Overview The -l or --limit option allows you to filter which hosts appear in the generated CMDB output. This works similarly to Ansible’s built-in limit functionality.
Host limiting requires the -i option to point to your inventory file. Without an inventory, ansible-cmdb cannot determine group memberships.
Basic Usage ansible-cmdb -i hosts -l 'pattern' out/ > cmdb.html
Pattern Syntax Ansible-cmdb supports the following pattern types:
Include all hosts in the inventory. ansible-cmdb -i hosts -l 'all' out/ > cmdb.html
Include a specific host by its exact name. ansible-cmdb -i hosts -l 'web1.example.com' out/ > cmdb.html
Include all hosts in a specific group. ansible-cmdb -i hosts -l 'webservers' out/ > cmdb.html
Exclude hosts matching the pattern (inversion). ansible-cmdb -i hosts -l '!development' out/ > cmdb.html
Combine multiple patterns with colon (:) separator. ansible-cmdb -i hosts -l 'webservers:databases' out/ > cmdb.html
Examples Single Group Include only hosts in the webservers group:
ansible-cmdb -i hosts -l 'webservers' out/ > webservers_cmdb.html
Specific Host Generate CMDB for a single host:
ansible-cmdb -i hosts -l 'db1.example.com' out/ > db1_cmdb.html
Multiple Groups Include hosts from multiple groups:
ansible-cmdb -i hosts -l 'webservers:databases' out/ > web_and_db_cmdb.html
Exclude Group Include all hosts except those in a specific group:
ansible-cmdb -i hosts -l 'all:!development' out/ > production_cmdb.html
Complex Pattern Combine inclusion and exclusion:
# Include all hosts in cust.acme, exclude the group itself, but add back foo.example.com ansible-cmdb -i hosts -l 'all:!cust.acme:foo.example.com' out/ > cmdb.html
Real-World Use Cases Environment Separation
Customer Segregation
Function-Based
Compliance Reporting
Generate separate CMDBs for each environment: # Development CMDB ansible-cmdb -i hosts -l 'development' out/ > dev_cmdb.html # Production CMDB ansible-cmdb -i hosts -l 'production' out/ > prod_cmdb.html # Non-production (test + dev) ansible-cmdb -i hosts -l 'development:testing' out/ > nonprod_cmdb.html
Generate CMDBs per customer: # Single customer ansible-cmdb -i hosts -l 'cust.acme' out/ > acme_cmdb.html # All customers except one ansible-cmdb -i hosts -l 'all:!cust.internal' out/ > external_cmdb.html
Generate CMDBs by infrastructure function: # Web tier only ansible-cmdb -i hosts -l 'webservers' out/ > web_tier.html # Database tier only ansible-cmdb -i hosts -l 'databases' out/ > db_tier.html # Application stack (web + app + db) ansible-cmdb -i hosts -l 'webservers:appservers:databases' out/ > app_stack.html
Generate compliance-specific reports: # PCI-compliant hosts only ansible-cmdb -i hosts -l 'pci_scope' out/ > pci_cmdb.html # Everything except PCI ansible-cmdb -i hosts -l 'all:!pci_scope' out/ > non_pci_cmdb.html
Sample Inventory To illustrate limiting, here’s a sample inventory structure:
[development] dev1.example.com dev2.example.com [testing] test1.example.com test2.example.com [production] web1.example.com web2.example.com db1.example.com [webservers] web1.example.com web2.example.com dev1.example.com [databases] db1.example.com [cust.acme] web1.example.com db1.example.com [cust.internal] dev1.example.com dev2.example.com test1.example.com test2.example.com
Example Limit Patterns Using the inventory above:
Production only
Production webservers
Everything except development
Specific customer with exception
ansible-cmdb -i hosts -l 'production' out/ > cmdb.html # Includes: web1, web2, db1
Limitations Current limitations of the --limit option:
No wildcards : Patterns like db*.example.com are not supportedNo host expansions : Patterns like db[0-3].example.com are not supportedRequires inventory : The -i option must be specified for limiting to work Unsupported Patterns # These do NOT work: ansible-cmdb -i hosts -l 'web*.example.com' out/ > cmdb.html # ✗ wildcards ansible-cmdb -i hosts -l 'web[1-3].example.com' out/ > cmdb.html # ✗ ranges # Use exact names or groups instead: ansible-cmdb -i hosts -l 'web1.example.com:web2.example.com:web3.example.com' out/ > cmdb.html # ✓ ansible-cmdb -i hosts -l 'webservers' out/ > cmdb.html # ✓
Combining with Templates Limiting works with all templates:
html_fancy
txt_table
json
csv
ansible-cmdb -i hosts -l 'production' -t html_fancy out/ > prod.html
ansible-cmdb -i hosts -l 'webservers' -t txt_table out/
ansible-cmdb -i hosts -l 'databases' -t json out/ > db.json
ansible-cmdb -i hosts -l 'production' -t csv out/ > prod.csv
Automation Examples Generate Multiple CMDBs Create separate CMDB files for different groups:
#!/bin/bash # Output directory OUTPUT_DIR = "/var/www/html/cmdb" # Generate CMDB for each environment for env in development testing production ; do ansible-cmdb -i /etc/ansible/hosts -l " $env " /var/cache/ansible/facts > " $OUTPUT_DIR /${ env }_cmdb.html" done # Generate CMDB for each customer for customer in acme globex initech ; do ansible-cmdb -i /etc/ansible/hosts -l "cust.${ customer }" /var/cache/ansible/facts > " $OUTPUT_DIR /${ customer }_cmdb.html" done
Scheduled Reports Use cron to generate regular reports:
# Generate production CMDB daily at 2 AM 0 2 * * * /usr/local/bin/ansible-cmdb -i /etc/ansible/hosts -l 'production' /var/cache/ansible/facts > /var/www/html/prod_cmdb.html # Generate development CMDB every 6 hours 0 */6 * * * /usr/local/bin/ansible-cmdb -i /etc/ansible/hosts -l 'development' /var/cache/ansible/facts > /var/www/html/dev_cmdb.html
Best Practices
Organize your inventory - Use meaningful group names that map to your limiting needsUse hierarchical groups - Create parent groups for easier limiting:
[production:children] prod_web prod_db prod_app
Document patterns - Keep a list of common limit patterns for your teamTest patterns - Verify your pattern matches expected hosts using Ansible first:
ansible -i hosts --list-hosts 'production:!databases'
Combine with parameters - Use limiting with template parameters for customized output:
ansible-cmdb -i hosts -l 'production' -p skip_empty= 1 out/ > prod.html
Troubleshooting No hosts in output If the generated CMDB is empty:
Verify the inventory contains matching hosts:
ansible -i hosts --list-hosts 'your-pattern'
Check that fact files exist for those hosts:
Ensure host names match exactly between inventory and fact files
Unexpected hosts included If wrong hosts appear:
Check group memberships in your inventory
Remember that patterns use OR logic (: means union)
Use ! to explicitly exclude unwanted groups
Limiting without inventory If you see an error about limiting requiring inventory:
# This won't work: ansible-cmdb -l 'production' out/ > cmdb.html # You must specify inventory: ansible-cmdb -i hosts -l 'production' out/ > cmdb.html