Cannot backup to SeaweedFS objectstore

When creating ObjectStore CR that points to SeaweedFS s3 objectstore it starts uploading the wal archives, makes a .upload directory, but then I got the error:
`
{"level":"error","ts":"2025-12-16T10:46:23.075022375Z","msg":"Error while handling GRPC request","logging_pod":"postgresql-1","info":{"Server":{"Client":{"Client":{}},"InstanceName":"postgresql-1","SpoolDirectory":"/controller/wal-restore-spool","PGDataPath":"/var/lib/postgresql/data/pgdata","PGWALPath":"/var/lib/postgresql/data/pgdata/pg_wal"},"FullMethod":"/cnpgi.wal.v1.WAL/Archive"},"error":"unexpected failure invoking barman-cloud-wal-archive: exit status 4","stacktrace":"github.com/cloudnative-pg/machinery/pkg/log.(*logger).Error\n\t/go/pkg/mod/github.com/cloudnative-pg/machinery@v0.3.1/pkg/log/log.go:125\ngithub.com/cloudnative-pg/cnpg-i-machinery/pkg/pluginhelper/http.(*Server).Start.logFailedRequestsUnaryServerInterceptor.func2\n\t/go/pkg/mod/github.com/cloudnative-pg/cnpg-i-machinery@v0.4.1/pkg/pluginhelper/http/grpc.go:53\ngoogle.golang.org/grpc.NewServer.chainUnaryServerInterceptors.chainUnaryInterceptors.func1\n\t/go/pkg/mod/google.golang.org/grpc@v1.76.0/server.go:1234\ngithub.com/cloudnative-pg/cnpg-i/pkg/wal._WAL_Archive_Handler\n\t/go/pkg/mod/github.com/cloudnative-pg/cnpg-i@v0.3.0/pkg/wal/wal_grpc.pb.go:196\ngoogle.golang.org/grpc.(*Server).processUnaryRPC\n\t/go/pkg/mod/google.golang.org/grpc@v1.76.0/server.go:1431\ngoogle.golang.org/grpc.(*Server).handleStream\n\t/go/pkg/mod/google.golang.org/grpc@v1.76.0/server.go:1842\ngoogle.golang.org/grpc.(*Server).serveStreams.func2.1\n\t/go/pkg/mod/google.golang.org/grpc@v1.76.0/server.go:1061"}
`

However, with awscli I can reach the bucket and can upload objects

Objectstore definition
`
apiVersion: barmancloud.cnpg.io/v1
kind: ObjectStore
metadata:
name: azure-backup-store
namespace: postgres
spec:
# Base configuration for Barman Cloud to connect to Azure
configuration:
destinationPath: "s3://backups"
endpointURL: "http://seaweedfs-s3.seaweedfs.svc.cluster.local:8333"
s3Credentials:
accessKeyId:
name: aws-creds
key: ACCESS_KEY_ID
secretAccessKey:
name: aws-creds
key: ACCESS_SECRET_KEY
wal:
compression: gzip
data:
jobs: 2
`

Cluster definition:
`
apiVersion: postgresql.cnpg.io/v1
kind: Cluster
metadata:
name: postgresql
namespace: postgres
spec:
instances: 1
storage:
size: 2Gi

plugins:
- name: barman-cloud.cloudnative-pg.io
isWALArchiver: true
parameters:
barmanObjectName: azure-backup-store
serverName: postgresql

bootstrap:
initdb:
database: authentik
owner: authentik
secret:
name: authentik-secret

enableSuperuserAccess: true
superuserSecret:
name: pgsuperuser
`

I also tried other options, and all of them worked except for the Barman Cloud Plugin, which drops an error.

首先针对 SeaweedFS 复现 ObjectStore 和 Cluster 配置，然后检查 WAL Archive request 中报告的 barman-cloud-wal-archive 失败。完成标准是 WAL 归档能够成功上传到配置的目标位置，且不会出现 exit status 4 错误。

由索引模型根据 Issue 内容生成。