mongo_extract_indexes_to_json.js

// Create an object to store all index information
var clusterIndexes = {};

db.getMongo().getDBs().databases.forEach(function(database) {
    if (database.name !== 'admin' && database.name !== 'local' && database.name !== 'config') {
        clusterIndexes[database.name] = {};
        var dbs = db.getSiblingDB(database.name);
        
        dbs.getCollectionNames().forEach(function(collName) {
            clusterIndexes[database.name][collName] = db.getCollection(collName).getIndexes();
        });
    }
});

// Print the final structured output
printjson(clusterIndexes);