Add role to validate minimum free disk space before installation

[gorjant-pythian]

Change Description:

• Implemented centralized disk space validation and integrated pre-flight checks across software staging, patching, installation, and database creation to fail fast with clear diagnostics instead of proceeding to partial or corrupt operations.
• Added a reusable role (roles/disk_space_check) and wired it into swlib, patch, rdbms-setup, gi-setup, rac-gi-setup, and db-create. Added Ansible 2.9-safe include_vars fallbacks where needed and updated config-rac-db.yml to run readiness checks and a RAC
  disk-space pre-check. Extended .gitignore for disk-space role Molecule paths.

Solution Overview:

• Central role: disk_space_check

  • Configurable thresholds per operation in roles/disk_space_check/defaults/main.yml, overridable via vars (MB).
  • Mount-aware checks: gathers mounts, finds the best matching mount (longest prefix) for each path, and supports delegation via disk_check_host.
  • Clear assert-based failures showing required, available, and shortfall; high-usage warnings via disk_space_warning_threshold_percent (default 80%). Can be switched to warn-only via disk_space_fail_on_insufficient: false.
  • Supported types: swlib, oracle_home, gi, rac, patch, db (DB checks run only when ora_disk_management == 'fs').

• Role integrations

  • swlib: pre-checks swlib_path and swlib_unzip_path capacity (via disk_check_type: swlib).
  • patch: pre-checks patch target home, extraction path, and /tmp (via disk_check_type: patch).
  • rdbms-setup: pre-checks Oracle Home/Base space (via disk_check_type: oracle_home).
  • gi-setup: pre-checks GI requirements (via disk_check_type: gi), plus explicit checks for GI patch extraction and GI software extraction paths.
  • rac-gi-setup: pre-checks RAC GI requirements (via disk_check_type: rac), plus RAC GI patch extraction path checks.
  • db-create: pre-checks data, recovery, and config paths for filesystem-managed deployments (skips when ASM/ASMLib).

• Default thresholds (overridable):

  • oracle: home 10GB, base 5GB, swlib 20GB, unzip 10GB
  • gi: home 15GB, base 5GB, unzip 10GB
  • rac: grid 20GB, oracle 15GB, unzip 15GB
  • patch: home 5GB, extract 10GB, temp 2GB
  • db: data 20GB, recovery 10GB, config 512MB

• Ansible 2.9 note: Dynamic role includes (include_role/import_role) do not honor role dependencies declared in meta/main.yml; dependencies are only applied when roles are listed under the play-level roles: key. Because several roles are included dynamically
  and expect baseline variables from the common role, we added a conditional fallback that loads roles/common/defaults via include_vars if oracle_base/oracle_home/grid_home are not defined. This prevents undefined-variable errors while remaining a no-op when
  those vars are already set by inventories, group_vars, or earlier roles. See Ansible 2.9 docs on role dependencies and include_role behavior: role dependencies, include_role, import_role, variable precedence, include_vars.

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[google-oss-prow]

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This pull-request has been approved by: gorjant-pythian
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[gorjant-pythian]

Testing output links:

With enough space: https://gist.github.com/gorjant-pythian/f73a6de7f435a6b1205d165c13e4b829
With NOT enough space: https://gist.github.com/gorjant-pythian/2b9358eb9aebd5b7ea31215626611606

[gorjant-pythian]

Test with XFS: https://gist.github.com/gorjant-pythian/a041523c4edfb2ecf9b18118987aeb84