ntfy-alertmanager/cache/redis.go

package cache

import (
	"context"
	"time"

	"github.com/redis/go-redis/v9"
)

const redisTimeout = 3 * time.Second

// RedisCache is the redis cache.
type RedisCache struct {
	client   *redis.Client
	duration time.Duration
}

// NewRedisCache creates a new redis cache/client.
func NewRedisCache(redisURL string, d time.Duration) (Cache, error) {
	c := new(RedisCache)
	ropts, err := redis.ParseURL(redisURL)
	if err != nil {
		return nil, err
	}

	rdb := redis.NewClient(ropts)
	ctx, cancel := context.WithTimeout(context.TODO(), redisTimeout)
	defer cancel()

	err = rdb.Ping(ctx).Err()
	if err != nil {
		return nil, err
	}

	c.client = rdb
	c.duration = d
	return c, nil
}

// Set saves an alert in the cache.
func (c *RedisCache) Set(fingerprint string, status string) error {
	ctx, cancel := context.WithTimeout(context.TODO(), redisTimeout)
	defer cancel()

	return c.client.SetEx(ctx, fingerprint, status, c.duration).Err()
}

// Contains checks if an alert with a given fingerprint is in the cache
// and if the status matches.
func (c *RedisCache) Contains(fingerprint string, status string) (bool, error) {
	ctx, cancel := context.WithTimeout(context.TODO(), redisTimeout)
	defer cancel()

	val, err := c.client.Get(ctx, fingerprint).Result()
	if err == redis.Nil {
		return false, nil
	} else if err != nil {
		return false, err
	}

	return val == status, nil
}

// Cleanup is an empty function that is simply here to implement the interface.
// Redis does its own cleanup.
func (c *RedisCache) Cleanup() {}