I forgot to mention earlier attempted debugging: I believe this is not because the keys are wrong, but because it is looking for a user that is not seen on the secondary:

debug 2020-11-03T16:37:47.330+0000 7f32e9859700  5 req 60 0.003999986s :post_period error reading user info, uid=ACCESS can't authenticate
debug 2020-11-03T16:37:47.330+0000 7f32e9859700 20 req 60 0.003999986s :post_period rgw::auth::s3::LocalEngine denied with reason=-2028
debug 2020-11-03T16:37:47.330+0000 7f32e9859700 20 req 60 0.003999986s :post_period rgw::auth::s3::AWSAuthStrategy denied with reason=-2028
debug 2020-11-03T16:37:47.330+0000 7f32e9859700  5 req 60 0.003999986s :post_period Failed the auth strategy, reason=-2028
debug 2020-11-03T16:37:47.330+0000 7f32e9859700 10 failed to authorize request

src/rgw/rgw_common.h:#define ERR_INVALID_ACCESS_KEY   2028

./src/rgw/rgw_rest_s3.cc
  if (rgw_get_user_info_by_access_key(ctl->user, access_key_id, user_info) < 0) {
      ldpp_dout(dpp, 5) << "error reading user info, uid=" << access_key_id
              << " can't authenticate" << dendl;

On Fri, 6 Nov 2020 at 11:38, Michael Breen <michael.breen@vikingenterprise.com> wrote:
Hi,

radosgw-admin -v
ceph version 15.2.4 (7447c15c6ff58d7fce91843b705a268a1917325c) octopus (stable)

Multisite sync was something I had working with a previous cluster and an earlier Ceph version, but it doesn't now, and I can't understand why.
If anyone with an idea of a possible cause could give me a clue I would be grateful.
I have clusters set up using Rook, but as far as I can tell, that's not a factor.

On the primary cluster, I have this:

radosgw-admin zonegroup get --rgw-zonegroup zonegroup-a
{
    "id": "b115d74a-2d5f-4127-b621-0223f1e96c71",
    "name": "zonegroup-a",
    "api_name": "zonegroup-a",
    "is_master": "true",
    "endpoints": [
        "http://192.168.30.8:80"
    ],
    "hostnames": [],
    "hostnames_s3website": [],
    "master_zone": "024687e0-1461-4f45-9149-9e571791c2b3",
    "zones": [
        {
            "id": "024687e0-1461-4f45-9149-9e571791c2b3",
            "name": "zone-a",
            "endpoints": [
                "http://192.168.30.8:80"
            ],
            "log_meta": "false",
            "log_data": "true",
            "bucket_index_max_shards": 11,
            "read_only": "false",
            "tier_type": "",
            "sync_from_all": "true",
            "sync_from": [],
            "redirect_zone": ""
        },
        {
            "id": "6ba0ee26-0155-48f9-b057-2803336f0d66",
            "name": "zone-b",
            "endpoints": [
                "http://192.168.30.108:80"
            ],
            "log_meta": "false",
            "log_data": "true",
            "bucket_index_max_shards": 11,
            "read_only": "false",
            "tier_type": "",
            "sync_from_all": "true",
            "sync_from": [],
            "redirect_zone": ""
        }
    ],
    "placement_targets": [
        {
            "name": "default-placement",
            "tags": [],
            "storage_classes": [
                "STANDARD"
            ]
        }
    ],
    "default_placement": "default-placement",
    "realm_id": "8c38fa05-c19d-4e30-bc98-e2bc84eccb68",
    "sync_policy": {
        "groups": []
    }
}

It's identical on the secondary (that's after a realm pull, an update of the zone-b endpoints, and a period commit), which I double-checked by piping the output to md5sum on both sides.
The system user created on the primary is

radosgw-admin user info --uid realm-a-system-user
{
    ...
    "keys": [
        {
            "user": "realm-a-system-user",
            "access_key": "IUs+USI5IjA8WkZPRjU=",
            "secret_key": "PGRDSzRERD4lbF9AYThuLzkvW1QvL148Q147PA=="
        }
    ...
}

The zones on both sides have these keys

radosgw-admin zone get --rgw-zone zone-a
{
    ...
    "system_key": {
        "access_key": "IUs+USI5IjA8WkZPRjU=",
        "secret_key": "PGRDSzRERD4lbF9AYThuLzkvW1QvL148Q147PA=="
    },
    ...
}

radosgw-admin zone get --rgw-zonegroup zonegroup-a --rgw-zone zone-b
{
    ...
    "system_key": {
        "access_key": "IUs+USI5IjA8WkZPRjU=",
        "secret_key": "PGRDSzRERD4lbF9AYThuLzkvW1QvL148Q147PA=="
    },
    ...
}


Yet, on the secondary

radosgw-admin sync status
          realm 8c38fa05-c19d-4e30-bc98-e2bc84eccb68 (realm-a)
      zonegroup b115d74a-2d5f-4127-b621-0223f1e96c71 (zonegroup-a)
           zone 6ba0ee26-0155-48f9-b057-2803336f0d66 (zone-b)
  metadata sync preparing for full sync
                full sync: 64/64 shards
                full sync: 0 entries to sync
                incremental sync: 0/64 shards
                metadata is behind on 64 shards
                behind shards: [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63]
      data sync source: 024687e0-1461-4f45-9149-9e571791c2b3 (zone-a)
                        syncing
                        full sync: 0/128 shards
                        incremental sync: 128/128 shards
                        data is caught up with source

and on the primary

radosgw-admin sync status
          realm 8c38fa05-c19d-4e30-bc98-e2bc84eccb68 (realm-a)
      zonegroup b115d74a-2d5f-4127-b621-0223f1e96c71 (zonegroup-a)
           zone 024687e0-1461-4f45-9149-9e571791c2b3 (zone-a)
  metadata sync no sync (zone is master)
2020-11-06T10:58:46.345+0000 7fa805c201c0  0 data sync zone:6ba0ee26 ERROR: failed to fetch datalog info
      data sync source: 6ba0ee26-0155-48f9-b057-2803336f0d66 (zone-b)
                        failed to retrieve sync info: (13) Permission denied

Given that all the keys above match, that "permission denied" is a mystery to me, but it does accord with:

export AWS_ACCESS_KEY_ID="IUs+USI5IjA8WkZPRjU="
export AWS_SECRET_ACCESS_KEY="PGRDSzRERD4lbF9AYThuLzkvW1QvL148Q147PA=="
s3cmd ls --no-ssl --host-bucket= --host=192.168.30.8     # OK, but:
s3cmd ls --no-ssl --host-bucket= --host=192.168.30.108
# ERROR: S3 error: 403 (InvalidAccessKeyId)
# Although
curl -L http://192.168.30.108  # works: <?xml version="1.0" encoding="UTF-8 ...

192.168.30.108 is the external IP, but just to be certain I was hitting zone-b, I tried this also within the cluster using its internal IP

s3cmd ls --no-ssl --host-bucket= --host=10.41.157.115
# ERROR: S3 error: 403 (InvalidAccessKeyId)

This seems to be the reason it's not syncing, but why?
The user with those keys existed on the primary before the realm pull, in agreement with every procedure I have seen for setting up multisite.

Any suggestions?
Regards,
Michael


CONFIDENTIALITY
This e-mail message and any attachments thereto, is intended only for use by the addressee(s) named herein and may contain legally privileged and/or confidential information. If you are not the intended recipient of this e-mail message, you are hereby notified that any dissemination, distribution or copying of this e-mail message, and any attachments thereto, is strictly prohibited. If you have received this e-mail message in error, please immediately notify the sender and permanently delete the original and any copies of this email and any prints thereof.
ABSENT AN EXPRESS STATEMENT TO THE CONTRARY HEREINABOVE, THIS E-MAIL IS NOT INTENDED AS A SUBSTITUTE FOR A WRITING. Notwithstanding the Uniform Electronic Transactions Act or the applicability of any other law of similar substance and effect, absent an express statement to the contrary hereinabove, this e-mail message its contents, and any attachments hereto are not intended to represent an offer or acceptance to enter into a contract and are not otherwise intended to bind the sender, Sanmina Corporation (or any of its subsidiaries), or any other person or entity.