fix: address review findings (network ns, journal path, CI semantics)

- network_mode: host so prometheus.exporter.unix reports real host
  interfaces (eth0...) rather than the alloy container's veth pair.
- loki.source.journal: set path = "/var/log/journal" explicitly so it
  doesn't silently fall through to /run/log/journal on volatile-journal
  hosts.
- cadvisor keep-list: add container_memory_working_set_bytes (drives
  several panels on the standard Docker dashboard).
- Drop /dev/kmsg device + extra_hosts:host.docker.internal — neither is
  needed by the current keep-lists, and host-network mode makes the
  extra_hosts entry meaningless.
- CI: extend Alloy validation beyond `fmt` (syntax-only) by booting
  alloy with the embedded config and asserting it stays running, which
  catches bad component refs / wrong arg names that fmt accepts.
- README: refresh Mounts table + Security note to match.

alloy/.github/workflows/validate.yml

@@ -34,3 +34,22 @@ jobs:
         run: |
           docker run --rm -v "$PWD/config.alloy:/config.alloy:ro" \
             grafana/alloy:v1.10.0 fmt /config.alloy > /dev/null
+
+      - name: Validate Alloy config semantics (parse + load components)
+        # `fmt` is syntax-only; this catches bad component refs, wrong arg
+        # types, and unknown component types by actually loading the graph.
+        # Components log scrape errors against the dummy URLs but alloy
+        # itself stays running, so liveness after sleep == config valid.
+        run: |
+          docker run --rm -d --name alloy-test \
+            -e ALLOY_HOSTNAME -e REMOTECFG_URL -e REMOTECFG_ID -e REMOTECFG_USER \
+            -e PROM_URL -e PROM_USER -e LOKI_URL -e LOKI_USER -e GRAFANA_TOKEN \
+            -v "$PWD/config.alloy:/etc/alloy/config.alloy:ro" \
+            grafana/alloy:v1.10.0 \
+            run --server.http.listen-addr=127.0.0.1:0 /etc/alloy/config.alloy
+          sleep 8
+          if [ "$(docker inspect -f '{{.State.Running}}' alloy-test 2>/dev/null)" != "true" ]; then
+            docker logs alloy-test
+            exit 1
+          fi
+          docker stop alloy-test >/dev/null

alloy/README.md

@@ -45,20 +45,20 @@ Same compose file on every host — change `ALLOY_HOSTNAME` and `REMOTECFG_ID` p
 
 ## Security note
 
-Runs as `privileged: true` (matching the upstream Grafana Cloud docker integration). This is required for cadvisor to read cgroups via `/sys` and for `/dev/kmsg` access. If you need least-privilege, see the upstream Alloy docker integration docs and tighten capabilities.
+Runs `privileged: true` + `network_mode: host`, matching the upstream Grafana Cloud docker integration. `network_mode: host` is required so `prometheus.exporter.unix` reports the host's real network interfaces (eth0…) instead of the alloy container's veth pair. If you need least-privilege, see the upstream Alloy docker integration docs and tighten capabilities.
 
 ## Mounts
 
 | Mount | Why |
 |---|---|
-| `/proc:/rootproc:ro` | node-exporter cpu/mem/load |
+| `/proc:/rootproc:ro` | node-exporter cpu/mem/load (referenced via `procfs_path`) |
 | `/sys:/sys:ro` | node-exporter + cadvisor cgroups |
-| `/:/rootfs:ro` | filesystem collector |
+| `/:/rootfs:ro` | filesystem collector (referenced via `rootfs_path`) |
-| `/dev/disk/:/dev/disk:ro` | diskstats device labels |
+| `/dev/disk/:/dev/disk:ro` | node-exporter diskstats device labels |
-| `/var/run/docker.sock` | docker discovery + log streaming |
+| `/var/run/docker.sock` | `discovery.docker` + `loki.source.docker` |
 | `/var/lib/docker:ro` | cadvisor container metadata |
 | `/var/log/journal:ro` | `loki.source.journal` |
-| `/dev/kmsg` (device) | cadvisor OOM detection |
+| `/etc/machine-id:ro` | stable host id for the journal reader |
 | `alloy-data` (named volume) | WAL + remotecfg cache |
 
 ## License

alloy/docker-compose.yml

@@ -9,6 +9,7 @@ services:
     restart: unless-stopped
     hostname: ${ALLOY_HOSTNAME:?required}
     privileged: true
+    network_mode: host                        # node_exporter netdev/netstat sees real host interfaces (eth0…) not veth
     environment:
       ALLOY_DEPLOY_MODE: docker
       REMOTECFG_URL: ${REMOTECFG_URL:?required}
@@ -29,10 +30,6 @@ services:
       - /var/lib/docker/:/var/lib/docker:ro
       - /var/log/journal:/var/log/journal:ro
       - /etc/machine-id:/etc/machine-id:ro    # stable host id for systemd journal reader
-    extra_hosts:
-      - 'host.docker.internal:host-gateway'
-    devices:
-      - /dev/kmsg
     configs:
       - { source: alloy_config, target: /etc/alloy/config.alloy }
     command: 'run --storage.path=/var/lib/alloy/data /etc/alloy/config.alloy'
@@ -151,6 +148,7 @@ configs:
 
         loki.source.journal "default"  {
             max_age       = "12h0m0s"
+            path          = "/var/log/journal"
             forward_to    = [loki.process.default.receiver]
             relabel_rules = loki.relabel.default.rules
         }
@@ -201,7 +199,7 @@ configs:
 
           rule {
               source_labels = ["__name__"]
-              regex         = "container_cpu_usage_seconds_total|container_fs_reads_total|container_fs_usage_bytes|container_fs_writes_total|container_last_seen|container_memory_usage_bytes|container_network_receive_bytes_total|container_network_receive_errors_total|container_network_receive_packets_dropped_total|container_network_transmit_bytes_total|container_network_transmit_errors_total|container_network_transmit_packets_dropped_total|container_spec_memory_reservation_limit_bytes|machine_memory_bytes|machine_scrape_error|up"
+              regex         = "container_cpu_usage_seconds_total|container_fs_reads_total|container_fs_usage_bytes|container_fs_writes_total|container_last_seen|container_memory_usage_bytes|container_memory_working_set_bytes|container_network_receive_bytes_total|container_network_receive_errors_total|container_network_receive_packets_dropped_total|container_network_transmit_bytes_total|container_network_transmit_errors_total|container_network_transmit_packets_dropped_total|container_spec_memory_reservation_limit_bytes|machine_memory_bytes|machine_scrape_error|up"
               action        = "keep"
           }
       }