fix(terraform): normalize numeric inputs and prevent phantom memory flags

[mfielding]

Summary

Fixes string comparison antipattern (var.X != "") on numeric Terraform variables in terraform/main.tf and terraform/variables.tf.

Problem Statement

1. Phantom CLI Flags (0 != "" Coercion):
   In terraform/variables.tf, ora_pga_target_mb and ora_sga_target_mb default to 0 to signal that the toolkit should automatically compute memory (45% of host RAM for SGA, HugePages allocation, and baseline PGA). However, terraform/main.tf checks:

   var.ora_pga_target_mb != "" ? "--ora-pga-target-mb ${var.ora_pga_target_mb}" : "",
   var.ora_sga_target_mb != "" ? "--ora-sga-target-mb ${var.ora_sga_target_mb}" : "",

   In HCL, comparing a number to "" performs implicit string coercion: "0" != "" evaluates to true. This causes --ora-pga-target-mb 0 and --ora-sga-target-mb 0 to always be passed on standard deployments when unset by the caller.
2. Runtime Errors on null:
   When callers pass null into module arguments, null != "" evaluates to true, and string template interpolation ("${var.ora_pga_target_mb}") aborts with:
   Invalid interpolation: null value cannot be formatted as a string.
3. Redo Log Count Typing & Validation:
   ora_redo_log_count was previously typed as string with a regex check (^[0-9]+$) to work around the string idiom. Passing null fails validation because null == "" is false and regex fails can().
4. Port Number Validation:
   ora_listener_port and tls_listener_port validation rules (var.port >= 1) crash if a caller passes null.

Solution

1. Replace String Checks with try(var.X > 0, false):
   In local.common_flags, replace var.num != "" with try(var.num > 0, false) for ora_pga_target_mb, ora_sga_target_mb, ora_listener_port, tls_listener_port, and ora_redo_log_count.
2. Null-Safe Validations:
   Update validation conditions across all numeric inputs in variables.tf to explicitly permit null.
3. Flexible ora_redo_log_count:
   Change ora_redo_log_count type to any with validation allowing numbers, strings (e.g. "2" in existing tfvars templates), empty string, or null.
4. Firewall Port Casting:
   Add tostring() to firewall rule port mapping to ensure strict schema compliance.

Test Results & Matrix

A verification test suite was executed across all 7 caller scenarios (defaults, explicit tuning, explicit zero, nulls, custom ports, string numbers, and TLS).

The full test matrix output is published in this GitHub Gist:
https://gist.github.com/mfielding/e7c3a4e9db5bd7594ff6d00309fe3a22

[AlexBasinov]

should we add tonumber() here as well?

[mfielding]

Added.

[AlexBasinov]

and here as well

[mfielding]

I actually added it to all the numerical checks.

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AlexBasinov, mfielding

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[mfielding]

/retest

[mfielding]

/test oracle-toolkit-install-26ai-data-guard-on-gcp
/test oracle-toolkit-install-data-guard-on-gcp

[mfielding]

/test oracle-toolkit-install-26ai-data-guard-on-gcp
/test oracle-toolkit-install-data-guard-on-gcp

[google-oss-prow]

New changes are detected. LGTM label has been removed.

[google-oss-prow]

@mfielding: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
oracle-toolkit-install-data-guard-on-gcp	226c506	link	true	/test oracle-toolkit-install-data-guard-on-gcp
oracle-toolkit-install-26ai-data-guard-on-gcp	226c506	link	true	/test oracle-toolkit-install-26ai-data-guard-on-gcp

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