Conditions

In addition to effect, principals, resources, and actions, you can specify conditions for a bucket policy. A bucket policy takes effect only when its condition expressions match values contained in the request. Conditions is an optional parameter. You can determine whether to use this parameter based on service requirements.

For example, if account A needs to be granted with full control permissions for an object uploaded by account B in bucket example, you can specify that the upload request must contain the acl key and set the policy effect to Allow for account A. The complete condition expression is as follows:

Condition Operator	Key	Value
StringEquals	acl	bucket-owner-full-control

A condition consists of three parts: condition operator, key, and value. Condition operators and keys are associated with each other. For example:

If a string type condition operator is selected, such as StringEquals, the key can only be of the string type, such as UserAgent.
If a date type key is selected, such as CurrentTime, the condition operator can only be of the date type, such as DateEquals.

Table 1 describes the predefined condition operators provided by OBS.

**Table 1** Condition operators
Type	Key	Description
String	StringEquals	Strict matching. Short version: streq
	StringNotEquals	Strict negated matching. Short version: strneq
	StringEqualsIgnoreCase	Strict matching, ignoring case. Short version: streqi
	StringNotEqualsIgnoreCase	Strict negated matching, ignoring case. Short version: strneqi
	StringLike	Loose case-sensitive matching. The values can include a multi-character match wildcard (*) or a single-character match wildcard (?) anywhere in the string. Short version: strl
	StringNotLike	Negated loose case-sensitive matching. The values can include a multi-character match wildcard (*) or a single-character match wildcard (?) anywhere in the string. Short version: strnl
Numeric	NumericEquals	Strict matching. Short version: numeq
	NumericNotEquals	Strict negated matching. Short version: numneq
	NumericLessThan	"Less than" matching. Short version: numlt
	NumericLessThanEquals	"Less than or equals" matching. Short version: numlteq
	NumericGreaterThan	"Greater than" matching. Short version: numgt
	NumericGreaterThanEquals	"Greater than or equals" matching. Short version: numgteq
Date	DateEquals	Strict matching. Short version: dateeq
	DateNotEquals	Strict negated matching. Short version: dateneq
	DateLessThan	Indicates that the date is earlier than a specific date. Short version: datelt
	DateLessThanEquals	Indicates that the date is earlier than or equal to a specific date. Short version: datelteq
	DateGreaterThan	Indicates that the date is later than a specific date. Short version: dategt
	DateGreaterThanEquals	Indicates that the date is later than or equal to a specific date. Short version: dategteq
Boolean	Bool	Strict Boolean matching
IP address	IpAddress	Takes effect only on a specified IP address or IP address range. Example: x.x.x.x/24
IP address	NotIpAddress	Takes effect only on all except the specified IP address or IP address range. Example: x.x.x.x/24

A condition can contain any of the three types of keys: general keys, keys related to bucket actions, and keys related to object actions.

**Table 2** General keys
Key	Type	Description
CurrentTime	Date	Indicates the date when the request is received by the server. The date format must comply with ISO 8601.
EpochTime	Numeric	Indicates the time when the request is received by the server, which is expressed as seconds since 1970.01.01 00:00:00 UTC, regardless of the leap seconds.
SecureTransport	Bool	Requests whether to use SSL.
SourceIp	IP address	Source IP address from which the request is sent
UserAgent	String	Requested client software agent
Referer	String	Indicates the link from which the request is sent.

**Table 3** Keys related to bucket actions
Action	Optional Key	Description	Description
ListBucket	prefix	Type: String. Lists objects that begin with the specified prefix.	If prefix, delimiter, and max-keys are configured, the key-value pair meeting the conditions must be specified in the List operation for the bucket policy to take effect. For example, if a bucket policy (with the conditional operator set to NumericEquals, the key to max-keys, and the value to 100) that allows anonymous users to read data is configured for a bucket, the anonymous users must add ?max-keys=100 to the end of the bucket domain name for listing objects. The listed objects are the first 100 objects in alphabetic order.
ListBucket	max-keys	Type: Numeric. Sets the maximum number of objects. Returned objects are listed in alphabetic order.
ListBucketVersions	prefix	Type: String. Lists multi-version objects whose name starts with the specified prefix.
ListBucketVersions	max-keys	Type: Numeric. Sets the maximum number of objects. Returned objects are listed in alphabetic order.
PutBucketAcl	acl	Type: String. Configures the bucket ACL. When modifying a bucket ACL, you can use the request that contains a canned ACL setting in its header. Value options of a canned ACL setting: private\|public-read\|public-read-write\|authenticated-read\|bucket-owner-read\|bucket-owner-full-control\|log-delivery-write	None

**Table 4** Keys related to object actions
Action	Optional Key	Description
PutObject	acl	Type: String. Configures the object ACL. When uploading an object, you can use the request that contains a canned ACL setting in its header. Value options of a canned ACL setting: private\|public-read\|public-read-write\|authenticated-read\|bucketowner-read\|bucket-owner-full-control\|log-delivery-write.
	copysource	Type: String. Specifies names of the source bucket and the source object. Format: /bucketname/keyname
	metadata-directive	Type: String. Specifies whether to copy the metadata from the source object or replace with the metadata in the request. Values: COPY\|REPLACE
PutObjectAcl	acl	Type: String. Configures the object ACL. When uploading an object, you can use the request that contains a canned ACL setting in its header. Value options of a canned ACL setting: private\|public-read\|public-read-write\|authenticated-read\|bucketowner-read\|bucket-owner-full-control\|log-delivery-write.
GetObjectVersion	VersionId	Type: String. Obtains the object with the specified version ID.
GetObjectVersionAcl	VersionId	Type: String. Obtains the ACL of the object with specified version ID.
PutObjectVersionAcl	VersionId	Type: String. Specifies a version ID.
PutObjectVersionAcl	acl	Type: String. Configures the ACL of the object with the specified version ID. When uploading an object, you can use the request that contains a canned ACL setting in its header. Value options of a canned ACL setting: private\|public-read\|public-read-write\|authenticated-read\|bucketowner-read\|bucket-owner-full-control\|log-delivery-write.
DeleteObjectVersion	VersionId	Type: String. Deletes the object with the specified version ID.