Superexporter provides the multi-target pattern for other exporters

Superexporter is a super server for memcached_exporter to support the multi-target pattern. You can scrape multiple memcahed metrics from a single superexporter endpoint by specifying the target in a query parameter.

It is designed for multiple remote targets, such as SaaS managed memcached (GCP Memorystore, AWS Elasticache).

How it works

Superexporter dynamically forks exporters for requested targets and acts as a HTTP proxy to them.

 \_ /bin/superexporter
     \_ /path/to/memcached_exporter --memcached.address memcached-host-a:11211 --web.listen-address localhost:45123
     \_ /path/to/memcached_exporter --memcached.address memcached-host-b:11211 --web.listen-address localhost:45321
     \_ /path/to/memcached_exporter --memcached.address memcached-host-c:11211 --web.listen-address localhost:46123

sequenceDiagram
    participant prometheus
    participant superexporter
    participant memcached_exporter 
    Note right of memcached_exporter: exporter for memcached-host-N
    prometheus->>superexporter: GET /scrape?target=memcached-host-N:11211
      superexporter->>memcached_exporter: proxy
        Note right of superexporter: fork & exec exporter if not exist
      memcached_exporter-->>superexporter: respond metrics
    superexporter-->>prometheus: respond metrics

And it cleans up child exporters that have not been requested for several minutes.

Running the exporter

Docker image

docker run -p 9150:9150 ghcr.io/gree/superexporter:latest

To verify:

curl 'localhost:9150/scrape?target=your-memcached-host:11211'

Pre-built binary

Pre-built binary is available at the releases.

Build from source

Prerequisite

The superexporter needs the memcached_exporter executable in PATH. You can find the released binaries on https://github.com/prometheus/memcached_exporter/releases.

Build and run

$ which memcached_exporter
/some/path/to/memcached_exporter

$ make
$ ./superexporter

To verify:

curl 'localhost:9150/scrape?target=your-memcached-host:11211'

Prometheus configuration for multiple memcached hosts

Use GET superexporter-host:9150/scrape endpoint with target=<memcached_addr:port> parameter like redis_exporter.

An example with static_configs is here:

  - job_name: memcached
    metrics_path: /scrape
    static_configs:
    - targets
      - memcached-host-a:11211
      - memcached-host-b:11211
      - memcached-host-c:11211
    relabel_configs:
    - source_labels: [__address__]
      target_label: __param_target
    - source_labels: [__param_target]
      target_label: instance
    - target_label: __address__
      replacement: superexporter-host:9150

  ## config for scraping the superexporter itself
  - job_name: superexporter
    metrics_path: /metrics
    static_configs:
    - targets
      - superexporter-host:9150

Of course, you can use other xxx_sd_configs. For example, this is for the case for file_sd_config.

  - job_name: memcached
    metrics_path: /scrape
    file_sd_configs:
    - files:
      - target-memcached-instances.json
    relabel_configs:
    - source_labels: [__address__]
      target_label: __param_target
    - source_labels: [__param_target]
      target_label: instance
    - target_label: __address__
      replacement: superexporter-host:9150

  ## config for scraping the superexporter itself
  - job_name: superexporter
    metrics_path: /metrics
    static_configs:
    - targets
      - superexporter-host:9150

Where target-memcached-instances.json is the following content:

[
  {
    "targets": [ "memcached-host-a:11211", "memcached-host-b:11211", "memcached-host-c:11211" ],
    "labels": { }
  }
]