (HTTP to the Blob REST API with a source SAS) to avoid pulling bytes through the flow.

Key Expressions

The flow is intentionally light on Power Fx / WDL gymnastics — the heaviest expressions are the branch-name concatenation and the approval outcome check. They are listed below in the order they appear in the flow.

equals(item()?['IsFolder'], false)

or(equals(length(outputs('Lookup_Existing_Sync_State')?['body/value']), 0), not(equals(first(outputs('Lookup_Existing_Sync_State')?['body/value'])?['flowlibs_etag'], items('Apply_to_each_Source_Blob')?['ETag'])))

flowlibs_name eq '@{items('Apply_to_each_Source_Blob')?['Path']}'

body('Get_Source_Blob_Content')