Monitor the proxy using Prometheus

The proxy uses Prometheus for recording metrics that can be used to understand how the proxy is behaving and performing. You can view and scrape these metrics by hitting the proxy's /metrics endpoint. For example, if you're running the proxy locally on port 7000, you can view the metrics it exposes by making the following request:

$ curl localhost:7000/metrics

Example Queries

To get started, here are some example promql queries that can be useful for monitoring how the proxy is performing.

Usecase	Promql query
Request Rate by Status Code	sum by (code) (rate(ff_proxy_http_requests_total[5m]))
Requests Rate by URL	sum by (url) ( rate ( ff_proxy_http_requests_total[5m]))
Cache Writes	sum by (error) (rate(ff_proxy_redis_cache_write_count[5m]))
Cache Reads	sum by (error) (rate(ff_proxy_redis_cache_read_count[5m]))
Cache Deletes	sum by (error) (rate(ff_proxy_redis_cache_read_count[5m]))
SSE Events Forwarded	sum by (error) (rate(ff_proxy_sse_publish[5m]))
SSE Streams Closed	sum by (error) (rate(ff ff_proxy_sse_stream_close[5m]))

As well as counter metrics, the proxy also exposes a number of histogram metrics that can be used to monitor request duration, payload sizes, and how long interactions with the cache take. If you are unfamilar with histogram metrics, we recommend reading this article for help with visualising histograms.

Example Prometheus Configuration

Below is an example prometheus configuration that can be used to scrape metrics from the proxy.

global:
  scrape_interval:     10s
  evaluation_interval: 10s

scrape_configs:
  - job_name: 'prometheus'
    scrape_interval: 30s
    static_configs:
      - targets: ['localhost:7000']

Metrics exposed

Below is a list of all the prometheus metrics exposed by the proxy.

Name	Type	Labels	Description
ff_proxy_http_requests_total	counter	code: The HTTP response code envID: The environmentID method: The HTTP method used for the request url: The requests URL	Records the number of requests to an endpoint
ff_proxy_http_requests_duration	histogram	envID: The environmentID url: The requests URL	Records the request duration for an endpoint
ff_http_requests_content_length_histogram	histogram	envID: The environmentID url: The requests URL	Records the value of the Content-Length header for an HTTP request
ff_proxy_metrics_forwarded	counter	envID: The environmentID error: Indicates if an error occurred during forwarding	Tracks the number of metrics forwarded from the proxy to SaaS Feature Flags
ff_proxy_sdk_usage	counter	envID: The environment ID sdk_language: The programming language of the SDK sdk_type: The type of the SDK (e.g., server, client, mobile) sdk_version: The version of the SDK	Tracks what SDKs are using the FF proxy
ff_proxy_sse_publish	counter	api_key: The API key used for authentication environment: The environment ID error: Indicates whether an error occurred during event forwarding	Records the number of Server-Sent Events (SSE) the proxy has received and forwarded on to clients
ff_proxy_sse_stream_close	counter	api_key: The API key used for authentication environment: The environment ID error: Indicates whether an error occurred during event forwarding	Records the number of times the proxy closes an SSE stream
ff_proxy_redis_cache_read_count	counter	error: Indicates if an error occurred during the read operation key: The cache key used for the read operation	Tracks how many reads are made to the cache
ff_proxy_redis_cache_write_count	counter	error: Indicates whether an error occurred during the write operation key: The cache key	Tracks how many writes are made to the cache
ff_proxy_redis_cache_remove_count	counter	key: The cache key	Tracks how many deletes are made to the cache
ff_proxy_redis_cache_delete_duration	histogram	N/A	Tracks how long delete operations to the cache take
ff_proxy_redis_cache_write_duration	histogram	N/A	Tracks how long write operations to the cache take
ff_proxy_redis_cache_read_duration	histogram	N/A	Tracks how long write operations to the cache take