用户可以基于Prometheus指标手动定义SLO，但过程相对繁琐。阿里云服务网格ASM提供了生成SLO以及配套的告警规则的能力，能够通过自定义资源YAML配置的方式简化这一流程。本文将介绍如何使用ASM定义应用服务级SLO。

系列文章：

在ASM中为应用服务启用SLO（1）：服务等级目标SLO概览

https://developer.aliyun.com/article/1114965

在ASM中为应用服务启用SLO（2）：服务网格中的SLO定义

https://developer.aliyun.com/article/1115135

在ASM中为应用服务启用SLO（3）：使用ASM定义应用服务级SLO

https://developer.aliyun.com/article/1115152

在ASM中为应用服务启用SLO（4）：导入生成的规则到Prometheus中执行SLO

https://developer.aliyun.com/article/1115171

在ASM中为应用服务启用SLO（5）：使用Grafana查看SLO

https://developer.aliyun.com/article/1115187

前提条件

已创建ASM实例，且ASM实例为1.15.3或以上版本。具体操作，请参见创建ASM实例。

定义SLO配置

下方的示例配置将为default命名空间下的httpbin服务生成服务可用性SLO，目标值为99%，持续时间为30天，并配置Page和Ticket两个等级的告警。如需进一步了解如何自定义配置文件请参考文档：https://developer.aliyun.com/article/1115135?spm=a2c6h.13262185.profile.58.6c9a35fe5AiH8r

将如下YAML格式的配置保存为prometheusservicelevel.yaml文件，使用ASM实例的kubeconfig连接运行kubectl命令部署到网格中。

kubectl apply -f prometheusservicelevel.yaml

apiVersion: istio.alibabacloud.com/v1beta1
kind: ServiceLevelObjective
metadata:  name: asm-slo-default-httpbin
  namespace: default # 自定义资源的命名空间spec:  service: httpbin # 目标服务名称  period: 30d # slo持续时间  slos:  - name: asm-slo # slo名称    objective: "99"# 目标值    sli:      plugin:        id: availability # 使用的插件类型    alerting:      name: asm-alert # 告警规则名称

自动生成Prometheus规则

执行完成后, 可以通过以下命令以查看执行结果：

# 在本示例中，大括号中内容请替换成 default 和 httpbinkubectl get prometheusservicelevel asm-slo-{目标服务所在命名空间}-{目标服务名} -o yaml

其中生成的status字段内容类似如下：

status:  ......
  status: success
  prometheusRules: # 生成的Prometheus规则文件

在prometheusRules字段中即为yaml格式的Prometheus规则。上述配置生成的Prometheus规则示例如下：

groups:- name: asm-slo-sli-recordings-httpbin-asm-slo
  rules:  - record: slo:sli_error:ratio_rate5m
    expr: "(\n(\n  sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\",response_code=~\"(5..|429)\"}[5m])) \n  /          \n  (sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\"}[5m])) > 0)\n) OR on() vector(0)\n)"    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
      slo_window: 5m
  - record: slo:sli_error:ratio_rate30m
    expr: "(\n(\n  sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\",response_code=~\"(5..|429)\"}[30m])) \n  /          \n  (sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\"}[30m])) > 0)\n) OR on() vector(0)\n)"    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
      slo_window: 30m
  - record: slo:sli_error:ratio_rate1h
    expr: "(\n(\n  sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\",response_code=~\"(5..|429)\"}[1h])) \n  /          \n  (sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\"}[1h])) > 0)\n) OR on() vector(0)\n)"    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
      slo_window: 1h
  - record: slo:sli_error:ratio_rate2h
    expr: "(\n(\n  sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\",response_code=~\"(5..|429)\"}[2h])) \n  /          \n  (sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\"}[2h])) > 0)\n) OR on() vector(0)\n)"    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
      slo_window: 2h
  - record: slo:sli_error:ratio_rate6h
    expr: "(\n(\n  sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\",response_code=~\"(5..|429)\"}[6h])) \n  /          \n  (sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\"}[6h])) > 0)\n) OR on() vector(0)\n)"    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
      slo_window: 6h
  - record: slo:sli_error:ratio_rate1d
    expr: "(\n(\n  sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\",response_code=~\"(5..|429)\"}[1d])) \n  /          \n  (sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\"}[1d])) > 0)\n) OR on() vector(0)\n)"    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
      slo_window: 1d
  - record: slo:sli_error:ratio_rate3d
    expr: "(\n(\n  sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\",response_code=~\"(5..|429)\"}[3d])) \n  /          \n  (sum(rate(istio_requests_total{ destination_service_name=\"httpbin\",destination_service_namespace=\"default\"}[3d])) > 0)\n) OR on() vector(0)\n)"    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
      slo_window: 3d
  - record: slo:sli_error:ratio_rate30d
    expr: |      sum_over_time(slo:sli_error:ratio_rate5m{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"}[30d])      / ignoring (slo_window)      count_over_time(slo:sli_error:ratio_rate5m{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"}[30d])    labels:      slo_window: 30d
- name: asm-slo-meta-recordings-httpbin-asm-slo
  rules:  - record: slo:objective:ratio
    expr: vector(0.99)
    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
  - record: slo:error_budget:ratio
    expr: vector(1-0.99)
    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
  - record: slo:time_period:days
    expr: vector(30)
    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
  - record: slo:current_burn_rate:ratio
    expr: |      slo:sli_error:ratio_rate5m{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"}      / on(slo_id, asm_slo, slo_service) group_left      slo:error_budget:ratio{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"}    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
  - record: slo:period_burn_rate:ratio
    expr: |      slo:sli_error:ratio_rate30d{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"}      / on(slo_id, asm_slo, slo_service) group_left      slo:error_budget:ratio{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"}    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
  - record: slo:period_error_budget_remaining:ratio
    expr: 1 - slo:period_burn_rate:ratio{asm_slo="asm-slo", slo_id="httpbin-asm-slo",
      slo_service="httpbin"}    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_service: httpbin
  - record: asm_slo_info
    expr: vector(1)
    labels:      asm_slo: asm-slo
      slo_id: httpbin-asm-slo
      slo_mode: cli-gen-prom
      slo_objective: "99"      slo_service: httpbin
      slo_spec: prometheus/v1
      slo_version: dev
- name: asm-slo-alerts-httpbin-asm-slo
  rules:  - alert: asm-alert
    expr: |      (          (slo:sli_error:ratio_rate5m{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"} > (14.4 * 0.01))          and ignoring (slo_window)          (slo:sli_error:ratio_rate1h{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"} > (14.4 * 0.01))      )      or ignoring (slo_window)      (          (slo:sli_error:ratio_rate30m{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"} > (6 * 0.01))          and ignoring (slo_window)          (slo:sli_error:ratio_rate6h{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"} > (6 * 0.01))      )    labels:      slo_severity: page
    annotations:      summary: '{{$labels.slo_service}} {{$labels.asm_slo}} SLO error budget burn        rate is over expected.'      title: (page) {{$labels.slo_service}}{{$labels.asm_slo}} SLO error budget burn
        rate is too fast.
  - alert: asm-alert
    expr: |      (          (slo:sli_error:ratio_rate2h{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"} > (3 * 0.01))          and ignoring (slo_window)          (slo:sli_error:ratio_rate1d{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"} > (3 * 0.01))      )      or ignoring (slo_window)      (          (slo:sli_error:ratio_rate6h{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"} > (1 * 0.01))          and ignoring (slo_window)          (slo:sli_error:ratio_rate3d{asm_slo="asm-slo", slo_id="httpbin-asm-slo", slo_service="httpbin"} > (1 * 0.01))      )    labels:      slo_severity: ticket
    annotations:      summary: '{{$labels.slo_service}} {{$labels.asm_slo}} SLO error budget burn        rate is over expected.'      title: (ticket) {{$labels.slo_service}}{{$labels.asm_slo}} SLO error budget
        burn rate is too fast.