reverseproxy

package module

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Versions in this module

v2

v2.2.0

Jan 27, 2026

Changes in this version

type CompositeHandler

+ func (h *CompositeHandler) SetResponseTransformer(transformer ResponseTransformer)

+ type CompositeStrategy string

+ const StrategyFirstSuccess

+ const StrategyMerge

+ const StrategySequential

+ type ResponseTransformer func(responses map[string]*http.Response) (*http.Response, error)

type ReverseProxyModule

+ func (m *ReverseProxyModule) SetResponseTransformer(pattern string, transformer ResponseTransformer)

v2.1.0

Nov 7, 2025

Changes in this version

type BackendServiceConfig

+ ResponseHeaderRewriting ResponseHeaderRewritingConfig

type EndpointConfig

+ ResponseHeaderRewriting ResponseHeaderRewritingConfig

+ type ResponseHeaderRewritingConfig struct

+ RemoveHeaders []string

+ SetHeaders map[string]string

type ReverseProxyConfig

+ ResponseHeaderConfig ResponseHeaderRewritingConfig

type ReverseProxyModule

+ func (m *ReverseProxyModule) SetResponseHeaderModifier(modifier func(*http.Response, string, modular.TenantID) error)

v2.0.0

Oct 30, 2025

Changes in this version

+ const EventTypeBackendAdded

+ const EventTypeBackendHealthy

+ const EventTypeBackendRemoved

+ const EventTypeBackendUnhealthy

+ const EventTypeCircuitBreakerClosed

+ const EventTypeCircuitBreakerHalfOpen

+ const EventTypeCircuitBreakerOpen

+ const EventTypeConfigLoaded

+ const EventTypeConfigValidated

+ const EventTypeDryRunComparison

+ const EventTypeError

+ const EventTypeLoadBalanceDecision

+ const EventTypeLoadBalanceRoundRobin

+ const EventTypeModuleStarted

+ const EventTypeModuleStopped

+ const EventTypeProxyCreated

+ const EventTypeProxyStarted

+ const EventTypeProxyStopped

+ const EventTypeRequestFailed

+ const EventTypeRequestProcessed

+ const EventTypeRequestProxied

+ const EventTypeRequestReceived

+ var ErrApplicationNil = errors.New("app cannot be nil")

+ var ErrBackendErrorStatus = errors.New("backend returned non-success status")

+ var ErrBackendIDRequired = errors.New("backend id required")

+ var ErrBackendNotConfigured = errors.New("backend not configured")

+ var ErrBackendNotFound = errors.New("backend not found")

+ var ErrBackendProxyNil = errors.New("backend proxy is nil")

+ var ErrBackendServiceNotFound = errors.New("backend service not found")

+ var ErrCannotRegisterRoutes = errors.New("cannot register routes: router is nil")

+ var ErrCircuitOpen = errors.New("circuit breaker is open")

+ var ErrConfigurationNil = errors.New("configuration is nil")

+ var ErrConfigurationNotLoaded = errors.New("configuration not loaded")

+ var ErrDefaultBackendNotDefined = errors.New("default backend is not defined in backend_services")

+ var ErrDryRunModeNotEnabled = errors.New("dry-run mode is not enabled")

+ var ErrEvaluatorFatal = errors.New("evaluator-fatal")

+ var ErrFeatureFlagNotFound = errors.New("feature flag not found")

+ var ErrInvalidDefaultFeatureFlagConfig = errors.New("invalid default configuration type for feature flags")

+ var ErrInvalidFeatureFlagConfigType = errors.New("invalid feature flag configuration type")

+ var ErrLoggerNil = errors.New("logger cannot be nil")

+ var ErrMaxRetriesReached = errors.New("maximum number of retries reached")

+ var ErrNoAvailableBackend = errors.New("no available backend")

+ var ErrNoBackendsConfigured = errors.New("no backends configured")

+ var ErrNoDecision = errors.New("no-decision")

+ var ErrNoEvaluatorDecision = errors.New("no evaluator provided decision for flag")

+ var ErrNoEvaluatorsAvailable = errors.New("no feature flag evaluators available")

+ var ErrNoFeatureFlagConfigProvider = errors.New("no configuration provider available for feature flags")

+ var ErrNoHostname = errors.New("no hostname in URL")

+ var ErrNoSubjectForEventEmission = errors.New("no subject available for event emission")

+ var ErrRequestTimeout = errors.New("request timed out")

+ var ErrServiceNotHandleFunc = errors.New("service does not implement HandleFunc interface")

+ var ErrServiceURLRequired = errors.New("service URL required")

+ var ErrTenantAwareConfigCreation = errors.New("failed to create tenant-aware config for feature flags")

+ var ErrTenantIDRequired = errors.New("tenant ID is required but TenantIDHeader is not set")

+ var ErrUnexpectedConfigType = errors.New("unexpected config type")

+ var ErrUnexpectedStatusCode = errors.New("unexpected status code")

+ func ProvideConfig() interface

+ func RetryWithPolicy(ctx context.Context, policy RetryPolicy, fn RetryFunc, ...) (interface{}, int, error)

+ func TenantIDFromRequest(tenantHeader string, r *http.Request) (string, bool)

+ type Backend struct

+ Client *http.Client

+ ID string

+ URL string

+ type BackendCircuitBreakerConfig struct

+ Enabled bool

+ FailureThreshold int

+ RecoveryTimeout time.Duration

+ type BackendEndpointRequest struct

+ Backend string

+ Headers map[string]string

+ Method string

+ Path string

+ QueryParams map[string]string

+ type BackendHealthCheckConfig struct

+ Enabled bool

+ ExpectedStatusCodes []int

+ Interval time.Duration

+ Timeout time.Duration

+ type BackendHealthConfig struct

+ Enabled bool

+ Endpoint string

+ ExpectedStatusCodes []int

+ Interval time.Duration

+ Timeout time.Duration

+ type BackendServiceConfig struct

+ AlternativeBackend string

+ AlternativeBackends []string

+ CircuitBreaker BackendCircuitBreakerConfig

+ ConnectionTimeout time.Duration

+ CustomHostname string

+ Endpoints map[string]EndpointConfig

+ FeatureFlag string

+ FeatureFlagID string

+ HeaderRewriting HeaderRewritingConfig

+ HealthCheck BackendHealthCheckConfig

+ HealthEndpoint string

+ HostnameHandling string

+ IdleTimeout time.Duration

+ MaxConnections int

+ MaxRetries int

+ PathRewrite string

+ PathRewriting PathRewritingConfig

+ QueueSize int

+ QueueTimeout time.Duration

+ RetryDelay time.Duration

+ URL string

+ type CachedResponse struct

+ Body []byte

+ ExpirationTime time.Time

+ Headers http.Header

+ LastAccessed time.Time

+ StatusCode int

+ type CircuitBreaker struct

+ func NewCircuitBreaker(backendName string, metricsCollector *MetricsCollector) *CircuitBreaker

+ func NewCircuitBreakerWithConfig(backendName string, config CircuitBreakerConfig, ...) *CircuitBreaker

+ func (cb *CircuitBreaker) Execute(req *http.Request, fn func(*http.Request) (*http.Response, error)) (*http.Response, error)

+ func (cb *CircuitBreaker) GetFailureCount() int

+ func (cb *CircuitBreaker) GetState() CircuitState

+ func (cb *CircuitBreaker) IsOpen() bool

+ func (cb *CircuitBreaker) RecordFailure()

+ func (cb *CircuitBreaker) RecordSuccess()

+ func (cb *CircuitBreaker) Reset()

+ func (cb *CircuitBreaker) WithFailureThreshold(threshold int) *CircuitBreaker

+ func (cb *CircuitBreaker) WithMetricsCollector(collector *MetricsCollector) *CircuitBreaker

+ func (cb *CircuitBreaker) WithRequestTimeout(timeout time.Duration) *CircuitBreaker

+ func (cb *CircuitBreaker) WithResetTimeout(timeout time.Duration) *CircuitBreaker

+ type CircuitBreakerConfig struct

+ Enabled bool

+ FailureThreshold int

+ HalfOpenAllowedRequests int

+ OpenTimeout time.Duration

+ RequestTimeout time.Duration

+ SuccessRateThreshold float64

+ SuccessThreshold int

+ WindowSize int

+ type CircuitBreakerInfo struct

+ FailureCount int

+ FailureThreshold int

+ Failures int

+ LastAttempt time.Time

+ LastFailure time.Time

+ ResetTimeout string

+ State string

+ SuccessCount int

+ type CircuitBreakerProvider func(backendID string) *HealthCircuitBreakerInfo

+ type CircuitState int

+ const DefaultRequestTimeout

+ const StateClosed

+ const StateHalfOpen

+ const StateOpen

+ func (s CircuitState) String() string

+ type ComparisonResult struct

+ BodyMatch bool

+ Differences []string

+ HeaderDiffs map[string]HeaderDiff

+ HeadersMatch bool

+ StatusCodeMatch bool

+ type CompositeHandler struct

+ func NewCompositeHandler(backends []*Backend, parallel bool, responseTimeout time.Duration) *CompositeHandler

+ func (h *CompositeHandler) ConfigureCircuitBreakers(globalConfig CircuitBreakerConfig, ...)

+ func (h *CompositeHandler) ServeHTTP(w http.ResponseWriter, r *http.Request)

+ func (h *CompositeHandler) SetEventEmitter(emitter func(eventType string, data map[string]interface{}))

+ func (h *CompositeHandler) SetResponseCache(cache *responseCache)

+ type CompositeResponse struct

+ Body []byte

+ Headers http.Header

+ StatusCode int

+ type CompositeRoute struct

+ AlternativeBackend string

+ Backends []string

+ FeatureFlagID string

+ Pattern string

+ Strategy string

+ type DebugConfig struct

+ BackendsEndpoint string

+ CircuitBreakersEndpoint string

+ Enabled bool

+ FlagsEndpoint string

+ HealthChecksEndpoint string

+ InfoEndpoint string

+ type DebugEndpointsConfig struct

+ AuthToken string

+ BasePath string

+ Enabled bool

+ RequireAuth bool

+ type DebugHandler struct

+ func NewDebugHandler(config DebugEndpointsConfig, featureFlagEval FeatureFlagEvaluator, ...) *DebugHandler

+ func (d *DebugHandler) HandleBackends(w http.ResponseWriter, r *http.Request)

+ func (d *DebugHandler) HandleCircuitBreakers(w http.ResponseWriter, r *http.Request)

+ func (d *DebugHandler) HandleFlags(w http.ResponseWriter, r *http.Request)

+ func (d *DebugHandler) HandleHealthChecks(w http.ResponseWriter, r *http.Request)

+ func (d *DebugHandler) HandleInfo(w http.ResponseWriter, r *http.Request)

+ func (d *DebugHandler) RegisterRoutes(mux *http.ServeMux)

+ func (d *DebugHandler) SetCircuitBreakers(circuitBreakers map[string]*CircuitBreaker)

+ func (d *DebugHandler) SetHealthCheckers(healthCheckers map[string]*HealthChecker)

+ type DebugInfo struct

+ BackendServices map[string]string

+ CircuitBreakers map[string]CircuitBreakerInfo

+ Environment string

+ Flags map[string]interface{}

+ HealthChecks map[string]HealthInfo

+ ModuleName string

+ Routes map[string]string

+ Tenant string

+ Timestamp time.Time

+ type DryRunConfig struct

+ CompareHeaders []string

+ DefaultResponseBackend string

+ Enabled bool

+ IgnoreHeaders []string

+ LogResponses bool

+ MaxResponseSize int64

+ type DryRunHandler struct

+ func NewDryRunHandler(config DryRunConfig, tenantIDHeader string, logger modular.Logger) *DryRunHandler

+ func (d *DryRunHandler) ProcessDryRun(ctx context.Context, req *http.Request, ...) (*DryRunResult, error)

+ type DryRunResult struct

+ Comparison ComparisonResult

+ Duration DurationInfo

+ Endpoint string

+ Method string

+ PrimaryBackend string

+ PrimaryResponse ResponseInfo

+ RequestID string

+ ReturnedResponse string

+ SecondaryBackend string

+ SecondaryResponse ResponseInfo

+ TenantID string

+ Timestamp time.Time

+ func (d *DryRunResult) GetReturnedResponse() ResponseInfo

+ type DurationInfo struct

+ Primary time.Duration

+ Secondary time.Duration

+ Total time.Duration

+ type EndpointConfig struct

+ AlternativeBackend string

+ FeatureFlagID string

+ HeaderRewriting HeaderRewritingConfig

+ PathRewriting PathRewritingConfig

+ Pattern string

+ type EndpointMapping struct

+ Endpoints []BackendEndpointRequest

+ ResponseTransformer func(ctx context.Context, req *http.Request, responses map[string]*http.Response) (*CompositeResponse, error)

+ type EndpointRewriteRule struct

+ Backend string

+ Pattern string

+ Replacement string

+ StripQueryParams bool

+ type ErrorHandlingConfig struct

+ ConnectionRetries int

+ EnableCustomPages bool

+ RetryAttempts int

+ RetryDelay time.Duration

+ type FeatureFlagAggregator struct

+ func NewFeatureFlagAggregator(app modular.Application, logger *slog.Logger) *FeatureFlagAggregator

+ func (a *FeatureFlagAggregator) EvaluateFlag(ctx context.Context, flagID string, tenantID modular.TenantID, ...) (bool, error)

+ func (a *FeatureFlagAggregator) EvaluateFlagWithDefault(ctx context.Context, flagID string, tenantID modular.TenantID, ...) bool

+ type FeatureFlagEvaluator interface

+ EvaluateFlag func(ctx context.Context, flagID string, tenantID modular.TenantID, ...) (bool, error)

+ EvaluateFlagWithDefault func(ctx context.Context, flagID string, tenantID modular.TenantID, ...) bool

+ type FeatureFlagsConfig struct

+ Enabled bool

+ Flags map[string]bool

+ type FileBasedFeatureFlagEvaluator struct

+ func NewFileBasedFeatureFlagEvaluator(ctx context.Context, app modular.Application, logger *slog.Logger) (*FileBasedFeatureFlagEvaluator, error)

+ func (f *FileBasedFeatureFlagEvaluator) EvaluateFlag(ctx context.Context, flagID string, tenantID modular.TenantID, ...) (bool, error)

+ func (f *FileBasedFeatureFlagEvaluator) EvaluateFlagWithDefault(ctx context.Context, flagID string, tenantID modular.TenantID, ...) bool

+ type HeaderConfig struct

+ RemoveHeaders []string

+ SetHeaders map[string]string

+ type HeaderDiff struct

+ Primary string

+ Secondary string

+ type HeaderRewritingConfig struct

+ CustomHostname string

+ HostnameHandling HostnameHandlingMode

+ RemoveHeaders []string

+ SetHeaders map[string]string

+ type HealthCheckConfig struct

+ BackendHealthCheckConfig map[string]BackendHealthConfig

+ Enabled bool

+ ExpectedStatusCodes []int

+ HealthEndpoints map[string]string

+ Interval time.Duration

+ RecentRequestThreshold time.Duration

+ Timeout time.Duration

+ type HealthChecker struct

+ func NewHealthChecker(config *HealthCheckConfig, backends map[string]string, httpClient *http.Client, ...) *HealthChecker

+ func (hc *HealthChecker) GetBackendHealthStatus(backendID string) (*HealthStatus, bool)

+ func (hc *HealthChecker) GetHealthStatus() map[string]*HealthStatus

+ func (hc *HealthChecker) GetOverallHealthStatus(includeDetails bool) *OverallHealthStatus

+ func (hc *HealthChecker) IsRunning() bool

+ func (hc *HealthChecker) RecordBackendRequest(backendID string)

+ func (hc *HealthChecker) SetCircuitBreakerProvider(provider CircuitBreakerProvider)

+ func (hc *HealthChecker) SetEventEmitter(emitter HealthEventEmitter)

+ func (hc *HealthChecker) Start(ctx context.Context) error

+ func (hc *HealthChecker) Stop(ctx context.Context)

+ func (hc *HealthChecker) UpdateBackends(ctx context.Context, backends map[string]string)

+ func (hc *HealthChecker) UpdateHealthConfig(ctx context.Context, cfg *HealthCheckConfig)

+ type HealthCircuitBreakerInfo struct

+ FailureCount int

+ IsOpen bool

+ State string

+ type HealthEventEmitter func(eventType string, data map[string]interface{})

+ type HealthInfo struct

+ ChecksSkipped int64

+ CircuitBreakerOpen bool

+ CircuitBreakerState string

+ CircuitFailureCount int

+ DNSResolved bool

+ HealthCheckPassing bool

+ LastCheck time.Time

+ LastError string

+ LastSuccess time.Time

+ ResolvedIPs []string

+ ResponseTime string

+ Status string

+ StatusCode int

+ SuccessfulChecks int64

+ TotalChecks int64

+ type HealthStatus struct

+ BackendID string

+ ChecksSkipped int64

+ CircuitBreakerOpen bool

+ CircuitBreakerState string

+ CircuitFailureCount int

+ DNSResolved bool

+ HealthCheckPassing bool

+ Healthy bool

+ LastCheck time.Time

+ LastError string

+ LastRequest time.Time

+ LastSuccess time.Time

+ ResolvedIPs []string

+ ResponseTime time.Duration

+ SuccessfulChecks int64

+ TotalChecks int64

+ URL string

+ type HostnameHandlingMode string

+ const HostnamePreserveOriginal

+ const HostnameUseBackend

+ const HostnameUseCustom

+ type MetricsCollector struct

+ func NewMetricsCollector() *MetricsCollector

+ func (m *MetricsCollector) GetMetrics() map[string]interface{}

+ func (m *MetricsCollector) MetricsHandler() http.HandlerFunc

+ func (m *MetricsCollector) RecordRequest(backend string, start time.Time, statusCode int, err error, ...)

+ func (m *MetricsCollector) SetCircuitBreakerStateString(backend string, state string)

+ func (m *MetricsCollector) SetCircuitBreakerStatus(backend string, isOpen bool)

+ type MetricsConfig struct

+ Enabled bool

+ Endpoint string

+ type OverallHealthStatus struct

+ BackendDetails map[string]*HealthStatus

+ CircuitOpenCount int

+ Healthy bool

+ HealthyBackends int

+ LastCheck time.Time

+ TotalBackends int

+ UnhealthyBackends int

+ type PathMatcher struct

+ func NewPathMatcher() *PathMatcher

+ func (pm *PathMatcher) AddRoutePattern(backendID, pattern string)

+ func (pm *PathMatcher) MatchBackend(path string) string

+ type PathRewritingConfig struct

+ BasePathRewrite string

+ EndpointRewrites map[string]EndpointRewriteRule

+ StripBasePath string

+ type ResponseInfo struct

+ Body string

+ BodySize int64

+ Error string

+ Headers map[string]string

+ ResponseTime time.Duration

+ StatusCode int

+ type RetryFunc func(ctx context.Context) (interface{}, int, error)

+ type RetryPolicy struct

+ BaseDelay time.Duration

+ Jitter float64

+ MaxDelay time.Duration

+ MaxRetries int

+ RetryableStatusCodes map[int]bool

+ Timeout time.Duration

+ func DefaultRetryPolicy() RetryPolicy

+ func (p RetryPolicy) CalculateBackoff(attempt int) time.Duration

+ func (p RetryPolicy) ShouldRetry(statusCode int) bool

+ func (p RetryPolicy) WithBaseDelay(baseDelay time.Duration) RetryPolicy

+ func (p RetryPolicy) WithJitter(jitter float64) RetryPolicy

+ func (p RetryPolicy) WithMaxDelay(maxDelay time.Duration) RetryPolicy

+ func (p RetryPolicy) WithMaxRetries(maxRetries int) RetryPolicy

+ func (p RetryPolicy) WithRetryableStatusCodes(codes ...int) RetryPolicy

+ func (p RetryPolicy) WithTimeout(timeout time.Duration) RetryPolicy

+ type ReverseProxyConfig struct

+ BackendCircuitBreakers map[string]CircuitBreakerConfig

+ BackendConfigs map[string]BackendServiceConfig

+ BackendServices map[string]string

+ CacheEnabled bool

+ CacheTTL time.Duration

+ CircuitBreakerConfig CircuitBreakerConfig

+ CompositeRoutes map[string]CompositeRoute

+ DebugConfig DebugConfig

+ DebugEndpoints DebugEndpointsConfig

+ DefaultBackend string

+ DryRun DryRunConfig

+ DryRunConfig DryRunConfig

+ ErrorHandling ErrorHandlingConfig

+ FeatureFlags FeatureFlagsConfig

+ GlobalTimeout time.Duration

+ HeaderConfig HeaderConfig

+ HealthCheck HealthCheckConfig

+ MetricsConfig MetricsConfig

+ MetricsEnabled bool

+ MetricsEndpoint string

+ MetricsPath string

+ RequestTimeout time.Duration

+ RequireTenantID bool

+ RouteConfigs map[string]RouteConfig

+ Routes map[string]string

+ TenantIDHeader string

+ type ReverseProxyModule struct

+ func NewModule() *ReverseProxyModule

+ func (m *ReverseProxyModule) AddBackend(backendID, serviceURL string) error

+ func (m *ReverseProxyModule) AddBackendRoute(backendID, routePattern string) error

+ func (m *ReverseProxyModule) AddCompositeRoute(pattern string, backends []string, strategy string)

+ func (m *ReverseProxyModule) Constructor() modular.ModuleConstructor

+ func (m *ReverseProxyModule) EmitEvent(ctx context.Context, event cloudevents.Event) error

+ func (m *ReverseProxyModule) GetBackendHealthStatus(backendID string) (*HealthStatus, bool)

+ func (m *ReverseProxyModule) GetConfig() *ReverseProxyConfig

+ func (m *ReverseProxyModule) GetHealthStatus() map[string]*HealthStatus

+ func (m *ReverseProxyModule) GetOverallHealthStatus(includeDetails bool) *OverallHealthStatus

+ func (m *ReverseProxyModule) GetRegisteredEventTypes() []string

+ func (m *ReverseProxyModule) Init(app modular.Application) error

+ func (m *ReverseProxyModule) IsHealthCheckEnabled() bool

+ func (m *ReverseProxyModule) Name() string

+ func (m *ReverseProxyModule) OnTenantRegistered(tenantID modular.TenantID)

+ func (m *ReverseProxyModule) OnTenantRemoved(tenantID modular.TenantID)

+ func (m *ReverseProxyModule) ProvidesServices() []modular.ServiceProvider

+ func (m *ReverseProxyModule) RegisterConfig(app modular.Application) error

+ func (m *ReverseProxyModule) RegisterCustomEndpoint(pattern string, mapping EndpointMapping)

+ func (m *ReverseProxyModule) RegisterObservers(subject modular.Subject) error

+ func (m *ReverseProxyModule) RemoveBackend(backendID string) error

+ func (m *ReverseProxyModule) RequiresServices() []modular.ServiceDependency

+ func (m *ReverseProxyModule) SetHttpClient(client *http.Client)

+ func (m *ReverseProxyModule) Start(ctx context.Context) error

+ func (m *ReverseProxyModule) Stop(ctx context.Context) error

+ type RouteConfig struct

+ AlternativeBackend string

+ AlternativeBackends []string

+ CompositeBackends []string

+ DryRun bool

+ DryRunBackend string

+ FeatureFlag string

+ FeatureFlagID string

+ PathRewrite string

+ Timeout time.Duration

+ type WeightedEvaluator interface

+ Weight func() int

Other modules containing this package

github.com/CrisisTextLine/modular/modules/reverseproxy

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