[DRAFT] Policy Specification

Lifecycle policy specification includes:

Cluster setting
Policy header on domain objects (optional)
Policy headers on bucket objects

Cluster Setting Values

The Swarm cluster setting policy.lifecycle supports two values:

disabled – By default, the evaluation of all lifecycle policies is disabled in the cluster to provide legacy behavior.
enabled – Lifecycle policies may be enabled or disabled at the domain level for domains where such policies are applied.

The policy.lifecycle setting can be set via Management API.

Policy Header Values

Domain objects support a Policy-Lifecycle header that controls the behavior of lifecycle policies for buckets in the domain. The header supports either of the following values:

<unspecified> – The lack of a defined policy header means that lifecycle policies are only enabled for buckets in the domain when the policy.lifecycle setting is enabled. This means that setting the policy at the domain level is optional.
enabled – The lifecycle policies are enabled for buckets in a domain when the policy.lifecycle cluster setting is enabled.
disabled – The lifecycle policies are disabled for buckets in a domain regardless of policy.lifecycle setting.

Lifecycle policy does not apply to unnamed content within a domain. Only named objects within buckets will have lifecycle policy applied to them.

Bucket objects support a Policy-Lifecycle header with multiple values.

Each header value encodes one lifecycle policy rule.
Each lifecycle rule is comprised of a number of optional attributes, expressed as <name>:<value> pairs separated by space. Extra spaces are allowed at the beginning, end, and before & after the colon.

Important

Duplicate names are not allowed across lifecycle rules for a bucket.
Unsupported names or values result in an 400 error on the bucket (or domain) write. The 400 response will indicate the source of the problem.

Supported Rule Attributes

Attribute	Value	Definition
RuleId	<unique rule id>	A required, user-defined id of the rule. The value must be contained within quotes. Values within the quotes must be URL-encoded.
Enabled	<true\|false>	An optional indication to confirm whether the rule is enabled or not. The absence of this attribute indicates the rule enabled.
NamePrefix	<prefix>	An optional prefix to be matched against the relative name of the object in question. The value must be quoted. Never use slash as a first character for the prefix. If the prefix is matched with the object name, then the rule is applied to the object. The absence of this prefix indicates the rule is applied to all objects in the bucket. The quoted value must be URL encoded.
ExpirationDays	<nonnegative integer>	The current version of an object is expired after the defined number of days.
ExpirationDate	<ISO 8601 date>	The current version of an object is expired after the defined date (midnight UTC time).
ObsoleteExpirationDays	<nonnegative integer>	A non-current version of an object is expired after the defined number of days when the object becomes non-current. This rule impacts nothing if the versioning is not enabled on the bucket.
ObsoleteExpirationDate	<ISO 8601 date>	A non-current version of the object is expired after the defined date (midnight UTC time). This rule impacts nothing if the versioning is not enabled on the bucket.

Rules with Attributes

Every rule:

Must have one or multiple expiration attributes.
ExpirationDays and ExpirationDate attributes are mutually-exclusive.
ObsoleteExpirationDays and ObsoleteExprirationDate attributes are mutually-exclusive.

Expiration Time Rule

For expiration days,
Expiration time = Creation time of the current version + Number of days indicated + Rounded up to the next midnight UTC
For obsolete expiration days,
Expiration time = Create time of the next newest object version + Number of days indicated + Rounded up to the next midnight UTC
ISO 8601 dates must unambiguously specify a calendar date. The (unspecified) expiration time is always midnight UTC of that date, so any timezone specification is not allowed.
Expiration of a current version of an object (i.e. non-delete marker in the versioning enabled bucket) means creating a delete marker, pushing the current version down the versioning stack.
In all other cases, the object or object version is permanently deleted.

The gateway supports SCSP reads & writes of domain and bucket headers with lifecycle policies specified. Gateway S3 interface is modified to support GET, PUT, DELETE, and related permissions for bucket lifecycle policies as specified in the S3 documentation. Gateway validates policies against the S3 specification. On PUT or DELETE permission, the gateway translates the client-supplied bucket policy specifications into the appropriate Swarm bucket headers. Bucket lifecycle policy features provided via S3 that Swarm does not support (such as storage class transitions) are dropped during this translation. On the bucket lifecycle policy GET reply, Gateway performs reverse translation for any Policy-Lifecycle headers on the bucket object into an S3-compatible format.

Swarm Content Portal provides a convenient method of managing policies. This information is provided for completeness.

Since lifecycle policies are part of the overall context-level policy framework, GET and HEAD requests on contexts and name objects (with the verbose query argument) return Policy-Lifecycle-Evaluated and Policy-Lifecycle-Evaluated-Constrained headers. They describe if the lifecycle policies are enforced at the various levels such as cluster, domain, and bucket.