boulder/features/features.go

// features provides the Config struct, which is used to define feature flags
// that can affect behavior across Boulder components. It also maintains a
// global singleton Config which can be referenced by arbitrary Boulder code
// without having to pass a collection of feature flags through the function
// call graph.
package features

import (
	"sync"
)

// Config contains one boolean field for every Boulder feature flag. It can be
// included directly in an executable's Config struct to have feature flags be
// automatically parsed by the json config loader; executables that do so must
// then call features.Set(parsedConfig) to load the parsed struct into this
// package's global Config.
type Config struct {
	// Deprecated features. These features have no effect. Removing them from
	// configuration is safe.
	//
	// Once all references to them have been removed from deployed configuration,
	// they can be deleted from this struct, after which Boulder will fail to
	// start if they are present in configuration.
	CAAAfterValidation                bool
	AllowNoCommonName                 bool
	SHA256SubjectKeyIdentifier        bool
	EnforceMultiVA                    bool
	MultiVAFullResults                bool
	CertCheckerRequiresCorrespondence bool
	ECDSAForAll                       bool

	// ServeRenewalInfo exposes the renewalInfo endpoint in the directory and for
	// GET requests. WARNING: This feature is a draft and highly unstable.
	ServeRenewalInfo bool

	// ExpirationMailerUsesJoin enables using a JOIN query in expiration-mailer
	// rather than a SELECT from certificateStatus followed by thousands of
	// one-row SELECTs from certificates.
	ExpirationMailerUsesJoin bool

	// CertCheckerChecksValidations enables an extra query for each certificate
	// checked, to find the relevant authzs. Since this query might be
	// expensive, we gate it behind a feature flag.
	CertCheckerChecksValidations bool

	// CertCheckerRequiresValidations causes cert-checker to fail if the
	// query enabled by CertCheckerChecksValidations didn't find corresponding
	// authorizations.
	CertCheckerRequiresValidations bool

	// AsyncFinalize enables the RA to return approximately immediately from
	// requests to finalize orders. This allows us to take longer getting SCTs,
	// issuing certs, and updating the database; it indirectly reduces the number
	// of issuances that fail due to timeouts during storage. However, it also
	// requires clients to properly implement polling the Order object to wait
	// for the cert URL to appear.
	AsyncFinalize bool

	// DOH enables DNS-over-HTTPS queries for validation
	DOH bool

	// EnforceMultiCAA causes the VA to kick off remote CAA rechecks when true.
	// When false, no remote CAA rechecks will be performed. The primary VA will
	// make a valid/invalid decision with the results. The primary VA will
	// return an early decision if MultiCAAFullResults is false.
	EnforceMultiCAA bool

	// MultiCAAFullResults will cause the main VA to block and wait for all of
	// the remote VA CAA recheck results instead of returning early if the
	// number of failures is greater than the configured
	// maxRemoteValidationFailures. Only used when EnforceMultiCAA is true.
	MultiCAAFullResults bool

	// TrackReplacementCertificatesARI, when enabled, triggers the following
	// behavior:
	//   - SA.NewOrderAndAuthzs: upon receiving a NewOrderRequest with a
	//     'replacesSerial' value, will create a new entry in the 'replacement
	//     Orders' table. This will occur inside of the new order transaction.
	//   - SA.FinalizeOrder will update the 'replaced' column of any row with
	//     a 'orderID' matching the finalized order to true. This will occur
	//     inside of the finalize (order) transaction.
	TrackReplacementCertificatesARI bool

	// MultipleCertificateProfiles, when enabled, triggers the following
	// behavior:
	//   - SA.NewOrderAndAuthzs: upon receiving a NewOrderRequest with a
	//     `certificateProfileName` value, will add that value to the database's
	//     `orders.certificateProfileName` column. Values in this column are
	//     allowed to be empty.
	MultipleCertificateProfiles bool

	// CheckRenewalExemptionAtWFE when enabled, triggers the following behavior:
	//  - WFE.NewOrder: checks if the order is a renewal and if so skips checks
	//    for NewOrdersPerAccount and NewOrdersPerDomain limits.
	//  - RA.NewOrderAndAuthzs: skips checks for legacy NewOrdersPerAccount and
	//    NewOrdersPerDomain limits if the WFE indicates that the order is a
	//    renewal.
	//
	// TODO(#7511): Remove this feature flag.
	CheckRenewalExemptionAtWFE bool

	// CheckIdentifiersPaused checks if any of the identifiers in the order are
	// currently paused at NewOrder time. If any are paused, an error is
	// returned to the Subscriber indicating that the order cannot be processed
	// until the paused identifiers are unpaused and the order is resubmitted.
	CheckIdentifiersPaused bool

	// UseKvLimitsForNewOrder when enabled, causes the key-value rate limiter to
	// be the authoritative source of rate limiting information for new-order
	// callers and disables the legacy rate limiting checks.
	//
	// Note: this flag does not disable writes to the certificatesPerName or
	// fqdnSets tables at Finalize time.
	UseKvLimitsForNewOrder bool

	// UseKvLimitsForNewAccount when enabled, causes the key-value rate limiter
	// to be the authoritative source of rate limiting information for
	// new-account callers and disables the legacy rate limiting checks.
	UseKvLimitsForNewAccount bool
}

var fMu = new(sync.RWMutex)
var global = Config{}

// Set changes the global FeatureSet to match the input FeatureSet. This
// overrides any previous changes made to the global FeatureSet.
//
// When used in tests, the caller must defer features.Reset() to avoid leaving
// dirty global state.
func Set(fs Config) {
	fMu.Lock()
	defer fMu.Unlock()
	// If the FeatureSet type ever changes, this must be updated to still copy
	// the input argument, never hold a reference to it.
	global = fs
}

// Reset resets all features to their initial state (false).
func Reset() {
	fMu.Lock()
	defer fMu.Unlock()
	global = Config{}
}

// Get returns a copy of the current global FeatureSet, indicating which
// features are currently enabled (set to true). Expected caller behavior looks
// like:
//
//	if features.Get().FeatureName { ...
func Get() Config {
	fMu.RLock()
	defer fMu.RUnlock()
	// If the FeatureSet type ever changes, this must be updated to still return
	// only a copy of the current state, never a reference directly to it.
	return global
}