diff --git a/samples/eventhubs/python/README.md b/samples/eventhubs/python/README.md
index dcc39c5..6d67beb 100644
--- a/samples/eventhubs/python/README.md
+++ b/samples/eventhubs/python/README.md
@@ -71,7 +71,8 @@ schema registry.
`LOCALSTACK_AUTH_TOKEN`
- [Docker](https://docs.docker.com/get-docker/)
- [Azure CLI](https://learn.microsoft.com/en-us/cli/azure/install-azure-cli) and
- [azlocal](https://pypi.org/project/azlocal/) (`pip install azlocal`)
+ [lstk](https://github.com/localstack/lstk) (`brew install localstack/tap/lstk` or
+ `npm install -g @localstack/lstk`)
- Python 3.12+ with `src/producers/requirements.txt` installed
- `jq` and `zip`
- [Terraform](https://developer.hashicorp.com/terraform/downloads) or the Bicep CLI, for
@@ -86,7 +87,7 @@ IMAGE_NAME=localstack/localstack-azure localstack start -d
localstack wait -t 120
# Route the Azure CLI to the emulator
-azlocal start-interception
+lstk az start-interception
cd samples/eventhubs/python
pip install -r src/producers/requirements.txt
diff --git a/samples/eventhubs/python/bicep/README.md b/samples/eventhubs/python/bicep/README.md
index 278b6d2..a0fb0c6 100644
--- a/samples/eventhubs/python/bicep/README.md
+++ b/samples/eventhubs/python/bicep/README.md
@@ -5,7 +5,7 @@ application code with the Azure CLI.
## Prerequisites
-- The LocalStack Azure emulator is running and `azlocal start-interception` has been run.
+- The LocalStack Azure emulator is running and `lstk az start-interception` has been run.
- The Bicep CLI (`az bicep install`) and `jq` are available.
## Usage
diff --git a/samples/eventhubs/python/scripts/README.md b/samples/eventhubs/python/scripts/README.md
index 0197288..93a27c0 100644
--- a/samples/eventhubs/python/scripts/README.md
+++ b/samples/eventhubs/python/scripts/README.md
@@ -1,7 +1,7 @@
# Azure CLI deployment
Deploys the payment fraud detection pipeline with the Azure CLI, then verifies and
-exercises it. Run `azlocal start-interception` first so every `az` call is routed to the
+exercises it. Run `lstk az start-interception` first so every `az` call is routed to the
LocalStack Azure emulator.
## Scripts
diff --git a/samples/eventhubs/python/scripts/deploy.sh b/samples/eventhubs/python/scripts/deploy.sh
index 34ca796..3c87a9a 100644
--- a/samples/eventhubs/python/scripts/deploy.sh
+++ b/samples/eventhubs/python/scripts/deploy.sh
@@ -17,7 +17,7 @@
# Web App (Python) operations dashboard
#
# Everything runs against the LocalStack Azure emulator; no real cloud resources
-# are created. Run 'azlocal start-interception' first.
+# are created. Run 'lstk az start-interception' first.
# =============================================================================
# Variables
diff --git a/samples/eventhubs/python/src/dashboard/app.py b/samples/eventhubs/python/src/dashboard/app.py
index ce54344..df05d79 100644
--- a/samples/eventhubs/python/src/dashboard/app.py
+++ b/samples/eventhubs/python/src/dashboard/app.py
@@ -40,6 +40,9 @@
API_VERSION = "2023-07-01"
# Upper bound on a single alerts read, so a page refresh can never hang the worker thread.
ALERT_READ_TIMEOUT_SECONDS = 15
+# How many alerts the table below the headline shows. The page labels itself with this, so the
+# label cannot drift from the list it describes - and the headline total is deliberately separate.
+ALERT_PAGE_SIZE = 25
def eventhub_connection() -> str:
@@ -59,12 +62,31 @@ def _namespace_host(conn_str: str) -> str:
return ""
-def partition_snapshot() -> list[dict]:
- """Live per-partition head positions for the payments hub."""
+def hub_total(hub_name: str) -> int:
+ """Events ever enqueued in a hub, summed from per-partition runtime metadata.
+
+ Counting by reading a hub does not scale and, worse, is bounded by whatever page size the
+ reader uses - which would silently turn a headline count into a page size. The runtime
+ metadata gives the real total without consuming anything.
+
+ High-water mark, not live occupancy: `last_enqueued_sequence_number` is the last event
+ *enqueued*, so this errs high once retention expires events - it never falls. For events still
+ retained the figure would be `last_enqueued_sequence_number - beginning_sequence_number + 1`.
+
+ A read failure is deliberately not caught. Returning 0 would be indistinguishable from an empty
+ hub, and since 0 is a real value the page's fallback would not fire: the headline would read 0
+ above a list of alerts, then flash a delta the size of the whole hub on the next good refresh.
+ https://learn.microsoft.com/en-us/dotnet/api/azure.messaging.eventhubs.partitionproperties
+ """
+ return sum(row["events"] for row in partition_snapshot(hub_name))
+
+
+def partition_snapshot(hub_name: str = EVENT_HUB_NAME) -> list[dict]:
+ """Live per-partition head positions for a hub."""
conn = eventhub_connection()
if not conn:
return []
- client = EventHubProducerClient.from_connection_string(conn, eventhub_name=EVENT_HUB_NAME)
+ client = EventHubProducerClient.from_connection_string(conn, eventhub_name=hub_name)
rows = []
with client:
for partition_id in client.get_partition_ids():
@@ -123,7 +145,7 @@ def checkpoint_snapshot(partitions: list[dict]) -> list[dict]:
return sorted(rows, key=lambda row: row["partition"])
-def recent_alerts(limit: int = 25) -> list[dict]:
+def recent_alerts(limit: int = ALERT_PAGE_SIZE) -> list[dict]:
"""Read the fraud-alerts hub from the beginning (the sample keeps volumes small)."""
conn = eventhub_connection()
if not conn:
@@ -266,7 +288,11 @@ def schema_snapshot() -> list[dict]:
@app.route("/")
def index():
- return render_template("index.html", refreshed=datetime.now(UTC).strftime("%H:%M:%S"))
+ return render_template(
+ "index.html",
+ refreshed=datetime.now(UTC).strftime("%H:%M:%S"),
+ alert_page_size=ALERT_PAGE_SIZE,
+ )
@app.route("/api/overview")
@@ -280,6 +306,8 @@ def overview():
"alert_hub": ALERT_HUB_NAME,
"consumer_group": FRAUD_CONSUMER_GROUP,
"total_events": sum(row["events"] for row in partitions),
+ # The real number of alerts, not the length of the page below it.
+ "total_alerts": hub_total(ALERT_HUB_NAME),
"partitions": partitions,
"checkpoints": checkpoint_snapshot(partitions),
"alerts": recent_alerts(),
diff --git a/samples/eventhubs/python/src/dashboard/static/style.css b/samples/eventhubs/python/src/dashboard/static/style.css
index 79d29dc..26d8ae0 100644
--- a/samples/eventhubs/python/src/dashboard/static/style.css
+++ b/samples/eventhubs/python/src/dashboard/static/style.css
@@ -29,3 +29,31 @@ table thead th {
color: #6c757d;
font-weight: 600;
}
+
+/* A refresh that changes nothing should look different from one that does: headline numbers
+ flash and show how much they moved, so cause and effect are visible while demonstrating. */
+.stat-changed {
+ animation: stat-flash 1.2s ease-out;
+}
+
+@keyframes stat-flash {
+ 0% { background: #fff3cd; }
+ 100% { background: transparent; }
+}
+
+.stat-delta {
+ display: inline-block;
+ margin-left: .35rem;
+ padding: .1rem .4rem;
+ border-radius: .35rem;
+ font-size: .75rem;
+ font-weight: 700;
+ color: #0f5132;
+ background: #d1e7dd;
+ opacity: 0;
+ transition: opacity .3s ease-in;
+}
+
+.stat-delta.show {
+ opacity: 1;
+}
diff --git a/samples/eventhubs/python/src/dashboard/templates/index.html b/samples/eventhubs/python/src/dashboard/templates/index.html
index a1bcd79..65ffd5c 100644
--- a/samples/eventhubs/python/src/dashboard/templates/index.html
+++ b/samples/eventhubs/python/src/dashboard/templates/index.html
@@ -20,21 +20,21 @@
Fraud alerts
-
-
+
hot path
Capture archives
-
-
+
cold path (Avro in Blob)
@@ -70,7 +70,7 @@
-
+
| Account | Amount | Merchant | Reasons |
|---|
@@ -114,6 +114,33 @@
.replace(/&/g, '&').replace(//g, '>');
}
+// Write a headline number and flash it when it moves, so a refresh that changes something
+// is obvious. Without this the page looks identical whether or not anything happened.
+function setStat(id, value) {
+ const element = document.getElementById(id);
+ const previous = element.dataset.value;
+ const next = String(value);
+ element.textContent = next;
+ if (previous !== undefined && previous !== next) {
+ element.classList.remove('stat-changed');
+ void element.offsetWidth; // restart the animation
+ element.classList.add('stat-changed');
+ const delta = Number(next) - Number(previous);
+ if (Number.isFinite(delta) && delta > 0) {
+ const badge = element.parentElement.querySelector('.stat-delta');
+ if (badge) {
+ badge.textContent = '+' + delta;
+ badge.classList.add('show');
+ // Cancel the previous hide: two changes less than the badge lifetime apart are normal at
+ // this refresh gap, and a stale timer would strip the badge the newer change just set.
+ clearTimeout(Number(badge.dataset.timer));
+ badge.dataset.timer = setTimeout(() => badge.classList.remove('show'), 4000);
+ }
+ }
+ }
+ element.dataset.value = next;
+}
+
async function refresh() {
let data;
try {
@@ -122,10 +149,10 @@
return;
}
- document.getElementById('stat-events').textContent = data.total_events ?? 0;
+ setStat('stat-events', data.total_events ?? 0);
document.getElementById('stat-hub').textContent = data.event_hub || '';
- document.getElementById('stat-alerts').textContent = (data.alerts || []).length;
- document.getElementById('stat-capture').textContent = (data.capture_files || []).length;
+ setStat('stat-alerts', data.total_alerts ?? (data.alerts || []).length);
+ setStat('stat-capture', (data.capture_files || []).length);
document.getElementById('stat-cg').textContent = data.consumer_group || '';
const lags = (data.checkpoints || []).map(row => row.lag).filter(value => value !== null);
@@ -169,8 +196,27 @@
'refreshed ' + new Date().toISOString().slice(11, 19) + ' UTC';
}
-refresh();
-setInterval(refresh, 5000);
+// Reading both hubs takes several seconds, so the next refresh is scheduled only after the
+// previous one finishes. A fixed interval shorter than the request would overlap requests,
+// land responses out of order, and make the page appear to update at random moments.
+const REFRESH_GAP_MS = 3000;
+
+async function refreshLoop() {
+ const updated = document.getElementById('updated');
+ updated.textContent = 'updating...';
+ try {
+ await refresh();
+ } finally {
+ if (updated.textContent === 'updating...') {
+ // refresh() bailed out before stamping a time. Say so: leaving 'updating...' up makes a
+ // broken pipeline look permanently busy, which is the opposite of what this page is for.
+ updated.textContent = 'refresh failed - retrying';
+ }
+ setTimeout(refreshLoop, REFRESH_GAP_MS);
+ }
+}
+
+refreshLoop();