## Invoke Lambda transformation via PresignedGET

Following example shows how you can use [`minio-go` PresignedGetObject](https://docs.min.io/community/minio-object-store/developers/go/API.html#presignedgetobject-ctx-context-context-bucketname-objectname-string-expiry-time-duration-reqparams-url-values-url-url-error)
```go
package main

import (
	"context"
	"log"
	"net/url"
	"time"
	"fmt"

	"github.com/minio/minio-go/v7"

	enablePrefixUsage := r.Form.Get("prefix-usage") == "true"

	isAllowedAccess := func(bucketName string) (rd, wr bool) {
		if globalIAMSys.IsAllowed(policy.Args{
			AccountName:     cred.AccessKey,
			Groups:          cred.Groups,
			Action:          policy.ListBucketAction,
			BucketName:      bucketName,
			ConditionValues: getConditionValues(r, "", cred),
			IsOwner:         owner,
			ObjectName:      "",

		dirQuorum: listingQuorum, // make sure to capture all quorum ratios
		objQuorum: listingQuorum, // make sure to capture all quorum ratios
		bucket:    bucketName,
	}

	err := listPathRaw(ctx, listPathRawOptions{
		disks:          disks,
		bucket:         bucketName,
		recursive:      true,
		forwardTo:      "",
		minDisks:       listingQuorum,
		reportNotFound: false,
		agreed:         fn,

			// Send audit for the lifecycle delete operation
			auditLogLifecycle(
				ctx,
				oi,
				ILMExpiry, tags, traceFn)

			evArgs := eventArgs{
				EventName:  event.ObjectRemovedDelete,
				BucketName: bucket,
				Object: ObjectInfo{
					Name:      dobj.ObjectName,
					VersionID: dobj.VersionID,
				},
				UserAgent: "Internal: [ILM-Expiry]",
				Host:      globalLocalNodeName,
			}

		Host:         req.Host,
		RequestID:    req.RequestID,
		UserAgent:    req.UserAgent,
		Time:         time.Now().UTC(),
		API: &log.API{
			Name: API,
			Args: &log.Args{
				Bucket:    req.BucketName,
				Object:    req.ObjectName,
				VersionID: req.VersionID,
				Objects:   objects,
			},
		},
	}

	if trace != nil {
		entry.Trace = &log.Trace{
			Message:   message,

type APIErrorResponse struct {
	XMLName          xml.Name `xml:"Error" json:"-"`
	Code             string
	Message          string
	Key              string `xml:"Key,omitempty" json:"Key,omitempty"`
	BucketName       string `xml:"BucketName,omitempty" json:"BucketName,omitempty"`
	Resource         string
	Region           string `xml:"Region,omitempty" json:"Region,omitempty"`
	RequestID        string `xml:"RequestId" json:"RequestId"`

	errBody string, reqURL *url.URL,
) {
	reqInfo := logger.GetReqInfo(ctx)
	errorResponse := APIErrorResponse{
		Code:       err.Code,
		Message:    errBody,
		Resource:   reqURL.Path,
		BucketName: reqInfo.BucketName,
		Key:        reqInfo.ObjectName,
		RequestID:  w.Header().Get(xhttp.AmzRequestID),
		HostID:     globalDeploymentID(),
	}
	encodedErrorResponse := encodeResponseJSON(errorResponse)

func (sys *IAMSys) ListPolicies(ctx context.Context, bucketName string) (map[string]policy.Policy, error) {
	if !sys.Initialized() {
		return nil, errServerNotInitialized
	}

	return sys.store.ListPolicies(ctx, bucketName)
}

// ListPolicyDocs - lists all canned policy docs.
func (sys *IAMSys) ListPolicyDocs(ctx context.Context, bucketName string) (map[string]PolicyDoc, error) {
	if !sys.Initialized() {

// - beginning of a string
// OR
// - end of a string
func hasSpaceBE(s string) bool {
	return strings.TrimSpace(s) != s
}

func request2BucketObjectName(r *http.Request) (bucketName, objectName string) {
	path, err := getResource(r.URL.Path, r.Host, globalDomainNames)
	if err != nil {
		logger.CriticalIf(GlobalContext, err)
	}

	return path2BucketObject(path)
}

				globalBucketConnStats.incS3OutputBytes(bucket, int64(tc.ResponseRecorder.Size()))
				globalBucketHTTPStats.updateHTTPStats(bucket, api, tc.ResponseRecorder)
			}
		}
	}
}

// Returns "/bucketName/objectName" for path-style or virtual-host-style requests.
func getResource(path string, host string, domains []string) (string, error) {
	if len(domains) == 0 {
		return path, nil
	}