A framework for creating and deploying Apache Storm streaming computations with less friction.
flux |fləks| noun
Bad things happen when configuration is hard-coded. No one should have to recompile or repackage an application in order to change configuration.
Flux is a framework and set of utilities that make defining and deploying Apache Storm topologies less painful and deveoper-intensive. One of the pain points often mentioned is the fact that the wiring for a Topology graph is often tied up in Java code, and that any changes require recompilation and repackaging of the topology jar file. Flux aims to alleviate that pain by allowing you to package all your Storm components in a single jar, and use an external text file to define the layout and configuration of your topologies.
${variable.name} substitution)To use Flux, add it as a dependency and package all your Storm components in a fat jar, then create a YAML document to define your topology (see below for YAML configuration options).
The easiest way to use Flux, is to add it as a Maven dependency in you project as described below.
If you would like to build Flux from source and run the unit/integration tests, you will need the following installed on your system:
mvn clean install
If you would like to build Flux without installing Python or Node.js you can simply skip the unit tests:
mvn clean install -DskipTests=true
Note that if you plan on using Flux to deploy topologies to a remote cluster, you will still need to have Python installed since it is required by Apache Storm.
mvn clean install -DskipIntegration=false
To enable Flux for your Storm components, you need to add it as a dependency such that it's included in the Storm topology jar. This can be accomplished with the Maven shade plugin (preferred) or the Maven assembly plugin (not recommended).
The current version of Flux is available in Maven Central at the following coordinates:
xml
<dependency>
<groupId>org.apache.storm</groupId>
<artifactId>flux-core</artifactId>
<version>${storm.version}</version>
</dependency>
Using shell spouts and bolts requires additional Flux Wrappers library:
xml
<dependency>
<groupId>org.apache.storm</groupId>
<artifactId>flux-wrappers</artifactId>
<version>${storm.version}</version>
</dependency>
The example below illustrates Flux usage with the Maven shade plugin:
<!-- include Flux and user dependencies in the shaded jar -->
<dependencies>
<!-- Flux include -->
<dependency>
<groupId>org.apache.storm</groupId>
<artifactId>flux-core</artifactId>
<version>${storm.version}</version>
</dependency>
<!-- Flux Wrappers include -->
<dependency>
<groupId>org.apache.storm</groupId>
<artifactId>flux-wrappers</artifactId>
<version>${storm.version}</version>
</dependency>
<!-- add user dependencies here... -->
</dependencies>
<!-- create a fat jar that includes all dependencies -->
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-shade-plugin</artifactId>
<version>1.4</version>
<configuration>
<createDependencyReducedPom>true</createDependencyReducedPom>
</configuration>
<executions>
<execution>
<phase>package</phase>
<goals>
<goal>shade</goal>
</goals>
<configuration>
<transformers>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ServicesResourceTransformer"/>
<transformer
implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
<mainClass>org.apache.storm.flux.Flux</mainClass>
</transformer>
</transformers>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
Once your topology components are packaged with the Flux dependency, you can run different topologies either locally
or remotely using the storm jar command. For example, if your fat jar is named myTopology-0.1.0-SNAPSHOT.jar you
could run it locally with the command:
storm jar myTopology-0.1.0-SNAPSHOT.jar org.apache.storm.flux.Flux --local my_config.yaml
usage: storm jar <my_topology_uber_jar.jar> org.apache.storm.flux.Flux
[options] <topology-config.yaml>
-d,--dry-run Do not run or deploy the topology. Just
build, validate, and print information about
the topology.
-e,--env-filter Perform environment variable substitution.
Replace keys identified with `${ENV-[NAME]}`
will be replaced with the corresponding
`NAME` environment value
-f,--filter <file> Perform property substitution. Use the
specified file as a source of properties,
and replace keys identified with {$[property
name]} with the value defined in the
properties file.
-i,--inactive Deploy the topology, but do not activate it.
-l,--local Run the topology in local mode.
-n,--no-splash Suppress the printing of the splash screen.
-q,--no-detail Suppress the printing of topology details.
-r,--remote Deploy the topology to a remote cluster.
-R,--resource Treat the supplied path as a classpath
resource instead of a file.
-s,--sleep <ms> When running locally, the amount of time to
sleep (in ms.) before killing the topology
and shutting down the local cluster.
-z,--zookeeper <host:port> When running in local mode, use the
ZooKeeper at the specified <host>:<port>
instead of the in-process ZooKeeper.
(requires Storm 0.9.3 or later)
NOTE: Flux tries to avoid command line switch collision with the storm command, and allows any other command line
switches to pass through to the storm command.
For example, you can use the storm command switch -c to override a topology configuration property. The following
example command will run Flux and override the nimbus.seeds configuration:
storm jar myTopology-0.1.0-SNAPSHOT.jar org.apache.storm.flux.Flux --remote my_config.yaml -c 'nimbus.seeds=["localhost"]'
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+- Apache Storm -+
+- data FLow User eXperience -+
Version: 0.3.0
Parsing file: /Users/hsimpson/Projects/donut_domination/storm/shell_test.yaml
---------- TOPOLOGY DETAILS ----------
Name: shell-topology
--------------- SPOUTS ---------------
sentence-spout[1](org.apache.storm.flux.wrappers.spouts.FluxShellSpout)
---------------- BOLTS ---------------
splitsentence[1](org.apache.storm.flux.wrappers.bolts.FluxShellBolt)
log[1](org.apache.storm.flux.wrappers.bolts.LogInfoBolt)
count[1](org.apache.storm.testing.TestWordCounter)
--------------- STREAMS ---------------
sentence-spout --SHUFFLE--> splitsentence
splitsentence --FIELDS--> count
count --SHUFFLE--> log
--------------------------------------
Submitting topology: 'shell-topology' to remote cluster...
Flux topologies are defined in a YAML file that describes a topology. A Flux topology definition consists of the following:
org.apache.storm.generated.StormTopology instance:
topologySource definition.For example, here is a simple definition of a wordcount topology using the YAML DSL:
name: "yaml-topology"
config:
topology.workers: 1
# spout definitions
spouts:
- id: "spout-1"
className: "org.apache.storm.testing.TestWordSpout"
parallelism: 1
# bolt definitions
bolts:
- id: "bolt-1"
className: "org.apache.storm.testing.TestWordCounter"
parallelism: 1
- id: "bolt-2"
className: "org.apache.storm.flux.wrappers.bolts.LogInfoBolt"
parallelism: 1
#stream definitions
streams:
- name: "spout-1 --> bolt-1" # name isn't used (placeholder for logging, UI, etc.)
from: "spout-1"
to: "bolt-1"
grouping:
type: FIELDS
args: ["word"]
- name: "bolt-1 --> bolt2"
from: "bolt-1"
to: "bolt-2"
grouping:
type: SHUFFLE
# worker hook definitions
workerHooks:
- id: "base-worker-hook"
className: "org.apache.storm.hooks.BaseWorkerHook"
It's common for developers to want to easily switch between configurations, for example switching deployment between a development environment and a production environment. This can be accomplished by using separate YAML configuration files, but that approach would lead to unnecessary duplication, especially in situations where the Storm topology does not change, but configuration settings such as host names, ports, and parallelism paramters do.
For this case, Flux offers properties filtering to allow you two externalize values to a .properties file and have
them substituted before the .yaml file is parsed.
To enable property filtering, use the --filter command line option and specify a .properties file. For example,
if you invoked flux like so:
storm jar myTopology-0.1.0-SNAPSHOT.jar org.apache.storm.flux.Flux --local my_config.yaml --filter dev.properties
With the following dev.properties file:
kafka.zookeeper.hosts: localhost:2181
You would then be able to reference those properties by key in your .yaml file using ${} syntax:
- id: "zkHosts"
className: "org.apache.storm.kafka.ZkHosts"
constructorArgs:
- "${kafka.zookeeper.hosts}"
In this case, Flux would replace ${kafka.zookeeper.hosts} with localhost:2181 before parsing the YAML contents.
Flux also allows environment variable substitution. For example, if an environment variable named ZK_HOSTS if defined,
you can reference it in a Flux YAML file with the following syntax:
${ENV-ZK_HOSTS}
Components are essentially named object instances that are made available as configuration options for spouts and bolts. If you are familiar with the Spring framework, components are roughly analagous to Spring beans.
Every component is identified, at a minimum, by a unique identifier (String) and a class name (String). For example,
the following will make an instance of the org.apache.storm.kafka.StringScheme class available as a reference under the key
"stringScheme" . This assumes the org.apache.storm.kafka.StringScheme has a default constructor.
components:
- id: "stringScheme"
className: "org.apache.storm.kafka.StringScheme"
It is also possible to use static factory methods from Flux. Given the following Java code:
public class TestBolt extends BaseBasicBolt {
public static TestBolt newInstance(Duration triggerTime) {
return new TestBolt(triggerTime);
}
}
public class Duration {
public static Duration ofSeconds(long seconds) {
return new Duration(seconds);
}
}
it is possible to use the factory methods as follows:
components:
- id: "time"
className: "java.time.Duration"
factory: "ofSeconds"
bolts:
- id: "testBolt"
className: "org.apache.storm.flux.test.TestBolt"
factory: "newInstance"
factoryArgs:
- ref: "time"
Arguments to a class constructor can be configured by adding a contructorArgs element to a components.
constructorArgs is a list of objects that will be passed to the class' constructor. The following example creates an
object by calling the constructor that takes a single string as an argument:
- id: "zkHosts"
className: "org.apache.storm.kafka.ZkHosts"
constructorArgs:
- "localhost:2181"
Each component instance is identified by a unique id that allows it to be used/reused by other components. To
reference an existing component, you specify the id of the component with the ref tag.
In the following example, a component with the id "stringScheme" is created, and later referenced, as a an argument
to another component's constructor:
components:
- id: "stringScheme"
className: "org.apache.storm.kafka.StringScheme"
- id: "stringMultiScheme"
className: "org.apache.storm.spout.SchemeAsMultiScheme"
constructorArgs:
- ref: "stringScheme" # component with id "stringScheme" must be declared above.
N.B.: References can only be used after (below) the object they point to has been declared.
In addition to calling constructors with different arguments, Flux also allows you to configure components using
JavaBean-like setter methods and fields declared as public:
- id: "spoutConfig"
className: "org.apache.storm.kafka.SpoutConfig"
constructorArgs:
# brokerHosts
- ref: "zkHosts"
# topic
- "myKafkaTopic"
# zkRoot
- "/kafkaSpout"
# id
- "myId"
properties:
- name: "ignoreZkOffsets"
value: true
- name: "scheme"
ref: "stringMultiScheme"
In the example above, the properties declaration will cause Flux to look for a public method in the SpoutConfig with
the signature setIgnoreZkOffsets(boolean b) and attempt to invoke it. If a setter method is not found, Flux will then
look for a public instance variable with the name ignoreZkOffsets and attempt to set its value.
References may also be used as property values.
Conceptually, configuration methods are similar to Properties and Constructor Args -- they allow you to invoke an arbitrary method on an object after it is constructed. Configuration methods are useful for working with classes that don't expose JavaBean methods or have constructors that can fully configure the object. Common examples include classes that use the builder pattern for configuration/composition.
The following YAML example creates a bolt and configures it by calling several methods:
bolts:
- id: "bolt-1"
className: "org.apache.storm.flux.test.TestBolt"
parallelism: 1
configMethods:
- name: "withFoo"
args:
- "foo"
- name: "withBar"
args:
- "bar"
- name: "withFooBar"
args:
- "foo"
- "bar"
The signatures of the corresponding methods are as follows:
public void withFoo(String foo);
public void withBar(String bar);
public void withFooBar(String foo, String bar);
Arguments passed to configuration methods work much the same way as constructor arguments, and support references as well.
enums in Contructor Arguments, References, Properties and Configuration MethodsYou can easily use Java enum values as arguments in a Flux YAML file, simply by referencing the name of the enum.
For example, Storm's HDFS module includes the following enum definition (simplified for brevity):
public static enum Units {
KB, MB, GB, TB
}
And the org.apache.storm.hdfs.bolt.rotation.FileSizeRotationPolicy class has the following constructor:
public FileSizeRotationPolicy(float count, Units units)
The following Flux component definition could be used to call the constructor:
- id: "rotationPolicy"
className: "org.apache.storm.hdfs.bolt.rotation.FileSizeRotationPolicy"
constructorArgs:
- 5.0
- MB
The above definition is functionally equivalent to the following Java code:
// rotate files when they reach 5MB
FileRotationPolicy rotationPolicy = new FileSizeRotationPolicy(5.0f, Units.MB);
The config section is simply a map of Storm topology configuration parameters that will be passed to the
org.apache.storm.StormSubmitter as an instance of the org.apache.storm.Config class:
config:
topology.workers: 4
topology.max.spout.pending: 1000
topology.message.timeout.secs: 30
If you have existing Storm topologies, you can still use Flux to deploy/run/test them. This feature allows you to leverage Flux Constructor Arguments, References, Properties, and Topology Config declarations for existing topology classes.
The easiest way to use an existing topology class is to define
a getTopology() instance method with one of the following signatures:
public StormTopology getTopology(Map<String, Object> config)
or:
public StormTopology getTopology(Config config)
You could then use the following YAML to configure your topology:
name: "existing-topology"
topologySource:
className: "org.apache.storm.flux.test.SimpleTopology"
If the class you would like to use as a topology source has a different method name (i.e. not getTopology), you can
override it:
name: "existing-topology"
topologySource:
className: "org.apache.storm.flux.test.SimpleTopology"
methodName: "getTopologyWithDifferentMethodName"
N.B.: The specified method must accept a single argument of type java.util.Map<String, Object> or
org.apache.storm.Config, and return a org.apache.storm.generated.StormTopology object.
Spout and Bolts are configured in their own respective section of the YAML configuration. Spout and Bolt definitions
are extensions to the component definition that add a parallelism parameter that sets the parallelism for a
component when the topology is deployed.
Because spout and bolt definitions extend component they support constructor arguments, references, and properties as
well.
Shell spout example:
spouts:
- id: "sentence-spout"
className: "org.apache.storm.flux.wrappers.spouts.FluxShellSpout"
# shell spout constructor takes 2 arguments: String[], String[]
constructorArgs:
# command line
- ["node", "randomsentence.js"]
# output fields
- ["word"]
parallelism: 1
Kafka spout example:
components:
- id: "stringScheme"
className: "org.apache.storm.kafka.StringScheme"
- id: "stringMultiScheme"
className: "org.apache.storm.spout.SchemeAsMultiScheme"
constructorArgs:
- ref: "stringScheme"
- id: "zkHosts"
className: "org.apache.storm.kafka.ZkHosts"
constructorArgs:
- "localhost:2181"
# Alternative kafka config
# - id: "kafkaConfig"
# className: "org.apache.storm.kafka.KafkaConfig"
# constructorArgs:
# # brokerHosts
# - ref: "zkHosts"
# # topic
# - "myKafkaTopic"
# # clientId (optional)
# - "myKafkaClientId"
- id: "spoutConfig"
className: "org.apache.storm.kafka.SpoutConfig"
constructorArgs:
# brokerHosts
- ref: "zkHosts"
# topic
- "myKafkaTopic"
# zkRoot
- "/kafkaSpout"
# id
- "myId"
properties:
- name: "ignoreZkOffsets"
value: true
- name: "scheme"
ref: "stringMultiScheme"
config:
topology.workers: 1
# spout definitions
spouts:
- id: "kafka-spout"
className: "org.apache.storm.kafka.KafkaSpout"
constructorArgs:
- ref: "spoutConfig"
Bolt Examples:
# bolt definitions
bolts:
- id: "splitsentence"
className: "org.apache.storm.flux.wrappers.bolts.FluxShellBolt"
constructorArgs:
# command line
- ["python3", "splitsentence.py"]
# output fields
- ["word"]
parallelism: 1
# ...
- id: "log"
className: "org.apache.storm.flux.wrappers.bolts.LogInfoBolt"
parallelism: 1
# ...
- id: "count"
className: "org.apache.storm.testing.TestWordCounter"
parallelism: 1
# ...
Streams in Flux are represented as a list of connections (Graph edges, data flow, etc.) between the Spouts and Bolts in a topology, with an associated Grouping definition.
A Stream definition has the following properties:
name: A name for the connection (optional, currently unused)
from: The id of a Spout or Bolt that is the source (publisher)
to: The id of a Spout or Bolt that is the destination (subscriber)
grouping: The stream grouping definition for the Stream
A Grouping definition has the following properties:
type: The type of grouping. One of ALL,CUSTOM,DIRECT,SHUFFLE,LOCAL_OR_SHUFFLE,FIELDS,GLOBAL, or NONE.
streamId: The Storm stream ID (Optional. If unspecified will use the default stream)
args: For the FIELDS grouping, a list of field names.
customClass For the CUSTOM grouping, a definition of custom grouping class instance
The streams definition example below sets up a topology with the following wiring:
kafka-spout --> splitsentence --> count --> log
#stream definitions
# stream definitions define connections between spouts and bolts.
# note that such connections can be cyclical
# custom stream groupings are also supported
streams:
- name: "kafka --> split" # name isn't used (placeholder for logging, UI, etc.)
from: "kafka-spout"
to: "splitsentence"
grouping:
type: SHUFFLE
- name: "split --> count"
from: "splitsentence"
to: "count"
grouping:
type: FIELDS
args: ["word"]
- name: "count --> log"
from: "count"
to: "log"
grouping:
type: SHUFFLE
Custom stream groupings are defined by setting the grouping type to CUSTOM and defining a customClass parameter
that tells Flux how to instantiate the custom class. The customClass definition extends component, so it supports
constructor arguments, references, and properties as well.
The example below creates a Stream with an instance of the org.apache.storm.testing.NGrouping custom stream grouping
class.
- name: "bolt-1 --> bolt2"
from: "bolt-1"
to: "bolt-2"
grouping:
type: CUSTOM
customClass:
className: "org.apache.storm.testing.NGrouping"
constructorArgs:
- 1
Flux allows you to include the contents of other YAML files, and have them treated as though they were defined in the same file. Includes may be either files, or classpath resources.
Includes are specified as a list of maps:
includes:
- resource: false
file: "src/test/resources/configs/shell_test.yaml"
override: false
If the resource property is set to true, the include will be loaded as a classpath resource from the value of the
file attribute, otherwise it will be treated as a regular file.
The override property controls how includes affect the values defined in the current file. If override is set to
true, values in the included file will replace values in the current file being parsed. If override is set to
false, values in the current file being parsed will take precedence, and the parser will refuse to replace them.
N.B.: Includes are not yet recursive. Includes from included files will be ignored.
Flux allows you to attach topology components that can be executed when a worker starts, and when a worker shuts down. It can be useful when you want to execute operations before topology processing starts, or cleanup operations before your workers shut down, e.g. managing application context. Worker Hooks should be an implementation of IWorkerHook. Other than that, they follow similar Bean definition semantics as Components for declaration within yaml file.
Worker Hooks are specified as a map of bean definitions:
workerHooks:
- id: "base-worker-hook"
className: "org.apache.storm.hooks.BaseWorkerHook"
This example uses a spout implemented in JavaScript, a bolt implemented in Python, and a bolt implemented in Java
Topology YAML config:
---
name: "shell-topology"
config:
topology.workers: 1
# spout definitions
spouts:
- id: "sentence-spout"
className: "org.apache.storm.flux.wrappers.spouts.FluxShellSpout"
# shell spout constructor takes 2 arguments: String[], String[]
constructorArgs:
# command line
- ["node", "randomsentence.js"]
# output fields
- ["word"]
parallelism: 1
# bolt definitions
bolts:
- id: "splitsentence"
className: "org.apache.storm.flux.wrappers.bolts.FluxShellBolt"
constructorArgs:
# command line
- ["python3", "splitsentence.py"]
# output fields
- ["word"]
parallelism: 1
- id: "log"
className: "org.apache.storm.flux.wrappers.bolts.LogInfoBolt"
parallelism: 1
- id: "count"
className: "org.apache.storm.testing.TestWordCounter"
parallelism: 1
#stream definitions
# stream definitions define connections between spouts and bolts.
# note that such connections can be cyclical
# custom stream groupings are also supported
streams:
- name: "spout --> split" # name isn't used (placeholder for logging, UI, etc.)
from: "sentence-spout"
to: "splitsentence"
grouping:
type: SHUFFLE
- name: "split --> count"
from: "splitsentence"
to: "count"
grouping:
type: FIELDS
args: ["word"]
- name: "count --> log"
from: "count"
to: "log"
grouping:
type: SHUFFLE
Currenty, the Flux YAML DSL only supports the Core Storm API, but support for Storm's micro-batching API is planned.
To use Flux with a Trident topology, define a topology getter method and reference it in your YAML config:
name: "my-trident-topology"
config:
topology.workers: 1
topologySource:
className: "org.apache.storm.flux.test.TridentTopologySource"
# Flux will look for "getTopology", this will override that.
methodName: "getTopologyWithDifferentMethodName"