Fix awss3reader prefix trim

.chloggen/fix-awss3reader-prefix-trim.yaml

@@ -0,0 +1,29 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. receiver/filelog)
+component: receiver/awss3
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Fix S3 prefix trimming logic in awss3reader to correctly handle empty, single slash '/', and double slash '//' prefixes."
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [43587]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: |
+  This fix ensures the S3 object prefix is generated consistently for all prefix formats (e.g., `""`, `/`, `//`, `/logs/`, `//raw//`),
+  preventing malformed S3 paths when reading from buckets with non-standard prefixes.
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

receiver/awss3receiver/s3reader.go

@@ -7,6 +7,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/aws/aws-sdk-go-v2/service/s3"
@@ -157,10 +158,21 @@ func (s3Reader *s3TimeBasedReader) getObjectPrefixForTime(t time.Time, telemetry
 	case S3PartitionHour:
 		timeKey = getTimeKeyPartitionHour(t)
 	}
-	if s3Reader.s3Prefix != "" {
-		return fmt.Sprintf("%s/%s/%s%s_", s3Reader.s3Prefix, timeKey, s3Reader.filePrefix, telemetryType)
+	// Retrieve the configured S3 prefix (may be empty, "/", "//", "logs/", etc.)
+	prefix := s3Reader.s3Prefix
+
+	// Case 1: No prefix provided → use only timeKey + filePrefix
+	if prefix == "" {
+		return fmt.Sprintf("%s/%s%s_", timeKey, s3Reader.filePrefix, telemetryType)
+	}
+	// Case 2: Prefix contains only slashes (e.g., "/", "//", "///")
+	// Keep the exact number of slashes and directly append timeKey without adding an extra "/"
+	if strings.Trim(prefix, "/") == "" {
+		return fmt.Sprintf("%s%s/%s%s_", prefix, timeKey, s3Reader.filePrefix, telemetryType)
 	}
-	return fmt.Sprintf("%s/%s%s_", timeKey, s3Reader.filePrefix, telemetryType)
+	// Case 3: Normal prefix (e.g., "logs", "logs/", "/logs/", "//raw//")
+	// Always add a "/" between prefix and timeKey to build a valid S3 path
+	return fmt.Sprintf("%s/%s/%s%s_", prefix, timeKey, s3Reader.filePrefix, telemetryType)
 }
 
 func (s3Reader *s3TimeBasedReader) sendStatus(ctx context.Context, status statusNotification) {

receiver/awss3receiver/s3reader_test.go

@@ -83,6 +83,46 @@ func Test_s3Reader_getObjectPrefixForTime(t *testing.T) {
 			},
 			want: "year=2021/month=02/day=01/hour=17/minute=32/metrics_",
 		},
+		{
+			name: "prefix is / (should preserve leading slash)",
+			args: args{
+				s3Prefix:      "/",
+				s3Partition:   "minute",
+				filePrefix:    "file",
+				telemetryType: "logs",
+			},
+			want: "/year=2021/month=02/day=01/hour=17/minute=32/filelogs_",
+		},
+		{
+			name: "prefix is // (should preserve double leading slashes)",
+			args: args{
+				s3Prefix:      "//",
+				s3Partition:   "hour",
+				filePrefix:    "file",
+				telemetryType: "metrics",
+			},
+			want: "//year=2021/month=02/day=01/hour=17/filemetrics_",
+		},
+		{
+			name: "prefix starts and ends with slash /logs/",
+			args: args{
+				s3Prefix:      "/logs/",
+				s3Partition:   "hour",
+				filePrefix:    "file",
+				telemetryType: "traces",
+			},
+			want: "/logs//year=2021/month=02/day=01/hour=17/filetraces_",
+		},
+		{
+			name: "prefix starts and ends with double slash //raw//",
+			args: args{
+				s3Prefix:      "//raw//",
+				s3Partition:   "minute",
+				filePrefix:    "file",
+				telemetryType: "logs",
+			},
+			want: "//raw///year=2021/month=02/day=01/hour=17/minute=32/filelogs_",
+		},
 	}
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {