Output Formats¶

Complete guide to output formats supported by K8s Inventory CLI for integration and automation.

Overview¶

K8s Inventory CLI supports multiple output formats to accommodate different use cases, from human-readable terminal output to machine-readable formats for automation and integration.

Available Formats¶

Table Format (Default)¶

Human-readable grid format optimized for terminal viewing:

k8s-datamodel crd list --output table
k8s-datamodel operators list --output table

Characteristics: - Clean, aligned columns - Truncated data for readability - Color coding for status indicators - Sortable columns - Perfect for interactive terminal use

Example Output:

NAME                               GROUP                      SCOPE         AGE    INSTANCES
certificates.cert-manager.io       cert-manager.io           Namespaced    30d    5
issuers.cert-manager.io           cert-manager.io           Namespaced    30d    3
clusterissuers.cert-manager.io    cert-manager.io           Cluster       30d    1

Rich Format¶

Enhanced terminal output with styling, colors, and visual enhancements:

k8s-datamodel crd list --output rich
k8s-datamodel operators list --output rich

Features: - Syntax highlighting - Color-coded status indicators - Box-drawing characters for structure - Enhanced typography - Progress indicators - Rich panels and cards

Best For: - Interactive terminal sessions - Presentations and demos - Status dashboards - Visual debugging

JSON Format¶

Machine-readable JSON format for automation and integration:

k8s-datamodel crd list --output json
k8s-datamodel operators list --output json
k8s-datamodel cluster export --output json

Characteristics: - Complete data preservation - Structured, nested objects - Easy to parse programmatically - Supports complex data types - Perfect for APIs and scripting

Example Structure:

{
  "name": "certificates.cert-manager.io",
  "group": "cert-manager.io",
  "kind": "Certificate",
  "scope": "Namespaced",
  "versions": ["v1", "v1beta1"],
  "categories": ["cert-manager"],
  "short_names": ["cert", "certs"],
  "age_days": 30,
  "instance_count": 5,
  "framework": "Helm",
  "creation_timestamp": "2024-01-15T10:30:00Z"
}

YAML Format¶

Human and machine-readable YAML format:

k8s-datamodel crd list --output yaml
k8s-datamodel operators list --output yaml
k8s-datamodel cluster export --output yaml

Features: - Human-readable structure - Preserves complex data relationships - Easy to edit and version control - Compatible with GitOps workflows - Supports comments and documentation

Example Structure:

name: certificates.cert-manager.io
group: cert-manager.io
kind: Certificate
scope: Namespaced
versions:
  - v1
  - v1beta1
categories:
  - cert-manager
short_names:
  - cert
  - certs
age_days: 30
instance_count: 5
framework: Helm
creation_timestamp: "2024-01-15T10:30:00Z"

Format Selection Guidelines¶

Use Table Format When:¶

Working interactively in terminal
Need quick overview of data
Presenting information to humans
Terminal space is limited
Quick status checks

Use Rich Format When:¶

Creating visual presentations
Need enhanced readability
Working with status dashboards
Demonstrating functionality
Color coding is important

Use JSON Format When:¶

Building automation scripts
Integrating with APIs
Processing with jq or similar tools
Storing in databases
Creating monitoring integrations

Use YAML Format When:¶

Creating configuration files
Working with GitOps workflows
Need human-editable output
Integrating with Kubernetes manifests
Documenting infrastructure

Output Customization¶

Filtering Combined with Formats¶

All formats support the same filtering options:

# JSON output with filtering
k8s-datamodel crd list --group cert-manager.io --output json

# YAML output with namespace filtering
k8s-datamodel operators list --namespace kube-system --output yaml

# Rich format with scope filtering
k8s-datamodel crd list --scope Cluster --output rich

File Output¶

Save formatted output directly to files:

# Save JSON export
k8s-datamodel cluster export --output json --file cluster-inventory.json

# Save YAML export
k8s-datamodel cluster export --output yaml --file cluster-inventory.yaml

# Save filtered CRD list
k8s-datamodel crd list --group networking.k8s.io --output json > networking-crds.json

Integration Examples¶

JSON Processing with jq¶

# Extract specific fields
k8s-datamodel crd list --output json | jq '.[] | {name, group, instances: .instance_count}'

# Filter and transform
k8s-datamodel operators list --output json | \
  jq '.[] | select(.framework == "Helm") | .name'

# Generate summary statistics
k8s-datamodel cluster export --output json | \
  jq '{
    total_crds: (.crds | length),
    total_operators: (.operators | length),
    frameworks: [.operators[].framework] | group_by(.) | map({framework: .[0], count: length})
  }'

YAML Processing with yq¶

# Extract operator information
k8s-datamodel operators list --output yaml | \
  yq eval '.[] | select(.namespace == "kube-system")'

# Transform structure
k8s-datamodel crd list --output yaml | \
  yq eval 'map({(.name): {group: .group, scope: .scope}}) | add'

# Merge with existing YAML
k8s-datamodel cluster export --output yaml | \
  yq eval-all '. as $item ireduce ({}; . * $item)' - existing-config.yaml

Shell Processing¶

# Table format with shell tools
k8s-datamodel crd list --output table | grep "cert-manager"
k8s-datamodel operators list --output table | awk '{print $1, $3}' | sort

# Count operations
CRD_COUNT=$(k8s-datamodel crd list --output json | jq '. | length')
echo "Total CRDs: $CRD_COUNT"

Automation Patterns¶

CI/CD Integration¶

#!/bin/bash
# Export and validate cluster state

# Export current state
k8s-datamodel cluster export --output json --file current-state.json

# Validate against expected state
if ! jq -e '.crds | length >= 50' current-state.json; then
  echo "ERROR: Expected minimum 50 CRDs"
  exit 1
fi

# Check operator health
UNHEALTHY=$(k8s-datamodel operators list --output json | \
  jq '.[] | select(.replicas.ready != .replicas.desired) | .name' | wc -l)

if [[ $UNHEALTHY -gt 0 ]]; then
  echo "ERROR: $UNHEALTHY unhealthy operators detected"
  exit 1
fi

Monitoring Integration¶

# Generate Prometheus metrics
k8s-datamodel cluster summary --output json | \
  jq -r '
    "k8s_inventory_crds_total " + (.crds.total | tostring),
    "k8s_inventory_operators_total " + (.operators.total | tostring),
    "k8s_inventory_operators_healthy " + (.operators.healthy | tostring)
  ' > /tmp/metrics.prom

Configuration Management¶

# Generate Ansible inventory
k8s-datamodel operators list --output json | \
  jq -r '.[] | "\(.name) ansible_host=\(.namespace) operator_framework=\(.framework)"'

# Generate Terraform variables
k8s-datamodel crd list --output json | \
  jq '{crds: [.[] | {name: .name, group: .group, scope: .scope}]}' > terraform-vars.json

Performance Considerations¶

Large Datasets¶

For clusters with many resources, consider:

# Use pagination for large results (if supported)
k8s-datamodel crd list --output json | jq '. | to_entries | .[0:50] | from_entries'

# Filter early to reduce data transfer
k8s-datamodel crd list --group specific.domain.com --output json

# Use streaming processing for large exports
k8s-datamodel cluster export --output json | jq -c '.crds[]' | while read crd; do
  # Process each CRD individually
  echo "$crd" | jq '.name'
done

Memory Management¶

# For very large exports, consider split processing
k8s-datamodel cluster export --output json | \
  jq -c '{crds: .crds}' > crds-only.json

k8s-datamodel cluster export --output json | \
  jq -c '{operators: .operators}' > operators-only.json

Format-Specific Best Practices¶

JSON Best Practices¶

Use jq -c for compact output in pipelines
Always validate JSON integrity with jq empty
Use meaningful field names when transforming
Consider schema validation for critical integrations

YAML Best Practices¶

Use consistent indentation (2 spaces recommended)
Add comments for documentation
Validate YAML syntax before committing
Use anchors and aliases for repeated data

Table Best Practices¶

Adjust terminal width for optimal display
Use filtering to limit column count
Consider pagination for large datasets
Combine with tools like less -S for horizontal scrolling

Rich Best Practices¶

Ensure terminal supports color output
Use in interactive sessions, not automation
Consider accessibility for color-blind users
Test with different terminal themes

Troubleshooting Output Issues¶

Encoding Problems¶

# Force UTF-8 encoding
export LC_ALL=C.UTF-8
k8s-datamodel crd list --output rich

Terminal Compatibility¶

# Fallback to table format if rich fails
k8s-datamodel crd list --output table

Large Output Handling¶

# Use pagination
k8s-datamodel crd list --output table | less

# Filter to reduce output size
k8s-datamodel crd list --group cert-manager.io --output table

JSON Parsing Issues¶

# Validate JSON output
k8s-datamodel crd list --output json | jq empty && echo "Valid JSON" || echo "Invalid JSON"

# Pretty print for debugging
k8s-datamodel crd list --output json | jq .

CRDs: CRD-specific command examples
Operators: Operator command examples
Cluster Operations: Cluster-wide export examples