This guide describes options common to every command in Flux.

Table of contents

Viewing usage

You can view usage for all Flux commands by running Flux without any command name or options:

  • ./bin/flux

  • bin\flux

To see a list of options for a particular command, run the help command followed by the name of the command you are interested in:

  • ./bin/flux help import-jdbc

  • bin\flux help import-jdbc

The “help” for each command will first list the command-specific options, with each required option having an asterisk next to it. The command-specific options are followed by the connection options for connecting to MarkLogic, and those are followed by a list of options common to every Flux command.

Command abbreviations

You can specify a command name without entering its full name, as long as you enter a sufficient number of characters such that Flux can uniquely identify the command name.

For example, instead of entering import-parquet-files, you can enter import-p as it is the only command in Flux beginning with that sequence of letters:

  • ./bin/flux import-p --path path/to/data etc...

  • bin\flux import-p --path path\to\data etc...

If Flux cannot uniquely identify the command name, it will print an error and list the command names that match what you entered.

Reading options from a file

Flux supports reading options from a file. In a text file, you can either add each option name and value to a separate line:

--host
localhost
--port
8000
etc...

Or you can put one or more options on the same line:

--host localhost
--port 8000
etc...

You then reference the file via the @ symbol followed by a filename:

  • ./bin/flux import-files @my-options.txt

  • bin\flux import-files @my-options.txt

You can reference multiple files this way and also include additional options on the command line.

Values in an options file can have whitespace in them, including newline symbols. If your values have whitespace, put double or single quotes around them. Within quoted values, backslashes must be escaped with another backslash. Newlines must then be represented by the same character you would use for a newline symbol in a normal value on the command line. For example, most Unix shells require a \ for allowing a value to continue onto the next line.

As an example, MarkLogic Optic queries are often easier to read when stretched across multiple lines. The following shows an example of such a query in an options file, using a \ to let the query continue to the next line:

--query
"op.fromView('Example', 'Employees', '')\
   .limit(10)"

Connecting to MarkLogic

Every command in Flux will need to connect to a MarkLogic database, either for reading data or writing data or both. Generally, you must include at least the following information for each command:

  • The name of a MarkLogic host.
  • The port of a MarkLogic REST API app server connected to the database you wish to interact with.
  • Authentication information.

Using a connection string

For the common use case of using digest or basic authentication with a MarkLogic app server, you can use the --connection-string option to specify the host, port, username, and password in a single concise option:

--connection-string user:password@host:port

You can also specify a database name in case the database you wish to interact with is not the one associated with the port of the app server you connect to:

--connection-string user:password@host:port/databaseName

In case your username or password use symbols like “@”, you can percent encode the values. For example, for a password of sp@r:k, you would use the following string:

--connection-string user:sp%40r%3Ak@host:8000

For other authentication mechanisms, you must use the --host and --port options to define the host and port for your MarkLogic app server.

Determining the connection type

The --connection-type option determines which of the following approaches Flux uses for connecting to MarkLogic:

  • GATEWAY = the default value; Flux assumes that it cannot directly connect to each host in the MarkLogic cluster, most likely due to the value of --host or the host value found in --connection-string being that of a load balancer that controls access to MarkLogic.
  • DIRECT = Flux will try to connect to each host in the MarkLogic cluster.

If you do not have a load balancer in front of MarkLogic, and if Flux is able to connect to each host that hosts one or more forests for the database you wish to access, then you can set --connection-type to a value of DIRECT. This will often improve performance as Flux will be able to both connect to multiple hosts, thereby utilizing the app server threads available on each host, and also write directly to a forest on the host that it connects to.

Configuring one-way SSL

Flux supports both one-way and two-way SSL connections to MarkLogic (the term “SSL” is used as a synonym for “TLS” in this context). The full list of SSL options is in the “Connection Options” table below. Please see the MarkLogic documentation for full details on configuring SSL for a MarkLogic app server.

For a one-way SSL connection, where Flux only needs to trust the certificate associated with your MarkLogic app server, you must configure the following options:

Option Description
--ssl-protocol Must define the desired SSL protocol; TLSv1.2 is a typical value.
--truststore-path Must define the path to a Java truststore file containing the certificate associated with your MarkLogic app server.
--truststore-password Must specify the password for your truststore file.
--ssl-hostname-verifier You may need to configure this option depending on the certificate authority associated with the app server certificate. See the section on SSL errors below for more information.

If the Java virtual machine (JVM) that you use to run Flux has the certificate associated with your MarkLogic app server already in the JVM’s default truststore, you can omit --truststore-path and --truststore-password and instead give the --ssl-protocol option a value of default.

Configuring two-way SSL

Two-way SSL connection is required when the MarkLogic app server has a value of true for its “SSL Require Client Certificate” field in the MarkLogic admin application. To configure two-way SSL with Flux, you must configure the following options:

Option Description
--keystore-path Must define the path of a Java keystore containing a client certificate trusted by your MarkLogic app server.
--keystore-password Must specify the password for your Java keystore.
--truststore-path Must define the path to a Java truststore file containing the certificate associated with your MarkLogic app server.
--truststore-password Must specify the password for your truststore file.
--ssl-hostname-verifier You may need to configure this option depending on the certificate authority associated with the app server certificate. See the section on SSL errors below for more information.

When specifying a keystore via --keystore-path, Flux will default the value of --ssl-protocol to TLSv1.2. You only need to specify this option if that default protocol is not correct for your application.

Similar to one-way SSL, if your JVM truststore contains your server certificate, you can set the value of --ssl-protocol to default to use your JVM truststore.

Common SSL errors

If you receive an error containing unable to find valid certification path to requested target, then your truststore is not able to trust the certificate associated with your MarkLogic app server. Verify that the truststore identified by --truststore-path, or the default JVM truststore if using --ssl-protocol default, contains the required app server certificate.

If you receive an error message containing Hostname (the hostname) not verified, this is typically due to the certificate authority associated with your app server certificate not being a trusted certificate authority. You can consider the use of --ssl-hostname-verifier ANY to disable hostname verification.

If you receive an error message containing No trusted certificate found, check to see if your MarkLogic app server has a value of true for the “SSL Client Issuer Authority Validation” field. If so, verify that the list of selected “SSL Client Certificate Authorities” includes a certificate authority associated with your client certificate.

Connection options

All available connection options are shown in the table below:

Option Description
--auth-type Type of authentication to use. Possible values are BASIC, DIGEST, CLOUD, KERBEROS, CERTIFICATE, and SAML.
--base-path Path to prepend to each call to a MarkLogic REST API app server.
--certificate-file File path for a keystore to be used for CERTIFICATE authentication.
--certificate-password Password for the keystore referenced by --certificate-file.
--connection-string Defines a connection string as user:password@host:port/optionalDatabaseName; only usable when using DIGEST or BASIC authentication.
--cloud-api-key API key for authenticating with a MarkLogic Cloud cluster when authentication type is CLOUD.
--connection-type Set to DIRECT if connections can be made directly to each host in the MarkLogic cluster. Defaults to GATEWAY. Possible values are DIRECT and GATEWAY.
--database Name of a database to connect if it differs from the one associated with the app server identified by --port.
--disable-gzipped-responses If included, responses from MarkLogic will not be gzipped. May improve performance when responses are very small.
--host The MarkLogic host to connect to.
--kerberos-principal Principal to be used with KERBEROS authentication.
--keystore-algorithm Algorithm of the keystore identified by --keystore-path; defaults to SunX509.
--keystore-password Password for the keystore identified by --keystore-path.
--keystore-path File path for a keystore for two-way SSL connections.
--keystore-type Type of the keystore identified by --keystore-path; defaults to JKS.
--password Password when using DIGEST or BASIC authentication.
--port Port of the REST API app server to connect to.
--saml-token Token to be used with SAML authentication.
--ssl-hostname-verifier Hostname verification strategy when connecting via SSL. Possible values are ANY, COMMON, and STRICT.
--ssl-protocol SSL protocol to use when the MarkLogic app server requires an SSL connection. If a keystore or truststore is configured, defaults to TLSv1.2.
--truststore-algorithm Algorithm of the truststore identified by --truststore-path; defaults to SunX509.
--truststore-password Password for the truststore identified by --truststore-path.
--truststore-path File path for a truststore for establishing trust with the certificate used by the MarkLogic app server.
--truststore-type Type of the truststore identified by --truststore-path; defaults to JKS.
--username Username when using DIGEST or BASIC authentication.

Previewing data

The --preview option works on every command in Flux. For example, given a set of Parquet files in a directory, you can preview an import without writing any of the data to MarkLogic:

  • ./bin/flux import-parquet-files \
    --path export/parquet \
    --connection-string "flux-example-user:password@localhost:8004" \ 
    --preview 10

  • bin\flux import-parquet-files ^
    --path export\parquet ^
    --connection-string "flux-example-user:password@localhost:8004" ^
    --preview 10

The number after --preview specifies how many records to show. You can use --preview-drop to specify potentially verbose columns to drop from the preview. And you can use --preview-list to see the results in a list instead of in a table:

  • ./bin/flux import-parquet-files \
    --connection-string "flux-example-user:password@localhost:8004" \
    --path export/parquet \
    --preview 10 \
    --preview-drop job_title,department \
    --preview-list

  • ./bin/flux import-parquet-files ^
    --connection-string "flux-example-user:password@localhost:8004" ^
    --path export\parquet ^
    --preview 10 ^
    --preview-drop job_title,department ^
    --preview-list

Note that in the case of previewing an import, Flux will show the data as it has been read, which consists of a set of Spark rows with columns. The data is not shown as a set of documents yet, as the transformation of rows to documents occurs when the data is written to MarkLogic.

For some commands, it may be helpful to see the schema of the data read from the command’s data source. For example, when exporting data with a MarkLogic Optic query, you may wish to verify that the datatypes of each column are what you expect before writing the data to a Parquet file or relational database. Use the --preview-schema option to request that Flux log the schema and not write any data:

  • ./bin/flux export-parquet-files \
    --connection-string "flux-example-user:password@localhost:8004" \
    --query "op.fromView('Example', 'Employees')" \
    --path export/parquet \
    --preview-schema

  • bin\flux export-parquet-files ^
    --connection-string "flux-example-user:password@localhost:8004" ^
    --query "op.fromView('Example', 'Employees')" ^
    --path export\parquet ^
    --preview-schema

Applying a limit

For many use cases, it can be useful to only process a small subset of the source data to ensure that the results are correct. The --limit option will achieve this by limiting the number of rows read by a command.

The following shows an example of only importing the first 10 rows from a delimited file:

  • ./bin/flux import-delimited-files \
    --path ../data/employees.csv.gz \
    --connection-string "flux-example-user:password@localhost:8004" \
    --permissions flux-example-role,read,flux-example-role,update \
    --collections employee \
    --uri-template "/employee/{id}.json" \
    --limit 10

  • bin\flux import-delimited-files ^
    --path ..\data\employees.csv.gz ^
    --connection-string "flux-example-user:password@localhost:8004" ^
    --permissions flux-example-role,read,flux-example-role,update ^
    --collections employee ^
    --uri-template "/employee/{id}.json" ^
    --limit 10

Counting records to process

Instead of viewing a preview of data or limiting how much data is processed by Flux, you may want to first obtain a count of records that will be read from the data source associated with the Flux command you are executing. This can be useful when dealing with a data source where it can be difficult to know how much data will be read, such as with very large aggregate XML or Parquet files.

To view a count, include the --count option, which results in Flux reading all the data but not writing any of it to the destination associated with the command:

  • ./bin/flux import-delimited-files \
    --path ../data/employees.csv.gz \
    --connection-string "flux-example-user:password@localhost:8004" \
    --count

  • bin\flux import-delimited-files ^
    --path ..\data\employees.csv.gz ^
    --connection-string "flux-example-user:password@localhost:8004" ^
    --count

Flux will then log the count:

[main] INFO com.marklogic.flux: Count: 1000

The performance of using --count is dependent on how quickly data can be read from the command’s data source. For example, commands that export documents from MarkLogic must read every document to be exported in order to calculate a count. For a scenario like that, you can likely much more quickly determine a count by running your query in MarkLogic’s qconsole application.

Viewing progress

Each Flux command supports a --log-progress option that you can use to specify how often you want a message logged indicating progress. Import commands will show progress in terms of writing data to MarkLogic, while export commands will show progress in terms of reading data from MarkLogic. The copy command can show both types of progress, with --log-progress specifying an interval for logging data that has been read and --output-log-progress specifying an interval for logging data that has been written. The reprocess command supports both --log-progress for processing data in MarkLogic and --log-read-progress for reading data from MarkLogic.

The --log-progress option defaults to a value of 10,000, with one exception - export commands that read rows from MarkLogic defaults --log-progress to a value of 100,000. For an import command with a value of 10,000, Flux will log a message at the INFO level every time it reads 10,000 documents - so at 10,000, 20,000, etc. You can change this value to suit your needs, though you typically will want it to be significantly larger than the value of --batch-size if the command supports that option.

Viewing a stacktrace

When a command fails, Flux will stop execution of the command and display an error message. If you wish to see the underlying stacktrace associated with the error, run the command with the --stacktrace option included. This is included primarily for debugging purposes, as the stacktrace may be fairly long with only a small portion of it potentially being helpful. The initial error message displayed by Flux is intended to be as helpful as possible.

Configuring logging

Flux uses a Log4J2 properties file to configure its logging. The file is located in a Flux installation at ./conf/log4j2.properties. You are free to customize this file to meet your needs for logging.

Configuring JVM options

The ./bin/flux and ./bin/flux.bat executables both apply JVM options defined by the JAVA_OPTS and FLUX_OPTS environment variables. The Java documentation provides a list of standard and extra options that affect how the JVM performs.

As a simple example, you could run the following on a Unix OS to configure the JVM to print its version information each time you run Flux:

export FLUX_OPTS=--show-version

Advanced Spark options

Flux is built on top of Apache Spark and provides a number of command line options for configuring the underlying Spark runtime environment used by Flux.

Configuring the number of partitions

Flux uses Spark partitions to allow for data to be read and written in parallel. Each partition can be thought of as a separate worker, operating in parallel with each other worker.

A number of partitions will be determined by the command that you run before it reads data. The nature of the data source directly impacts the number of partitions that will be created.

If you find that an insufficient number of partitions are created - i.e. the writer phase of your Flux command is not sending as much data to MarkLogic as it could - consider using the --repartition option to force a number of partitions to be created after the data has been read. The downside to using --repartition is that all the data must be read first. Generally, this option will help when data can be read quickly and the performance of writing can be improved by using more partitions than were created when reading data.

Configuring a Spark URL

By default, Flux creates a Spark session with a master URL of local[*]. You can change this via the --spark-master-url option; please see the Spark documentation for examples of valid values. If you are looking to run a Flux command on a remote Spark cluster, please instead see the Spark Integration guide for details on integrating Flux with spark-submit.

Configuring the Spark runtime

Some Flux commands reuse Spark data sources that accept configuration items via the Spark runtime. You can provide these configuration items via the -C option. For example, the Spark Avro data source identifies several configuration items, such as spark.sql.avro.compression.codec. You can set this value by including -Cspark.sql.avro.compression.codec=snappy as a command line option.

Note that the majority of Spark cluster configuration properties cannot be set via the -C option as those options must be set before a Spark session is created. For further control over the Spark session, please see the Spark Integration guide for details on integrating Flux with spark-submit.