This change allows the MinIO server to be configured with a special (read-only)
LDAP account to perform user DN lookups.
The following configuration parameters are added (along with corresponding
environment variables) to LDAP identity configuration (under `identity_ldap`):
- lookup_bind_dn / MINIO_IDENTITY_LDAP_LOOKUP_BIND_DN
- lookup_bind_password / MINIO_IDENTITY_LDAP_LOOKUP_BIND_PASSWORD
- user_dn_search_base_dn / MINIO_IDENTITY_LDAP_USER_DN_SEARCH_BASE_DN
- user_dn_search_filter / MINIO_IDENTITY_LDAP_USER_DN_SEARCH_FILTER
This lookup-bind account is a service account that is used to lookup the user's
DN from their username provided in the STS API. When configured, searching for
the user DN is enabled and configuration of the base DN and filter for search is
required. In this "lookup-bind" mode, the username format is not checked and must
not be specified. This feature is to support Active Directory setups where the
DN cannot be simply derived from the username.
When the lookup-bind is not configured, the old behavior is enabled: the minio
server performs LDAP lookups as the LDAP user making the STS API request and the
username format is checked and configuring it is required.
Fixes support for using multiple base DNs for user search in the LDAP directory
allowing users from different subtrees in the LDAP hierarchy to request
credentials.
- The username in the produced credentials is now the full DN of the LDAP user
to disambiguate users in different base DNs.
Current implementation requires server pools to have
same erasure stripe sizes, to facilitate same SLA
and expectations.
This PR allows server pools to be variadic, i.e they
do not have to be same erasure stripe sizes - instead
they should have SLA for parity ratio.
If the parity ratio cannot be guaranteed by the new
server pool, the deployment is rejected i.e server
pool expansion is not allowed.
Synchronous replication can be enabled by setting the --sync
flag while adding a remote replication target.
This PR also adds proxying on GET/HEAD to another node in a
active-active replication setup in the event of a 404 on the current node.
Use separate sync.Pool for writes/reads
Avoid passing buffers for io.CopyBuffer()
if the writer or reader implement io.WriteTo or io.ReadFrom
respectively then its useless for sync.Pool to allocate
buffers on its own since that will be completely ignored
by the io.CopyBuffer Go implementation.
Improve this wherever we see this to be optimal.
This allows us to be more efficient on memory usage.
```
385 // copyBuffer is the actual implementation of Copy and CopyBuffer.
386 // if buf is nil, one is allocated.
387 func copyBuffer(dst Writer, src Reader, buf []byte) (written int64, err error) {
388 // If the reader has a WriteTo method, use it to do the copy.
389 // Avoids an allocation and a copy.
390 if wt, ok := src.(WriterTo); ok {
391 return wt.WriteTo(dst)
392 }
393 // Similarly, if the writer has a ReadFrom method, use it to do the copy.
394 if rt, ok := dst.(ReaderFrom); ok {
395 return rt.ReadFrom(src)
396 }
```
From readahead package
```
// WriteTo writes data to w until there's no more data to write or when an error occurs.
// The return value n is the number of bytes written.
// Any error encountered during the write is also returned.
func (a *reader) WriteTo(w io.Writer) (n int64, err error) {
if a.err != nil {
return 0, a.err
}
n = 0
for {
err = a.fill()
if err != nil {
return n, err
}
n2, err := w.Write(a.cur.buffer())
a.cur.inc(n2)
n += int64(n2)
if err != nil {
return n, err
}
```
