Fix to ensure only one User-Agent header is added to request.

[eehlin]

Background / history

Here at University of Skövde we have not been able to upgrade to versions > 4.18 of DSW since later versions are unable to communicate with our S3 storage (Qumulo based).

Errors received:
GeneralServerError "Error in S3: MErrValidation (MErrVJsonParse "Error in $: key \"Code\" not found")"
(for example when putting a document template using dsw-tdk tool.)

Solution

Now when I'm more familiar with the project(s) in DSW and also been able to get a local development environment running I've been able to probe the behavior/issue deeper and I came up with the following information that hopefully backs the solution provided in PR:

Raw HTTP-response from S3-call (gathered from within minio-hs library after some local changes):

--- S3 Response Debug Log ---
Status: 400 Bad Request
Headers: [("Content-Type","application/json"),("Content-Length","698"),("Connection","close")]
Raw Body:
{"module": "server", "error_class": "http_bad_request_error", "description": "Header 'User-Agent' repeated", "stack": ["add_header_block_invoke at protocols/http/request.c:363", "add_header at protocols/http/request.c:370", "parse_headers at protocols/http/request.c:400", "http_request_parse at protocols/http/request.c:657", "process_request_stream_headers at protocols/http/server.c:904", "http_connection_process_decoded_request at protocols/http/server.c:1014", "http_connection_process_decoded_request at protocols/http/server.c:1020", "http_connection_process_request at protocols/http/server.c:1082", "http_connection_process_stream at protocols/http/server.c:1100"], "user_visible": false}
-----------------------------

TLDR; Duplicate User-Agent headers not allowed here apparently even though the HTTP spec. is somewhat vague in this area but it explains at least why a plain 400 http status code is returned and thus the lack of "Code" element in the body expected in the S3-communication.

Request headers inspection

After setting log level to DEBUG and enabling httpClientDebug for wizard-server it is easy to shed some light on the issue:

[Info ] �[98m[I:dfc5b07b-a4e8-4a16-8e7e-fe594c0910c8] [T:a6ddaa49-3868-44b4-8367-46f8bce6bc8e] [S3          ] Put object: 'templates/hs:vr-eng:0.10.3/3510fed5-22b2-478c-b277-4cc26139b3fe'�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Retrieving 'https://<redacted>.local/forskningsdata-staginglocation'�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Request Method 'GET'�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Request Headers: '[("User-Agent","wizard-http-client"),("Host","<redacted>.local:9000"),("Authorization","<redacted>, SignedHeaders=host;x-amz-content-sha256;x-amz-date, Signature=<redacted>"),("X-Amz-Date","20251203T081337Z"),("x-amz-content-sha256","UNSIGNED-PAYLOAD")]'�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Request Body ''�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Retrieving 'https://<redacted>.local/forskningsdata-staginglocation'�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Request Method 'GET'�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Request Headers: '[("User-Agent","wizard-http-client"),("User-Agent","wizard-http-client"),("Host","<redacted>.local:9000"),("Authorization","<redacted>, SignedHeaders=host;x-amz-content-sha256;x-amz-date, Signature=<redacted>"),("X-Amz-Date","20251203T081337Z"),("x-amz-content-sha256","UNSIGNED-PAYLOAD")]'�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Request Body ''�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Retrieved Response�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Response StatusCode: 'Status {statusCode = 400, statusMessage = "Bad Request"}'�[0m
[Debug] �[98m[I:------------------------------------] [T:------------------------------------] [HTTP Client ] Response Headers: '[("Content-Type","application/json"),("Content-Length","698"),("Connection","close")]'�[0m
[Info ] �[98m[I:dfc5b07b-a4e8-4a16-8e7e-fe594c0910c8] [T:a6ddaa49-3868-44b4-8367-46f8bce6bc8e] [S3          ] MErrValidation (MErrVJsonParse "Error in $: key \"Code\" not found")�[0m
[Info ] �[98m[I:dfc5b07b-a4e8-4a16-8e7e-fe594c0910c8] [T:a6ddaa49-3868-44b4-8367-46f8bce6bc8e] [Database    ] Transaction rollback�[0m
[Warn ] �[95m[I:dfc5b07b-a4e8-4a16-8e7e-fe594c0910c8] [T:a6ddaa49-3868-44b4-8367-46f8bce6bc8e] [Database    ] GeneralServerError "Error in S3: MErrValidation (MErrVJsonParse \"Error in $: key \\\"Code\\\" not found\")"�[0m
[Error] �[91m[I:------------------------------------] [T:------------------------------------] [API         ] Error in S3: MErrValidation (MErrVJsonParse "Error in $: key \"Code\" not found")�[0m
[Error] �[91m[I:dfc5b07b-a4e8-4a16-8e7e-fe594c0910c8] [T:------------------------------------] [API         ] 500 Internal Server Error POST /wizard-api/document-template-drafts/hs:vr-eng:0.10.3/assets�[0m

TLDR; At line 8 we can see that there are duplicate User-Agent headers and that also got confirmed by my added logging inside the minio-hs library.

Fix

By ensuring that there's only one User-Agent header for the requests that passes through the HttpClientFactory we can address the issue(s) listed and I have also tested it locally and it works fine.

Note/thoughts: I wonder if there are redirects that are causing this issue, I've not been able to debug that further but it is just a possible conclusion that popped up between my ears.

Best regards,
Eddie