Graphics images are not sent to Alert

Grafana Alerting
1 
version: '2'

services:
  grafana:
    image: grafana/grafana-oss:latest
    restart: always
    ports:
      - '3000:3000'
    depends_on:
      - renderer
    environment:
      GF_RENDERING_SERVER_URL: http://renderer:8081/render
      GF_RENDERING_CALLBACK_URL: http://grafana:3000/
      GF_UNIFIED_ALERTING_SCREENSHOTS_ENABLED: "true"
      GF_LOG_FILTERS: rendering:debug
    volumes:
      - ./etc/grafana:/etc/grafana
      - ./lib/grafana:/var/lib/grafana
  renderer:
    image: grafana/grafana-image-renderer:latest
    ports:
      - 8081
    volumes:
      - ./redering-grafana/config.json:/usr/src/app/config.json

{
  "service": {
    "host": null,
    "port": 8081,

    "metrics": {
      "enabled": false,
      "collectDefaultMetrics": true,
      "requestDurationBuckets": [1, 5, 7, 9, 11, 13, 15, 20, 30]
    },

    "logging": {
      "level": "debug",
      "console": {
        "json": true,
        "colorize": true
      }
    }
  },
  "rendering": {
    "chromeBin": null,
    "args": [
      "--no-sandbox"
    ],
    "ignoresHttpsErrors": false,

    "timezone": null,
    "acceptLanguage": null,
    "width": 1000,
    "height": 500,
    "deviceScaleFactor": 1,
    "maxWidth": 3080,
    "maxHeight": 3000,
    "maxDeviceScaleFactor": 4,

    "mode": "clustered",
    "clustering": {
      "mode": "browser",
      "maxConcurrency": 5,
      "timeout": 30
    },

    "verboseLogging": true,
    "dumpio": false
  }
}

Value: [ var='B0' metric='NoData' labels={} value=null ]
Labels:
 - alertname = DatasourceNoData
 - rule_uid = emAInG67k
 - rulename = KW Dacha alert
Annotations:
Source: http://grafana.staged-by-discourse.com/alerting/grafana/emAInG67k/view
Silence: http://grafana.staged-by-discourse.com/alerting/silence/new?alertmanager=grafana&matcher=alertname%3DDatasourceNoData&matcher=rule_uid%3DemAInG67k&matcher=rulename%3DKW+Dacha+alert
Dashboard: http://grafana.staged-by-discourse.com/d/haQGQEUMk
Panel: http://grafana.staged-by-discourse.com/d/haQGQEUMk?viewPanel=4