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134 lines
5.7 KiB
Markdown
134 lines
5.7 KiB
Markdown
---
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title: Monitoring etcd
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---
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Each etcd server provides local monitoring information on its client port through http endpoints. The monitoring data is useful for both system health checking and cluster debugging.
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## Debug endpoint
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If `--debug` is set, the etcd server exports debugging information on its client port under the `/debug` path. Take care when setting `--debug`, since there will be degraded performance and verbose logging.
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The `/debug/pprof` endpoint is the standard go runtime profiling endpoint. This can be used to profile CPU, heap, mutex, and goroutine utilization. For example, here `go tool pprof` gets the top 10 functions where etcd spends its time:
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```sh
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$ go tool pprof http://localhost:2379/debug/pprof/profile
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Fetching profile from http://localhost:2379/debug/pprof/profile
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Please wait... (30s)
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Saved profile in /home/etcd/pprof/pprof.etcd.localhost:2379.samples.cpu.001.pb.gz
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Entering interactive mode (type "help" for commands)
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(pprof) top10
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310ms of 480ms total (64.58%)
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Showing top 10 nodes out of 157 (cum >= 10ms)
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flat flat% sum% cum cum%
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130ms 27.08% 27.08% 130ms 27.08% runtime.futex
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70ms 14.58% 41.67% 70ms 14.58% syscall.Syscall
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20ms 4.17% 45.83% 20ms 4.17% github.com/coreos/etcd/vendor/golang.org/x/net/http2/hpack.huffmanDecode
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20ms 4.17% 50.00% 30ms 6.25% runtime.pcvalue
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20ms 4.17% 54.17% 50ms 10.42% runtime.schedule
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10ms 2.08% 56.25% 10ms 2.08% github.com/coreos/etcd/vendor/github.com/coreos/etcd/etcdserver.(*EtcdServer).AuthInfoFromCtx
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10ms 2.08% 58.33% 10ms 2.08% github.com/coreos/etcd/vendor/github.com/coreos/etcd/etcdserver.(*EtcdServer).Lead
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10ms 2.08% 60.42% 10ms 2.08% github.com/coreos/etcd/vendor/github.com/coreos/etcd/pkg/wait.(*timeList).Trigger
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10ms 2.08% 62.50% 10ms 2.08% github.com/coreos/etcd/vendor/github.com/prometheus/client_golang/prometheus.(*MetricVec).hashLabelValues
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10ms 2.08% 64.58% 10ms 2.08% github.com/coreos/etcd/vendor/golang.org/x/net/http2.(*Framer).WriteHeaders
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```
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The `/debug/requests` endpoint gives gRPC traces and performance statistics through a web browser. For example, here is a `Range` request for the key `abc`:
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```
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When Elapsed (s)
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2017/08/18 17:34:51.999317 0.000244 /etcdserverpb.KV/Range
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17:34:51.999382 . 65 ... RPC: from 127.0.0.1:47204 deadline:4.999377747s
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17:34:51.999395 . 13 ... recv: key:"abc"
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17:34:51.999499 . 104 ... OK
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17:34:51.999535 . 36 ... sent: header:<cluster_id:14841639068965178418 member_id:10276657743932975437 revision:15 raft_term:17 > kvs:<key:"abc" create_revision:6 mod_revision:14 version:9 value:"asda" > count:1
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```
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## Metrics endpoint
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Each etcd server exports metrics under the `/metrics` path on its client port and optionally on locations given by `--listen-metrics-urls`.
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The metrics can be fetched with `curl`:
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```sh
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$ curl -L http://localhost:2379/metrics | grep -v debugging # ignore unstable debugging metrics
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# HELP etcd_disk_backend_commit_duration_seconds The latency distributions of commit called by backend.
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# TYPE etcd_disk_backend_commit_duration_seconds histogram
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etcd_disk_backend_commit_duration_seconds_bucket{le="0.002"} 72756
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etcd_disk_backend_commit_duration_seconds_bucket{le="0.004"} 401587
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etcd_disk_backend_commit_duration_seconds_bucket{le="0.008"} 405979
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etcd_disk_backend_commit_duration_seconds_bucket{le="0.016"} 406464
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...
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```
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## Health Check
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Since v3.3.0, in addition to responding to the `/metrics` endpoint, any locations specified by `--listen-metrics-urls` will also respond to the `/health` endpoint. This can be useful if the standard endpoint is configured with mutual (client) TLS authentication, but a load balancer or monitoring service still needs access to the health check.
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## Prometheus
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Running a [Prometheus][prometheus] monitoring service is the easiest way to ingest and record etcd's metrics.
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First, install Prometheus:
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```sh
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PROMETHEUS_VERSION="2.0.0"
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wget https://github.com/prometheus/prometheus/releases/download/v$PROMETHEUS_VERSION/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz -O /tmp/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz
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tar -xvzf /tmp/prometheus-$PROMETHEUS_VERSION.linux-amd64.tar.gz --directory /tmp/ --strip-components=1
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/tmp/prometheus -version
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```
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Set Prometheus's scraper to target the etcd cluster endpoints:
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```sh
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cat > /tmp/test-etcd.yaml <<EOF
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global:
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scrape_interval: 10s
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scrape_configs:
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- job_name: test-etcd
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static_configs:
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- targets: ['10.240.0.32:2379','10.240.0.33:2379','10.240.0.34:2379']
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EOF
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cat /tmp/test-etcd.yaml
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```
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Set up the Prometheus handler:
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```sh
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nohup /tmp/prometheus \
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-config.file /tmp/test-etcd.yaml \
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-web.listen-address ":9090" \
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-storage.local.path "test-etcd.data" >> /tmp/test-etcd.log 2>&1 &
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```
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Now Prometheus will scrape etcd metrics every 10 seconds.
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### Alerting
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There is a set of default alerts for etcd v3 clusters for [Prometheus 1.x](./etcd3_alert.rules) as well as [Prometheus 2.x](./etcd3_alert.rules.yml).
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> Note: `job` labels may need to be adjusted to fit a particular need. The rules were written to apply to a single cluster so it is recommended to choose labels unique to a cluster.
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### Grafana
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[Grafana][grafana] has built-in Prometheus support; just add a Prometheus data source:
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```
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Name: test-etcd
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Type: Prometheus
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Url: http://localhost:9090
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Access: proxy
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```
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Then import the default [etcd dashboard template][template] and customize. For instance, if Prometheus data source name is `my-etcd`, the `datasource` field values in JSON also need to be `my-etcd`.
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Sample dashboard:
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[prometheus]: https://prometheus.io/
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[grafana]: http://grafana.org/
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[template]: ./grafana.json
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