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NATS Surveyor

NATS Monitoring, Simplified.

NATS surveyor polls the NATS server for Statz messages to generate data for Prometheus. This allows a single exporter to connect to any NATS server and get an entire picture of a NATS deployment without requiring extra monitoring components or sidecars. Surveyor has been used extensively by Synadia.

System accounts must be enabled to use surveyor.

Usage

Usage:
  nats-surveyor [flags]

Flags:
      --accounts                            Export per account metrics
  -a, --addr string                         Network host to listen on. (default "0.0.0.0")
      --config string                       config file (default is ./nats-surveyor.yaml)
  -c, --count int                           Expected number of servers (-1 for undefined). (default 1)
      --creds string                        Credentials File
  -h, --help                                help for nats-surveyor
      --http-pass string                    Set the password for HTTP scrapes. NATS bcrypt supported.
      --http-tlscacert string               Client certificate CA for verification (used with HTTPS).
      --http-tlscert string                 Server certificate file (Enables HTTPS).
      --http-tlskey string                  Private key for server certificate (used with HTTPS).
      --http-user string                    Enable basic auth and set user name for HTTP scrapes.
      --jetstream string                    Listen for JetStream Advisories based on config files in a directory.
      --jwt string                          User JWT. Use in conjunction with --seed
      --log-level string                    Log level, one of: trace|debug|info|warn|error|fatal|panic (default "info")
      --nkey string                         Nkey Seed File
      --observe string                      Listen for observation statistics based on config files in a directory.
      --password string                     NATS user password
  -p, --port int                            Port to listen on. (default 7777)
      --prefix string                       Replace the default prefix for all the metrics.
      --seed string                         Private key (nkey seed). Use in conjunction with --jwt
      --server-discovery-timeout duration   Maximum wait time between responses from servers during server discovery. Use in conjunction with -count=-1. (default 500ms)
  -s, --servers string                      NATS Cluster url(s) (default "nats://127.0.0.1:4222")
      --timeout duration                    Polling timeout (default 3s)
      --tlscacert string                    Client certificate CA on NATS connections.
      --tlscert string                      Client certificate file for NATS connections.
      --tlskey string                       Client private key for NATS connections.
      --user string                         NATS user name or token
  -v, --version                             version for nats-surveyor

At this time, NATS 2.0 System credentials are required for meaningful usage. Those can be provided in 2 ways:

  • using --creds option to supply chained credentials file (containing JWT and NKey seed):
./nats-surveyor --creds ./test/SYS.creds
2019/10/14 21:35:40 Connected to NATS Deployment: 127.0.0.1:4222
2019/10/14 21:35:40 No certificate file specified; using http.
2019/10/14 21:35:40 Prometheus exporter listening at http://0.0.0.0:7777/metrics
  • using --jwt and --seed options to provide user JWT and NKey seed directly:
./nats-surveyor --jwt $NATS_USER_JWT --seed $NATS_NKEY_SEED
2019/10/14 21:35:40 Connected to NATS Deployment: 127.0.0.1:4222
2019/10/14 21:35:40 No certificate file specified; using http.
2019/10/14 21:35:40 Prometheus exporter listening at http://0.0.0.0:7777/metrics

Config

Config Files

Surveyor uses Viper to read configs, so it will support all file types that Viper supports (JSON, TOML, YAML, HCL, envfile, and Java properties)

To use a config file pass the --config flag. The defaults are /etc/nats-surveyor/nats-surveyor[.ext] and ./nats-surveyor[.ext] with one of the supported extensions.

The config is simple, just set each flag in the config file. Example nats-surveyor.yaml:

servers: nats://127.0.0.1:4222
accounts: true
log-level: debug

Environment Variables

Environment variables are also taken into account. Any environment variable that is prefixed with NATS_SURVEYOR_ will be read.

Each flag has a matching environment variable, flag names should be converted to uppercase and dashes replaced with underscores. Example:

NATS_SURVEYOR_SERVERS=nats://127.0.0.1:4222
NATS_SURVEYOR_ACCOUNTS=true
NATS_SURVEYOR_LOG_LEVEL=debug

Metrics

Scrape output is the in form of nats_core_NNNN_metric, where NNN is server, route, or gateway.

To aid filtering, each metric has labels. These include server_cluster, server_name, and server_id. Routes have the additional label server_route_name and gateways have the additional label server_gateway_name.

The info metrics has a nats_server_version label with the current version.

Additionally, there is a nats_up metric that will normally return 1, but will return 0 and no additional NATS metrics when there is no connectivity to the NATS system. This allows users to differentiate between a problem with the exporter itself connectivity with the NATS system.

Docker Compose

An easy way to start the NATS Surveyor stack (Grafana, Prometheus, and NATS Surveyor) is through docker-compose.

Follow these links for installation instructions:

Environment Variables

The following environment variables MUST be set, either in your environment or through the .env file that is automatically read by docker-compose. There is a survey.sh script that will set them for you as a convenience.

Environment Variable Example Description
NATS_SURVEYOR_SERVERS nats://hostname:4222 The URLs of any deployed NATS server(s)
NATS_SURVEYOR_CREDS ./SYS.creds NATS 2.0 System Account credentials
NATS_SURVEYOR_SERVER_COUNT 9 Number of expected NATS servers
PROMETHEUS_STORAGE ./storage/prometheus Path to store prometheus data locally
SURVEYOR_DOCKER_TAG latest Surveyor docker tag to pull
PROMETHEUS_DOCKER_TAG latest Prometheus docker tag to pull
GRAFANA_DOCKER_TAG latest Grafana docker tag to pull

Note: For referencing files and paths, docker always expects volume mounts to be either a fully qualified directory, or a relative directory beginning with with ./.

Server URLs

You only need to connect to a single NATS server to monitor your entire NATS deployment. In configuring NATS_SURVEYOR_SERVERS, only one server is required, but it's recommended you provide a list for backup servers to connect to, e.g. nats://host1:4222,nats://host2:5222. Valid urls are formatted as hostname (defaulting to port 4222), hostname:port, or nats://hostname:port.

Starting Up

You can start the Surveyor stack two ways. The first is through docker compose. Ensure the environment varibles are set, that you are working from the /docker-compose directory and run docker-compose up.

$ docker-compose up
Recreating nats-surveyor ... done
Recreating prometheus    ... done
Recreating grafana       ... done
Attaching to nats-surveyor, prometheus, grafana
...

Alternatively, you can pass variables into the survey.sh script in the docker-compose directory.

$ ./survey.sh
usage: survey.sh <url> <server count> <system credentials>

e.g.

./survey.sh nats://mydeployment:4222 24 /privatekeys/SYS.creds

If things aren't working, look in the output for any lines that contain exited with code 1 and address the problem. They are usually docker volume mount problems or connectivity problems.

Next, with your browser, navigate to http://127.0.0.1:3000, or if you are running the Surveyor stack remotely, the hostname of the host running the NATS surveyor stack, e.g. http://yourremotehost:3000.

The first time you connect, you'll need to login:

  • User: admin
  • Password: admin

After logging in, navigate to "Manage dashboards" and you'll see a dashboard available named NATS Surveyor, where you'll be able to monitor your entire NATS deployment.

Stopping (while keeping the containers)

To stop the surveyor stack, but keep the containers run: docker-compose stop

Restarting Surveyor

To restart the surveyor stack after being stopped, run: docker-compose up

Stopping and removing containers

To cleanup your installation, run: docker-compose down

Running Surveyor as a service

For platforms that support systemd, surveyor.service is provided as a service definition template. Modify and save this file as /etc/systemd/system/surveyor.service.

systemctl start surveyor will launch the service.

Errors

The logs should normally contain enough information about the cause of problems or errors.

If you encounter a Prometheus error of: panic: Unable to create mmap-ed active query log, set the UID of the container to match the UID of your user in the docker-compose file.

e.g:

  prometheus:
    image: prom/prometheus:${PROMETHEUS_DOCKER_TAG}
    user: "1000:1000"

If the above doesn't work, using root will work but may pose a security thread to the node it is running on.

  prometheus:
    image: prom/prometheus:${PROMETHEUS_DOCKER_TAG}
    user: root

More information can be found here.

Service Observations

Services can be observed by creating JSON files in the observations directory. The file extension must be .json. Only one authentication method needs to be provided. Example file format:

{
  "name":       "my service",
  "topic":      "email.subscribe.>",
  "jwt":        "jwt portion of creds, must include seed also",
  "seed":       "seed portion of creds, must include jwt also",
  "credential": "/path/to/file.creds",
  "nkey":       "nkey seed",
  "token":      "token",
  "username":   "username, must include password also",
  "password":   "password, must include user also",
  "tls_ca":     "/path/to/ca.pem, defaults to surveyor's ca if one exists",
  "tls_cert":   "/path/to/cert.pem, defaults to surveyor's cert if one exists",
  "tls_key":    "/path/to/key.pem, defaults to surveyor's key if one exists"
}

Files are watched and updated using fsnotify

JetStream

JetStream can be monitored on a per-account basis by creating JSON files in the jetstream directory. The file extension must be .json. Only one authentication method needs to be provided. e sure that you give access to the $JS.EVENT.> subject to your user. Example file format:

Credentials

{
  "name":       "my account",
  "jwt":        "jwt portion of creds, must include seed also",
  "seed":       "seed portion of creds, must include jwt also",
  "credential": "/path/to/file.creds",
  "nkey":       "nkey seed",
  "token":      "token",
  "username":   "username, must include password also",
  "password":   "password, must include user also",
  "tls_ca":     "/path/to/ca.pem, defaults to surveyor's ca if one exists",
  "tls_cert":   "/path/to/cert.pem, defaults to surveyor's cert if one exists",
  "tls_key":    "/path/to/key.pem, defaults to surveyor's key if one exists"
}

Files are watched and updated using fsnotify

TODO

  • Windows builds
  • Other events (connections, disconnects, etc)
  • Best Guess Server Count

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