Per-level log rate

Logs/sec grouped by level over 5m window. modern: logfmt parser for key=value lines.

sum by (level) (rate({app="api"} | logfmt [5m]))

More loki commands

Quantile over unwrapped latency

quantile_over_time(0.99, {app="api"} | json | unwrap latency_ms [5m]) by (route)

p99 latency from a numeric log field per route. note: unwrap needs a numeric label/field.
Count matching lines over time

sum(count_over_time({namespace="prod"} |~ "timeout|deadline exceeded" [1m]))

Count regex-matched error lines per minute across a namespace. |~ is regex match.
logcli ad-hoc query

logcli query '{job="app/api"} |= "panic"' --since=1h --limit=200 --output=jsonl

CLI query for last hour with line cap and JSONL output. set LOKI_ADDR env first.
Loki query_range via API

curl -sG "$LOKI_ADDR/loki/api/v1/query_range" --data-urlencode 'query=sum(rate({app="api"}[5m]))' --data-urlencode 'step=60' | jq '.data.result'

Run a range metric query over HTTP and extract result with jq. step is in seconds.
Push log lines to Loki

curl -s -H 'Content-Type: application/json' -XPOST "$LOKI_ADDR/loki/api/v1/push" -d '{"streams":[{"stream":{"app":"test"},"values":[["'$(date +%s%N)'","hello loki"]]}]}'

Manually push a log entry to verify ingestion. note: timestamp must be ns epoch.