Namespace: urn:mace:shibboleth:2.0:metadata
Schema: http://shibboleth.net/schema/idp/shibboleth-metadata.xsd
The FileBackedHTTPMetadataProvider loads a metadata file from an HTTP server. The provider periodically reloads the metadata file if necessary.
The FileBackedHTTPMetadataProvider spools the metadata contents to a local backing file, which is used at startup. Note that the backing file is only used at startup. A refresh operation never consults the backing file since the latter can't possibly represent newer metadata than what is already cached in memory.
XML Attributes
| Name | Type | Req? | Default | Description |
|---|
metadataURL
| URL | Y |
| The URL that the metadata is served from |
backingFile | File pathname | Y |
| Specifies where the backing file is located. If the remote server is unavailable at startup, the backing file is loaded instead. |
initializeFromBackupFile | Boolean |
| true | Flag indicating whether initialization should first attempt to load metadata from the backup file. If true, foreground initialization will be performed by loading the backing file, and then a refresh from the remote HTTP server will be scheduled to execute in a background thread, after a configured delay. This can improve IdP startup times when the remote HTTP file is large in size. |
backupFileInitNextRefreshDelay | Delay (ISO8601 format) |
| PT5S | Delay du |
XML Elements
| Name | Cardinality | Description |
|---|
<TLSTrustEngine> | 0 or 1 | A custom TrustEngine used to evaluate TLS server certificates. It contains a single <security:TrustEngine> element. |
Common XML Attributes
Name | Type | Default | Description |
|---|
The following attributes are required on all metadata provider types: |
|---|
id | String |
| Identifier for logging, identification for command line reload, etc. |
xsi:type | String | | Specifies the exact type of provider to use (from those listed above, or a custom extension type) |
The following attributes are common to all metadata provider types except the ChainingMetadataProvider type: |
|---|
requireValidMetadata | Boolean | true | Whether candidate metadata found by the resolver must be valid in order to be returned (where validity is implementation specific, but in SAML cases generally depends on a validUntil attribute.) If this flag is true, then invalid candidate metadata will not be returned. |
failFastInitialization
| Boolean | true | Whether to fail initialization of the underlying MetadataResolverService (and possibly the IdP as a whole) if the initialization of a metadata provider fails. When false, the IdP may start, and will continue to attempt to reload valid metadata if configured to do so, but operations that require valid metadata will fail until it does. |
sortKey | Integer | | Defines the order in which metadata providers are searched (see below), can only be specified on top level <MetadataProvider> elements. |
The following are advanced settings supporting a new low-level feature allowing metadata lookup by keys other than the unique entityID and are rarely of use to a deployer. |
|---|
criterionPredicateRegistryRef | Bean ID | | Identifies the a custom CriterionPredicateRegistry bean used in resolving predicates from non-predicate input criteria |
useDefaultPredicateRegistry | Boolean | true | Flag which determines whether the default CriterionPredicateRegistry will be used if a custom one is not supplied explicitly |
satisfyAnyPredicates | Boolean | false | Flag which determines whether predicates used in filtering are connected by a logical 'OR' (true) or by logical 'AND' (false) |
Reloading XML Attributes
The following attributes are common to all reloading "batch-oriented" metadata providers (i.e., FileBackedHTTPMetadataProvider, FilesystemMetadataProvider, and ResourceBackedMetadataProvider):
Name | Type | Default | Description |
|---|
minRefreshDelay | Duration | PT30S | Lower bound on the next refresh from the time calculated based on the metadata's expiration |
maxRefreshDelay | Duration | PT4H | Upper bound on the next refresh from the time calculated based on the metadata's expiration |
refreshDelayFactor | Real Number (strictly between 0.0 and 1.0) | 0.75 | A factor applied to the initially determined refresh time in order to determine the next refresh time (typically to ensure refresh takes place prior to the metadata's expiration). Attempts to refresh metadata will generally begin around the product of this number and the maximum refresh delay. |
expirationWarningThreshold | Duration | PT0S (disabled) | For each attempted metadata refresh (whether or not fresh metadata is obtained), if requireValidMetadata is true, and there is a validUntil XML attribute on the document root element, and the difference between validUntil and the current time is less than expirationWarningThreshold, the system logs a warning about the impending expiration. |
indexesRef | Bean ID |
| Bean ID of a Set<MetadataIndex> used to support resolution of metadata based on criteria other than an entityID, e.g. resolving by protocol endpoint for CAS or by SAML Artifact source ID. |
resolveViaPredicatesOnly | Boolean | false | Flag indicating whether resolution may be performed solely by applying predicates to the entire metadata collection, when an entityID input criterion is not supplied |
parserPoolRef
| Bean ID | shibboleth.ParserPool | Identifies a Spring bean for the XML parser used to parse metadata. Generally should not be changed. |
taskTimerRef | Bean ID |
| Identifies a Spring bean containing a Java Timer used to schedule reloads. When not set, an internal one is created. Generally should not be changed. |
HTTP XML Attributes
The following attributes are common to all HTTP metadata providers (i.e., DynamicHTTPMetadataProvider FileBackedHTTPMetadataProvider
An HTTP metadata provider includes a default implementation of the org.apache.http.client.HttpClient interface. The attributes in the following subsections control the behavior of the default HTTP client. In most cases, the default behavior is sufficient.
To override the default client implementation, configure the following attribute:
Name | Type | Description |
|---|
httpClientRef | Bean ID | A reference to an externally defined Spring bean that specifies an org.apache.http.client.HttpClient object. This attribute conflicts with and overrides all of the other HTTP attributes. See the HttpClientConfiguration topic for more information. |
Use of the httpClientRef attribute precludes the use of any and all of the HTTP attributes in the following subsections.
HTTP Connection Attributes
The following attributes apply to the HTTP connections obtained and managed by an HTTP metadata provider:
Name | Type | Default | Description |
|---|
connectionRequestTimeout | Duration | Depends on provider type | The maximum amount of time to wait for a connection to be returned from the HTTP client's connection pool manager. Set to PT0S to disable. |
connectionTimeout | Duration | Depends on provider type | The maximum amount of time to wait to establish a connection with the remote server. Set to PT0S to disable. |
socketTimeout | Duration | Depends on provider type | The maximum amount of time to wait between two consecutive packets while reading from the socket connected to the remote server. Set to PT0S to disable. |
HTTP Security Attributes
The following security-related attributes apply to any HTTP metadata provider:
Name | Type | Default | Description |
|---|
disregardTLSCertificate | Boolean | false | If true, no TLS certificate checking will take place over an HTTPS connection. Be careful with this setting, it is typically only used during testing. See the HttpClientConfiguration topic for more information. |
httpClientSecurityParametersRef | Bean ID | | A reference to an externally defined Spring bean that specifies an HttpClientSecurityParameters instance, which consolidates all HTTP security parameters including advanced TLS usage. This attribute conflicts with and overrides any explicit TrustEngine implementation configured as an inline <TLSTrustEngine> element. See the HttpClientConfiguration topic for more information. |
HTTP Proxy Attributes
The following attributes configure an HTTP proxy for use with an HTTP metadata provider:
Name | Type | Description |
|---|
proxyHost | String | The hostname of the HTTP proxy through which connections will be made |
proxyPort | String | The port of the HTTP proxy through which connections will be made |
proxyUser | String | The username used with the HTTP proxy through which connections will be made |
proxyPassword | String | The password used with the HTTP proxy through which connections will be made |
For a FileBackedHTTPMetadataProvider, the HTTP Connection Attributes each have a 60 second timeout default. Since the batch metadata refresh process runs in a background thread, a browser user will not notice such a delay
Common XML Elements
The following child element is common to all MetadataProvider types except the ChainingMetadataProvider type:
<MetadataFilter> | 0 or more | A metadata filter applied to candidate metadata as it flows through the metadata pipeline |
A typical use of FileBackedHTTPMetadataProvider is to load (and periodically reload) a metadata aggregate from a remote source via HTTP:
Load a metadata aggregate from a remote server
<!--
Load (and reload) a signed metadata aggregate from a remote HTTP server.
This sample configuration assumes: (1) the top-level element of the XML
document is signed; (2) the top-level element of the XML document is
decorated with a validUntil attribute; (3) the validity interval is two
weeks (P14D) in duration; and (4) the server supports HTTP conditional GET.
The metadata refresh process is influenced by the configured values of
the minRefreshDelay attribute (default: PT30S) and the maxRefreshDelay
attribute (default: PT4H) and also by any cacheDuration and validUntil
attributes in the metadata itself. If the server does not support HTTP
conditional GET, the attributes should be adjusted accordingly.
-->
<MetadataProvider id="RemoteMetadataAggregate" xsi:type="FileBackedHTTPMetadataProvider"
backingFile="%{idp.home}/metadata/federation-metadata-copy.xml"
metadataURL="http://example.org/metadata/federation-metadata.xml">
<!--
Verify the signature on the root element of the metadata aggregate
using a trusted metadata signing certificate.
-->
<MetadataFilter xsi:type="SignatureValidation" requireSignedRoot="true"
certificateFile="%{idp.home}/conf/metadata/md-cert.pem"/>
<!--
Require a validUntil XML attribute on the root element and
make sure its value is no more than 14 days into the future.
-->
<MetadataFilter xsi:type="RequiredValidUntil" maxValidityInterval="P14D"/>
<!-- Consume all SP metadata in the aggregate -->
<MetadataFilter xsi:type="EntityRole">
<RetainedRole>md:SPSSODescriptor</RetainedRole>
</MetadataFilter>
</MetadataProvider>
Note that the metadata is loaded (and reloaded) out-of-band and therefore will not interfere with any SAML protocol exchange.
See also Troubleshooting.
A FileBackedHTTPMetadataProvider loads (and reloads) metadata in the background, independent of normal IdP operation. The frequency of metadata refresh is influenced by the Reloading Attributes. In particular, the minRefreshDelay and maxRefreshDelay attributes strongly influence the frequency of metadata refresh. Any cacheDuration and validUntil attributes in the metadata itself also influence the process.
Large metadata files consume a significant amount of memory, especially during the reload process (when the IdP must have both the old and the new metadata at hand). Precise memory requirements depend on overall IdP load and other deployment-specific factors but large metadata files (such as those distributed by some federations) may require a system configured with 2GB of memory or even more. Ask your federation operator for specific recommendations.
Although metadata refresh can put significant load on the system, all refresh operations are performed in the background, independent of normal IdP operation. Assuming there are no resource limiting factors (such as inadequate memory), end users will not notice the effects of metadata refresh.
There are at least two things you can do to help minimize the impact of the metadata refresh process: 1) install and configure adequate memory on your system, and 2) customize the frequency of metadata refresh for optimal performance. In any case, the FileBackedHTTPMetadataProvider implementation has two features that positively affect metadata refresh: background processing and HTTP conditional GET. Neither of these features is configurable, however, so there is nothing further you need to do beyond the two items mentioned above.
A conforming server will respond to an HTTP conditional GET request (RFC 7232) with a 304 (Not Modified) status code if the target resource has not changed since the last time it was requested. Note that a 304 response does not include a response body, which is more efficient than the corresponding 200 response (especially for large metadata files). More importantly, due to the manner in which the FileBackedHTTPMetadataProvider is implemented, the IdP can safely ignore a 304 response, which precludes the need to redundantly process the metadata. For large signed metadata files, the savings can be quite significant.
To influence the frequency of metadata refresh, configure the following attributes on a FileBackedHTTPMetadataProvider instance: minRefreshDelay, maxRefreshDelay, and refreshDelayFactor. Optimal values for these attributes depend on 1) whether or not the server supports HTTP conditional GET, 2) the life cycle of metadata published on the server, and possibly other factors. Ask the metadata publisher for recommended best practices with respect to published metadata.
The backing file is only used at startup. If the remote server is unavailable at startup, the backing file is loaded instead and all the configured filters are run on the backing file. If a single filter fails, the backing file is not loaded. For example, if the provider contains a SignatureValidationFilter but the signature on the backing file can not be verified, the entire load operation fails.
If a FileBackedHTTPMetadataProvider is unable to load the backing file at startup, and the failFastInitialization attribute on the provider is set to true (the default), the metadata initialization process will halt. Additionally, if the idp.service.metadata.failFast property is set to true (not the default), the IdP as a whole will fail to initialize.
Yes, it does so internally, though not across restarts of the system (it will not have a cache tag at startup but will maintain one in memory after the initial request for metadata and do conditional GETs until the next restart).