PromQL Query Generator

Overview

This skill provides a comprehensive, interactive workflow for generating production-ready PromQL queries with best practices built-in. Generate queries for monitoring dashboards, alerting rules, and ad-hoc analysis with an emphasis on user collaboration and planning before code generation.

When to Use This Skill

Invoke this skill when:

Creating new PromQL queries from scratch
Building monitoring dashboards (Grafana, Prometheus UI, etc.)
Implementing alerting rules for Prometheus Alertmanager
Analyzing metrics for troubleshooting or capacity planning
Converting monitoring requirements into PromQL expressions
Learning PromQL or teaching others
The user asks to "create", "generate", "build", or "write" PromQL queries
Working with Prometheus metrics (counters, gauges, histograms, summaries)
Implementing RED (Rate, Errors, Duration) or USE (Utilization, Saturation, Errors) metrics

Interactive Query Planning Workflow

CRITICAL: This skill emphasizes interactive planning before query generation. Always engage the user in a collaborative planning process to ensure the generated query matches their exact intentions.

Follow this workflow when generating PromQL queries:

Stage 1: Understand the Monitoring Goal

Start by understanding what the user wants to monitor or measure. Ask clarifying questions to gather requirements:

Primary Goal: What are you trying to monitor or measure?
- Request rate (requests per second)
- Error rate (percentage of failed requests)
- Latency/duration (response times, percentiles)
- Resource usage (CPU, memory, disk, network)
- Availability/uptime
- Queue depth, saturation, throughput
- Custom business metrics
Use Case: What will this query be used for?
- Dashboard visualization (Grafana, Prometheus UI)
- Alerting rule (firing when threshold exceeded)
- Ad-hoc troubleshooting/analysis
- Recording rule (pre-computed aggregation)
- Capacity planning or SLO tracking
Context: Any additional context?
- Service/application name
- Team or project
- Priority level
- Existing metrics or naming conventions

Use the AskUserQuestion tool to gather this information if not provided.

When to Ask vs. Infer: If the user's initial request already clearly specifies the goal, use case, and context (e.g., "Create an alert for P95 latency > 500ms for payment-service"), you may acknowledge these details in your response instead of re-asking. Only ask clarifying questions for information that is missing or ambiguous.

Stage 2: Identify Available Metrics

Determine which metrics are available and relevant:

Metric Discovery: What metrics are available?
- Ask the user for metric names
- If uncertain, suggest common naming patterns
- Check for metric type indicators in the name:
  - _total suffix → Counter
  - _bucket, _sum, _count suffix → Histogram
  - No suffix → Likely Gauge
  - _created suffix → Counter creation timestamp
Metric Type Identification: Confirm the metric type(s)
- Counter: Cumulative metric that only increases (or resets to zero)
  - Examples: http_requests_total, errors_total, bytes_sent_total
  - Use with: rate(), irate(), increase()
- Gauge: Point-in-time value that can go up or down
  - Examples: memory_usage_bytes, cpu_temperature_celsius, queue_length
  - Use with: avg_over_time(), min_over_time(), max_over_time(), or directly
- Histogram: Buckets of observations with cumulative counts
  - Examples: http_request_duration_seconds_bucket, response_size_bytes_bucket
  - Use with: histogram_quantile(), rate()
- Summary: Pre-calculated quantiles with count and sum
  - Examples: rpc_duration_seconds{quantile="0.95"}
  - Use _sum and _count for averages; don't average quantiles
Label Discovery: What labels are available on these metrics?
- Common labels: job, instance, environment, service, endpoint, status_code, method
- Ask which labels are important for filtering or grouping

Use the AskUserQuestion tool to confirm metric names, types, and available labels.

Stage 3: Determine Query Parameters

Gather specific requirements for the query.

Pre-confirmation for User-Provided Parameters

IMPORTANT: When the user has already specified parameters in their initial request (e.g., "5-minute window", "500ms threshold", "> 5% error rate"), you MUST:

Acknowledge the provided values explicitly in your response
Present them as pre-filled defaults in AskUserQuestion with the first option being "Use specified values"
Allow quick confirmation rather than re-asking for information already given

Example: If user says "alert when P95 latency exceeds 500ms", use:

AskUserQuestion:
- Question: "Confirm the alert threshold?"
- Options:
  1. "500ms (as specified)" - Use the threshold from your request
  2. "Different threshold" - Let me specify a different value

This respects the user's input and speeds up the workflow while still allowing modifications.

Time Range: What time window should the query cover?
- Instant value (current)
- Rate over time ([5m], [1h], [1d])
- For rate calculations: typically [1m] to [5m] for real-time, [1h] to [1d] for trends
- Rule of thumb: Rate range should be at least 4x the scrape interval
Label Filtering: Which labels should filter the data?
- Exact matches: job="api-server", status_code="200"
- Negative matches: status_code!="200"
- Regex matches: instance=~"prod-.*"
- Multiple conditions: {job="api", environment="production"}
Aggregation: Should the data be aggregated?
- No aggregation: Return all time series as-is
- Aggregate by labels: sum by (job, endpoint), avg by (instance)
- Aggregate without labels: sum without (instance, pod), avg without (job)
- Common aggregations: sum, avg, max, min, count, topk, bottomk
Thresholds or Conditions: Are there specific conditions?
- For alerting: threshold values (e.g., error rate > 5%)
- For filtering: only show series above/below a value
- For comparison: compare against historical data (offset)

Use the AskUserQuestion tool to gather or confirm these parameters. When the user has already provided values (e.g., "5-minute window", "> 5%"), present them as the default option for confirmation.

Stage 4: Present the Query Plan

BEFORE GENERATING ANY CODE, present a plain-English query plan and ask for user confirmation:

## PromQL Query Plan

Based on your requirements, here's what the query will do:

**Goal**: [Describe the monitoring goal in plain English]

**Query Structure**:
1. Start with metric: `[metric_name]`
2. Filter by labels: `{label1="value1", label2="value2"}`
3. Apply function: `[function_name]([metric][time_range])`
4. Aggregate: `[aggregation] by ([label_list])`
5. Additional operations: [any calculations, ratios, or transformations]

**Expected Output**:
- Data type: [instant vector/scalar]
- Labels in result: [list of labels]
- Value represents: [what the number means]
- Typical range: [expected value range]

**Example Interpretation**:
If the query returns `0.05`, it means: [plain English explanation]

**Does this match your intentions?**
- If yes, I'll generate the query and validate it
- If no, let me know what needs to change

Use the AskUserQuestion tool to confirm the plan with options:

"Yes, generate this query"
"Modify [specific aspect]"
"Show me alternative approaches"

When the user chooses:

"Modify [specific aspect]": ask one focused follow-up question about what to change (metric, labels, function, time range, threshold, or output shape), then present an updated plan before generating.
"Show me alternative approaches": provide at least two valid query plans with trade-offs (accuracy, cost, cardinality, readability), then ask the user to choose one before generating.

Stage 5: Generate the PromQL Query

Once the user confirms the plan, generate the actual PromQL query following best practices.

IMPORTANT: Consult Reference Files Before Generating

Before writing any query code, you MUST:

Identify the query category first (histogram, RED, USE, function-specific, optimization, etc.).
Read only the relevant reference section(s) using the Read tool:
- For histogram queries → Read references/metric_types.md (Histogram section)
- For error/latency patterns → Read references/promql_patterns.md (RED method section)
- For resource monitoring → Read references/promql_patterns.md (USE method section)
- For optimization questions → Read references/best_practices.md
- For specific functions → Read references/promql_functions.md
- Re-read a section only if requirements changed or you have not consulted it yet in the current thread.
If a needed reference cannot be read, state the issue and continue with best-effort generation using the most applicable documented pattern you already have.

Cite the applicable pattern or best practice in your response:

As documented in references/promql_patterns.md (Pattern 3: Latency Percentile):
# 95th percentile latency
histogram_quantile(0.95, sum by (le) (rate(...)))

Reference example files when generating similar queries:

Based on examples/red_method.promql (lines 64-82):
# P95 latency with proper histogram_quantile usage

This keeps generated queries aligned with documented patterns while avoiding unnecessary full-file rereads on iterative follow-ups.

Best Practices for Query Generation

Always Use Label Filters

# Good: Specific filtering reduces cardinality
rate(http_requests_total{job="api-server", environment="prod"}[5m])

# Bad: Matches all time series, high cardinality
rate(http_requests_total[5m])

Use Appropriate Functions for Metric Types

# Counter: Use rate() or increase()
rate(http_requests_total[5m])

# Gauge: Use directly or with *_over_time()
memory_usage_bytes
avg_over_time(memory_usage_bytes[5m])

# Histogram: Use histogram_quantile()
histogram_quantile(0.95,
  sum by (le) (rate(http_request_duration_seconds_bucket[5m]))
)

Apply Aggregations with by() or without()

# Aggregate by specific labels (keeps only these labels)
sum by (job, endpoint) (rate(http_requests_total[5m]))

# Aggregate without specific labels (removes these labels)
sum without (instance, pod) (rate(http_requests_total[5m]))

Use Exact Matches Over Regex When Possible

# Good: Faster exact match
http_requests_total{status_code="200"}

# Bad: Slower regex match when not needed
http_requests_total{status_code=~"200"}

Calculate Ratios Properly

# Error rate: errors / total requests
sum(rate(http_requests_total{status_code=~"5.."}[5m]))
/
sum(rate(http_requests_total[5m]))

Use Recording Rules for Complex Queries
- If a query is used frequently or is computationally expensive
- Pre-aggregate data to reduce query load
- Follow naming convention: level:metric:operations

Format for Readability

# Good: Multi-line for complex queries
histogram_quantile(0.95,
  sum by (le, job) (
    rate(http_request_duration_seconds_bucket{job="api-server"}[5m])
  )
)

Common Query Patterns

Pattern 1: Request Rate

# Requests per second
rate(http_requests_total{job="api-server"}[5m])

# Total requests per second across all instances
sum(rate(http_requests_total{job="api-server"}[5m]))

Pattern 2: Error Rate

# Error ratio (0 to 1)
sum(rate(http_requests_total{job="api-server", status_code=~"5.."}[5m]))
/
sum(rate(http_requests_total{job="api-server"}[5m]))

# Error percentage (0 to 100)
(
  sum(rate(http_requests_total{job="api-server", status_code=~"5.."}[5m]))
  /
  sum(rate(http_requests_total{job="api-server"}[5m]))
) * 100

Pattern 3: Latency Percentile (Histogram)

# 95th percentile latency
histogram_quantile(0.95,
  sum by (le) (
    rate(http_request_duration_seconds_bucket{job="api-server"}[5m])
  )
)

Pattern 4: Resource Usage

# Current memory usage
process_resident_memory_bytes{job="api-server"}

# Average CPU usage over 5 minutes
avg_over_time(process_cpu_seconds_total{job="api-server"}[5m])

Pattern 5: Availability

# Percentage of up instances
(
  count(up{job="api-server"} == 1)
  /
  count(up{job="api-server"})
) * 100

Pattern 6: Saturation/Queue Depth

# Average queue length
avg_over_time(queue_depth{job="worker"}[5m])

# Maximum queue depth in the last hour
max_over_time(queue_depth{job="worker"}[1h])

Stage 6: Validate the Generated Query

ALWAYS attempt to validate the generated query first using the devops-skills:promql-validator skill:

After generating the query, automatically invoke:
Skill(devops-skills:promql-validator)

The devops-skills:promql-validator skill will:
1. Check syntax correctness
2. Validate semantic logic (correct functions for metric types)
3. Identify anti-patterns and inefficiencies
4. Suggest optimizations
5. Explain what the query does
6. Verify it matches user intent

Validation checklist:

Syntax is correct (balanced brackets, valid operators)
Metric type matches function usage
Label filters are specific enough
Aggregation is appropriate
Time ranges are reasonable
No known anti-patterns
Query is optimized for performance

If validation fails, fix issues and re-validate until all checks pass.

If the validator skill is unavailable, fails to run, or cannot complete after two fix/re-validate cycles:

Report the validator failure briefly (tool unavailable, timeout, parsing error, etc.).
Run a manual fallback check (syntax shape, metric/function compatibility, label filtering, aggregation, time range sanity).
Mark any unchecked areas as UNVERIFIED and ask the user whether to proceed with best-effort output or provide more context for another validation attempt.

IMPORTANT: Display Validation Results to User

After running validation, you MUST display the structured results to the user in this format:

## PromQL Validation Results

### Syntax Check
- Status: ✅ VALID / ⚠️ WARNING / ❌ ERROR / ⚠️ UNVERIFIED
- Issues: [list any syntax errors]

### Best Practices Check
- Status: ✅ OPTIMIZED / ⚠️ CAN BE IMPROVED / ❌ HAS ISSUES / ⚠️ UNVERIFIED
- Issues: [list any problems found]
- Suggestions: [list optimization opportunities]

### Validation Coverage
- Validator tool run: [successful / failed / unavailable]
- Checks completed: [syntax, semantics, anti-patterns, performance, intent-match]
- Checks skipped: [list any skipped checks, or "None"]

### Query Explanation
- **What it measures**: [plain English description]
- **Output labels**: [list labels in result, or "None (scalar)"]
- **Expected result structure**: [instant vector / scalar / etc.]

This transparency helps users understand the validation process and any recommendations.

Stage 7: Provide Usage Instructions

After generation and validation (or manual fallback validation), provide the user with:

The Final Query:
```
[Generated and validated PromQL query]
```
Query Explanation:
- What the query measures
- How to interpret the results
- Expected value range
- Labels in the output
How to Use It:
- For Dashboards: Copy into Grafana/Prometheus UI panel query
- For Alerts: Integrate into Alertmanager rule with threshold
- For Recording Rules: Add to Prometheus recording rule config
- For Ad-hoc: Run directly in Prometheus expression browser
Customization Notes:
- Time ranges that might need adjustment
- Labels to modify for different environments
- Threshold values to tune
- Alternative functions if requirements change
Related Queries:
- Suggest complementary queries
- Mention recording rule opportunities
- Recommend dashboard panels

Native Histograms (Prometheus 3.x+)

Native histograms are now stable in Prometheus 3.0+ (released November 2024). They offer significant advantages over classic histograms:

Sparse bucket representation with near-zero cost for empty buckets
No configuration of bucket boundaries during instrumentation
Coverage of the full float64 range
Efficient mergeability across histograms
Simpler query syntax

Important: Starting with Prometheus v3.8.0, native histograms are fully stable. However, scraping native histograms still requires explicit activation via the scrape_native_histograms configuration setting. Starting with v3.9, no feature flag is needed but scrape_native_histograms must be set explicitly.

Native vs Classic Histogram Syntax

# Classic histogram (requires _bucket suffix and le label)
histogram_quantile(0.95,
  sum by (job, le) (rate(http_request_duration_seconds_bucket[5m]))
)

# Native histogram (simpler - no _bucket suffix, no le label needed)
histogram_quantile(0.95,
  sum by (job) (rate(http_request_duration_seconds[5m]))
)

Native Histogram Functions

# Get observation count rate from native histogram
histogram_count(rate(http_request_duration_seconds[5m]))

# Get sum of observations from native histogram
histogram_sum(rate(http_request_duration_seconds[5m]))

# Calculate fraction of observations between two values
histogram_fraction(0, 0.1, rate(http_request_duration_seconds[5m]))

# Average request duration from native histogram
histogram_sum(rate(http_request_duration_seconds[5m]))
/
histogram_count(rate(http_request_duration_seconds[5m]))

Detecting Native vs Classic Histograms

Native histograms are identified by:

No _bucket suffix on the metric name
No le label in the time series
The metric stores histogram data directly (not separate bucket counters)

When querying, check if your Prometheus instance has native histograms enabled:

# prometheus.yml - Enable native histogram scraping
scrape_configs:
  - job_name: 'my-app'
    scrape_native_histogram: true  # Prometheus 3.x+

Custom Bucket Native Histograms (NHCB)

Prometheus 3.4+ supports custom bucket native histograms (schema -53), allowing classic histogram to native histogram conversion. This is a key migration path for users with existing classic histograms.

Benefits of NHCB:

Keep existing instrumentation (no code changes needed)
Store classic histograms as native histograms for lower costs
Query with native histogram syntax
Improved reliability and compression

Configuration (Prometheus 3.4+):

# prometheus.yml - Convert classic histograms to NHCB on scrape
global:
  scrape_configs:
    - job_name: 'my-app'
      convert_classic_histograms_to_nhcb: true  # Prometheus 3.4+

Querying NHCB:

# Query NHCB metrics the same way as native histograms
histogram_quantile(0.95, sum by (job) (rate(http_request_duration_seconds[5m])))

# histogram_fraction also works with NHCB (Prometheus 3.4+)
histogram_fraction(0, 0.2, rate(http_request_duration_seconds[5m]))

Note: Schema -53 indicates custom bucket boundaries. These histograms with different custom bucket boundaries are generally not mergeable with each other.

SLO, Error Budget, and Burn Rate Patterns

Service Level Objectives (SLOs) are critical for modern SRE practices. These patterns help implement SLO-based monitoring and alerting.

Error Budget Calculation

# Error budget remaining (for 99.9% SLO over 30 days)
# Returns value between 0 and 1 (1 = full budget, 0 = exhausted)
1 - (
  sum(rate(http_requests_total{job="api", status_code=~"5.."}[30d]))
  /
  sum(rate(http_requests_total{job="api"}[30d]))
) / 0.001  # 0.001 = 1 - 0.999 (allowed error rate)

# Simplified: Availability over 30 days
sum(rate(http_requests_total{job="api", status_code!~"5.."}[30d]))
/
sum(rate(http_requests_total{job="api"}[30d]))

Burn Rate Calculation

Burn rate measures how fast you're consuming error budget. A burn rate of 1 means you'll exhaust the budget exactly at the end of the SLO window.

# Current burn rate (1 hour window, 99.9% SLO)
# Burn rate = (current error rate) / (allowed error rate)
(
  sum(rate(http_requests_total{job="api", status_code=~"5.."}[1h]))
  /
  sum(rate(http_requests_total{job="api"}[1h]))
) / 0.001  # 0.001 = allowed error rate for 99.9% SLO

# Burn rate > 1 means consuming budget faster than allowed
# Burn rate of 14.4 consumes 2% of monthly budget in 1 hour

Multi-Window, Multi-Burn-Rate Alerts (Google SRE Standard)

The recommended approach for SLO alerting uses multiple windows to balance detection speed and precision:

# Page-level alert: 2% budget in 1 hour (burn rate 14.4)
# Long window (1h) AND short window (5m) must both exceed threshold
(
  (
    sum(rate(http_requests_total{job="api", status_code=~"5.."}[1h]))
    /
    sum(rate(http_requests_total{job="api"}[1h]))
  ) > 14.4 * 0.001
)
and
(
  (
    sum(rate(http_requests_total{job="api", status_code=~"5.."}[5m]))
    /
    sum(rate(http_requests_total{job="api"}[5m]))
  ) > 14.4 * 0.001
)

# Ticket-level alert: 5% budget in 6 hours (burn rate 6)
(
  (
    sum(rate(http_requests_total{job="api", status_code=~"5.."}[6h]))
    /
    sum(rate(http_requests_total{job="api"}[6h]))
  ) > 6 * 0.001
)
and
(
  (
    sum(rate(http_requests_total{job="api", status_code=~"5.."}[30m]))
    /
    sum(rate(http_requests_total{job="api"}[30m]))
  ) > 6 * 0.001
)

SLO Recording Rules

Pre-compute SLO metrics for efficient alerting:

# Recording rules for SLO calculations
groups:
  - name: slo_recording_rules
    interval: 30s
    rules:
      # Error ratio over different windows
      - record: job:slo_errors_per_request:ratio_rate1h
        expr: |
          sum by (job) (rate(http_requests_total{status_code=~"5.."}[1h]))
          /
          sum by (job) (rate(http_requests_total[1h]))

      - record: job:slo_errors_per_request:ratio_rate5m
        expr: |
          sum by (job) (rate(http_requests_total{status_code=~"5.."}[5m]))
          /
          sum by (job) (rate(http_requests_total[5m]))

      # Availability (success ratio)
      - record: job:slo_availability:ratio_rate1h
        expr: |
          1 - job:slo_errors_per_request:ratio_rate1h

Latency SLO Queries

# Percentage of requests faster than SLO target (200ms)
(
  sum(rate(http_request_duration_seconds_bucket{le="0.2", job="api"}[5m]))
  /
  sum(rate(http_request_duration_seconds_count{job="api"}[5m]))
) * 100

# Requests violating latency SLO (slower than 500ms)
(
  sum(rate(http_request_duration_seconds_count{job="api"}[5m]))
  -
  sum(rate(http_request_duration_seconds_bucket{le="0.5", job="api"}[5m]))
)
/
sum(rate(http_request_duration_seconds_count{job="api"}[5m]))

Burn Rate Reference Table

Burn Rate	Budget Consumed	Time to Exhaust 30-day Budget	Alert Severity
1	100% over 30d	30 days	None
2	100% over 15d	15 days	Low
6	5% in 6h	5 days	Ticket
14.4	2% in 1h	~2 days	Page
36	5% in 1h	~20 hours	Page (urgent)

Advanced Query Techniques

Using Subqueries

Subqueries enable complex time-based calculations:

# Maximum 5-minute rate over the past 30 minutes
max_over_time(
  rate(http_requests_total[5m])[30m:1m]
)

Syntax: <query>[<range>:<resolution>]

<range>: Time window to evaluate over
<resolution>: Step size between evaluations

Using Offset Modifier

Compare current data with historical data:

# Compare current rate with rate from 1 week ago
rate(http_requests_total[5m])
-
rate(http_requests_total[5m] offset 1w)

Using @ Modifier

Query metrics at specific timestamps:

# Rate at the end of the range query
rate(http_requests_total[5m] @ end())

# Rate at specific Unix timestamp
rate(http_requests_total[5m] @ 1609459200)

Binary Operators and Vector Matching

Combine metrics with operators and control label matching:

# One-to-one matching (default)
metric_a + metric_b

# Many-to-one with group_left
rate(http_requests_total[5m])
* on (job, instance) group_left (version)
  app_version_info

# Ignoring specific labels
metric_a + ignoring(instance) metric_b

Logical Operators

Filter time series based on conditions:

# Return series only where value > 100
http_requests_total > 100

# Return series present in both
metric_a and metric_b

# Return series in A but not in B
metric_a unless metric_b

Documentation Lookup

If the user asks about specific Prometheus features, operators, or custom metrics:

Try context7 MCP first (preferred):

Use mcp__context7__resolve-library-id with "prometheus"
Then use mcp__context7__get-library-docs with:
- context7CompatibleLibraryID: /prometheus/docs
- topic: [specific feature, function, or operator]
- page: 1 (fetch additional pages if needed)

Fallback to WebSearch:

Search query pattern:
"Prometheus PromQL [function/operator/feature] documentation [version] examples"

Examples:
"Prometheus PromQL rate function documentation examples"
"Prometheus PromQL histogram_quantile documentation best practices"
"Prometheus PromQL aggregation operators documentation"

Common Monitoring Scenarios

RED Method (for Request-Driven Services)

Rate: Request throughput

sum(rate(http_requests_total{job="api"}[5m])) by (endpoint)

Errors: Error rate

sum(rate(http_requests_total{job="api", status_code=~"5.."}[5m]))
/
sum(rate(http_requests_total{job="api"}[5m]))

Duration: Latency percentiles

histogram_quantile(0.95,
  sum by (le) (rate(http_request_duration_seconds_bucket{job="api"}[5m]))
)

USE Method (for Resources)

Utilization: Resource usage percentage

(
  avg(rate(node_cpu_seconds_total{mode!="idle"}[5m]))
  /
  count(node_cpu_seconds_total{mode="idle"})
) * 100

Saturation: Queue depth or resource contention
```
avg_over_time(node_load1[5m])
```

Errors: Error counters

rate(node_network_receive_errs_total[5m])

Alerting Rules

When generating queries for alerting:

Include the Threshold: Make the condition explicit

# Alert when error rate exceeds 5%
(
  sum(rate(http_requests_total{status_code=~"5.."}[5m]))
  /
  sum(rate(http_requests_total[5m]))
) > 0.05

Use Boolean Operators: Return 1 (fire) or 0 (no alert)

# Returns 1 when memory usage > 90%
(process_resident_memory_bytes / node_memory_MemTotal_bytes) > 0.9

Consider for Duration: Alerts typically use for clause

alert: HighErrorRate
expr: |
  (
    sum(rate(http_requests_total{status_code=~"5.."}[5m]))
    /
    sum(rate(http_requests_total[5m]))
  ) > 0.05
for: 10m  # Only fire after 10 minutes of continuous violation

Recording Rules

When generating queries for recording rules:

Follow Naming Convention: level:metric:operations

# level: aggregation level (job, instance, etc.)
# metric: base metric name
# operations: functions applied

- record: job:http_requests:rate5m
  expr: sum by (job) (rate(http_requests_total[5m]))

Pre-aggregate Expensive Queries:

# Recording rule for frequently-used latency query
- record: job_endpoint:http_request_duration_seconds:p95
  expr: |
    histogram_quantile(0.95,
      sum by (job, endpoint, le) (
        rate(http_request_duration_seconds_bucket[5m])
      )
    )

Use Recorded Metrics in Dashboards:

# Instead of expensive query, use pre-recorded metric
job_endpoint:http_request_duration_seconds:p95{job="api-server"}

Error Handling

Common Issues and Solutions

Empty Results:
- Check if metrics exist: up{job="your-job"}
- Verify label filters are correct
- Check time range is appropriate
- Confirm metric is being scraped
Too Many Series (High Cardinality):
- Add more specific label filters
- Use aggregation to reduce series count
- Consider using recording rules
- Check for label explosion (dynamic labels)
Incorrect Values:
- Verify metric type (counter vs gauge)
- Check function usage (rate on counters, not gauges)
- Verify time range is appropriate
- Check for counter resets
Performance Issues:
- Reduce time range for range vectors
- Add label filters to reduce cardinality
- Use recording rules for complex queries
- Avoid expensive regex patterns
- Consider query timeout settings

Communication Guidelines

When generating queries:

Explain the Plan: Always present a plain-English plan before generating
Ask Questions: Use AskUserQuestion tool to gather requirements
Confirm Intent: Verify the query matches user goals before finalizing
Educate: Explain why certain functions or patterns are used
Provide Context: Show how to interpret results
Suggest Improvements: Offer optimizations or alternative approaches
Validate Proactively: Always validate and fix issues
Follow Up: Ask if adjustments are needed

Fallback When AskUserQuestion Is Unavailable

If a structured question tool is unavailable, continue with an explicit inline questionnaire in plain text:

Ask for goal, metric names/types, labels, time range, aggregation, and use case in one compact prompt.
If the user provides partial answers, proceed with conservative defaults and clearly mark assumptions.
If core inputs are still ambiguous, offer 2-3 concrete query-plan options and ask the user to pick one.
Do not block generation indefinitely waiting for perfect context; generate a best-effort query with assumption notes.

Relevant Reference Criteria and Trivial-Case Skip Rules

Use references deterministically, but avoid unnecessary reads for trivial requests.

Read references when ANY of the following is true:

Histogram or summary quantiles are requested
Query uses joins/vector matching, subqueries, offsets, or recording/alerting rules
Query is for SLO/burn-rate/error-budget workflows
Query includes optimization or cardinality concerns
Metric type is unknown or contested

Skip reference reads only when ALL of the following are true:

Single-metric, single-function query (rate, increase, sum, avg, max, min)
No joins, no recording/alert rules, no advanced functions
Metric type and labels are clearly provided by the user

When skipping, explicitly state: Reference read skipped (trivial case) and keep validation mandatory.

Integration with devops-skills:promql-validator

After generating any PromQL query, automatically invoke the devops-skills:promql-validator skill to ensure quality:

Steps:
1. Generate the PromQL query based on user requirements
2. Invoke devops-skills:promql-validator skill with the generated query
3. Review validation results (syntax, semantics, performance)
4. Fix any issues identified by the validator
5. Re-validate until all checks pass
6. Provide the final validated query with usage instructions
7. Ask user if further refinements are needed

This ensures all generated queries follow best practices and are production-ready.

Resources

IMPORTANT: Explicit Reference Consultation

When generating queries, you SHOULD explicitly read the relevant reference files using the Read tool and cite applicable best practices. This ensures generated queries follow documented patterns and helps users understand why certain approaches are recommended.

references/

promql_functions.md

Comprehensive reference of all PromQL functions
Grouped by category (aggregation, math, time, histogram, etc.)
Usage examples for each function
Read this file when: implementing specific function requirements or when user asks about function behavior

promql_patterns.md

Common query patterns for typical monitoring scenarios
RED method patterns (Rate, Errors, Duration)
USE method patterns (Utilization, Saturation, Errors)
Alerting and recording rule patterns
Read this file when: implementing standard monitoring patterns like error rates, latency, or resource usage

best_practices.md

PromQL best practices and anti-patterns
Performance optimization guidelines
Cardinality management
Query structure recommendations
Read this file when: optimizing queries, reviewing for anti-patterns, or when cardinality concerns arise

metric_types.md

Detailed guide to Prometheus metric types
Counter, Gauge, Histogram, Summary
When to use each type
Appropriate functions for each type
Read this file when: clarifying metric type questions or determining appropriate functions for a metric

examples/

common_queries.promql

Collection of commonly-used PromQL queries
Request rate, error rate, latency queries
Resource usage queries
Availability and uptime queries
Can be copied and customized

red_method.promql

Complete RED method implementation
Request rate queries
Error rate queries
Duration/latency queries

use_method.promql

Complete USE method implementation
Utilization queries
Saturation queries
Error queries

alerting_rules.yaml

Example Prometheus alerting rules
Various threshold-based alerts
Best practices for alert expressions

recording_rules.yaml

Example Prometheus recording rules
Pre-aggregated metrics
Naming conventions

slo_patterns.promql

SLO, error budget, and burn rate queries
Multi-window, multi-burn-rate alerting patterns
Latency SLO compliance queries

kubernetes_patterns.promql

Kubernetes monitoring patterns
kube-state-metrics queries (pods, deployments, nodes)
cAdvisor container metrics (CPU, memory)
Vector matching and joins for Kubernetes

Important Notes

Always Plan Interactively: Never generate a query without confirming the plan with the user
Use AskUserQuestion: Leverage the tool to gather requirements and confirm plans
Validate Everything: Always invoke devops-skills:promql-validator after generation
Educate Users: Explain what the query does and why it's structured that way
Consider Use Case: Tailor the query based on whether it's for dashboards, alerts, or analysis
Think About Performance: Always include label filters and consider cardinality
Follow Metric Types: Use appropriate functions for counters, gauges, and histograms
Format for Readability: Use multi-line formatting for complex queries

Success Criteria

A successful query generation session should meet these measurable checkpoints:

Requirement capture completed: goal/use-case/metric/time-range/aggregation recorded.
Plan confirmation completed: user approved plan OR explicit assumption set documented.
Reference decision recorded: consulted with file names OR skipped (trivial case) with reason.
Query validity completed: syntax passes validator or manual fallback check.
Semantic sanity completed: function choice matches metric type (counter/gauge/histogram/summary).
Cardinality guard completed: query includes explicit filters or aggregation rationale.
Delivery completed: final query + interpretation + next-step customization guidance provided.

Remember

The goal is to collaboratively plan and generate PromQL queries that exactly match user intentions. Always prioritize clarity, correctness, and performance. The interactive planning phase is the most important part of this skill—never skip it!

promql-generator