Configuration

All options are set via AddLookout(options => { ... }) in Program.cs. Every option has a sane default — you only touch what you need.

builder.Services.AddLookout(options =>
{
    options.MaxAgeHours   = 24;      // keep entries for 24 hours (default)
    options.MaxEntryCount = 50_000;  // hard cap (default)
});

---

General

Property	Type	Default	Description
AllowInEnvironments	IList<string>	["Development"]	Environments where Lookout is allowed to run. Lookout throws LookoutEnvironmentException on startup in any other environment.
AllowInProduction	bool	false	When true, allows Lookout to run in any environment including Production. Logs a startup warning. Prefer AllowInEnvironments for named non-Production environments.
AllowNonLoopback	bool	false	Suppresses the startup warning when the app is bound to a non-loopback address.
StoragePath	string	%LocalAppData%/Lookout/<EntryAssemblyName>/lookout.db	Path to the SQLite database file. Scoped by entry assembly so multiple apps on the same machine don't share a database.
MaxAgeHours	int	24	Entries older than this many hours are pruned by the background retention service.
MaxEntryCount	int	50_000	Secondary retention cap. When exceeded after time-based pruning, oldest entries are removed first.
ChannelCapacity	int	10_000	Capacity of the in-memory channel between the request path and the background flusher. When full, the oldest entry is dropped.
FlushBatchSize	int	50	Maximum entries written to SQLite in a single transaction per flusher cycle. Higher = lower transaction overhead; lower = lower per-write latency.
UserClaimType	string?	null	Claim type used to resolve the authenticated user name. When null, HttpContext.User.Identity?.Name is used.

---

HTTP request capture

Property	Type	Default	Description
CaptureRequestBody	bool	true	Captures inbound request bodies (content-type gated, size-capped). Set to false to skip buffering.
CaptureResponseBody	bool	true	Captures HTTP response bodies. Same gating as request body.
MaxBodyBytes	int	65_536 (64 KiB)	Maximum bytes captured per request or response body. Larger bodies are truncated with a marker.
SkipPaths	HashSet<string>	/healthz, /health, /ready, /favicon.ico	Paths skipped entirely by the HTTP capture middleware. Case-insensitive. /lookout is always skipped.
SkipStaticAssetExtensions	HashSet<string>	.js, .css, .map, .woff, .woff2, .ttf, .otf, .eot, .svg, .png, .jpg, .jpeg, .gif, .webp, .ico	File extensions skipped entirely by the HTTP capture middleware. Prevents UseStaticFiles() traffic from drowning real API requests. Clear the set to capture asset requests.
CapturedContentTypes	HashSet<string>	application/json, application/x-www-form-urlencoded, text/*	Content types eligible for body capture. Supports text/* wildcard.

---

EF Core (options.Ef)

Property	Type	Default	Description
CaptureParameterValues	bool	true	Captures actual SQL parameter values (after redaction).
CaptureParameterTypesOnly	bool	false	Captures only parameter type names — never values. Overrides CaptureParameterValues.
MaxStackFrames	int	20	Maximum user-code frames captured per query.
N1DetectionMinOccurrences	int	3	Minimum identical-shaped queries within one request before flagging as N+1.
N1IgnorePatterns	IList<Regex>	[]	SQL shape keys matching any of these patterns are excluded from N+1 detection.

options.Ef.N1DetectionMinOccurrences = 5;  // only flag 5+ repeated queries
options.Ef.N1IgnorePatterns.Add(new Regex("SELECT.*__EFMigrationsHistory"));

---

Outbound HTTP (options.Http)

Property	Type	Default	Description
CaptureOutbound	bool	true	Master switch for outbound HttpClient capture.
CaptureOutboundRequestBody	bool	true	Captures outbound request bodies (content-type gated).
CaptureOutboundResponseBody	bool	true	Captures outbound response bodies (content-type gated).
OutboundBodyMaxBytes	int	65_536 (64 KiB)	Maximum bytes captured per outbound body.

---

Cache (options.Cache)

Registration order

AddLookout() decorates IMemoryCache and IDistributedCache by wrapping whichever implementations are already registered at call time. Call AddMemoryCache() / AddDistributedMemoryCache() (or equivalent) before AddLookout(), otherwise the decorator finds nothing to wrap and cache capture is silently skipped.

If you use a framework that registers caches inside modules (ABP, Orchard Core, etc.), move AddLookout() to after those module registrations complete. See Troubleshooting for details.

Property	Type	Default	Description
CaptureMemoryCache	bool	true	Captures IMemoryCache get/set/remove operations.
CaptureDistributedCache	bool	true	Captures IDistributedCache get/set/refresh/remove operations.
SensitiveKeyPatterns	IList<Regex>	[]	Cache keys matching these patterns are replaced with *** before storage.

---

Logging (options.Logging)

Property	Type	Default	Description
Capture	bool	true	Master switch for log capture.
MinimumLevel	LogLevel	Information	Minimum log level captured. Raise to Warning to reduce noise.
IgnoreCategories	IList<string>	Microsoft.*, System.*	Logger category patterns dropped before recording. Trailing * is a prefix wildcard.
MaxScopeFrames	int	5	Maximum active scope frames captured per log entry.

options.Logging.MinimumLevel = LogLevel.Warning;
options.Logging.IgnoreCategories.Add("Hangfire.*");

---

Exceptions (options.Exceptions)

Property	Type	Default	Description
Capture	bool	true	Master switch for exception capture.
IgnoreExceptionTypes	IList<string>	TaskCanceledException, OperationCanceledException	Full CLR type names dropped before recording. Hot-reload cancellation is excluded by default.
MaxStackFrames	int	20	Maximum user-code frames captured per exception.

---

Dump (options.Dump)

Property	Type	Default	Description
Capture	bool	true	Master switch for Lookout.Dump() entries.
MaxBytes	int	65_536	Maximum characters serialised per dump entry before truncation.

---

Hangfire (options.Hangfire)

Requires the Lookout.Hangfire package.

Property	Type	Default	Description
Capture	bool	true	Master switch for Hangfire job capture.
CaptureArguments	bool	true	Serialises job argument values before recording.
ArgumentMaxBytes	int	8_192	Maximum bytes per job argument value before truncation.
IgnoreJobTypes	IList<string>	[]	Full CLR type names of job classes to skip (e.g. chatty heartbeat jobs).

options.Hangfire.IgnoreJobTypes.Add("MyApp.Jobs.HeartbeatJob");

---

Redaction (options.Redaction)

Lookout redacts sensitive values before writing to storage. Matched values are replaced with ***.

Property	Type	Default members
Headers	HashSet<string>	Authorization, Cookie, Set-Cookie, X-Api-Key
QueryParams	HashSet<string>	password, token, access_token, refresh_token, secret, api_key, apikey
FormFields	HashSet<string>	same as QueryParams
JsonFields	HashSet<string>	same as QueryParams — applied recursively to captured JSON bodies
SqlParameters	HashSet<string>	same as QueryParams

Add your own:

options.Redaction.Headers.Add("X-Internal-Token");
options.Redaction.JsonFields.Add("creditCardNumber");

For custom redaction logic, use the Redact callback — it runs after built-in redactors:

options.Redact = entry =>
{
    // Scrub a custom field from JSON body captures
    if (entry.Type == "http" && entry.Content.Contains("loyaltyCardNumber"))
    {
        var scrubbed = Regex.Replace(entry.Content, @"""loyaltyCardNumber""\s*:\s*""[^""]*""", @"""loyaltyCardNumber"":""***""");
        return entry with { Content = scrubbed };
    }
    return entry;
};

---

Filtering and tagging

Drop entries before enqueue

// Per-entry filter: runs synchronously on the request path — keep it fast
options.Filter = entry => entry.Type != "log";  // drop all log entries

Drop entries in the background flusher

// Batch filter: runs off the request path, may be slower
options.FilterBatch = entries =>
    entries.Where(e => e.DurationMs > 5).ToList();

Attach custom tags

options.Tag = (entry, tags) =>
{
    tags["tenant"] = GetCurrentTenantId();
};

Tags appear as filterable chips in the dashboard.