Merge pull request #52 from helios-ag/memcached

Memcached

checkers/memcached.go

@@ -0,0 +1,168 @@
+package checkers
+
+import (
+	"bytes"
+	"fmt"
+	"github.com/bradfitz/gomemcache/memcache"
+	"net"
+	"net/url"
+)
+
+const (
+	// MemcachedDefaultSetValue will be used if the "Set" check method is enabled
+	// and "MemcachedSetOptions.Value" is _not_ set.
+	MemcachedDefaultSetValue = "go-health/memcached-check"
+)
+
+// MongoConfig is used for configuring the go-mongo check.
+//
+// "Url" is _required_; memcached connection url, format is "10.0.0.1:11011". Port (:11011) is mandatory
+// "Timeout" defines timeout for socket write/read (useful for servers hosted on different machine)
+// "Ping" is optional; Ping establishes tcp connection to memcached server.
+type MemcachedConfig struct {
+	Url        string
+	Timeout    int32
+	Ping       bool
+	Set        *MemcachedSetOptions
+	Get        *MemcachedGetOptions
+}
+
+type MemcachedClient interface {
+	Get(key string) (item *memcache.Item, err error)
+	Set(item *memcache.Item) error
+}
+
+type Memcached struct {
+	Config *MemcachedConfig
+	wrapper *MemcachedClientWrapper
+}
+
+// MemcachedSetOptions contains attributes that can alter the behavior of the memcached
+// "SET" check.
+//
+// "Key" is _required_; the name of the key we are attempting to "SET".
+//
+// "Value" is optional; what the value should hold; if not set, it will be set
+// to "MemcachedDefaultSetValue".
+//
+// "Expiration" is optional; if set, a TTL will be attached to the key.
+type MemcachedSetOptions struct {
+	Key        string
+	Value      string
+	Expiration int32
+}
+
+// MemcachedGetOptions contains attributes that can alter the behavior of the memcached
+// "GET" check.
+//
+// "Key" is _required_; the name of the key that we are attempting to "GET".
+//
+// "Expect" is optional; optionally verify that the value for the key matches
+// the Expect value.
+//
+// "NoErrorMissingKey" is optional; by default, the "GET" check will error if
+// the key we are fetching does not exist; flip this bool if that is normal/expected/ok.
+type MemcachedGetOptions struct {
+	Key               string
+	Expect            []byte
+	NoErrorMissingKey bool
+}
+
+func NewMemcached(cfg *MemcachedConfig) (*Memcached, error) {
+	// validate settings
+	if err := validateMemcachedConfig(cfg); err != nil {
+		return nil, fmt.Errorf("unable to validate memcached config: %v", err)
+	}
+
+	mcWrapper := &MemcachedClientWrapper{memcache.New(cfg.Url)}
+
+	return &Memcached{
+		Config: cfg,
+		wrapper: mcWrapper,
+	}, nil
+}
+
+func (mc *Memcached) Status() (interface{}, error) {
+
+	if mc.Config.Ping {
+		if _, err := net.Dial("tcp", mc.Config.Url); err != nil {
+			return nil, fmt.Errorf("Ping failed: %v", err)
+		}
+	}
+
+	if mc.Config.Set != nil {
+		err := mc.wrapper.GetClient().Set(&memcache.Item{Key: mc.Config.Set.Key, Value: []byte(mc.Config.Set.Value), Expiration: mc.Config.Set.Expiration})
+		if err != nil {
+			return nil, fmt.Errorf("Unable to complete set: %v", err)
+		}
+	}
+
+	if mc.Config.Get != nil {
+		val, err := mc.wrapper.GetClient().Get(mc.Config.Get.Key);
+		if err != nil {
+			if err == memcache.ErrCacheMiss {
+				if !mc.Config.Get.NoErrorMissingKey {
+					return nil, fmt.Errorf("Unable to complete get: '%v' not found", mc.Config.Get.Key)
+				}
+			} else {
+				return nil, fmt.Errorf("Unable to complete get: %v", err)
+			}
+		}
+
+		if mc.Config.Get.Expect != nil {
+			if !bytes.Equal(mc.Config.Get.Expect, val.Value) {
+				return nil, fmt.Errorf("Unable to complete get: returned value '%v' does not match expected value '%v'",
+					val, mc.Config.Get.Expect)
+			}
+		}
+	}
+
+	return nil, nil
+}
+
+func validateMemcachedConfig(cfg *MemcachedConfig) error {
+	if cfg == nil {
+		return fmt.Errorf("Main config cannot be nil")
+	}
+
+	if cfg.Url == "" {
+		return fmt.Errorf("Url string must be set in config")
+	}
+
+	if _, err := url.Parse(cfg.Url); err != nil {
+		return fmt.Errorf("Unable to parse URL: %v", err)
+	}
+
+	// At least one check method must be set
+	if !cfg.Ping && cfg.Set == nil && cfg.Get == nil {
+		return fmt.Errorf("At minimum, either cfg.Ping, cfg.Set or cfg.Get must be set")
+	}
+
+	// If .Set is set, verify that at minimum .Key is set
+	if cfg.Set != nil {
+		if cfg.Set.Key == "" {
+			return fmt.Errorf("If cfg.Set is used, cfg.Set.Key must be set")
+		}
+
+		if cfg.Set.Value == "" {
+			cfg.Set.Value = MemcachedDefaultSetValue
+		}
+	}
+
+	// If .Get is set, verify that at minimum .Key is set
+	if cfg.Get != nil {
+		if cfg.Get.Key == "" {
+			return fmt.Errorf("If cfg.Get is used, cfg.Get.Key must be set")
+		}
+	}
+
+	return nil
+}
+// Used to simplify testing routines
+type MemcachedClientWrapper struct {
+	MemcachedClient
+}
+
+func (mcw MemcachedClientWrapper) GetClient() MemcachedClient {
+	return mcw.MemcachedClient
+}