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package sarama
import (
"compress/gzip"
"crypto/tls"
"fmt"
"io/ioutil"
"net"
"regexp"
"time"
"github.com/rcrowley/go-metrics"
)
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
// 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 authentication
User string
Password string
// 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
}
// 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
}
// 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
}
// 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
}
}
}
// 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.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 == false && c.Net.TLS.Config != nil {
Logger.Println("Net.TLS is disabled but a non-nil configuration was provided.")
}
if c.Net.SASL.Enable == false {
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:
// For backwards compatibility, empty mechanism value defaults to PLAIN
isSASLPlain := len(c.Net.SASL.Mechanism) == 0 || c.Net.SASL.Mechanism == SASLTypePlaintext
if isSASLPlain {
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")
}
} else if c.Net.SASL.Mechanism == SASLTypeOAuth {
if c.Net.SASL.TokenProvider == nil {
return ConfigurationError("An AccessTokenProvider instance must be provided to Net.SASL.User.TokenProvider")
}
} else {
msg := fmt.Sprintf("The SASL mechanism configuration is invalid. Possible values are `%s` and `%s`",
SASLTypeOAuth, SASLTypePlaintext)
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")
}
// 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
}