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This enables fetching device statistics from UNMS, extracting the ping RTT values from it, and export them back to prometheus. Since fetching statistics requires talking to another, device-specific endpoint, the context timeout is increased from 5 to 30s. A future change should pass the request context from the promhttp endpoint down to the fetchDeviceData() method, to make the timout depend on Prometheus' scrape request life cycle.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,91 @@ | ||
| package exporter | ||
|
|
||
| import ( | ||
| "testing" | ||
| "time" | ||
|
|
||
| "github.com/ffddorf/unms-exporter/models" | ||
| ) | ||
|
|
||
| const ( | ||
| ms = time.Millisecond | ||
| µs = time.Microsecond //nolint:asciicheck | ||
| ) | ||
|
|
||
| type metricExpectation map[string]struct { | ||
| actual interface{} | ||
| satisfied bool | ||
| } | ||
|
|
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| func comparePingMetrics(t *testing.T, expectations metricExpectation, actual *PingMetrics) { | ||
| t.Helper() | ||
|
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| anyFailure := false | ||
| for field, expectation := range expectations { | ||
| if !expectation.satisfied { | ||
| anyFailure = true | ||
| t.Errorf("unexpected value for field %q: %v", field, expectation.actual) | ||
| } | ||
| } | ||
| if anyFailure { | ||
| t.FailNow() | ||
| } | ||
| } | ||
|
|
||
| func TestDevice_PingMetrics_connected(t *testing.T) { | ||
| t.Parallel() | ||
|
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| subject := Device{ | ||
| Statistics: &models.DeviceStatistics{ | ||
| Ping: models.ListOfCoordinates{{Y: 5}, {Y: 10}, {Y: 25}, {Y: 15}, {Y: 1}}, // x values are ignored | ||
| }, | ||
| } | ||
|
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| actual := subject.PingMetrics() | ||
| if actual == nil { | ||
| t.Error("expected PingMetrics() to return somthing, got nil") | ||
| } | ||
|
|
||
| comparePingMetrics(t, metricExpectation{ | ||
| "packets sent": {actual.PacketsSent, actual.PacketsSent == 5}, | ||
| "packets lost": {actual.PacketsLost, actual.PacketsLost == 0}, | ||
| "rtt best": {actual.Best, actual.Best == 1*ms}, | ||
| "rtt worst": {actual.Worst, actual.Worst == 25*ms}, | ||
| "rtt median": {actual.Median, actual.Median == 10*ms}, | ||
| "rtt meain": {actual.Mean, actual.Mean == 11200*µs}, // 11.2ms | ||
| "rtt std dev": {actual.StdDev, 8350*µs < actual.StdDev && actual.StdDev < 8360*µs}, // ~8.352245ms | ||
| }, actual) | ||
| } | ||
|
|
||
| func TestDevice_PingMetrics_missingPackets(t *testing.T) { | ||
| t.Parallel() | ||
|
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| subject := Device{ | ||
| Statistics: &models.DeviceStatistics{ | ||
| Ping: models.ListOfCoordinates{nil, {Y: 100}, {Y: 250}, nil, {Y: 120}}, | ||
| }, | ||
| } | ||
|
|
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| actual := subject.PingMetrics() | ||
| if actual == nil { | ||
| t.Error("expected PingMetrics() to return somthing, got nil") | ||
| } | ||
|
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||
| comparePingMetrics(t, metricExpectation{ | ||
| "packets sent": {actual.PacketsSent, actual.PacketsSent == 5}, | ||
| "packets lost": {actual.PacketsLost, actual.PacketsLost == 2}, | ||
| "rtt best": {actual.Best, actual.Best == 100*ms}, | ||
| "rtt worst": {actual.Worst, actual.Worst == 250*ms}, | ||
| "rtt median": {actual.Median, actual.Median == 120*ms}, | ||
| "rtt meain": {actual.Mean, 156666*µs < actual.Mean && actual.Mean < 156667*µs}, // 156.66666ms | ||
| "rtt std dev": {actual.StdDev, 66499*µs < actual.StdDev && actual.StdDev < 66500*µs}, // ~66.499791ms | ||
| }, actual) | ||
| } | ||
|
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| func TestDevice_PingMetrics_disconnected(t *testing.T) { | ||
| t.Parallel() | ||
|
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| if actual := (&Device{}).PingMetrics(); actual != nil { | ||
| t.Errorf("expected PingMetrics() to return nil, got %+v", actual) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,95 @@ | ||
| package exporter | ||
|
|
||
| import ( | ||
| "math" | ||
| "sort" | ||
| "time" | ||
| ) | ||
|
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||
| // PingMetrics is a dumb data point computed from a list of PingResults. | ||
| type PingMetrics struct { | ||
| PacketsSent int // number of packets sent | ||
| PacketsLost int // number of packets lost | ||
| Best time.Duration // best RTT | ||
| Worst time.Duration // worst RTT | ||
| Median time.Duration // median RTT | ||
| Mean time.Duration // mean RTT | ||
| StdDev time.Duration // RTT std deviation | ||
| } | ||
|
|
||
| // PingResult stores the information about a single ping, in particular | ||
| // the round-trip time or whether the packet was lost. | ||
| type PingResult struct { | ||
| RTT time.Duration | ||
| Lost bool | ||
| } | ||
|
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| // PingHistory represents the ping history for a single node/device. | ||
| type PingHistory []PingResult | ||
|
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| // NewHistory creates a new History object with a specific capacity. | ||
| func NewHistory(capacity int) PingHistory { | ||
| return make(PingHistory, 0, capacity) | ||
| } | ||
|
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| // AddResult saves a ping result into the internal history. | ||
| func (h *PingHistory) Add(rtt time.Duration, lost bool) { | ||
| *h = append(*h, PingResult{RTT: rtt, Lost: lost}) | ||
| } | ||
|
|
||
| // Compute aggregates the result history into a single data point. | ||
| func (h PingHistory) Compute() *PingMetrics { | ||
| numFailure := 0 | ||
| numTotal := len(h) | ||
|
|
||
| if numTotal == 0 { | ||
| return nil | ||
| } | ||
|
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| data := make([]float64, 0, numTotal) | ||
| var best, worst, mean, stddev, total, sumSquares float64 | ||
|
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| for _, curr := range h { | ||
| if curr.Lost { | ||
| numFailure++ | ||
| continue | ||
| } | ||
|
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| rtt := curr.RTT.Seconds() | ||
| if rtt < best || len(data) == 0 { | ||
| best = rtt | ||
| } | ||
| if rtt > worst || len(data) == 0 { | ||
| worst = rtt | ||
| } | ||
| data = append(data, rtt) | ||
| total += rtt | ||
| } | ||
|
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| size := float64(numTotal - numFailure) | ||
| mean = total / size | ||
| for _, rtt := range data { | ||
| sumSquares += math.Pow(rtt-mean, 2) | ||
| } | ||
| stddev = math.Sqrt(sumSquares / size) | ||
|
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| median := math.NaN() | ||
| if l := len(data); l > 0 { | ||
| sort.Float64Slice(data).Sort() | ||
| if l%2 == 0 { | ||
| median = (data[l/2-1] + data[l/2]) / 2 | ||
| } else { | ||
| median = data[l/2] | ||
| } | ||
| } | ||
|
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| return &PingMetrics{ | ||
| PacketsSent: numTotal, | ||
| PacketsLost: numFailure, | ||
| Best: time.Duration(best * float64(time.Second)), | ||
| Worst: time.Duration(worst * float64(time.Second)), | ||
| Median: time.Duration(median * float64(time.Second)), | ||
| Mean: time.Duration(mean * float64(time.Second)), | ||
| StdDev: time.Duration(stddev * float64(time.Second)), | ||
| } | ||
| } |