Golectra is a tiny, self-hosted metrics stack in pure Go: a lightweight agent collects Go runtime + host metrics and ships them (gzipped JSON) to a server with a simple HTTP API and optional integrity checks.

• Agent samples Go runtime.MemStats + system metrics (CPU, RAM) via gopsutil.
• Gzipped JSON transport with automatic retries and rate-limited workers.
• Optional HashSHA256 header (HMAC-like) to protect request/response integrity.
• Storage: Postgres (auto-migrate) or in-memory with JSON file persistence & restore.
• HTTP API (Gin) + a quick HTML dashboard at / (tables of gauges/counters).
• Zero deps at runtime (server/agent binaries). Go 1.21+.

1. Run the server

go run ./cmd/server -a :8080 -f metrics-db.json -i 300
# Flags:
# -a listen address, -f file path for snapshots, -i store interval seconds (0 = sync)

2. Run the agent

go run ./cmd/agent -a http://localhost:8080 -r 10 -p 2 -l 2
# -r report interval (s), -p poll interval (s), -l parallel senders

Open http://localhost:8080 to see metrics.

Path params:

• Update one (plain text): POST /update/:type/:name/:value where type is gauge or counter
• Read one (plain text): GET /value/:type/:name
• Read HTML dashboard: GET /
• JSON (recommended):

# Upsert one
curl -X POST http://localhost:8080/update \
  -H "Content-Type: application/json" \
  -d '{"id":"Alloc","type":"gauge","value":12345}'

# Read one
curl -X POST http://localhost:8080/value \
  -H "Content-Type: application/json" \
  -d '{"id":"Alloc","type":"gauge"}'

# Upsert batch
curl -X POST http://localhost:8080/updates \
  -H "Content-Type: application/json" \
  -d '[{"id":"foo","type":"gauge","value":1.23},{"id":"bar","type":"counter","delta":7}]'

# Health
curl http://localhost:8080/ping

Start both server and agent with the same secret key (-k or KEY env). The server will validate HashSHA256 for incoming POST bodies and will always set a HashSHA256 response header.

Example with curl:

BODY='{"id":"temp","type":"gauge","value":42}'
KEY='your-secret'
HASH=$(printf '%s' "$BODY$KEY" | openssl dgst -sha256 -binary | xxd -p -c 256)

curl -X POST http://localhost:8080/update \
  -H "Content-Type: application/json" \
  -H "HashSHA256: $HASH" \
  -d "$BODY" -i

You can use ENV, CLI flags, or defaults (ENV > CLI > defaults).

Go runtime gauges like Alloc, HeapAlloc, NumGC, PauseTotalNs, plus host gauges TotalMemory, FreeMemory, and per-core CPUutilization{N}; counters include PollCount, etc.