Monitoring

Health checks

Status

The status endpoint check that the service has been started. It can be used as a readiness probe. It does not provide any information on the individual modules running as part of the executable. The main goal of the service is to give a YES/NO answer for if the service is running:

GET /status

Returns an “OK” response body with status code 200.

Note

The provided Docker containers are configured to perform this healthcheck out of the box. However, if the internal endpoints port (:8081) has been changed, the healthcheck will fail and Docker will mark the container as unhealthy. Override the default healthcheck to solve this.

Health

The health endpoint provides more fine grained health checks on the Nuts node. It can be used as a liveness probe. It reports in a format compatible with Spring Boot’s Health Actuator. The endpoint is available over HTTP:

GET /health

Each component in the health check can have one of the statuses UP, UNKNOWN, or DOWN. The overall status is determined by the lowest common denominator, so if one components is DOWN, the overall system status is DOWN. The overall system statuses UP and UNKNOWN map to HTTP status code 200, and status DOWN maps to status code 503.

Example response when all checks succeeded (formatted for readability):

{
  "status": "UP",
  "details": {
    "crypto.filesystem": {
      "status": "UP"
    },
    "network.auth_config": {
      "status": "UP",
      "details": "no node DID"
    },
    "network.tls": {
      "status": "UP"
    }
  }
}

Example response when one or more checks failed:

{
  "status": "DOWN",
  "details": {
    "network.tls": {
      "status": "DOWN",
      "details": "x509: certificate signed by unknown authority"
    }
  }
}

Basic diagnostics

GET /status/diagnostics

Note

this page is intended to be read by humans, not machines

Returns the status of the various services in yaml format:

network:
    connections:
        connected_peers:
            - id: d38c6df5-63d2-4b2c-87f4-2e8bbfa5612f
              address: nuts.nl:5555
              nodedid: did:nuts:abc123
        connected_peers_count: 1
    state:
        dag_xor: 6aada4464e380db16d0316e597956fcdaeada0e8f6023be82eeb9c798e1815c6
        stored_database_size_bytes: 106496005
        transaction_count: 9001
vcr:
    credential_count: 7
    issuer:
        issued_credentials_count: 0
        revoked_credentials_count: 0
    verifier:
        revocations_count: 18
vdr:
    did_documents_count: 5
    conflicted_did_documents:
        total_count: 2
        owned_count: 0
status:
    git_commit: d36837bae48b780bfb76134e85b506472fc207a6
    os_arch: linux/amd64
    software_version: master
    uptime: 4h14m12s

If you supply application/json for the Accept HTTP header it will return the diagnostics in JSON format.

Explanation of ambiguous/complex entries in the diagnostics:

vcr.credential_count holds the total number of credentials known to the node (public VCs, and private VCs issued to a DID on the local node)
vcr.issuer.issued_credentials_count holds the total number of credentials issued by the local node
vcr.issuer.revoked_credentials_count holds the total number of revoked credentials issued by the local node
vcr.verifier.revocations_count holds the total number of revoked credentials (public and private VCs)
vdr.conflicted_did_documents.total_count holds the total number of DID documents that are conflicted (have parallel updates). This may indicate a stolen private key
vdr.conflicted_did_documents.owned_count holds the number of conflicted DID documents you control as a node owner

Note: the network and vdr entries only apply to did:nuts.

Metrics

The Nuts service executable has build-in support for Prometheus. Prometheus is a time-series database which supports a wide variety of services. It also allows for exporting metrics to different visualization solutions like Grafana. See https://prometheus.io/ for more information on how to run Prometheus. The metrics are exposed at /metrics

Configuration

In order for metrics to be gathered by Prometheus. A job has to be added to the prometheus.yml configuration file. Below is a minimal configuration file that will only gather Nuts metrics:

# my global config
global:
  scrape_interval:     15s # Set the scrape interval to every 15 seconds. Default is every 1 minute.
  evaluation_interval: 15s # Evaluate rules every 15 seconds. The default is every 1 minute.
  # scrape_timeout is set to the global default (10s).

# Load rules once and periodically evaluate them according to the global 'evaluation_interval'.
rule_files:
# - "first_rules.yml"
# - "second_rules.yml"

# A scrape configuration containing exactly one endpoint to scrape:
scrape_configs:
  # The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.
  - job_name: 'nuts'
    metrics_path: '/metrics'
    scrape_interval: 5s
    static_configs:
      - targets: ['127.0.0.1:8081']

It’s important to enter the correct IP/domain and port where the Nuts node can be found!

Exported metrics

The Nuts service executable exports the following metric namespaces:

nuts_ contains metrics related to the functioning of the Nuts node
process_ contains OS metrics related to the process
go_ contains Go metrics related to the process
promhttp_ contains metrics related to HTTP calls to the Nuts node’s /metrics endpoint

CPU profiling

It’s possible to enable CPU profiling by passing the --cpuprofile=/some/location.dmp option. This will write a CPU profile to the given location when the node shuts down. The resulting file can be analyzed with Go tooling:

go tool pprof /some/location.dmp

The tooling includes a help function to get you started. To get started use the web command inside the tooling. It’ll open a SVG in a browser and give an overview of what the node was doing.