Observe Metrics

Observe Cluster Metrics

Use this guide to discover and query Prometheus/Thanos metrics on an OpenShift cluster using the oc metrics CLI.

Important — combine related metrics: When the user asks about related metrics (e.g. network RX and TX, CPU and memory, storage read and write), always use a single query-range call with repeated --query and --name flags. This produces aligned timestamps, a single multi-column result, and requires only one CLI call.

For detailed per-domain queries, labels, and metrics tables:

• Storage (Ceph/ODF): ref-storage.md
• Network traffic: ref-network.md
• Pods and containers: ref-pods.md
• KubeVirt VMs: ref-vms.md
• Forklift/MTV migrations: ref-mtv.md

Required CLI Tools

This skill requires:

• oc metrics (kubectl-metrics) -- for Prometheus queries

If missing, install with the secure version-pinned installer:

curl -sSLO https://raw.githubusercontent.com/kubev2v/mtv-skills/main/tools/install-tools.sh
curl -sSL  https://raw.githubusercontent.com/kubev2v/mtv-skills/main/SHA256SUMS | shasum -a 256 --check --ignore-missing
bash install-tools.sh kubectl-metrics && rm install-tools.sh

Getting Help

Before querying, call --help to learn available subcommands and flags:

oc metrics --help
oc metrics query --help
oc metrics query-range --help
oc metrics discover --help

Step 1: Discover Available Metrics

List all metric names (or search by keyword)

oc metrics discover
oc metrics discover --keyword ceph
oc metrics discover --keyword kubevirt
oc metrics discover --keyword mtv

Group metric names by prefix

oc metrics discover --keyword mtv --group-by-prefix

List labels for a specific metric

oc metrics labels --metric container_network_receive_bytes_total

Step 2: Instant Queries

Use instant queries for point-in-time health checks:

oc metrics query --query "up"
oc metrics query --query "ceph_health_status"
oc metrics query --query "count by (phase)(kube_pod_status_phase == 1)"

Step 3: Range Queries (Time-Series Trends)

Use query-range for time-series data. Repeat --query and --name flags to fetch multiple related metrics in a single call.

Single metric trend

oc metrics query-range --query "rate(http_requests_total[5m])" --start "-1h" --step 60s

Multi-metric trend (preferred for related metrics)

Combine related metrics in one call — each query gets its own named column:

oc metrics query-range \
  --query "sum(rate(container_network_receive_bytes_total{namespace=\"TARGET_NS\"}[5m]))" \
  --query "sum(rate(container_network_transmit_bytes_total{namespace=\"TARGET_NS\"}[5m]))" \
  --name rx_bytes_per_sec --name tx_bytes_per_sec \
  --start "-1h" --step 60s

oc metrics query-range \
  --query "sum(rate(container_cpu_usage_seconds_total[5m])) by (namespace)" \
  --query "sum(container_memory_working_set_bytes) by (namespace)" \
  --name cpu --name mem \
  --start "-1h"

Filtering results

Use PromQL label selectors directly in the query to narrow results:

oc metrics query-range \
  --query "rate(container_network_receive_bytes_total{namespace=\"konveyor-forklift\"}[5m])" \
  --start "-1h"

Selector operators: = (equal), != (not equal), =~ (regex), !~ (negative regex). Combine with commas: namespace="prod",pod=~"nginx.*".

Quick Health Dashboard

Run these queries for a cluster overview:

oc metrics query-range \
  --query "avg(instance:node_cpu:ratio) * 100" \
  --query "(1 - sum(node_memory_MemAvailable_bytes) / sum(node_memory_MemTotal_bytes)) * 100" \
  --name cpu_pct --name mem_pct \
  --start "-1h"

oc metrics query --query "sum(kube_node_status_condition{condition='Ready',status='true'})"
oc metrics query --query "count by (phase)(kube_pod_status_phase == 1)"
oc metrics query --query "topk(10, sort_desc(kube_pod_container_status_restarts_total))"
oc metrics query --query "ceph_health_status"

Visualizing Range Queries with gnuplot

When the user asks for a chart, graph, or visualization of metrics, use gnuplot to open an interactive window. Use the --filename flag so the CLI writes TSV directly to a temp file — the LLM never needs to see or copy the raw data.

Steps

1. Run the range query with --output tsv and --filename metrics.tsv. The CLI writes the data to a temp file and returns a short summary with the full file path, row count, and column names.
2. Extract the full file path from the summary and build a gnuplot script that reads from it. Run gnuplot -p.

Example metrics call

oc metrics query-range \
  --query "sum(rate(container_network_receive_bytes_total{namespace=\"konveyor-forklift\"}[5m]))" \
  --query "sum(rate(container_network_transmit_bytes_total{namespace=\"konveyor-forklift\"}[5m]))" \
  --name rx_bytes_per_sec --name tx_bytes_per_sec \
  --start "-24h" --step 5m \
  --output tsv --filename metrics.tsv

The response will be short, e.g.: Wrote 288 rows to /var/folders/.../T/metrics.tsv\nColumns: timestamp rx_bytes_per_sec tx_bytes_per_sec

Use the full path from the response in the gnuplot script.

gnuplot template

Replace FILE_PATH with the full path from the CLI response:

gnuplot -p <<'GP'
set terminal qt size 900,500 font "Helvetica,11"
set datafile separator "\t"
set xdata time
set timefmt "%s"
set format x "%H:%M"
set xlabel "Time"
set ylabel "UNIT"
set title "TITLE"
set grid
set key outside right top
plot "FILE_PATH" using 1:2 with lines lw 2 title "COL2", \
     "FILE_PATH" using 1:3 with lines lw 2 title "COL3"
GP

Adapting the template

• Replace FILE_PATH with the full path returned by oc metrics in its summary.
• Replace TITLE, UNIT, and column titles with descriptive values from the query.
• Use the column names from the summary returned by oc metrics for the plot titles.
• Add one using 1:N clause per data column (skip the header row automatically).
• For a single data column, drop the \ continuation and use only one plot entry.
• Use set format x "%m/%d %H:%M" when the range spans multiple days.
• The qt terminal requires GUI access. If running in a sandbox, request unsandboxed execution (e.g., required_permissions: ["all"]), otherwise the window will fail silently.
• If gnuplot or the qt terminal is not available, fall back to set terminal dumb size 120 30 for ASCII output in the shell.
• Multi-query range results produce multi-column TSV — one column per named query.
• Always pass the --filename flag for range queries intended for gnuplot. This keeps the response small and avoids slow token generation.

PromQL Quick Reference

Selecting metrics

metric_name                          all time series for this metric
metric_name{label="value"}           filter by exact label match
metric_name{label=~"pattern.*"}      filter by regex match
metric_name{label!="value"}          exclude a label value
metric_name{l1="a", l2="b"}         combine multiple filters

Rate and increase (for counters)

Counters only go up. Use rate or increase to get meaningful values:

rate(metric[5m])                     per-second rate over 5 minutes
increase(metric[1h])                 total increase over 1 hour

Aggregation

sum(metric)                          total across all series
sum by (label)(metric)               total grouped by label
avg by (label)(metric)               average grouped by label
count by (label)(metric)             count of series grouped by label
topk(10, metric)                     top 10 series by value
sort_desc(metric)                    sort descending

Arithmetic

metric_a / metric_b                  ratio of two metrics
metric * 100                         scale a metric
1 - (available / total)              compute used percentage

Common patterns

topk(10, sort_desc(sum by (namespace)(rate(container_network_receive_bytes_total[5m]))))
rate(ceph_osd_op_latency_sum[5m]) / rate(ceph_osd_op_latency_count[5m])
100 - avg by (instance)(rate(node_cpu_seconds_total{mode="idle"}[5m])) * 100

Self-Learning Rule

When you need to discover available flags or verify syntax:

oc metrics query --help
oc metrics query-range --help
oc metrics discover --help