CONFIGURE.md - nifi-minifi-cpp - Git at Google

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 # Apache NiFi -  Configuring MiNiFi - C++

 ## Table of Contents

 - [Table of Contents](#table-of-contents)
 - [Configuring](#configuring)
   - [Configuring flow configuration format](#configuring-flow-configuration-format)
   - [Scheduling strategies](#scheduling-strategies)
   - [Configuring encryption for flow configuration](#configuring-encryption-for-flow-configuration)
   - [Configuring additional sensitive properties](#configuring-additional-sensitive-properties)
   - [Backup previous flow configuration on flow update](#backup-previous-flow-configuration-on-flow-update)
   - [Set number of flow threads](#set-number-of-flow-threads)
   - [OnTrigger runtime alert](#ontrigger-runtime-alert)
   - [Event driven processor time slice](#event-driven-processor-time-slice)
   - [Administrative yield duration](#administrative-yield-duration)
   - [Bored yield duration](#bored-yield-duration)
   - [Graceful shutdown period](#graceful-shutdown-period)
   - [FlowController drain timeout](#flowcontroller-drain-timeout)
   - [SiteToSite Security Configuration](#sitetosite-security-configuration)
   - [HTTP SiteToSite Configuration](#http-sitetosite-configuration)
   - [HTTP SiteToSite Proxy Configuration](#http-sitetosite-proxy-configuration)
   - [Command and Control Configuration](#command-and-control-configuration)
   - [State Storage](#state-storage)
   - [Configuring Repositories](#configuring-repositories)
   - [Configuring Volatile Repositories](#configuring-volatile-repositories)
   - [Configuring Repository storage locations](#configuring-repository-storage-locations)
   - [Configuring compression for rocksdb database](#configuring-compression-for-rocksdb-database)
   - [Configuring compaction for rocksdb database](#configuring-compaction-for-rocksdb-database)
     - [Shared database](#shared-database)
   - [Configuring Repository encryption](#configuring-repository-encryption)
     - [Mixing encryption with shared backend](#mixing-encryption-with-shared-backend)
   - [Configuring Repository Cleanup](#configuring-repository-cleanup)
     - [Caveats](#caveats)
   - [Configuring provenance repository storage](#configuring-provenance-repository-storage)
   - [Provenance Reporter](#provenance-reporter)
   - [REST API access](#rest-api-access)
   - [UID generation](#uid-generation)
   - [Asset directory](#asset-directory)
   - [Controller Services](#controller-services)
   - [Linux Power Manager Controller Service](#linux-power-manager-controller-service)
   - [MQTT Controller service](#mqtt-controller-service)
   - [Network Prioritizer Controller Service](#network-prioritizer-controller-service)
   - [Disk space watchdog](#disk-space-watchdog)
   - [Extension configuration](#extension-configuration)
   - [JNI Functionality](#jni-functionality)
 - [Log configuration](#log-configuration)
   - [Log appenders](#log-appenders)
   - [Log levels](#log-levels)
   - [Log pattern](#log-pattern)
   - [Log compression](#log-compression)
   - [Shortening log messages](#shortening-log-messages)
 - [Recommended Antivirus Exclusions](#recommended-antivirus-exclusions)


 ## Configuring
 The 'conf' directory in the root contains a template config.yml document.

 This is partly compatible with the format used with the Java MiNiFi application. MiNiFi C++ is currently compatible with version 1 of the MiNiFi YAML schema.
 Additional information on the YAML format for the config.yml and schema versioning can be found in the [MiNiFi System Administrator Guide](https://nifi.apache.org/minifi/system-admin-guide.html).

 MiNiFi Toolkit Converter (version 0.0.1 - schema version 1) is considered as deprecated from MiNiFi C++ 0.7.0. It was to aid in creating a flow configuration from a generated template exported from a NiFi instance. The MiNiFi Toolkit Converter tool can be downloaded from http://nifi.apache.org/minifi/download.html under the `MiNiFi Toolkit Binaries` section.  Information on its usage is available at https://nifi.apache.org/minifi/minifi-toolkit.html. Using the toolkit is no longer supported and maintained.

 It's recommended to create your configuration in YAML format or configure the agent via Command and Control protocol (see below)


     Flow Controller:
         id: 471deef6-2a6e-4a7d-912a-81cc17e3a205
         name: MiNiFi Flow

     Processors:
         - name: GetFile
           id: 471deef6-2a6e-4a7d-912a-81cc17e3a206
           class: org.apache.nifi.processors.standard.GetFile
           max concurrent tasks: 1
           scheduling strategy: TIMER_DRIVEN
           scheduling period: 1 sec
           penalization period: 30 sec
           yield period: 1 sec
           run duration nanos: 0
           auto-terminated relationships list:
           Properties:
               Input Directory: /tmp/getfile
               Keep Source File: true

     Connections:
         - name: TransferFilesToRPG
           id: 471deef6-2a6e-4a7d-912a-81cc17e3a207
           source name: GetFile
           source id: 471deef6-2a6e-4a7d-912a-81cc17e3a206
           source relationship name: success
           destination id: 471deef6-2a6e-4a7d-912a-81cc17e3a204
           max work queue size: 0
           max work queue data size: 1 MB
           flowfile expiration: 60 sec
           drop empty: false

     Remote Processing Groups:
         - name: NiFi Flow
           id: 471deef6-2a6e-4a7d-912a-81cc17e3a208
           url: http://localhost:8080/nifi
           timeout: 30 secs
           yield period: 10 sec
           Input Ports:
               - id: 471deef6-2a6e-4a7d-912a-81cc17e3a204
                 name: From Node A
                 max concurrent tasks: 1
                 Properties:

 **NOTE:** Make sure to specify id for each component (Processor, Connection, Controller, RPG etc.) to make sure that Apache MiNiFi C++ can reload the state after a process restart. The id should be unique in the flow configuration.

 ### Configuring flow configuration format

 MiNiFi supports YAML and JSON configuration formats. The desired configuration format can be set in the minifi.properties file, but it is automatically identified by default. The default value is `adaptiveconfiguration`, but we can force to use YAML with the `yamlconfiguration` value.

     # in minifi.properties
     nifi.flow.configuration.class.name=adaptiveconfiguration

 ### Scheduling strategies
 Currently Apache NiFi MiNiFi C++ supports TIMER_DRIVEN, EVENT_DRIVEN, and CRON_DRIVEN. TIMER_DRIVEN uses periods to execute your processor(s) at given intervals.
 The EVENT_DRIVEN strategy awaits for data be available or some other notification mechanism to trigger execution. EVENT_DRIVEN is the recommended strategy for non-source processors.
 CRON_DRIVEN executes at the desired intervals based on the CRON periods. Apache NiFi MiNiFi C++ supports standard CRON expressions ( */5 * * * * ).

 ### Configuring encryption for flow configuration

 To encrypt flow configuration set the following property to true.

     # in minifi.properties
     nifi.flow.configuration.encrypt=true

 ### Configuring additional sensitive properties

 It is possible to set a comma seperated list of encrypted configuration options beyond the default sensitive property list.

     # in minifi.properties
     nifi.sensitive.props.additional.keys=nifi.flow.configuration.file, nifi.rest.api.password

 ### Backup previous flow configuration on flow update

 It is possible to backup the previous flow configuration file with `.bak` extension in case of a flow update (e.g. through C2 or controller socket protocol).

     # in minifi.properties
     nifi.flow.configuration.backup.on.update=true

 ### Set number of flow threads

 The number of threads used by the flow scheduler can be set in the MiNiFi configuration. The default value is 5.

     # in minifi.properties
     nifi.flow.engine.threads=5

 ### OnTrigger runtime alert

 MiNiFi writes warning logs in case a processor has been running for too long. The period for these alerts can be set in the configuration file with the default being 5 seconds.

     # in minifi.properties
     nifi.flow.engine.alert.period=5 sec

 ### Event driven processor time slice

 The flow scheduler can be configured how much time it should allocate at maximum for event driven processors. The processor is triggered until it has work to do, but no more than the configured time slice. The default value is 500 milliseconds.

     # in minifi.properties
     nifi.flow.engine.event.driven.time.slice=500 millis

 ### Administrative yield duration

 In case an uncaught exception is thrown while running a processor, the processor will yield for the configured administrative yield time. The default yield duration is 30 seconds.

     # in minifi.properties
     nifi.administrative.yield.duration=30 sec

 ### Bored yield duration

 If a processor is triggered but has no work available, it will yield for the configured bored yield time. The default yield duration is 100 milliseconds.

     # in minifi.properties
     nifi.bored.yield.duration=100 millis

 ### Graceful shutdown period

 It is possible to configure a graceful shutdown period, the period the flow controller will wait to unload the flow configuration and stop running processors.

     # in minifi.properties
     nifi.flowcontroller.graceful.shutdown.period=30 sec

 ### FlowController drain timeout

 Timeout period for finishing processing of flow files in progress when shutting down flow controller. When not set we do not wait for flow files to finish processing.

     # in minifi.properties
     nifi.flowcontroller.drain.timeout=500 millis

 ### SiteToSite Security Configuration

     # in minifi.properties

     # enable tls
     nifi.remote.input.secure=true

     # if you want to enable client certificate base authorization
     nifi.security.need.ClientAuth=true
     # setup the client certificate and private key PEM files
     nifi.security.client.certificate=./conf/client.pem
     nifi.security.client.private.key=./conf/client.pem
     # setup the client private key passphrase file
     nifi.security.client.pass.phrase=./conf/password
     # setup the client CA certificate file
     nifi.security.client.ca.certificate=./conf/nifi-cert.pem

     # if you do not want to enable client certificate base authorization
     nifi.security.need.ClientAuth=false

 It can also be configured to use the system certificate store.

     # in minifi.properties
     nifi.security.use.system.cert.store=true

 Windows specific certificate options with the following default values:

     # in minifi.properties
     nifi.security.windows.cert.store.location=LocalMachine
     nifi.security.windows.server.cert.store=ROOT
     nifi.security.windows.client.cert.store=MY

     # The CN that the client certificate is required to match; default: use the first available client certificate in the store
     # nifi.security.windows.client.cert.cn=

     # Comma-separated list of enhanced key usage values that the client certificate is required to have
     nifi.security.windows.client.cert.key.usage=Client Authentication

 You have the option of specifying an SSL Context Service definition for the RPGs instead of the properties above.
 This will link to a corresponding SSL Context service defined in the flow.

 To do this specify the SSL Context Service Property in your RPGs and link it to
 a defined controller service. If you do not take this approach the options, above, will be used
 for TCP and secure HTTPS communications.

     Remote Processing Groups:
     - name: NiFi Flow
       id: 2438e3c8-015a-1000-79ca-83af40ec1998
       url: http://127.0.0.1:8080/nifi
       timeout: 30 secs
       yield period: 5 sec
       Input Ports:
           - id: 2438e3c8-015a-1000-79ca-83af40ec1999
             name: fromnifi
             max concurrent tasks: 1
             Properties:
                 SSL Context Service: SSLServiceName
       Output Ports:
           - id: ac82e521-015c-1000-2b21-41279516e19a
             name: tominifi
             max concurrent tasks: 2
             Properties:
                 SSL Context Service: SSLServiceName
     Controller Services:
     - name: SSLServiceName
       id: 2438e3c8-015a-1000-79ca-83af40ec1974
       class: SSLContextService
       Properties:
           Client Certificate: <client cert path>
           Private Key: < private key path >
           Passphrase: <passphrase path or passphrase>
           CA Certificate: <CA cert path>

 If the SSL certificates are not provided with an absolute path or cannot be found on the given relative path, MiNiFi will try to find them on the default path provided in the configuration file.

     # in minifi.properties

     # default minifi resource path
     nifi.default.directory=/path/to/cert/files/


 ### HTTP SiteToSite Configuration
 To enable HTTPSiteToSite for a remote process group.
     Remote Processing Groups:
     - name: NiFi Flow
       transport protocol: HTTP

 ### HTTP SiteToSite Proxy Configuration
 To enable HTTP Proxy for a remote process group.

     Remote Processing Groups:
     - name: NiFi Flow
       transport protocol: HTTP
       proxy host: localhost
       proxy port: 8888
       proxy user:
       proxy password:

 ### Command and Control Configuration
 Please see the [C2 readme](C2.md) for more informatoin

 ### State Storage

 State storage is used for keeping the state of stateful processors like TailFile. This is done using RocksDB database, but can be configured to use a different state storage with custom options.

 The default location of the RocksDB local state storage is the `corecomponentstate` directory under the MiNiFi root directory. This can be reconfigured if other directory is preferred.

     # in minifi.properties
     nifi.state.storage.local.path=/var/tmp/minifi-state/

 To have a custom state storage one option is to configure it in the flow configuration file and set the created controller in the minifi.properties file.

     # in config.yml
     Controller Services:
     - name: testcontroller
       id: 2438e3c8-015a-1000-79ca-83af40ec1994
       class: PersistentMapStateStorage
       Properties:
         Auto Persistence Interval:
             - value: 0 sec
         Always Persist:
             - value: true
         File:
             - value: state.txt

     # in minifi.properties
     nifi.state.storage.local=2438e3c8-015a-1000-79ca-83af40ec1994

 Another option to define a state storage is to use the following properties in the minifi.properties file.

     # in minifi.properties
     nifi.state.storage.local.class.name=PersistentMapStateStorage
     nifi.state.storage.local.always.persist=true
     nifi.state.storage.local.auto.persistence.interval=0 sec


 ### Configuring Repositories

 Apache MiNiFi C++ uses three repositories similarly to Apache NiFi:
 - The Flow File Repository holds the metadata (like flow file attributes) of the flow files.
 - The Content Repository holds the content of the flow files.
 - The Provenance Repository holds the history of the flow files.

 The underlying implementation to use for these repositories can be configured in the minifi.properties file.

 The Flow File Repository can be configured with the `nifi.flowfile.repository.class.name` property. If not specified, it uses the `FlowFileRepository` class by default, which stores the flow file metadata in a RocksDB database. Alternatively it can be configured to use a `VolatileFlowFileRepository` that keeps the state in memory (so the state gets lost upon restart), or the `NoOpRepository` for not keeping any state.

     # in minifi.properties
     nifi.flowfile.repository.class.name=VolatileFlowFileRepository

 The Content Repository can be configured with the `nifi.content.repository.class.name` property. If not specified, it uses the `DatabaseContentRepository` class by default, which persists the content in a RocksDB database. `DatabaseContentRepository` is also the default value specified in the minifi.properties file. Alternatively it can be configured to use a `VolatileContentRepository` that keeps the state in memory (so the state gets lost upon restart), or the `FileSystemRepository` to keep the state in regular files.

 **NOTE:** RocksDB database has a limit of 4GB for the size of a database object. Due to this if you expect to process larger flow files than 4GB you should use the `FileSystemRepository`. The downside of using `FileSystemRepository` is that it does not have the transactional guarantees of the RocksDB repository implementation.

     # in minifi.properties
     nifi.content.repository.class.name=FileSystemRepository

 The Provenance Repository can be configured with the `nifi.provenance.repository.class.name` property. If not specified, it uses the `ProvenanceRepository` class by default, which persists the provenance events in a RocksDB database. Alternatively it can be configured to use a `VolatileProvenanceRepository` that keeps the state in memory (so the state gets lost upon restart), or the `NoOpRepository` to not keep track of the provenance events. By default we do not keep track of the provenance data, so `NoOpRepository` is the value specified in the default minifi.properties file.

     # in minifi.properties
     nifi.flowfile.repository.class.name=NoOpRepository


 ### Configuring Volatile Repositories
 As stated before each of the repositories can be configured to be volatile (state kept in memory and flushed upon restart) or persistent. Volatile repositories have some additional options, that can be specified in the following ways:

     # in minifi.properties
     # For Volatile Repositories:
     nifi.flowfile.repository.class.name=VolatileFlowFileRepository
     nifi.provenance.repository.class.name=VolatileProvenanceRepository
     nifi.content.repository.class.name=VolatileContentRepository

     # configuration options
     # maximum number of entries to keep in memory
     nifi.volatile.repository.options.flowfile.max.count=15000
     # maximum number of bytes to keep in memory, also limited by option above
     nifi.volatile.repository.options.flowfile.max.bytes=7680 KB

     # maximum number of entries to keep in memory
     nifi.volatile.repository.options.provenance.max.count=15000
     # maximum number of bytes to keep in memory, also limited by option above
     nifi.volatile.repository.options.provenance.max.bytes=7680 KB

     # maximum number of entries to keep in memory
     nifi.volatile.repository.options.content.max.count=15000
     # maximum number of bytes to keep in memory, also limited by option above
     nifi.volatile.repository.options.content.max.bytes=7680 KB
     # limits locking for the content repository
     nifi.volatile.repository.options.content.minimal.locking=true

 **NOTE:** If the volatile repository reaches the maximum number of entries, it will start to drop the oldest entries, and replace them with the new entries in round robin manner. Make sure to set the maximum number of entries to a reasonable value, so that the repository does not run out of memory.

 ### Configuring Repository storage locations
 Persistent repositories, such as the Flow File repository, use a configurable path to store data.
 The repository locations and their defaults are defined below. By default the MINIFI_HOME env
 variable is used. If this is not specified we extrapolate the path and use the root installation
 folder. You may specify your own path in place of these defaults.

     # in minifi.properties
     nifi.provenance.repository.directory.default=${MINIFI_HOME}/provenance_repository
     nifi.flowfile.repository.directory.default=${MINIFI_HOME}/flowfile_repository
     nifi.database.content.repository.directory.default=${MINIFI_HOME}/content_repository

 ### Configuring compression for rocksdb database

 Rocksdb has an option to set compression type for its database to use less disk space.
 If content repository or flow file repository is set to use the rocksdb database as their storage, then we have the option to compress those repositories. On Unix operating systems `zlib`, `bzip2`, `zstd`, `lz4` and `lz4hc` compression types and on Windows `xpress` compression type is supported by MiNiFi C++. If the property is set to `auto` then `xpress` will be used on Windows, `zstd` on Unix operating systems. These options can be set in the minifi.properies file with the following properties:

      # in minifi.properties
      nifi.flowfile.repository.rocksdb.compression=zlib
      nifi.content.repository.rocksdb.compression=auto

 ### Configuring compaction for rocksdb database

 Rocksdb has an option to run compaction at specific intervals not just when needed.

      # in minifi.properties
      nifi.flowfile.repository.rocksdb.compaction.period=2 min
      nifi.database.content.repository.rocksdb.compaction.period=2 min

 #### Shared database

 It is also possible to use a single database to store multiple repositories with the `minifidb://` scheme.
 This could help with migration and centralize agent state persistence. In the scheme the final path segment designates the
 column family in the repository, while the preceding path indicates the directory the rocksdb database is
 created into. E.g. in `minifidb:///home/user/minifi/agent_state/flowfile` a directory will be created at
 `/home/user/minifi/agent_state` populated with rocksdb-specific content, and in that repository a logically
 separate "subdatabase" is created under the name `"flowfile"`.

     # in minifi.properties
     nifi.flowfile.repository.directory.default=minifidb://${MINIFI_HOME}/agent_state/flowfile
     nifi.database.content.repository.directory.default=minifidb://${MINIFI_HOME}/agent_state/content
     nifi.state.storage.local.path=minifidb://${MINIFI_HOME}/agent_state/processor_states

 We should not simultaneously use the same directory with and without the `minifidb://` scheme.
 Moreover the `"default"` name is restricted and should not be used.


     # in minifi.properties
     nifi.flowfile.repository.directory.default=minifidb://${MINIFI_HOME}/agent_state/flowfile
     nifi.database.content.repository.directory.default=${MINIFI_HOME}/agent_state
     ^ error: using the same database directory without the "minifidb://" scheme
     nifi.state.storage.local.path=minifidb://${MINIFI_HOME}/agent_state/default
     ^ error: "default" is restricted

 ### Configuring Repository encryption

 It is possible to provide rocksdb-backed repositories a key to request their
 encryption.

     in conf/bootstrap.conf
     nifi.flowfile.repository.encryption.key=805D7B95EF44DC27C87FFBC4DFDE376DAE604D55DB2C5496DEEF5236362DE62E
     nifi.database.content.repository.encryption.key=
     # nifi.state.management.provider.local.encryption.key=

 In the above configuration the first line will cause `FlowFileRepository` to use the specified `256` bit key.
 The second line will trigger the generation of a random (`256` bit) key persisted back into `conf/bootstrap.conf`, which `DatabaseContentRepository` will then use for encryption.
 (This way one can request encryption while not bothering with what key to use.)
 Finally, as the last line is commented out, it will make the state manager use plaintext storage, and not trigger encryption.

 #### Mixing encryption with shared backend

 When multiple repositories use the same directory (as with `minifidb://` scheme) they should either be all plaintext or all encrypted with the same key.

 ### Configuring Repository Cleanup

 When a flow file content is no longer needed we can specify the deletion strategy.

     # any value other than 0 enables garbage collection with the specified frequency
     # while a value of 0 sec triggers an immediate deletion as soon as the resource
     # is not needed
     # (the default value is 1 sec)
     nifi.database.content.repository.purge.period = 1 sec

  #### Caveats
  Systems that have limited memory must be cognizant of the options above. Limiting the max count for the number of entries limits memory consumption but also limits the number of events that can be stored. If you are limiting the amount of volatile content you are configuring, you may have excessive session rollback due to invalid stream errors that occur when a claim cannot be found.

  The content repository has a default option for "minimal.locking" set to true. This will attempt to use lock free structures. This may or may not be optimal as this requires additional additional searching of the underlying vector. This may be optimal for cases where max.count is not excessively high. In cases where object permanence is low within the repositories, minimal locking will result in better performance. If there are many processors and/or timing is such that the content repository fills up quickly, performance may be reduced. In all cases a locking cache is used to avoid the worst case complexity of O(n) for the content repository; however, this caching is more heavily used when "minimal.locking" is set to false.

 ### Configuring provenance repository storage

 Provenance repository size buffer size and TTL can be configured when used with RocksDB. If not set it uses the available maximum RocksDB values.

     #in minifi.properties
     nifi.provenance.repository.max.storage.size=16 MB
     nifi.provenance.repository.max.storage.time=30 days

 ### Provenance Reporter

     Add Provenance Reporting to config.yml
     Provenance Reporting:
       scheduling strategy: TIMER_DRIVEN
       scheduling period: 1 sec
       url: http://localhost:8080/nifi
       port uuid: 471deef6-2a6e-4a7d-912a-81cc17e3a204
       batch size: 100

 ### REST API access

     Configure REST API user name and password
     nifi.rest.api.user.name=admin
     nifi.rest.api.password=password

     if you want to enable client certificate
     nifi.https.need.ClientAuth=true
     nifi.https.client.certificate=./conf/client.pem
     nifi.https.client.private.key=./conf/client.key
     nifi.https.client.pass.phrase=./conf/password
     nifi.https.client.ca.certificate=./conf/nifi-cert.pem

 ### UID generation

 MiNiFi needs to generate many unique identifiers in the course of operations.  There are a few different uid implementations available that can be configured in minifi-uid.properties.

 Implementation for uid generation can be selected using the uid.implementation property values:
 1. time - use uuid_generate_time (default option if the file or property value is missing or invalid)
 2. random - use uuid_generate_random
 3. uuid_default - use uuid_generate (will attempt to use uuid_generate_random and fall back to uuid_generate_time if no high quality randomness is available)
 4. minifi_uid - use custom uid algorthim

 If minifi_uuid is selected MiNiFi will use a custom uid algorthim consisting of first N bits device identifier, second M bits as bottom portion of a timestamp where N + M = 64, the last 64 bits is an atomic incrementor.

 This is faster than the random uuid generator and encodes the device id and a timestamp into every value, making tracing of flowfiles, etc easier.

 It does require more configuration.  uid.minifi.device.segment.bits is used to specify how many bits at the beginning to reserve for the device identifier.  It also puts a limit on how many distinct devices can be used.  With the default of 16 bits, there are a maximum of 65,535 unique device identifiers that can be used.  The 48 bit timestamp won't repeat for almost 9,000 years.  With 24 bits for the device identifier, there are a maximum of 16,777,215 unique device identifiers and the 40 bit timestamp won't repeat for about 35 years.

 Additionally, a unique hexadecimal uid.minifi.device.segment should be assigned to each MiNiFi instance.

 ### Asset directory

 It is possible to make agents download an asset (triggered through the c2 protocol). The target directory can be specified
 using the `nifi.asset.directory` agent property, which defaults to `${MINIFI_HOME}/asset`.

 ### Controller Services
  If you need to reference a controller service in your config.yml file, use the following template. In the example, below, ControllerServiceClass is the name of the class defining the controller Service. ControllerService1
  is linked to ControllerService2, and requires the latter to be started for ControllerService1 to start.

     Controller Services:
       - name: ControllerService1
         id: 2438e3c8-015a-1000-79ca-83af40ec1974
         class: ControllerServiceClass
         Properties:
           Property one: value
           Linked Services:
           - value: ControllerService2
       - name: ControllerService2
         id: 2438e3c8-015a-1000-79ca-83af40ec1992
         class: ControllerServiceClass
         Properties:

 ### Linux Power Manager Controller Service
   The linux power manager controller service can be configured to monitor the battery level and status ( discharging or charging ) via the following configuration.
   Simply provide the capacity path and status path along with your threshold for the trigger and low battery alarm and you can monitor your battery and throttle
   the threadpools within MiNiFi C++. Note that the name is identified must be ThreadPoolManager.

     Controller Services:
     - name: ThreadPoolManager
       id: 2438e3c8-015a-1000-79ca-83af40ec1888
       class: LinuxPowerManagerService
       Properties:
           Battery Capacity Path: /path/to/battery/capacity
           Battery Status Path: /path/to/battery/status
           Trigger Threshold: 90
           Low Battery Threshold: 50
           Wait Period: 500 ms

 ### MQTT Controller service
 The MQTTController Service can be configured for MQTT connectivity and provide that capability to your processors when MQTT is built.

     Controller Services:
     - name: mqttservice
       id: 294491a38-015a-1000-0000-000000000001
       class: MQTTContextService
       Properties:
           Broker URI: localhost:1883
           Client ID: client ID
           Quality of Service: 2

 ### Network Prioritizer Controller Service
   The network prioritizer controller service can be configured to manage prioritizing and binding to specific network interfaces. Linked Services, can be used
   as a prioritized list to create a disjunction among multiple networking prioritizers. This allows you to create classes with different configurations that
   create multiple prioritizations. Max Throughput is the maximum throughput in bytes per second. Max Payload is the maximum number of bytes supported by that
   prioritizer. If a prioritizer is configured with the option "Default Prioritizer: true," then all socket communications will use that default prioritizer.

   In the configuration below there are two classes defined under "NetworkPrioritizerService", one class "NetworkPrioritizerService2" defines en0, and en1.
   If en0 is down at any point, then en1 will be given priority before resorting to en2 and en3 of  "NetworkPrioritizerService3". If the throughput for
   "NetworkPrioritizerService2" exceeds the defined throughput or the max payload of 1024, then "NetworkPrioritizerService3" will be used. If Max Payload and
   Max Throughput are not defined, then they will not be limiting factors.

   Since connection queues can't be re-prioritized, this can create a starvation problem if no connection is available.
   The configuration is required to account for this.

    Controller Services:
    - name: NetworkPrioritizerService
      id: 2438e3c8-015a-1000-79ca-83af40ec1883
      class: NetworkPrioritizerService
      Properties:
          Linked Services: NetworkPrioritizerService2,NetworkPrioritizerService3
    - name: NetworkPrioritizerService2
      id: 2438e3c8-015a-1000-79ca-83af40ec1884
      class: NetworkPrioritizerService
      Properties:
          Network Controllers: en0,en1
          Max Throughput: 1,024,1024
          Max Payload: 1024
    - name: NetworkPrioritizerService3
      id: 2438e3c8-015a-1000-79ca-83af40ec1884
      class: NetworkPrioritizerService
      Properties:
          Network Controllers: en2,en3
          Max Throughput: 1,024,1024
          Max Payload: 1,024,1024

 ### Disk space watchdog #

 Stops MiNiFi FlowController activity (excluding C2), when the available disk space on either of the repository volumes go below stop.threshold, checked every interval, then restarts when the available space on all repository volumes reach at least restart.threshold.

     # in minifi.properties
     minifi.disk.space.watchdog.enable=true
     minifi.disk.space.watchdog.interval=15 sec
     minifi.disk.space.watchdog.stop.threshold=100 MB
     minifi.disk.space.watchdog.restart.threshold=150 MB

 ### Extension configuration
 To notify the agent which extensions it should load see [Loading extensions](Extensions.md#Loading extensions).

 ### JNI Functionality
 Please see the [JNI Configuration Guide](JNI.md).

 ## Log configuration
 By default the application logs for Apache MiNiFi C++ can be found in the ${MINIFI_HOME}/logs/minifi-app.log file with default INFO level logging. The logger can be reconfigured in the ${MINIFI_HOME}/conf/minifi-log.properties file to use different output streams, log level, and output format.

 ### Log appenders
 In the configuration file it is possible to define different output streams by defining what type of appenders (log sinks) should be used for logging. The following appenders are supported:
 - rollingappender - logs written to this log sink are written to a file with a rolling policy
 - stdout - logs written to this log sink are written to the standard output
 - stderr - logs written to this log sink are written to the standard error
 - syslog - logs written to this log sink are written to the syslog
 - alert - logs written to this log sink are critical logs forwarded through HTTP as alerts
 - nullappender - logs written to this log sink are discarded

 Defining a new appender can be done in the format `appender.<appender name>=<appender type>` followed by defining its properties. For example here is how to define a rolling file appender:

     # in minifi-log.properties
     appender.rolling=rollingappender
     appender.rolling.directory=${MINIFI_HOME}/logs
     appender.rolling.file_name=minifi-app.log
     appender.rolling.max_files=3
     appender.rolling.max_file_size=5 MB

 Here's an example of an alert appender with its available properties:

     # in minifi-log.properties
     appender.alert1=alert
     appender.alert1.url=<URL>
     appender.alert1.filter=<regex pattern to match logs against>
     appender.alert1.rate.limit=10 min
     appender.alert1.flush.period=5 s
     appender.alert1.batch.size=100 KB
     appender.alert1.buffer.limit=1 MB
     appender.alert1.level=TRACE
     appender.alert1.ssl.context.service=<Name of the SSLContextService>

 ### Log levels
 After the appenders are defined you can set the log level and logging target for each of them. Appenders can be set to log everything on a specific log level, but you can also define some appenders to only write logs from specific namespaces or classes with different log levels. The log level can be set to one of the following values: OFF, TRACE, DEBUG, INFO, WARN, ERROR, CRITICAL. The log levels can be set in the following way:

     # in minifi-log.properties
     # Set the rolling appender to log everything with INFO level
     logger.root=INFO,rolling
     # But only write logs from the org::apache::nifi::minifi::FlowController class with ERROR level
     logger.org::apache::nifi::minifi::core::logging::FlowController=ERROR,rolling

     # Write all error logs in the minifi namespace to the alert1 appender
     logger.org::apache::nifi::minifi=ERROR,alert1

     # Logs from the FlowController class should be written to the stderr and rolling appenders with DEBUG level
     logger.org::apache::nifi::minifi::FlowController=DEBUG,stderr,rolling

     # Log warnings and errors from the LoggerConfiguration class to all appenders
     logger.org::apache::nifi::minifi::core::logging::LoggerConfiguration=WARN

 ### Log pattern
 The log pattern can be changed if needed using the `spdlog.pattern` property. The documentation of the pattern flags can be found on the [spdlog's custom formatting wiki page](https://github.com/gabime/spdlog/wiki/3.-Custom-formatting#customizing-format-using-set_pattern). The default log pattern is the following, but there are additional examples in the default minifi-log.properties file:

     # in minifi-log.properties
     spdlog.pattern=[%Y-%m-%d %H:%M:%S.%e] [%n] [%l] %v

 ### Log compression
 Logs can be retrieved with the C2 Debug command through the C2 protocol. For this functionality some logs are kept in memory in compressed form. The following properties can be used to configure the limits for this compression:

     # in minifi-log.properties
     compression.cached.log.max.size=8 MB
     compression.compressed.log.max.size=8 MB

 ### Shortening log messages
 There are some additional properties that can be used to shorten log messages:

     # in minifi-log.properties
     # The spdlog.shorten_names can be set to prune package names from logs
     spdlog.shorten_names=true

     # Use the following if you do not want to include the UUID of the component at the end of log lines
     logger.include.uuid=false

     # You can set the maximum length of the log entries
     max.log.entry.length=1024

 **NOTE:** All log configuration properties can be changed through C2 protocol with the property update command, using the `nifi.log.` prefix. For example to change the root log level with the `logger.root` property through C2, the C2 property update command should change the `nifi.log.logger.root` property.

 ## Recommended Antivirus Exclusions
 Antivirus software can take a long time to scan large directories and the numerous files within them. Additionally, if the antivirus software locks files or directories during a scan, those resources are unavailable to the MiNiFi C++ process. To prevent these performance and reliability issues from occurring, it is highly recommended to configure your antivirus software to skip scans on the following MiNiFi C++ directories (or the specified alternatives defined in the minifi.properties file):

 - content_repository
 - flowfile_repository
 - logs
 - provenance_repository
 - corecomponentstate