diff --git a/vendor/github.com/Shopify/sarama/config.go b/vendor/github.com/Shopify/sarama/config.go
new file mode 100644
index 0000000..e2e6513
--- /dev/null
+++ b/vendor/github.com/Shopify/sarama/config.go
@@ -0,0 +1,695 @@
+package sarama
+
+import (
+	"compress/gzip"
+	"crypto/tls"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"regexp"
+	"time"
+
+	"github.com/rcrowley/go-metrics"
+	"golang.org/x/net/proxy"
+)
+
+const defaultClientID = "sarama"
+
+var validID = regexp.MustCompile(`\A[A-Za-z0-9._-]+\z`)
+
+// Config is used to pass multiple configuration options to Sarama's constructors.
+type Config struct {
+	// Admin is the namespace for ClusterAdmin properties used by the administrative Kafka client.
+	Admin struct {
+		// The maximum duration the administrative Kafka client will wait for ClusterAdmin operations,
+		// including topics, brokers, configurations and ACLs (defaults to 3 seconds).
+		Timeout time.Duration
+	}
+
+	// Net is the namespace for network-level properties used by the Broker, and
+	// shared by the Client/Producer/Consumer.
+	Net struct {
+		// How many outstanding requests a connection is allowed to have before
+		// sending on it blocks (default 5).
+		MaxOpenRequests int
+
+		// All three of the below configurations are similar to the
+		// `socket.timeout.ms` setting in JVM kafka. All of them default
+		// to 30 seconds.
+		DialTimeout  time.Duration // How long to wait for the initial connection.
+		ReadTimeout  time.Duration // How long to wait for a response.
+		WriteTimeout time.Duration // How long to wait for a transmit.
+
+		TLS struct {
+			// Whether or not to use TLS when connecting to the broker
+			// (defaults to false).
+			Enable bool
+			// The TLS configuration to use for secure connections if
+			// enabled (defaults to nil).
+			Config *tls.Config
+		}
+
+		// SASL based authentication with broker. While there are multiple SASL authentication methods
+		// the current implementation is limited to plaintext (SASL/PLAIN) authentication
+		SASL struct {
+			// Whether or not to use SASL authentication when connecting to the broker
+			// (defaults to false).
+			Enable bool
+			// SASLMechanism is the name of the enabled SASL mechanism.
+			// Possible values: OAUTHBEARER, PLAIN (defaults to PLAIN).
+			Mechanism SASLMechanism
+			// Version is the SASL Protocol Version to use
+			// Kafka > 1.x should use V1, except on Azure EventHub which use V0
+			Version int16
+			// Whether or not to send the Kafka SASL handshake first if enabled
+			// (defaults to true). You should only set this to false if you're using
+			// a non-Kafka SASL proxy.
+			Handshake bool
+			//username and password for SASL/PLAIN  or SASL/SCRAM authentication
+			User     string
+			Password string
+			// authz id used for SASL/SCRAM authentication
+			SCRAMAuthzID string
+			// SCRAMClientGeneratorFunc is a generator of a user provided implementation of a SCRAM
+			// client used to perform the SCRAM exchange with the server.
+			SCRAMClientGeneratorFunc func() SCRAMClient
+			// TokenProvider is a user-defined callback for generating
+			// access tokens for SASL/OAUTHBEARER auth. See the
+			// AccessTokenProvider interface docs for proper implementation
+			// guidelines.
+			TokenProvider AccessTokenProvider
+
+			GSSAPI GSSAPIConfig
+		}
+
+		// KeepAlive specifies the keep-alive period for an active network connection.
+		// If zero, keep-alives are disabled. (default is 0: disabled).
+		KeepAlive time.Duration
+
+		// LocalAddr is the local address to use when dialing an
+		// address. The address must be of a compatible type for the
+		// network being dialed.
+		// If nil, a local address is automatically chosen.
+		LocalAddr net.Addr
+
+		Proxy struct {
+			// Whether or not to use proxy when connecting to the broker
+			// (defaults to false).
+			Enable bool
+			// The proxy dialer to use enabled (defaults to nil).
+			Dialer proxy.Dialer
+		}
+	}
+
+	// Metadata is the namespace for metadata management properties used by the
+	// Client, and shared by the Producer/Consumer.
+	Metadata struct {
+		Retry struct {
+			// The total number of times to retry a metadata request when the
+			// cluster is in the middle of a leader election (default 3).
+			Max int
+			// How long to wait for leader election to occur before retrying
+			// (default 250ms). Similar to the JVM's `retry.backoff.ms`.
+			Backoff time.Duration
+			// Called to compute backoff time dynamically. Useful for implementing
+			// more sophisticated backoff strategies. This takes precedence over
+			// `Backoff` if set.
+			BackoffFunc func(retries, maxRetries int) time.Duration
+		}
+		// How frequently to refresh the cluster metadata in the background.
+		// Defaults to 10 minutes. Set to 0 to disable. Similar to
+		// `topic.metadata.refresh.interval.ms` in the JVM version.
+		RefreshFrequency time.Duration
+
+		// Whether to maintain a full set of metadata for all topics, or just
+		// the minimal set that has been necessary so far. The full set is simpler
+		// and usually more convenient, but can take up a substantial amount of
+		// memory if you have many topics and partitions. Defaults to true.
+		Full bool
+
+		// How long to wait for a successful metadata response.
+		// Disabled by default which means a metadata request against an unreachable
+		// cluster (all brokers are unreachable or unresponsive) can take up to
+		// `Net.[Dial|Read]Timeout * BrokerCount * (Metadata.Retry.Max + 1) + Metadata.Retry.Backoff * Metadata.Retry.Max`
+		// to fail.
+		Timeout time.Duration
+	}
+
+	// Producer is the namespace for configuration related to producing messages,
+	// used by the Producer.
+	Producer struct {
+		// The maximum permitted size of a message (defaults to 1000000). Should be
+		// set equal to or smaller than the broker's `message.max.bytes`.
+		MaxMessageBytes int
+		// The level of acknowledgement reliability needed from the broker (defaults
+		// to WaitForLocal). Equivalent to the `request.required.acks` setting of the
+		// JVM producer.
+		RequiredAcks RequiredAcks
+		// The maximum duration the broker will wait the receipt of the number of
+		// RequiredAcks (defaults to 10 seconds). This is only relevant when
+		// RequiredAcks is set to WaitForAll or a number > 1. Only supports
+		// millisecond resolution, nanoseconds will be truncated. Equivalent to
+		// the JVM producer's `request.timeout.ms` setting.
+		Timeout time.Duration
+		// The type of compression to use on messages (defaults to no compression).
+		// Similar to `compression.codec` setting of the JVM producer.
+		Compression CompressionCodec
+		// The level of compression to use on messages. The meaning depends
+		// on the actual compression type used and defaults to default compression
+		// level for the codec.
+		CompressionLevel int
+		// Generates partitioners for choosing the partition to send messages to
+		// (defaults to hashing the message key). Similar to the `partitioner.class`
+		// setting for the JVM producer.
+		Partitioner PartitionerConstructor
+		// If enabled, the producer will ensure that exactly one copy of each message is
+		// written.
+		Idempotent bool
+
+		// Return specifies what channels will be populated. If they are set to true,
+		// you must read from the respective channels to prevent deadlock. If,
+		// however, this config is used to create a `SyncProducer`, both must be set
+		// to true and you shall not read from the channels since the producer does
+		// this internally.
+		Return struct {
+			// If enabled, successfully delivered messages will be returned on the
+			// Successes channel (default disabled).
+			Successes bool
+
+			// If enabled, messages that failed to deliver will be returned on the
+			// Errors channel, including error (default enabled).
+			Errors bool
+		}
+
+		// The following config options control how often messages are batched up and
+		// sent to the broker. By default, messages are sent as fast as possible, and
+		// all messages received while the current batch is in-flight are placed
+		// into the subsequent batch.
+		Flush struct {
+			// The best-effort number of bytes needed to trigger a flush. Use the
+			// global sarama.MaxRequestSize to set a hard upper limit.
+			Bytes int
+			// The best-effort number of messages needed to trigger a flush. Use
+			// `MaxMessages` to set a hard upper limit.
+			Messages int
+			// The best-effort frequency of flushes. Equivalent to
+			// `queue.buffering.max.ms` setting of JVM producer.
+			Frequency time.Duration
+			// The maximum number of messages the producer will send in a single
+			// broker request. Defaults to 0 for unlimited. Similar to
+			// `queue.buffering.max.messages` in the JVM producer.
+			MaxMessages int
+		}
+
+		Retry struct {
+			// The total number of times to retry sending a message (default 3).
+			// Similar to the `message.send.max.retries` setting of the JVM producer.
+			Max int
+			// How long to wait for the cluster to settle between retries
+			// (default 100ms). Similar to the `retry.backoff.ms` setting of the
+			// JVM producer.
+			Backoff time.Duration
+			// Called to compute backoff time dynamically. Useful for implementing
+			// more sophisticated backoff strategies. This takes precedence over
+			// `Backoff` if set.
+			BackoffFunc func(retries, maxRetries int) time.Duration
+		}
+	}
+
+	// Consumer is the namespace for configuration related to consuming messages,
+	// used by the Consumer.
+	Consumer struct {
+
+		// Group is the namespace for configuring consumer group.
+		Group struct {
+			Session struct {
+				// The timeout used to detect consumer failures when using Kafka's group management facility.
+				// The consumer sends periodic heartbeats to indicate its liveness to the broker.
+				// If no heartbeats are received by the broker before the expiration of this session timeout,
+				// then the broker will remove this consumer from the group and initiate a rebalance.
+				// Note that the value must be in the allowable range as configured in the broker configuration
+				// by `group.min.session.timeout.ms` and `group.max.session.timeout.ms` (default 10s)
+				Timeout time.Duration
+			}
+			Heartbeat struct {
+				// The expected time between heartbeats to the consumer coordinator when using Kafka's group
+				// management facilities. Heartbeats are used to ensure that the consumer's session stays active and
+				// to facilitate rebalancing when new consumers join or leave the group.
+				// The value must be set lower than Consumer.Group.Session.Timeout, but typically should be set no
+				// higher than 1/3 of that value.
+				// It can be adjusted even lower to control the expected time for normal rebalances (default 3s)
+				Interval time.Duration
+			}
+			Rebalance struct {
+				// Strategy for allocating topic partitions to members (default BalanceStrategyRange)
+				Strategy BalanceStrategy
+				// The maximum allowed time for each worker to join the group once a rebalance has begun.
+				// This is basically a limit on the amount of time needed for all tasks to flush any pending
+				// data and commit offsets. If the timeout is exceeded, then the worker will be removed from
+				// the group, which will cause offset commit failures (default 60s).
+				Timeout time.Duration
+
+				Retry struct {
+					// When a new consumer joins a consumer group the set of consumers attempt to "rebalance"
+					// the load to assign partitions to each consumer. If the set of consumers changes while
+					// this assignment is taking place the rebalance will fail and retry. This setting controls
+					// the maximum number of attempts before giving up (default 4).
+					Max int
+					// Backoff time between retries during rebalance (default 2s)
+					Backoff time.Duration
+				}
+			}
+			Member struct {
+				// Custom metadata to include when joining the group. The user data for all joined members
+				// can be retrieved by sending a DescribeGroupRequest to the broker that is the
+				// coordinator for the group.
+				UserData []byte
+			}
+		}
+
+		Retry struct {
+			// How long to wait after a failing to read from a partition before
+			// trying again (default 2s).
+			Backoff time.Duration
+			// Called to compute backoff time dynamically. Useful for implementing
+			// more sophisticated backoff strategies. This takes precedence over
+			// `Backoff` if set.
+			BackoffFunc func(retries int) time.Duration
+		}
+
+		// Fetch is the namespace for controlling how many bytes are retrieved by any
+		// given request.
+		Fetch struct {
+			// The minimum number of message bytes to fetch in a request - the broker
+			// will wait until at least this many are available. The default is 1,
+			// as 0 causes the consumer to spin when no messages are available.
+			// Equivalent to the JVM's `fetch.min.bytes`.
+			Min int32
+			// The default number of message bytes to fetch from the broker in each
+			// request (default 1MB). This should be larger than the majority of
+			// your messages, or else the consumer will spend a lot of time
+			// negotiating sizes and not actually consuming. Similar to the JVM's
+			// `fetch.message.max.bytes`.
+			Default int32
+			// The maximum number of message bytes to fetch from the broker in a
+			// single request. Messages larger than this will return
+			// ErrMessageTooLarge and will not be consumable, so you must be sure
+			// this is at least as large as your largest message. Defaults to 0
+			// (no limit). Similar to the JVM's `fetch.message.max.bytes`. The
+			// global `sarama.MaxResponseSize` still applies.
+			Max int32
+		}
+		// The maximum amount of time the broker will wait for Consumer.Fetch.Min
+		// bytes to become available before it returns fewer than that anyways. The
+		// default is 250ms, since 0 causes the consumer to spin when no events are
+		// available. 100-500ms is a reasonable range for most cases. Kafka only
+		// supports precision up to milliseconds; nanoseconds will be truncated.
+		// Equivalent to the JVM's `fetch.wait.max.ms`.
+		MaxWaitTime time.Duration
+
+		// The maximum amount of time the consumer expects a message takes to
+		// process for the user. If writing to the Messages channel takes longer
+		// than this, that partition will stop fetching more messages until it
+		// can proceed again.
+		// Note that, since the Messages channel is buffered, the actual grace time is
+		// (MaxProcessingTime * ChanneBufferSize). Defaults to 100ms.
+		// If a message is not written to the Messages channel between two ticks
+		// of the expiryTicker then a timeout is detected.
+		// Using a ticker instead of a timer to detect timeouts should typically
+		// result in many fewer calls to Timer functions which may result in a
+		// significant performance improvement if many messages are being sent
+		// and timeouts are infrequent.
+		// The disadvantage of using a ticker instead of a timer is that
+		// timeouts will be less accurate. That is, the effective timeout could
+		// be between `MaxProcessingTime` and `2 * MaxProcessingTime`. For
+		// example, if `MaxProcessingTime` is 100ms then a delay of 180ms
+		// between two messages being sent may not be recognized as a timeout.
+		MaxProcessingTime time.Duration
+
+		// Return specifies what channels will be populated. If they are set to true,
+		// you must read from them to prevent deadlock.
+		Return struct {
+			// If enabled, any errors that occurred while consuming are returned on
+			// the Errors channel (default disabled).
+			Errors bool
+		}
+
+		// Offsets specifies configuration for how and when to commit consumed
+		// offsets. This currently requires the manual use of an OffsetManager
+		// but will eventually be automated.
+		Offsets struct {
+			// How frequently to commit updated offsets. Defaults to 1s.
+			CommitInterval time.Duration
+
+			// The initial offset to use if no offset was previously committed.
+			// Should be OffsetNewest or OffsetOldest. Defaults to OffsetNewest.
+			Initial int64
+
+			// The retention duration for committed offsets. If zero, disabled
+			// (in which case the `offsets.retention.minutes` option on the
+			// broker will be used).  Kafka only supports precision up to
+			// milliseconds; nanoseconds will be truncated. Requires Kafka
+			// broker version 0.9.0 or later.
+			// (default is 0: disabled).
+			Retention time.Duration
+
+			Retry struct {
+				// The total number of times to retry failing commit
+				// requests during OffsetManager shutdown (default 3).
+				Max int
+			}
+		}
+
+		// IsolationLevel support 2 mode:
+		// 	- use `ReadUncommitted` (default) to consume and return all messages in message channel
+		//	- use `ReadCommitted` to hide messages that are part of an aborted transaction
+		IsolationLevel IsolationLevel
+	}
+
+	// A user-provided string sent with every request to the brokers for logging,
+	// debugging, and auditing purposes. Defaults to "sarama", but you should
+	// probably set it to something specific to your application.
+	ClientID string
+	// The number of events to buffer in internal and external channels. This
+	// permits the producer and consumer to continue processing some messages
+	// in the background while user code is working, greatly improving throughput.
+	// Defaults to 256.
+	ChannelBufferSize int
+	// The version of Kafka that Sarama will assume it is running against.
+	// Defaults to the oldest supported stable version. Since Kafka provides
+	// backwards-compatibility, setting it to a version older than you have
+	// will not break anything, although it may prevent you from using the
+	// latest features. Setting it to a version greater than you are actually
+	// running may lead to random breakage.
+	Version KafkaVersion
+	// The registry to define metrics into.
+	// Defaults to a local registry.
+	// If you want to disable metrics gathering, set "metrics.UseNilMetrics" to "true"
+	// prior to starting Sarama.
+	// See Examples on how to use the metrics registry
+	MetricRegistry metrics.Registry
+}
+
+// NewConfig returns a new configuration instance with sane defaults.
+func NewConfig() *Config {
+	c := &Config{}
+
+	c.Admin.Timeout = 3 * time.Second
+
+	c.Net.MaxOpenRequests = 5
+	c.Net.DialTimeout = 30 * time.Second
+	c.Net.ReadTimeout = 30 * time.Second
+	c.Net.WriteTimeout = 30 * time.Second
+	c.Net.SASL.Handshake = true
+	c.Net.SASL.Version = SASLHandshakeV0
+
+	c.Metadata.Retry.Max = 3
+	c.Metadata.Retry.Backoff = 250 * time.Millisecond
+	c.Metadata.RefreshFrequency = 10 * time.Minute
+	c.Metadata.Full = true
+
+	c.Producer.MaxMessageBytes = 1000000
+	c.Producer.RequiredAcks = WaitForLocal
+	c.Producer.Timeout = 10 * time.Second
+	c.Producer.Partitioner = NewHashPartitioner
+	c.Producer.Retry.Max = 3
+	c.Producer.Retry.Backoff = 100 * time.Millisecond
+	c.Producer.Return.Errors = true
+	c.Producer.CompressionLevel = CompressionLevelDefault
+
+	c.Consumer.Fetch.Min = 1
+	c.Consumer.Fetch.Default = 1024 * 1024
+	c.Consumer.Retry.Backoff = 2 * time.Second
+	c.Consumer.MaxWaitTime = 250 * time.Millisecond
+	c.Consumer.MaxProcessingTime = 100 * time.Millisecond
+	c.Consumer.Return.Errors = false
+	c.Consumer.Offsets.CommitInterval = 1 * time.Second
+	c.Consumer.Offsets.Initial = OffsetNewest
+	c.Consumer.Offsets.Retry.Max = 3
+
+	c.Consumer.Group.Session.Timeout = 10 * time.Second
+	c.Consumer.Group.Heartbeat.Interval = 3 * time.Second
+	c.Consumer.Group.Rebalance.Strategy = BalanceStrategyRange
+	c.Consumer.Group.Rebalance.Timeout = 60 * time.Second
+	c.Consumer.Group.Rebalance.Retry.Max = 4
+	c.Consumer.Group.Rebalance.Retry.Backoff = 2 * time.Second
+
+	c.ClientID = defaultClientID
+	c.ChannelBufferSize = 256
+	c.Version = MinVersion
+	c.MetricRegistry = metrics.NewRegistry()
+
+	return c
+}
+
+// Validate checks a Config instance. It will return a
+// ConfigurationError if the specified values don't make sense.
+func (c *Config) Validate() error {
+	// some configuration values should be warned on but not fail completely, do those first
+	if !c.Net.TLS.Enable && c.Net.TLS.Config != nil {
+		Logger.Println("Net.TLS is disabled but a non-nil configuration was provided.")
+	}
+	if !c.Net.SASL.Enable {
+		if c.Net.SASL.User != "" {
+			Logger.Println("Net.SASL is disabled but a non-empty username was provided.")
+		}
+		if c.Net.SASL.Password != "" {
+			Logger.Println("Net.SASL is disabled but a non-empty password was provided.")
+		}
+	}
+	if c.Producer.RequiredAcks > 1 {
+		Logger.Println("Producer.RequiredAcks > 1 is deprecated and will raise an exception with kafka >= 0.8.2.0.")
+	}
+	if c.Producer.MaxMessageBytes >= int(MaxRequestSize) {
+		Logger.Println("Producer.MaxMessageBytes must be smaller than MaxRequestSize; it will be ignored.")
+	}
+	if c.Producer.Flush.Bytes >= int(MaxRequestSize) {
+		Logger.Println("Producer.Flush.Bytes must be smaller than MaxRequestSize; it will be ignored.")
+	}
+	if (c.Producer.Flush.Bytes > 0 || c.Producer.Flush.Messages > 0) && c.Producer.Flush.Frequency == 0 {
+		Logger.Println("Producer.Flush: Bytes or Messages are set, but Frequency is not; messages may not get flushed.")
+	}
+	if c.Producer.Timeout%time.Millisecond != 0 {
+		Logger.Println("Producer.Timeout only supports millisecond resolution; nanoseconds will be truncated.")
+	}
+	if c.Consumer.MaxWaitTime < 100*time.Millisecond {
+		Logger.Println("Consumer.MaxWaitTime is very low, which can cause high CPU and network usage. See documentation for details.")
+	}
+	if c.Consumer.MaxWaitTime%time.Millisecond != 0 {
+		Logger.Println("Consumer.MaxWaitTime only supports millisecond precision; nanoseconds will be truncated.")
+	}
+	if c.Consumer.Offsets.Retention%time.Millisecond != 0 {
+		Logger.Println("Consumer.Offsets.Retention only supports millisecond precision; nanoseconds will be truncated.")
+	}
+	if c.Consumer.Group.Session.Timeout%time.Millisecond != 0 {
+		Logger.Println("Consumer.Group.Session.Timeout only supports millisecond precision; nanoseconds will be truncated.")
+	}
+	if c.Consumer.Group.Heartbeat.Interval%time.Millisecond != 0 {
+		Logger.Println("Consumer.Group.Heartbeat.Interval only supports millisecond precision; nanoseconds will be truncated.")
+	}
+	if c.Consumer.Group.Rebalance.Timeout%time.Millisecond != 0 {
+		Logger.Println("Consumer.Group.Rebalance.Timeout only supports millisecond precision; nanoseconds will be truncated.")
+	}
+	if c.ClientID == defaultClientID {
+		Logger.Println("ClientID is the default of 'sarama', you should consider setting it to something application-specific.")
+	}
+
+	// validate Net values
+	switch {
+	case c.Net.MaxOpenRequests <= 0:
+		return ConfigurationError("Net.MaxOpenRequests must be > 0")
+	case c.Net.DialTimeout <= 0:
+		return ConfigurationError("Net.DialTimeout must be > 0")
+	case c.Net.ReadTimeout <= 0:
+		return ConfigurationError("Net.ReadTimeout must be > 0")
+	case c.Net.WriteTimeout <= 0:
+		return ConfigurationError("Net.WriteTimeout must be > 0")
+	case c.Net.KeepAlive < 0:
+		return ConfigurationError("Net.KeepAlive must be >= 0")
+	case c.Net.SASL.Enable:
+		if c.Net.SASL.Mechanism == "" {
+			c.Net.SASL.Mechanism = SASLTypePlaintext
+		}
+
+		switch c.Net.SASL.Mechanism {
+		case SASLTypePlaintext:
+			if c.Net.SASL.User == "" {
+				return ConfigurationError("Net.SASL.User must not be empty when SASL is enabled")
+			}
+			if c.Net.SASL.Password == "" {
+				return ConfigurationError("Net.SASL.Password must not be empty when SASL is enabled")
+			}
+		case SASLTypeOAuth:
+			if c.Net.SASL.TokenProvider == nil {
+				return ConfigurationError("An AccessTokenProvider instance must be provided to Net.SASL.TokenProvider")
+			}
+		case SASLTypeSCRAMSHA256, SASLTypeSCRAMSHA512:
+			if c.Net.SASL.User == "" {
+				return ConfigurationError("Net.SASL.User must not be empty when SASL is enabled")
+			}
+			if c.Net.SASL.Password == "" {
+				return ConfigurationError("Net.SASL.Password must not be empty when SASL is enabled")
+			}
+			if c.Net.SASL.SCRAMClientGeneratorFunc == nil {
+				return ConfigurationError("A SCRAMClientGeneratorFunc function must be provided to Net.SASL.SCRAMClientGeneratorFunc")
+			}
+		case SASLTypeGSSAPI:
+			if c.Net.SASL.GSSAPI.ServiceName == "" {
+				return ConfigurationError("Net.SASL.GSSAPI.ServiceName must not be empty when GSS-API mechanism is used")
+			}
+
+			if c.Net.SASL.GSSAPI.AuthType == KRB5_USER_AUTH {
+				if c.Net.SASL.GSSAPI.Password == "" {
+					return ConfigurationError("Net.SASL.GSSAPI.Password must not be empty when GSS-API " +
+						"mechanism is used and Net.SASL.GSSAPI.AuthType = KRB5_USER_AUTH")
+				}
+			} else if c.Net.SASL.GSSAPI.AuthType == KRB5_KEYTAB_AUTH {
+				if c.Net.SASL.GSSAPI.KeyTabPath == "" {
+					return ConfigurationError("Net.SASL.GSSAPI.KeyTabPath must not be empty when GSS-API mechanism is used" +
+						" and  Net.SASL.GSSAPI.AuthType = KRB5_KEYTAB_AUTH")
+				}
+			} else {
+				return ConfigurationError("Net.SASL.GSSAPI.AuthType is invalid. Possible values are KRB5_USER_AUTH and KRB5_KEYTAB_AUTH")
+			}
+			if c.Net.SASL.GSSAPI.KerberosConfigPath == "" {
+				return ConfigurationError("Net.SASL.GSSAPI.KerberosConfigPath must not be empty when GSS-API mechanism is used")
+			}
+			if c.Net.SASL.GSSAPI.Username == "" {
+				return ConfigurationError("Net.SASL.GSSAPI.Username must not be empty when GSS-API mechanism is used")
+			}
+			if c.Net.SASL.GSSAPI.Realm == "" {
+				return ConfigurationError("Net.SASL.GSSAPI.Realm must not be empty when GSS-API mechanism is used")
+			}
+		default:
+			msg := fmt.Sprintf("The SASL mechanism configuration is invalid. Possible values are `%s`, `%s`, `%s`, `%s` and `%s`",
+				SASLTypeOAuth, SASLTypePlaintext, SASLTypeSCRAMSHA256, SASLTypeSCRAMSHA512, SASLTypeGSSAPI)
+			return ConfigurationError(msg)
+		}
+	}
+
+	// validate the Admin values
+	switch {
+	case c.Admin.Timeout <= 0:
+		return ConfigurationError("Admin.Timeout must be > 0")
+	}
+
+	// validate the Metadata values
+	switch {
+	case c.Metadata.Retry.Max < 0:
+		return ConfigurationError("Metadata.Retry.Max must be >= 0")
+	case c.Metadata.Retry.Backoff < 0:
+		return ConfigurationError("Metadata.Retry.Backoff must be >= 0")
+	case c.Metadata.RefreshFrequency < 0:
+		return ConfigurationError("Metadata.RefreshFrequency must be >= 0")
+	}
+
+	// validate the Producer values
+	switch {
+	case c.Producer.MaxMessageBytes <= 0:
+		return ConfigurationError("Producer.MaxMessageBytes must be > 0")
+	case c.Producer.RequiredAcks < -1:
+		return ConfigurationError("Producer.RequiredAcks must be >= -1")
+	case c.Producer.Timeout <= 0:
+		return ConfigurationError("Producer.Timeout must be > 0")
+	case c.Producer.Partitioner == nil:
+		return ConfigurationError("Producer.Partitioner must not be nil")
+	case c.Producer.Flush.Bytes < 0:
+		return ConfigurationError("Producer.Flush.Bytes must be >= 0")
+	case c.Producer.Flush.Messages < 0:
+		return ConfigurationError("Producer.Flush.Messages must be >= 0")
+	case c.Producer.Flush.Frequency < 0:
+		return ConfigurationError("Producer.Flush.Frequency must be >= 0")
+	case c.Producer.Flush.MaxMessages < 0:
+		return ConfigurationError("Producer.Flush.MaxMessages must be >= 0")
+	case c.Producer.Flush.MaxMessages > 0 && c.Producer.Flush.MaxMessages < c.Producer.Flush.Messages:
+		return ConfigurationError("Producer.Flush.MaxMessages must be >= Producer.Flush.Messages when set")
+	case c.Producer.Retry.Max < 0:
+		return ConfigurationError("Producer.Retry.Max must be >= 0")
+	case c.Producer.Retry.Backoff < 0:
+		return ConfigurationError("Producer.Retry.Backoff must be >= 0")
+	}
+
+	if c.Producer.Compression == CompressionLZ4 && !c.Version.IsAtLeast(V0_10_0_0) {
+		return ConfigurationError("lz4 compression requires Version >= V0_10_0_0")
+	}
+
+	if c.Producer.Compression == CompressionGZIP {
+		if c.Producer.CompressionLevel != CompressionLevelDefault {
+			if _, err := gzip.NewWriterLevel(ioutil.Discard, c.Producer.CompressionLevel); err != nil {
+				return ConfigurationError(fmt.Sprintf("gzip compression does not work with level %d: %v", c.Producer.CompressionLevel, err))
+			}
+		}
+	}
+
+	if c.Producer.Idempotent {
+		if !c.Version.IsAtLeast(V0_11_0_0) {
+			return ConfigurationError("Idempotent producer requires Version >= V0_11_0_0")
+		}
+		if c.Producer.Retry.Max == 0 {
+			return ConfigurationError("Idempotent producer requires Producer.Retry.Max >= 1")
+		}
+		if c.Producer.RequiredAcks != WaitForAll {
+			return ConfigurationError("Idempotent producer requires Producer.RequiredAcks to be WaitForAll")
+		}
+		if c.Net.MaxOpenRequests > 1 {
+			return ConfigurationError("Idempotent producer requires Net.MaxOpenRequests to be 1")
+		}
+	}
+
+	// validate the Consumer values
+	switch {
+	case c.Consumer.Fetch.Min <= 0:
+		return ConfigurationError("Consumer.Fetch.Min must be > 0")
+	case c.Consumer.Fetch.Default <= 0:
+		return ConfigurationError("Consumer.Fetch.Default must be > 0")
+	case c.Consumer.Fetch.Max < 0:
+		return ConfigurationError("Consumer.Fetch.Max must be >= 0")
+	case c.Consumer.MaxWaitTime < 1*time.Millisecond:
+		return ConfigurationError("Consumer.MaxWaitTime must be >= 1ms")
+	case c.Consumer.MaxProcessingTime <= 0:
+		return ConfigurationError("Consumer.MaxProcessingTime must be > 0")
+	case c.Consumer.Retry.Backoff < 0:
+		return ConfigurationError("Consumer.Retry.Backoff must be >= 0")
+	case c.Consumer.Offsets.CommitInterval <= 0:
+		return ConfigurationError("Consumer.Offsets.CommitInterval must be > 0")
+	case c.Consumer.Offsets.Initial != OffsetOldest && c.Consumer.Offsets.Initial != OffsetNewest:
+		return ConfigurationError("Consumer.Offsets.Initial must be OffsetOldest or OffsetNewest")
+	case c.Consumer.Offsets.Retry.Max < 0:
+		return ConfigurationError("Consumer.Offsets.Retry.Max must be >= 0")
+	case c.Consumer.IsolationLevel != ReadUncommitted && c.Consumer.IsolationLevel != ReadCommitted:
+		return ConfigurationError("Consumer.IsolationLevel must be ReadUncommitted or ReadCommitted")
+	}
+
+	// validate IsolationLevel
+	if c.Consumer.IsolationLevel == ReadCommitted && !c.Version.IsAtLeast(V0_11_0_0) {
+		return ConfigurationError("ReadCommitted requires Version >= V0_11_0_0")
+	}
+
+	// validate the Consumer Group values
+	switch {
+	case c.Consumer.Group.Session.Timeout <= 2*time.Millisecond:
+		return ConfigurationError("Consumer.Group.Session.Timeout must be >= 2ms")
+	case c.Consumer.Group.Heartbeat.Interval < 1*time.Millisecond:
+		return ConfigurationError("Consumer.Group.Heartbeat.Interval must be >= 1ms")
+	case c.Consumer.Group.Heartbeat.Interval >= c.Consumer.Group.Session.Timeout:
+		return ConfigurationError("Consumer.Group.Heartbeat.Interval must be < Consumer.Group.Session.Timeout")
+	case c.Consumer.Group.Rebalance.Strategy == nil:
+		return ConfigurationError("Consumer.Group.Rebalance.Strategy must not be empty")
+	case c.Consumer.Group.Rebalance.Timeout <= time.Millisecond:
+		return ConfigurationError("Consumer.Group.Rebalance.Timeout must be >= 1ms")
+	case c.Consumer.Group.Rebalance.Retry.Max < 0:
+		return ConfigurationError("Consumer.Group.Rebalance.Retry.Max must be >= 0")
+	case c.Consumer.Group.Rebalance.Retry.Backoff < 0:
+		return ConfigurationError("Consumer.Group.Rebalance.Retry.Backoff must be >= 0")
+	}
+
+	// validate misc shared values
+	switch {
+	case c.ChannelBufferSize < 0:
+		return ConfigurationError("ChannelBufferSize must be >= 0")
+	case !validID.MatchString(c.ClientID):
+		return ConfigurationError("ClientID is invalid")
+	}
+
+	return nil
+}