feat: add NATs discovery provider (#15)

.golangci.yml

@@ -55,6 +55,7 @@ linters-settings:
     ignore-words:
       - cancelled
       - behaviour
+      - initialised
 
   goheader:
     template: |-

discovery/error.go

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2024 Tochemey
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy of
+ * this software and associated documentation files (the "Software"), to deal in
+ * the Software without restriction, including without limitation the rights to
+ * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+ * the Software, and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+ * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+ * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package discovery
+
+import "errors"
+
+var (
+	// ErrAlreadyInitialized is used when attempting to re-initialize the discovery provider
+	ErrAlreadyInitialized = errors.New("provider already initialized")
+	// ErrNotInitialized is used when the provider is not initialized
+	ErrNotInitialized = errors.New("provider not initialized")
+	// ErrAlreadyRegistered is used when attempting to re-register the provider
+	ErrAlreadyRegistered = errors.New("provider already registered")
+	// ErrNotRegistered is used when attempting to de-register the provider
+	ErrNotRegistered = errors.New("provider is not registered")
+)

discovery/nats/config.go

@@ -0,0 +1,89 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2022-2024 Tochemey
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package nats
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/tochemey/gokv/internal/validation"
+)
+
+// Config represents the nats provider discoConfig
+type Config struct {
+	// Server defines the nats server in the format nats://host:port
+	Server string
+	// Subject defines the custom NATS subject
+	Subject string
+	// Timeout defines the nodes discovery timeout
+	Timeout time.Duration
+	// MaxJoinAttempts denotes the maximum number of attempts to connect an existing NATs server
+	// Default to 5
+	MaxJoinAttempts int
+	// ReconnectWait sets the time to backoff after attempting a reconnect
+	// to a server that we were already connected to previously.
+	// Defaults to 2s.
+	ReconnectWait time.Duration
+	// Host specifies the host
+	Host string
+	// DiscoveryPort specifies the node discovery port
+	DiscoveryPort uint16
+}
+
+// Validate checks whether the given discovery configuration is valid
+func (config Config) Validate() error {
+	return validation.New(validation.FailFast()).
+		AddValidator(validation.NewEmptyStringValidator("Server", config.Server)).
+		AddValidator(NewServerAddrValidator(config.Server)).
+		AddValidator(validation.NewEmptyStringValidator("Subject", config.Subject)).
+		AddValidator(validation.NewEmptyStringValidator("Host", config.Host)).
+		AddAssertion(config.DiscoveryPort > 0, "DiscoveryPort is invalid").
+		Validate()
+}
+
+// ServerAddrValidator helps validates the NATs server address
+type ServerAddrValidator struct {
+	server string
+}
+
+// NewServerAddrValidator validates the nats server address
+func NewServerAddrValidator(server string) validation.Validator {
+	return &ServerAddrValidator{server: server}
+}
+
+// Validate execute the validation code
+func (x *ServerAddrValidator) Validate() error {
+	// make sure that the nats prefix is set in the server address
+	if !strings.HasPrefix(x.server, "nats") {
+		return fmt.Errorf("invalid nats server address: %s", x.server)
+	}
+
+	hostAndPort := strings.SplitN(x.server, "nats://", 2)[1]
+	return validation.NewTCPAddressValidator(hostAndPort).Validate()
+}
+
+// enforce compilation error
+var _ validation.Validator = (*ServerAddrValidator)(nil)

discovery/nats/config_test.go

@@ -0,0 +1,48 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2024 Tochemey
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package nats
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestConfig(t *testing.T) {
+	t.Run("With valid configuration", func(t *testing.T) {
+		config := Config{
+			Server:        fmt.Sprintf("nats://%s", "127.0.0.1:234"),
+			Subject:       "subject",
+			Host:          "host",
+			DiscoveryPort: 123,
+		}
+		assert.NoError(t, config.Validate())
+	})
+	t.Run("With invalid configuration", func(t *testing.T) {
+		config := Config{}
+		assert.Error(t, config.Validate())
+	})
+}