Replace unmaintained transmission-exporter with homegrown Python exporter

Swap out docker.io/metalmatze/transmission-exporter:master for a minimal
Python exporter using prometheus_client and transmission-rpc with the
collect-on-scrape pattern. Same metric names so Grafana dashboards work
unchanged. Uses uv for dependency management in the container build.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

argocd/manifests/torrent/deployment.yaml

@@ -56,7 +56,7 @@ spec:
             initialDelaySeconds: 10
             periodSeconds: 10
         - name: transmission-exporter
-          image: docker.io/metalmatze/transmission-exporter:master
+          image: registry.ops.eblu.me/blumeops/transmission-exporter
           env:
             - name: TRANSMISSION_ADDR
               value: "http://localhost:9091"

argocd/manifests/torrent/kustomization.yaml

@@ -11,3 +11,5 @@ resources:
 images:
   - name: registry.ops.eblu.me/blumeops/transmission
     newTag: v4.1.1-r1-ab34cbd
+  - name: registry.ops.eblu.me/blumeops/transmission-exporter
+    newTag: v1.0.0

containers/transmission-exporter/Dockerfile

@@ -0,0 +1,31 @@
+# Transmission Prometheus exporter - collect-on-scrape, no polling loop
+# Two-stage build: uv installs deps into venv, runtime is minimal Alpine
+
+ARG CONTAINER_APP_VERSION=1.0.0
+
+FROM python:3.12-alpine3.22 AS base
+
+FROM base AS builder
+WORKDIR /app
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
+COPY exporter.py .
+RUN uv venv .venv && \
+    uv pip install --python .venv/bin/python \
+        "prometheus-client>=0.24,<1.0" \
+        "transmission-rpc>=7.0,<8.0" && \
+    find /app/.venv \( -type d -a -name test -o -name tests \) \
+      -o \( -type f -a -name '*.pyc' -o -name '*.pyo' \) -exec rm -rf '{}' \+
+
+FROM base
+
+LABEL org.opencontainers.image.title="Transmission Exporter"
+LABEL org.opencontainers.image.description="Prometheus exporter for Transmission BitTorrent client"
+
+ENV PYTHONUNBUFFERED=1
+WORKDIR /app
+COPY --from=builder /app /app
+ENV PATH="/app/.venv/bin:$PATH"
+
+EXPOSE 19091
+USER 65534:65534
+CMD ["python", "-u", "/app/exporter.py"]

containers/transmission-exporter/exporter.py

@@ -0,0 +1,154 @@
+# /// script
+# requires-python = ">=3.12"
+# dependencies = [
+#     "prometheus-client>=0.24,<1.0",
+#     "transmission-rpc>=7.0,<8.0",
+# ]
+# ///
+"""Minimal Prometheus exporter for Transmission, using collect-on-scrape."""
+
+import os
+import sys
+import urllib.parse
+
+from prometheus_client import start_http_server
+from prometheus_client.core import REGISTRY, GaugeMetricFamily
+from transmission_rpc import Client
+
+
+def parse_addr(addr: str) -> dict:
+    """Parse TRANSMISSION_ADDR into kwargs for transmission_rpc.Client."""
+    parsed = urllib.parse.urlparse(addr)
+    kwargs: dict = {}
+    if parsed.hostname:
+        kwargs["host"] = parsed.hostname
+    if parsed.port:
+        kwargs["port"] = parsed.port
+    if parsed.scheme == "https":
+        kwargs["protocol"] = "https"
+    if parsed.path and parsed.path != "/":
+        kwargs["path"] = parsed.path.strip("/")
+    if parsed.username:
+        kwargs["username"] = parsed.username
+    if parsed.password:
+        kwargs["password"] = parsed.password
+    return kwargs
+
+
+class TransmissionCollector:
+    def __init__(self, client_kwargs: dict):
+        self._client_kwargs = client_kwargs
+
+    def collect(self):
+        try:
+            client = Client(**self._client_kwargs)
+            session = client.session_stats()
+            torrents = client.get_torrents()
+        except Exception as e:
+            print(f"Error collecting metrics: {e}", file=sys.stderr)
+            return
+
+        # Session stats
+        yield _gauge(
+            "transmission_session_stats_download_speed_bytes",
+            "Current download speed in bytes/s",
+            session.download_speed,
+        )
+        yield _gauge(
+            "transmission_session_stats_upload_speed_bytes",
+            "Current upload speed in bytes/s",
+            session.upload_speed,
+        )
+        yield _gauge(
+            "transmission_session_stats_torrents_active",
+            "Number of active torrents",
+            session.active_torrent_count,
+        )
+        yield _gauge(
+            "transmission_session_stats_torrents_total",
+            "Total number of torrents",
+            session.torrent_count,
+        )
+
+        downloaded = GaugeMetricFamily(
+            "transmission_session_stats_downloaded_bytes",
+            "Total bytes downloaded",
+            labels=["type"],
+        )
+        downloaded.add_metric(["cumulative"], session.cumulative_stats.downloaded_bytes)
+        yield downloaded
+
+        uploaded = GaugeMetricFamily(
+            "transmission_session_stats_uploaded_bytes",
+            "Total bytes uploaded",
+            labels=["type"],
+        )
+        uploaded.add_metric(["cumulative"], session.cumulative_stats.uploaded_bytes)
+        yield uploaded
+
+        # Per-torrent metrics
+        t_download = GaugeMetricFamily(
+            "transmission_torrent_download_bytes",
+            "Torrent total downloaded bytes",
+            labels=["name"],
+        )
+        t_upload = GaugeMetricFamily(
+            "transmission_torrent_upload_bytes",
+            "Torrent total uploaded bytes",
+            labels=["name"],
+        )
+        t_ratio = GaugeMetricFamily(
+            "transmission_torrent_ratio",
+            "Torrent upload ratio",
+            labels=["name"],
+        )
+        t_uploaded_ever = GaugeMetricFamily(
+            "transmission_torrent_uploaded_ever",
+            "Torrent total uploaded ever in bytes",
+            labels=["name"],
+        )
+        t_done = GaugeMetricFamily(
+            "transmission_torrent_done",
+            "Torrent percent done (0.0-1.0)",
+            labels=["name"],
+        )
+
+        for t in torrents:
+            name = t.name or "unknown"
+            t_download.add_metric([name], t.total_size * t.percent_done)
+            t_upload.add_metric([name], t.uploaded_ever)
+            t_ratio.add_metric([name], t.ratio)
+            t_uploaded_ever.add_metric([name], t.uploaded_ever)
+            t_done.add_metric([name], t.percent_done)
+
+        yield t_download
+        yield t_upload
+        yield t_ratio
+        yield t_uploaded_ever
+        yield t_done
+
+
+def _gauge(name: str, doc: str, value: float) -> GaugeMetricFamily:
+    g = GaugeMetricFamily(name, doc)
+    g.add_metric([], value)
+    return g
+
+
+def main():
+    addr = os.environ.get("TRANSMISSION_ADDR", "http://localhost:9091")
+    port = int(os.environ.get("EXPORTER_PORT", "19091"))
+
+    client_kwargs = parse_addr(addr)
+    REGISTRY.register(TransmissionCollector(client_kwargs))
+
+    print(f"Listening on :{port}, scraping {addr}")
+    start_http_server(port)
+
+    # Block forever
+    import threading
+
+    threading.Event().wait()
+
+
+if __name__ == "__main__":
+    main()

docs/changelog.d/feature-transmission-exporter-python.infra.md

@@ -0,0 +1 @@
+Replace unmaintained `metalmatze/transmission-exporter` sidecar with homegrown Python exporter using `prometheus_client` and `transmission-rpc`. Same metric names, so Grafana dashboards work unchanged.

service-versions.yaml

@@ -173,6 +173,13 @@ services:
     current-version: "4.1.1-r1"
     upstream-source: https://github.com/transmission/transmission/releases
 
+  - name: transmission-exporter
+    type: argocd
+    last-reviewed: 2026-03-04
+    current-version: "1.0.0"
+    upstream-source: null
+    notes: Homegrown Python exporter, no upstream
+
   - name: kiwix
     type: argocd
     last-reviewed: null