move example relay implementations to examples/ folder.

examples/basic/.gitignore

@@ -0,0 +1 @@
+relayer-basic

examples/basic/Dockerfile

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+FROM golang:1.18
+
+WORKDIR /go/src/app
+COPY ./ .
+
+RUN go get -d -v ./...
+RUN go install -v ./...
+RUN cd basic && make

examples/basic/Makefile

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+relayer-basic: $(shell find .. -name "*.go")
+	CC=$$(which musl-gcc) go build -ldflags='-s -w -linkmode external -extldflags "-static"' -o ./relayer-basic

examples/basic/README.md

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+relayer basic
+=============
+
+  - a basic relay implementation based on relayer.
+  - uses postgres, which I think must be over version 12 since it uses generated columns.
+  - it has some antispam limits, tries to delete old stuff so things don't get out of control, and some other small optimizations.
+
+running
+-------
+
+grab a binary from the releases page and run it with the environment variable POSTGRESQL_DATABASE set to some postgres url:
+
+    POSTGRESQL_DATABASE=postgres://name:pass@localhost:5432/dbname ./relayer-basic
+
+it also accepts a HOST and a PORT environment variables.
+
+compiling
+---------
+
+if you know Go you already know this:
+
+    go install github.com/fiatjaf/relayer/basic
+
+or something like that.

examples/basic/docker-compose.yml

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+version: "3.8"
+services:
+
+  relay:
+    build:
+      context: ../
+      dockerfile: ./basic/Dockerfile
+    environment:
+      PORT: 2700
+      POSTGRESQL_DATABASE: postgres://nostr:nostr@postgres:5432/nostr?sslmode=disable
+    depends_on:
+      postgres:
+        condition: service_healthy
+    ports:
+      - 2700:2700
+    command: "./basic/relayer-basic"
+
+  postgres:
+    image: postgres
+    restart: always
+    environment:
+      POSTGRES_DB: nostr
+      POSTGRES_USER: nostr
+      POSTGRES_PASSWORD: nostr
+      POSTGRES_HOST_AUTH_METHOD: trust # allow all connections without a password. This is *not* recommended for prod
+    ports:
+      - 5432:5432
+    healthcheck:
+      test: ["CMD-SHELL", "pg_isready -U nostr"] # database username here - nostr, should be changed if other user
+      interval: 10s
+      timeout: 5s
+      retries: 5

examples/basic/main.go

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+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"time"
+
+	"github.com/fiatjaf/relayer/v2"
+	"github.com/fiatjaf/relayer/v2/storage/postgresql"
+	"github.com/kelseyhightower/envconfig"
+	"github.com/nbd-wtf/go-nostr"
+)
+
+type Relay struct {
+	PostgresDatabase string `envconfig:"POSTGRESQL_DATABASE"`
+
+	storage *postgresql.PostgresBackend
+}
+
+func (r *Relay) Name() string {
+	return "BasicRelay"
+}
+
+func (r *Relay) Storage(ctx context.Context) relayer.Storage {
+	return r.storage
+}
+
+func (r *Relay) Init() error {
+	err := envconfig.Process("", r)
+	if err != nil {
+		return fmt.Errorf("couldn't process envconfig: %w", err)
+	}
+
+	// every hour, delete all very old events
+	go func() {
+		db := r.Storage(context.TODO()).(*postgresql.PostgresBackend)
+
+		for {
+			time.Sleep(60 * time.Minute)
+			db.DB.Exec(`DELETE FROM event WHERE created_at < $1`, time.Now().AddDate(0, -3, 0).Unix()) // 3 months
+		}
+	}()
+
+	return nil
+}
+
+func (r *Relay) AcceptEvent(ctx context.Context, evt *nostr.Event) bool {
+	// block events that are too large
+	jsonb, _ := json.Marshal(evt)
+	if len(jsonb) > 10000 {
+		return false
+	}
+
+	return true
+}
+
+func main() {
+	r := Relay{}
+	if err := envconfig.Process("", &r); err != nil {
+		log.Fatalf("failed to read from env: %v", err)
+		return
+	}
+	r.storage = &postgresql.PostgresBackend{DatabaseURL: r.PostgresDatabase}
+	server, err := relayer.NewServer(&r)
+	if err != nil {
+		log.Fatalf("failed to create server: %v", err)
+	}
+	if err := server.Start("0.0.0.0", 7447); err != nil {
+		log.Fatalf("server terminated: %v", err)
+	}
+}