Observability

Prometheus metrics

Substrukt exposes a /metrics endpoint in Prometheus text format. This endpoint is unauthenticated (intended for internal scraping by your monitoring stack).

Available metrics

Metric	Type	Labels	Description
`http_requests_total`	Counter	`method`, `path`, `status`	Total HTTP requests
`http_request_duration_seconds`	Histogram	`method`, `path`	Request latency
`http_connections_active`	Gauge	–	Currently active connections
`content_entries_total`	Gauge	`schema`	Number of entries per schema
`uploads_total`	Gauge	–	Total uploaded files
`uploads_size_bytes`	Gauge	–	Total size of all uploads

Content and upload gauges are updated on each scrape (when /metrics is requested).

Scraping

Add Substrukt to your Prometheus configuration:

scrape_configs:
  - job_name: 'substrukt'
    static_configs:
      - targets: ['localhost:3000']
    metrics_path: '/metrics'
    scrape_interval: 30s

Example output

# HELP http_requests_total Total HTTP requests
http_requests_total{method="GET",path="/",status="200"} 42
http_requests_total{method="POST",path="/content/{schema_slug}/{entry_id}",status="302"} 7

# HELP http_request_duration_seconds Request duration in seconds
http_request_duration_seconds_bucket{method="GET",path="/",le="0.01"} 40

# HELP content_entries_total Content entries per schema
content_entries_total{schema="blog-posts"} 15
content_entries_total{schema="faq"} 8

# HELP uploads_total Total uploaded files
uploads_total 23

# HELP uploads_size_bytes Total upload storage in bytes
uploads_size_bytes 15728640

Audit logging

Substrukt maintains an audit log in a separate SQLite database (audit.db in the data directory). Audit writes are asynchronous – they do not block request handling.

Logged actions

Action	Resource type	When
`login`	session	User logs in
`logout`	session	User logs out
`user_create`	user	Admin account created during setup
`schema_create`	schema	Schema created via UI
`schema_update`	schema	Schema updated via UI
`schema_delete`	schema	Schema deleted via UI
`content_create`	content	Entry created via UI or API
`content_update`	content	Entry updated via UI or API
`content_delete`	content	Entry deleted via UI or API
`token_create`	api_token	API token created
`token_delete`	api_token	API token deleted
`import`	bundle	Content bundle imported
`export`	bundle	Content bundle exported
`webhook_fire`	webhook	Webhook fired (with success/failure status)

Audit log schema

Each audit entry contains:

Column	Description
`timestamp`	ISO 8601 timestamp
`actor`	User ID, `"api"`, or `"system"`
`action`	Action name (see table above)
`resource_type`	Type of resource affected
`resource_id`	Identifier of the affected resource
`details`	Optional JSON string with additional context

Viewing the audit log

The audit log is viewable in the web UI at Settings > Audit Log. You can also query it directly with SQLite:

sqlite3 data/audit.db "SELECT timestamp, actor, action, resource_type, resource_id FROM audit_log ORDER BY timestamp DESC LIMIT 20"

Structured logging

HTTP request/response tracing is provided by tower-http::TraceLayer. Each request is logged with method, path, status code, and duration.

Control log verbosity with the RUST_LOG environment variable:

RUST_LOG=substrukt=debug,tower_http=debug ./substrukt serve

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