* iceberg: vend table-scoped credentials to clients that ask for delegation
The catalog recognised X-Iceberg-Access-Delegation: vended-credentials
and then deliberately said nothing, because it had nothing to vend: it
withheld even the S3 endpoint so the client would keep the credentials it
was configured with. That left every engine expecting the catalog to hand
out access - Snowflake, Databricks, Trino with vending, any multi-tenant
setup - needing static S3 keys distributed out of band.
Mint an STS session per request instead, scoped by a session policy to
the table's own prefix plus the bucket listing needed to resolve it, and
return it in the load response config and storage-credentials. The role
to assume is named by -s3.iceberg.credentialRole; its trust policy is
what decides whether a caller may assume it, and vending stays off until
it is set. A failed mint falls back to the old silence rather than
handing back an endpoint the client cannot sign for.
* iceberg: keep vended credentials inside the table prefix
Review follow-ups on credential vending:
Listing was granted on the bucket ARN with no condition, so a credential
vended for one table could enumerate every other table's object names.
Constrain s3:prefix to the table's own prefix, which the S3 gateway
already populates for list requests.
A table location carrying * or ? would have gone into the policy's
resource pattern unescaped and widened the session to sibling prefixes.
Refuse to vend for such a location rather than escaping it; nothing the
catalog generates contains those characters.
DurationSeconds skipped the 900..43200 bounds the other assume-role paths
enforce, so -s3.iceberg.credentialDurationSeconds could ask for a session
outside them. The check is now shared by all three entry points.
* iceberg: return the vended credentials from buildFileIOConfig itself
buildStorageConfig was a second name for what buildFileIOConfig already
did; it now returns the storage credentials alongside the properties, and
callers that only want the properties drop them.
* iceberg: split the vended bucket grants, and refuse a whole-bucket scope
The prefix condition sat on a statement that also granted
GetBucketLocation and ListBucketMultipartUploads, neither of which carries
an s3:prefix to satisfy it, so both were denied for every vended
credential. GetBucketLocation moves to its own unconditioned statement.
ListBucketMultipartUploads is dropped: Iceberg writers complete and abort
by upload id, and granting it either leaks in-flight keys bucket-wide or
breaks on the same missing prefix.
A table whose location has no prefix - one registered at the bucket root -
would have been vended read and write over every other table in the
bucket. Refuse, the way a location with wildcards is refused.
see https://blog.aqwari.net/xml-schema-go/
1. go get aqwari.net/xml/cmd/xsdgen
2. Add EncodingType element for ListBucketResult in AmazonS3.xsd
3. xsdgen -o s3api_xsd_generated.go -pkg s3api AmazonS3.xsd
4. Remove empty Grantee struct in s3api_xsd_generated.go
5. Remove xmlns: sed s'/http:\/\/s3.amazonaws.com\/doc\/2006-03-01\/\ //' s3api_xsd_generated.go
Chris LuandGitHub
7522e17b6d