Flume入门——Selector、Chanel等
1、selector
（http://blog.csdn.net/looklook5/article/details/40430965）
（http://blog.csdn.net/xiao_jun_0820/article/details/38116103#）
选择器可以工作在复制 多路复用(路由) 模式下
复制模式
属性说明：
selector.type replicating 类型名称，必须是 replicating
selector.optional – 标志通道为可选
多路复用（路由）模式
属性说明：
selector.type 类型，必须是"multiplexing"
selector.header 指定要监测的头的名称
selector.default –
selector.mapping.* –
举例：
a1.sources = r1
a1.channels = c1 c2 c3 c4
a1.sources.r1.selector.type = multiplexing
a1.sources.r1.selector.header = state
a1.sources.r1.selector.mapping.CZ = c1
a1.sources.r1.selector.mapping.US = c2 c3
a1.sources.r1.selector.default = c4
8.Processor
1.概述
Sink Group允许用户将多个Sink组合成一个实体。
Flume Sink Processor 可以通过切换组内Sink用来实现负载均衡的效果，或在一个Sink故障时切换到另一个Sink。
sinks – 用空格分隔的Sink集合
processor.type default 类型名称，必须是 default、failover 或 load_balance
2.Default Sink Processor
Default Sink Processor 只接受一个 Sink。
不要求用户为单一Sink创建processor
3.Failover Sink Processor
Failover Sink Processor 维护一个sink们的优先表。确保只要一个是可用的就事件就可以被处理。
失败处理原理是，为失效的sink指定一个冷却时间，在冷却时间到达后再重新使用。
sink们可以被配置一个优先级，数字越大优先级越高。
如果sink发送事件失败，则下一个最高优先级的sink将会尝试接着发送事件。
如果没有指定优先级，则优先级顺序取决于sink们的配置顺序，先配置的默认优先级高于后配置的。
在配置的过程中，设置一个group processor ，并且为每个sink都指定一个优先级。
优先级必须是唯一的。
另外可以设置maxpenalty属性指定限定失败时间。
sinks – Space-separated list of sinks that are participating in the group
processor.type default The component type name, needs to be failover
processor.priority.<sinkName> – Priority value. <sinkName> must be one of the sink instances associated with the current sink group A higher priority value Sink gets activated earlier. A larger absolute value indicates higher priority
processor.maxpenalty 30000 The maximum backoff period for the failed Sink (in millis)
Example for agent named a1:
------
a1.sinkgroups = g1
a1.sinkgroups.g1.sinks = k1 k2
a1.sinkgroups.g1.processor.type = failover
a1.sinkgroups.g1.processor.priority.k1 = 5
a1.sinkgroups.g1.processor.priority.k2 = 10
a1.sinkgroups.g1.processor.maxpenalty = 10000
------
4.Load balancing Sink Processor
Load balancing Sink processor 提供了在多个sink之间实现负载均衡的能力。
它维护了一个活动sink的索引列表。
它支持轮询 或 随机方式的负载均衡，默认值是轮询方式，可以通过配置指定。
也可以通过实现AbstractSinkSelector接口实现自定义的选择机制。
!processor.sinks – Space-separated list of sinks that are participating in the group
!processor.type default The component type name, needs to be load_balance
processor.backoff false Should failed sinks be backed off exponentially.
processor.selector round_robin Selection mechanism. Must be either round_robin, random or FQCN of custom class that inherits from AbstractSinkSelector
processor.selector.maxTimeOut 30000 Used by backoff selectors to limit exponential backoff (in milliseconds)
------
a1.sinkgroups = g1
a1.sinkgroups.g1.sinks = k1 k2
a1.sinkgroups.g1.processor.type = load_balance
a1.sinkgroups.g1.processor.backoff = true
a1.sinkgroups.g1.processor.selector = random
------
9.Interceptors - 拦截器
1.概述
Flume有能力在运行阶段修改/删除Event，这是通过拦截器（Interceptors）来实现的。
拦截器需要实现org.apache.flume.interceptor.Interceptor接口。
拦截器可以修改或删除事件基于开发者在选择器中选择的任何条件。
拦截器采用了责任链模式，多个拦截器可以按指定顺序拦截。
一个拦截器返回的事件列表被传递给链中的下一个拦截器。
如果一个拦截器需要删除事件，它只需要在返回的事件集中不包含要删除的事件即可。
如果要删除所有事件，只需返回一个空列表。
2.Timestamp Interceptor
这个拦截器在事件头中插入以毫秒为单位的当前处理时间。
头的名字为timestamp，值为当前处理的时间戳。
如果在之前已经有这个时间戳，则保留原有的时间戳。
参数说明：
!type – 类型名称，必须是timestamp或自定义类的全路径名
preserveExisting false 如果时间戳已经存在是否保留
3.Host Interceptor
这个拦截器插入当前处理Agent的主机名或ip
头的名字为host或配置的名称
值是主机名或ip地址，基于配置。
参数说明：
!type – 类型名称，必须是host
preserveExisting false 如果主机名已经存在是否保留
useIP true 如果配置为true则用IP，配置为false则用主机名
hostHeader host 加入头时使用的名称
4.Static Interceptor
此拦截器允许用户增加静态头信息使用静态的值到所有事件。
目前的实现中不允许一次指定多个头。
如果需要增加多个静态头可以指定多个Static interceptors
属性说明:
!type – 类型，必须是static
preserveExisting true 如果配置头已经存在是否应该保留
key key 要增加的透明
value value 要增加的头值
5.UUID Interceptor
这个拦截器在所有事件头中增加一个全局一致性标志。
其实就是UUID。
属性说明：
!type – 类型名称，必须是org.apache.flume.sink.solr.morphline.UUIDInterceptor$Builder
headerName id 头名称
preserveExisting true 如果头已经存在，是否保留
prefix “” 在UUID前拼接的字符串前缀
6.Morphline Interceptor
7.Search and Replace Interceptor
这个拦截器提供了简单的基于字符串的正则搜索和替换功能。
属性说明：
type – 类型名称，必须是"search_replace"
searchPattern – 要搜索和替换的正则表达式
replaceString – 要替换为的字符串
charset UTF-8 字符集编码，默认utf-8
8.Regex Filtering Interceptor
此拦截器通过解析事件体去匹配给定正则表达式来筛选事件。
所提供的正则表达式即可以用来包含或刨除事件。
属性说明：
!type – 类型，必须设定为regex_filter
regex ”.*” 所要匹配的正则表达式
excludeEvents false 如果是true则刨除匹配的事件，false则包含匹配的事件。
9.Regex Extractor Interceptor
使用指定正则表达式匹配事件，并将匹配到的组作为头加入到事件中。
它也支持插件化的序列化器用来格式化匹配到的组在加入他们作为头之前。
属性说明：
!type – 类型，必须是regex_extractor
!regex – 要匹配的正则表达式
!serializers – Space-separated list of serializers for mapping matches to header names and serializing their values. (See example below) Flume provides built-in support for the following serializers: org.apache.flume.interceptor.RegexExtractorInterceptorPassThroughSerializer org.apache.flume.interceptor.RegexExtractorInterceptorMillisSerializer
serializers.<s1>.type default Must be default (org.apache.flume.interceptor.RegexExtractorInterceptorPassThroughSerializer), org.apache.flume.interceptor.RegexExtractorInterceptorMillisSerializer, or the FQCN of a custom class that implements org.apache.flume.interceptor.RegexExtractorInterceptorSerializer
serializers.<s1>.name –
serializers.* – Serializer-specific properties
----
If the Flume event body contained 1:2:3.4foobar5 and the following configuration was used
a1.sources.r1.interceptors.i1.regex = (\\d):(\\d):(\\d)
a1.sources.r1.interceptors.i1.serializers = s1 s2 s3
a1.sources.r1.interceptors.i1.serializers.s1.name = one
a1.sources.r1.interceptors.i1.serializers.s2.name = two
a1.sources.r1.interceptors.i1.serializers.s3.name = three
The extracted event will contain the same body but the following headers will have been added one=>1, two=>2, three=>3
----
10.channel
!!!1.Memory Channel 内存通道
事件将被存储在内存中的具有指定大小的队列中。
非常适合那些需要高吞吐量但是失败是会丢失数据的场景下。
属性说明：
!type – 类型，必须是“memory”
capacity 100 事件存储在信道中的最大数量
transactionCapacity 100 每个事务中的最大事件数
keep-alive 3 添加或删除操作的超时时间
byteCapacityBufferPercentage 20 Defines the percent of buffer between byteCapacity and the estimated total size of all events in the channel, to account for data in headers. See below.
byteCapacity see description Maximum total bytes of memory allowed as a sum of all events in this channel. The implementation only counts the Event body, which is the reason for providing the byteCapacityBufferPercentage configuration parameter as well. Defaults to a computed value equal to 80% of the maximum memory available to the JVM (i.e. 80% of the -Xmx value passed on the command line). Note that if you have multiple memory channels on a single JVM, and they happen to hold the same physical events (i.e. if you are using a replicating channel selector from a single source) then those event sizes may be double-counted for channel byteCapacity purposes. Setting this value to 0 will cause this value to fall back to a hard internal limit of about 200 GB.
案例:参看入门案例
2.JDBC Channel
事件被持久存储在可靠的数据库中。目前支持嵌入式的Derby数据库。如果可恢复性非常的重要可以使用这种方式。
!!!3.File Channel
性能会比较低下，但是即使程序出错数据不会丢失
属性说明:
!type – 类型，必须是“file”
checkpointDir ~/.flume/file-channel/checkpoint 检查点文件存放的位置
useDualCheckpoints false Backup the checkpoint. If this is set to true, backupCheckpointDir must be set
backupCheckpointDir – The directory where the checkpoint is backed up to. This directory must not be the same as the data directories or the checkpoint directory
dataDirs ~/.flume/file-channel/data 逗号分隔的目录列表，用以存放日志文件。使用单独的磁盘上的多个目录可以提高文件通道效率。
transactionCapacity 10000 The maximum size of transaction supported by the channel
checkpointInterval 30000 Amount of time (in millis) between checkpoints
maxFileSize 2146435071 一个日志文件的最大尺寸
minimumRequiredSpace 524288000 Minimum Required free space (in bytes). To avoid data corruption, File Channel stops accepting take/put requests when free space drops below this value
capacity 1000000 Maximum capacity of the channel
keep-alive 3 Amount of time (in sec) to wait for a put operation
use-log-replay-v1 false Expert: Use old replay logic
use-fast-replay false Expert: Replay without using queue
checkpointOnClose true Controls if a checkpoint is created when the channel is closed. Creating a checkpoint on close speeds up subsequent startup of the file channel by avoiding replay.
encryption.activeKey – Key name used to encrypt new data
encryption.cipherProvider – Cipher provider type, supported types: AESCTRNOPADDING
encryption.keyProvider – Key provider type, supported types: JCEKSFILE
encryption.keyProvider.keyStoreFile – Path to the keystore file
encrpytion.keyProvider.keyStorePasswordFile – Path to the keystore password file
encryption.keyProvider.keys – List of all keys (e.g. history of the activeKey setting)
encyption.keyProvider.keys.*.passwordFile – Path to the optional key password file
!!!4.Spillable Memory Channel -- 内存溢出通道
事件被存储在内存队列和磁盘中。
内存队列作为主存储，而磁盘作为溢出内容的存储。
内存存储通过embedded File channel来进行管理。
当内存队列已满时，后续的事件将被存储在文件通道中。
这个通道适用于正常操作期间适用内存通道已期实现高效吞吐，而在高峰期间适用文件通道实现高耐受性。通过降低吞吐效率提高系统可耐受性。
如果Agent崩溃，则只有存储在文件系统中的事件可以被恢复。
此通道处于试验阶段，不建议在生产环境中使用。
属性说明：
!type – 类型，必须是"SPILLABLEMEMORY"
memoryCapacity 10000 内存中存储事件的最大值，如果想要禁用内存缓冲区将此值设置为0。
overflowCapacity 100000000 可以存储在磁盘中的事件数量最大值。设置为0可以禁用磁盘存储。
overflowTimeout 3 The number of seconds to wait before enabling disk overflow when memory fills up.
byteCapacityBufferPercentage 20 Defines the percent of buffer between byteCapacity and the estimated total size of all events in the channel, to account for data in headers. See below.
byteCapacity see description Maximum bytes of memory allowed as a sum of all events in the memory queue. The implementation only counts the Event body, which is the reason for providing the byteCapacityBufferPercentage configuration parameter as well. Defaults to a computed value equal to 80% of the maximum memory available to the JVM (i.e. 80% of the -Xmx value passed on the command line). Note that if you have multiple memory channels on a single JVM, and they happen to hold the same physical events (i.e. if you are using a replicating channel selector from a single source) then those event sizes may be double-counted for channel byteCapacity purposes. Setting this value to 0 will cause this value to fall back to a hard internal limit of about 200 GB.
avgEventSize 500 Estimated average size of events, in bytes, going into the channel
<file channel properties> see file channel Any file channel property with the exception of ‘keep-alive’ and ‘capacity’ can be used. The keep-alive of file channel is managed by Spillable Memory Channel. Use ‘overflowCapacity’ to set the File channel’s capacity.
5.自定义通道
自定义渠道需要自己实现Channel接口。
自定义Channle类及其依赖类必须在Flume启动前放置到类加载的目录下。
参数说明：
type - 自己实现的Channle类的全路径名称
