go-ansible/kb/Executor.md

Executor

Module: dappco.re/go/core/ansible

The Executor is the main playbook runner. It manages SSH connections, variable resolution, conditional evaluation, loops, blocks, roles, handlers, and module execution.

Execution Flow

1. Parse playbook YAML into []Play
2. For each play:
   • Resolve target hosts from inventory (apply Limit filter)
   • Merge play variables
   • Gather facts (SSH into hosts, collect OS/hostname/kernel info)
   • Execute pre_tasks, roles, tasks, post_tasks
   • Run notified handlers
3. Each task goes through:
   • Tag matching (Tags, SkipTags)
   • Block/rescue/always handling
   • Include/import resolution
   • when condition evaluation
   • Loop expansion
   • Module execution via SSH
   • Result registration and handler notification

Templating

Jinja2-like {{ var }} syntax is supported:

• Variable resolution from play vars, task vars, host vars, facts, registered results
• Dotted access: {{ result.stdout }}, {{ result.rc }}
• Filters: | default(value), | bool, | trim
• Lookups: lookup('env', 'HOME'), lookup('file', '/path')

Conditionals

when supports:

• Boolean literals: true, false
• Inline boolean expressions with and, or, and parentheses
• Registered variable checks: result is success, result is failed, result is changed, result is defined
• Negation: not condition
• Variable truthiness checks

SSH Client Features

• Key-based and password authentication
• Known hosts verification
• Privilege escalation (become/sudo) with password support
• File upload via cat (no SCP dependency)
• File download, stat, exists checks
• Context-based timeout and cancellation