monitoring

import { CodeExample } from "components/CodeExample";

To ensure that your instance of Horizon is performing correctly, we encourage you to monitor it, and provide both logs and metrics to do so.

Horizon will output logs to standard out. Information about what requests are coming in will be reported, but more importantly, warnings or errors will also be emitted by default. A correctly running Horizon instance will not output any warning or error log entries.

Metrics are collected while a Horizon process is running and they are exposed at the /metrics path. You can see an example at https://horizon-testnet.stellar.org/metrics.

Below we present a few standard log entries with associated fields. You can use them to build metrics and alerts. Please note that these represent Horizon app metrics only. You should also monitor your hardware metrics like CPU or RAM Utilization.

Starting HTTP request

Key	Value
msg	Starting request
client_name	Value of X-Client-Name HTTP header representing client name
client_version	Value of X-Client-Version HTTP header representing client version
app_name	Value of X-App-Name HTTP header representing app name
app_version	Value of X-App-Version HTTP header representing app version
forwarded_ip	First value of X-Forwarded-For header
host	Value of Host header
ip	IP of a client sending HTTP request
ip_port	IP and port of a client sending HTTP request
method	HTTP method (GET, POST, ...)
path	Full request path, including query string (ex. /transactions?order=desc)
streaming	Boolean, true if request is a streaming request
referer	Value of Referer header
req	Random value that uniquely identifies a request, attached to all logs within this HTTP request

Finished HTTP request

Key	Value
msg	Finished request
bytes	Number of response bytes sent
client_name	Value of X-Client-Name HTTP header representing client name
client_version	Value of X-Client-Version HTTP header representing client version
app_name	Value of X-App-Name HTTP header representing app name
app_version	Value of X-App-Version HTTP header representing app version
duration	Duration of request in seconds
forwarded_ip	First value of X-Forwarded-For header
host	Value of Host header
ip	IP of a client sending HTTP request
ip_port	IP and port of a client sending HTTP request
method	HTTP method (GET, POST, ...)
path	Full request path, including query string (ex. /transactions?order=desc)
route	Route pattern without query string (ex. /accounts/{id})
status	HTTP status code (ex. 200)
streaming	Boolean, true if request is a streaming request
referer	Value of Referer header
req	Random value that uniquely identifies a request, attached to all logs within this HTTP request

Metrics

Using the entries above you can build metrics that will help understand performance of a given Horizon node. For example:

• Number of requests per minute.

• Number of requests per route (the most popular routes).

• Average response time per route.

• Maximum response time for non-streaming requests.

• Number of streaming vs. non-streaming requests.

• Number of rate-limited requests.

• List of rate-limited IPs.

• Unique IPs.

• The most popular SDKs/apps sending requests to a given Horizon node.

• Average ingestion time of a ledger.

• Average ingestion time of a transaction.

Alerts

Below are example alerts with potential causes and solutions. Feel free to add more alerts using your metrics:

Alert	Cause	Solution
Spike in number of requests	Potential DoS attack	Lower rate-limiting threshold
Large number of rate-limited requests	Rate-limiting threshold too low	Increase rate-limiting threshold
Ingestion is slow	Horizon server spec too low	Increase hardware spec
Spike in average response time of a single route	Possible bug in a code responsible for rendering a route	Report an issue in Horizon repository.

I'm Stuck! Help!

If any of the above steps don't work or you are otherwise prevented from correctly setting up Horizon, please join our community and let us know. Either post a question at our Stack Exchange or chat with us on Keybase in #dev_discussion to ask for help.