feat(yolo-backup): add ability to ignore tables and databases from MySQL backups

[Copilot]

Overview

This PR adds the ability to exclude specific tables and/or databases from MySQL backups when using the yolo-backup script. This is useful for skipping temporary data, cache tables, or test databases that don't need to be backed up.

Changes

New Environment Variables

• MYSQL_IGNORE_TABLES: Space-separated list of tables to exclude from backups (format: database.table)
• MYSQL_IGNORE_DATABASES: Space-separated list of databases to exclude from backups

Implementation Details

xtrabackup Support

The xtrabackup backup function now builds exclude options dynamically:

• Uses --databases-exclude=<database> for each excluded database
• Uses --tables-exclude=<db.table> for each excluded table
• Logs each exclusion for audit trail

mysqldump Support

The mysqldump backup function implements intelligent database filtering:

• Uses --ignore-table=<db.table> for excluding specific tables
• When databases are excluded, dynamically queries all databases and filters out:
  • User-specified databases (via MYSQL_IGNORE_DATABASES)
  • System databases (information_schema, performance_schema, sys)
• Uses --databases <filtered_list> when exclusions are present
• Falls back to --all-databases when no database exclusions are specified

Usage Examples

Exclude specific tables:

MYSQL_IGNORE_TABLES="mydb.cache mydb.sessions" yolo-backup

Exclude entire databases:

MYSQL_IGNORE_DATABASES="test_db temp_db" yolo-backup

Exclude both tables and databases:

MYSQL_IGNORE_DATABASES="test_db temp_db" \
MYSQL_IGNORE_TABLES="prod.cache prod.sessions prod.logs" \
yolo-backup

Backward Compatibility

All changes are fully backward compatible:

• If environment variables are not set, the script behaves exactly as before (backs up all databases)
• Existing backups and restore procedures remain unaffected
• No changes to the script's interface or other functionality

Testing

• ✅ Shell syntax validation (bash -n)
• ✅ Shellcheck linting via pre-commit hooks
• ✅ Manual verification of exclude logic for both xtrabackup and mysqldump
• ✅ Database filtering logic tested with simulated database lists
• ✅ Help output verified to include new variables and examples

References

• Percona XtraBackup Documentation
• MySQL mysqldump Documentation

Closes #<issue_number>

Original prompt

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This section details on the original issue you should resolve

<issue_title>feat(yolo-backup): add the ability to ignore tables and/or databases from mysql backups</issue_title>
<issue_description># Context

When backuping MySQL, we need the ability to ignore certaines tables and/or databases.

Goal

• Add a new env vars to injects tables and/or databases to ignore from backup
• Add options flags to xtrabackup and mysqldump
• Here is xtrabackup docs https://docs.percona.com/percona-xtrabackup/2.4/xtrabackup_bin/xbk_option_reference.html
• Here is mysqlsqump docs https://dev.mysql.com/doc/refman/8.0/en/mysqldump.html</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #113

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