docs/victorialogs: change fluentd input type in examples (#7123)

### Describe Your Changes

Use fluentd logging driver in examples to have enriched data in
VictoriaLogs

### Checklist

The following checks are **mandatory**:

- [ ] My change adheres [VictoriaMetrics contributing
guidelines](https://docs.victoriametrics.com/contributing/).

deployment/docker/victorialogs/fluentd/Dockerfile

@@ -1,6 +1,8 @@
-FROM fluent/fluentd:v1.17
+FROM fluent/fluentd:v1.17-debian-1
 USER root
 RUN \
+  apt update && \
+  apt install -y netcat-traditional && \
   gem install \
     fluent-plugin-datadog \
     fluent-plugin-grafana-loki \

deployment/docker/victorialogs/fluentd/compose.yml

@@ -9,3 +9,22 @@ services:
     depends_on: [victorialogs]
     ports:
       - "5140:5140"
+      - "24224:24224"
+    healthcheck:
+      test: ["CMD", "nc", "-z", "-n", "-v", "127.0.0.1", "24224"]
+      start_period: 3s
+  nginx:
+    image: nginx:1.27
+    healthcheck:
+      test: ["CMD", "curl", "-f", "http://localhost"]
+      start_period: 3s
+    ports:
+      - "8080:80"
+    logging:
+      driver: fluentd
+      options:
+        fluentd-address: 127.0.0.1:24224
+        labels: com.docker.compose.service
+    depends_on:
+      fluentd:
+        condition: service_healthy

deployment/docker/victorialogs/fluentd/elasticsearch/fluent.conf

@@ -1,13 +1,13 @@
 <source>
-  @type tail
+  @type forward
-  format none
+  port 24224
-  tag docker.testlog
+  bind 0.0.0.0
-  path /var/lib/docker/containers/**/*.log
 </source>
 
 <match **>
   @type elasticsearch
   host victorialogs
   path /insert/elasticsearch
+  custom_headers {"VL-Msg-Field": "log", "VL-Stream-Fields": "com.docker.compose.service"}
   port 9428
 </match>

deployment/docker/victorialogs/fluentd/jsonline/fluent.conf

@@ -1,12 +1,11 @@
 <source>
-  @type tail
+  @type forward
-  format none
+  port 24224
-  tag docker.testlog
+  bind 0.0.0.0
-  path /var/lib/docker/containers/**/*.log
 </source>
 
 <match **>
   @type http
   endpoint "http://victorialogs:9428/insert/jsonline"
-  headers {"VL-Msg-Field": "log", "VL-Time-Field": "time", "VL-Stream-Fields": "path"}
+  headers {"VL-Msg-Field": "log", "VL-Stream-Fields": "com.docker.compose.service"}
 </match>

deployment/docker/victorialogs/fluentd/loki/fluent.conf

@@ -1,10 +1,17 @@
 <source>
-  @type tail
+  @type forward
-  format none
+  port 24224
-  tag docker.testlog
+  bind 0.0.0.0
-  path /var/lib/docker/containers/**/*.log
 </source>
 
+<filter **>
+  @type record_transformer
+  enable_ruby true
+  <record>
+    service ${record['com.docker.compose.service']}
+  </record>
+</filter>
+
 <match **>
   @type loki
   url "http://victorialogs:9428/insert"
@@ -12,6 +19,8 @@
     flush_interval 10s
     flush_at_shutdown true
   </buffer>
-  custom_headers {"VL-Msg-Field": "log", "VL-Time-Field": "time", "VL-Stream-Fields": "path"}
+  <label>
+    service
+  </label>
   buffer_chunk_limit 1m
 </match>