Switched to redis/postgres, major refactoring

- loginMetadata is passed to shards through redis now
- shards announce they're alive via redis.AnnounceShard() which just
  populates a hashset keyed 'shards'
- login servers grab the 'shards' hashset and randomly picks a shard to
  pass the player to (for now)
- ./service shard && ./service login
- Many new environment variables, check config/config.go for more info.
  or for a tl;dr just read the Dockerfile for the required ones
- Shard and login services now run in different processes ! (and
  containers?? wooaaah)

core/redis/redis.go

@@ -0,0 +1,112 @@
+package redis
+
+/*
+	used for state management between shard and login servers
+*/
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"strconv"
+
+	"github.com/CPunch/gopenfusion/config"
+
+	"github.com/redis/go-redis/v9"
+)
+
+type RedisHandler struct {
+	client *redis.Client
+	ctx    context.Context
+}
+
+type LoginMetadata struct {
+	FEKey    []byte `json:",omitempty"`
+	PlayerID int32  `json:",omitempty"`
+}
+
+type ShardMetadata struct {
+	IP   string
+	Port int
+}
+
+const (
+	SHARD_SET = "shards"
+)
+
+func OpenRedis(addr string) (*RedisHandler, error) {
+	client := redis.NewClient(&redis.Options{
+		Addr:                addr,
+		CredentialsProvider: config.GetRedisCredentials(),
+	})
+
+	_, err := client.Ping(context.Background()).Result()
+	return &RedisHandler{client: client, ctx: context.Background()}, err
+}
+
+func (r *RedisHandler) Close() error {
+	return r.client.Close()
+}
+
+// we store login queues into redis with the name "loginMetadata_<serialKey>"
+// set to expire after config.LOGIN_TIMEOUT duration. this way we can easily
+// have a shared pool of active serial keys & player login data which any
+// shard can pull from
+
+func makeLoginMetadataKey(serialKey int64) string {
+	return fmt.Sprintf("loginMetadata_%s", strconv.Itoa(int(serialKey)))
+}
+
+func (r *RedisHandler) QueueLogin(serialKey int64, data LoginMetadata) error {
+	value, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+
+	// add to table
+	return r.client.Set(r.ctx, makeLoginMetadataKey(serialKey), value, config.LOGIN_TIMEOUT).Err()
+}
+
+func (r *RedisHandler) GetLogin(serialKey int64) (LoginMetadata, error) {
+	value, err := r.client.Get(r.ctx, makeLoginMetadataKey(serialKey)).Result()
+	if err != nil {
+		return LoginMetadata{}, err
+	}
+
+	var data LoginMetadata
+	if err := json.Unmarshal([]byte(value), &data); err != nil {
+		return LoginMetadata{}, err
+	}
+
+	return data, nil
+}
+
+func (r *RedisHandler) RemoveLogin(serialKey int64) error {
+	return r.client.Del(r.ctx, makeLoginMetadataKey(serialKey)).Err()
+}
+
+func (r *RedisHandler) RegisterShard(shard ShardMetadata) error {
+	value, err := json.Marshal(shard)
+	if err != nil {
+		return err
+	}
+
+	return r.client.SAdd(r.ctx, SHARD_SET, value).Err()
+}
+
+func (r *RedisHandler) GetShards() []ShardMetadata {
+	shardData := r.client.SMembers(r.ctx, SHARD_SET).Val()
+
+	// unmarshal all shards
+	shards := make([]ShardMetadata, 0, len(shardData))
+	for _, data := range shardData {
+		var shard ShardMetadata
+		if err := json.Unmarshal([]byte(data), &shard); err != nil {
+			continue
+		}
+
+		shards = append(shards, shard)
+	}
+
+	return shards
+}