fix(price-pusher): provision Loki + Promtail in sample monitoring stack

apps/price_pusher/README.md

@@ -293,7 +293,7 @@ pnpm run dev evm --config config.evm.mainnet.json --metrics-port 9091
 
 ### Running Locally with Docker
 
-You can run the monitoring stack (Prometheus and Grafana) using the provided docker-compose configuration:
+You can run the monitoring stack (Prometheus, Loki, Promtail, and Grafana) using the provided docker-compose configuration:
 
 1. Use the sample docker-compose file for metrics:
 
@@ -303,9 +303,11 @@ docker-compose -f docker-compose.metrics.sample.yaml up
 
 This will start:
 - Prometheus server on port 9090 with the alerts configured in alerts.sample.yml
+- Loki server on port 3100 (log aggregation)
+- Promtail, configured by promtail.sample.yml to ship every Docker container's logs into Loki and tag them with `namespace=<container_name>`
 - Grafana server on port 3000 with default credentials (admin/admin)
 
-The docker-compose.metrics.sample.yaml file includes a pre-configured Grafana dashboard (see the [Dashboard](#dashboard) section below) that displays all the metrics mentioned above. This dashboard provides monitoring of your price pusher operations with panels for configured feeds, active feeds, wallet balance, update statistics, and error tracking. The dashboard is automatically provisioned when you start the stack with docker-compose.
+The docker-compose.metrics.sample.yaml file includes a pre-configured Grafana dashboard (see the [Dashboard](#dashboard) section below) that displays all the metrics mentioned above plus log panels (Tx Hash, All Logs, Error Logs) backed by Loki. The dashboard is automatically provisioned when you start the stack with docker-compose; the `chain` template variable lists every container name Promtail has seen, so running one pusher container per chain gives you per-chain log views out of the box.
 
 ### Example Grafana Queries
 

apps/price_pusher/datasource.sample.yml

@@ -1,8 +1,20 @@
 apiVersion: 1
 
 datasources:
+  # Both UIDs below are referenced from grafana-dashboard.sample.json (the
+  # Prometheus UID by every metric panel, the Loki UID by Tx Hash / All Logs
+  # / Error Logs and the `chain` template variable). Without explicit UIDs
+  # Grafana auto-generates per-provision random values and the dashboard's
+  # hardcoded references fail to resolve. Keep them in sync if the dashboard
+  # is regenerated.
   - name: Prometheus
     type: prometheus
     access: proxy
     url: http://prometheus:9090
+    uid: edryyydtht14wa
     isDefault: true
+  - name: Loki
+    type: loki
+    access: proxy
+    url: http://loki:3100
+    uid: ads9ouz3jh4hsa

apps/price_pusher/docker-compose.metrics.sample.yaml

@@ -17,6 +17,28 @@ services:
     networks:
       - monitoring
 
+  loki:
+    image: grafana/loki:latest
+    container_name: loki
+    ports:
+      - "3100:3100"
+    command: -config.file=/etc/loki/local-config.yaml
+    networks:
+      - monitoring
+
+  promtail:
+    image: grafana/promtail:latest
+    container_name: promtail
+    volumes:
+      - ./promtail.sample.yml:/etc/promtail/config.yml
+      - /var/lib/docker/containers:/var/lib/docker/containers:ro
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+    command: -config.file=/etc/promtail/config.yml
+    depends_on:
+      - loki
+    networks:
+      - monitoring
+
   grafana:
     image: grafana/grafana:latest
     container_name: grafana
@@ -33,6 +55,7 @@ services:
       - GF_USERS_ALLOW_SIGN_UP=false
     depends_on:
       - prometheus
+      - loki
     networks:
       - monitoring
 

apps/price_pusher/promtail.sample.yml

@@ -0,0 +1,47 @@
+# Sample Promtail config that ships Docker container logs to the local Loki
+# instance defined in docker-compose.metrics.sample.yaml. It tags every line
+# with `namespace=<container_name>` so the `chain` template variable in
+# grafana-dashboard.sample.json (which filters `{namespace=~"$chain"}`) picks
+# up one entry per pusher container you run alongside this stack.
+#
+# Run one pusher container per chain (e.g. `price-pusher-evm`,
+# `price-pusher-sui`) and the dashboard's chain selector will list them.
+
+server:
+  http_listen_port: 9080
+  grpc_listen_port: 0
+
+positions:
+  filename: /tmp/positions.yaml
+
+clients:
+  - url: http://loki:3100/loki/api/v1/push
+
+scrape_configs:
+  - job_name: docker
+    docker_sd_configs:
+      - host: unix:///var/run/docker.sock
+        refresh_interval: 5s
+    relabel_configs:
+      # Use the container name (without the leading slash Docker prepends) as
+      # the `namespace` label that the Grafana dashboard filters on.
+      - source_labels: ["__meta_docker_container_name"]
+        regex: "/(.*)"
+        target_label: namespace
+      - source_labels: ["__meta_docker_container_id"]
+        target_label: container_id
+    pipeline_stages:
+      # Surface pino's standard `level` field so the Error Logs panel
+      # (`detected_level = error`) can detect log levels emitted as JSON.
+      # Pino emits numeric severities by default (10=trace, 20=debug,
+      # 30=info, 40=warn, 50=error, 60=fatal) and Loki's detected_level
+      # only recognises the string forms, so translate before labelling.
+      - json:
+          expressions:
+            level: level
+            msg: msg
+      - template:
+          source: level
+          template: '{{ if eq .Value "10" }}trace{{ else if eq .Value "20" }}debug{{ else if eq .Value "30" }}info{{ else if eq .Value "40" }}warn{{ else if eq .Value "50" }}error{{ else if eq .Value "60" }}fatal{{ else }}{{ .Value }}{{ end }}'
+      - labels:
+          level: