19088: Document S3 properties-as-metadata feature.

[arvados.git] / doc / api / keep-s3.html.textile.liquid

diff --git a/doc/api/keep-s3.html.textile.liquid b/doc/api/keep-s3.html.textile.liquid
index ad27b221fc25c88b57a48a33587c744f83a1216e..2e0c90ef47617e7aabc1d01928c4d7496842654d 100644 (file)
--- a/doc/api/keep-s3.html.textile.liquid
+++ b/doc/api/keep-s3.html.textile.liquid
@@ -21,7 +21,11 @@ To access Arvados S3 using an S3 client library, you must tell it to use the URL
 
 The "bucket name" is an Arvados collection uuid, portable data hash, or project uuid.
 
-The bucket name must be encoded as the first path segment of every request.  This is what the S3 documentation calls "Path-Style Requests".
+Path-style and virtual host-style requests are supported.
+* A path-style request uses the hostname indicated by @Services.WebDAVDownload.ExternalURL@, with the bucket name in the first path segment: @https://download.example.com/zzzzz-4zz18-asdfgasdfgasdfg/@.
+* A virtual host-style request uses the hostname pattern indicated by @Services.WebDAV.ExternalURL@, with a bucket name in place of the leading @*@: @https://zzzzz-4zz18-asdfgasdfgasdfg.collections.example.com/@.
+
+If you have wildcard DNS, TLS, and routing set up, an S3 client configured with endpoint @collections.example.com@ should work regardless of which request style it uses.
 
 h3. Supported Operations
 
@@ -66,6 +70,22 @@ h4. GetBucketVersioning
 
 Bucket versioning is presently not supported, so this will always respond that bucket versioning is not enabled.
 
+h3. Accessing collection/project properties as metadata
+
+GetObject, HeadObject, and HeadBucket return Arvados object properties as S3 metadata headers, e.g., @X-Amz-Meta-Foo: bar@.
+
+If the requested path indicates a file or directory placeholder inside a collection, or the top level of a collection, GetObject and HeadObject return the collection properties.
+
+If the requested path indicates a directory placeholder corresponding to a project, GetObject and HeadObject return the properties of the project.
+
+HeadBucket returns the properties of the collection or project corresponding to the bucket name.
+
+Non-string property values are returned in a JSON representation, e.g., @["foo","bar"]@.
+
+As in Amazon S3, property values containing non-ASCII characters are returned in BASE64-encoded form as described in RFC 2047, e.g., @=?UTF-8?b?4pu1?=@.
+
+It is not possible to modify collection or project properties using the S3 API.
+
 h3. Authorization mechanisms
 
 Keep-web accepts AWS Signature Version 4 (AWS4-HMAC-SHA256) as well as the older V2 AWS signature.