loki alert setup with grafana-loki helm chart

Question

please can anyone tell me can i set up alerts with Loki? alert should trigger to slack. my loki installation done through helm. also grafana & prometheus deployed through helm. i have dashboard to show error message and their count so , if an error message occurs it should send to slack.code is below.

loki:
  enabled: true
  isDefault: true
  url: http://{{(include "loki.serviceName" .)}}:{{ .Values.loki.service.port }}
  ruler:
    enable_api: true
    enable_alertmanager_v2: true
    enable_sharding: true
    wal:
      dir: /var/loki/wal
  alert_rules:
  - alert: AppError
    expr: |
       {namespace="health-help", pod="stgidentity-6fc88f9fb-6l5v7"} |= `request completed`
    for: 5m
    labels:
      severity: critical
    annotations:
      summary: "{{ $labels.errorMessage }} errors from {{ $labels.namespace }}/{{ $labels.app }}"
      description: "{{ $value }} errors have occurred in the last 5 minutes."
  readinessProbe:
    httpGet:
      path: /ready
      port: http-metrics
    initialDelaySeconds: 45
  livenessProbe:
    httpGet:
      path: /ready
      port: http-metrics
    initialDelaySeconds: 45
  datasource:
    jsonData: {}
    uid: ""
  env:
    - name: AWS_ACCESS_KEY_ID
      valueFrom:
        secretKeyRef:
          name: loki-s3
          key: AWS_ACCESS_KEY_ID
    - name: AWS_SECRET_ACCESS_KEY
      valueFrom:
        secretKeyRef:
          name: loki-s3
          key: AWS_SECRET_ACCESS_KEY
  config:
    query_scheduler:
      max_outstanding_requests_per_tenant: 2048

    query_range:
      parallelise_shardable_queries: false
      split_queries_by_interval: 0
    storage_config:
      aws:
        s3: s3://us-east-1/****
        s3forcepathstyle: true
        bucketnames: hh-stg-app-logs
        region: us-east-1
        insecure: false
        sse_encryption: false
      boltdb_shipper:
        shared_store: s3
        cache_ttl: 24h

here is my dashboard which i build. loki-dashboard for logs count

i need this dashboard result of logs count should send alert to slack