What's Embulk?

Embulk is a parallel bulk data loader that helps data transfer between various storages, databases, NoSQL and cloud services.

Embulk supports plugins to add functions. You can share the plugins to keep your custom scripts readable, maintainable, and reusable.

Embulk, an open-source plugin-based parallel bulk data loader at Slideshare

Document

Embulk documents: http://www.embulk.org/docs/

Quick Start

Linux & Mac & BSD

Embulk is a Java application. Please make sure that Java is installed.

Following 4 commands install embulk to your home directory:

curl --create-dirs -o ~/.embulk/bin/embulk -L "http://dl.embulk.org/embulk-latest.jar"
chmod +x ~/.embulk/bin/embulk
echo 'export PATH="$HOME/.embulk/bin:$PATH"' >> ~/.bashrc
source ~/.bashrc

Next step: Running example in 4 commands

Windows

Embulk is a Java application. Please make sure that Java is installed.

You can download embulk.bat using this command on cmd.exe or PowerShell.exe:

PowerShell -Command "& {Invoke-WebRequest http://dl.embulk.org/embulk-latest.jar -OutFile embulk.bat}"

Next step: Running example in 4 commands

Running example

embulk example command generates a sample CSV file so that you can try embulk quickly:

embulk example ./try1
embulk guess   ./try1/example.yml -o config.yml
embulk preview config.yml
embulk run     config.yml

Next step: Using plugins

Using plugins

You can use plugins to load data from/to various systems and file formats. Here is the list of publicly released plugins: list of plugins by category.

An example is embulk-output-command plugin. It executes an external command to output the records.

To install plugins, you can use embulk gem install <name> command:

embulk gem install embulk-output-command
embulk gem list

Embulk bundles some built-in plugins such as embulk-encoder-gzip or embulk-formatter-csv. You can use those plugins with following configuration file:

in:
  type: file
  path_prefix: "./try1/csv/sample_"
out:
  type: command
  command: "cat - > task.$INDEX.$SEQID.csv.gz"
  encoders:
    - {type: gzip}
  formatter:
    type: csv

Resuming a failed transaction

Embulk supports resuming failed transactions. To enable resuming, you need to start transaction with -r PATH option:

embulk run config.yml -r resume-state.yml

If the transaction fails, embulk stores state some states to the yaml file. You can retry the transaction using exactly same command:

embulk run config.yml -r resume-state.yml

If you give up on resuming the transaction, you can use embulk cleanup subcommand to delete intermediate data:

embulk cleanup config.yml -r resume-state.yml

Using plugin bundle

embulk mkbundle subcommand creates a isolated bundle of plugins. You can install plugins (gems) to the bundle directory instead of ~/.embulk directory. This makes it easy to manage versions of plugins. To use the bundle, add -b <bundle_dir> option to guess, preview, or run subcommand. embulk mkbundle also generates some example plugins to <bundle_dir>/embulk/*.rb directory.

See the generated <bundle_dir>/Gemfile file how to plugin bundles work.

embulk mkbundle ./embulk_bundle  # please edit ./embulk_bundle/Gemfile to add plugins. Detailed usage is written in the Gemfile
embulk guess -b ./embulk_bundle ...
embulk run   -b ./embulk_bundle ...

Use cases

• Scheduled bulk data loading to Elasticsearch + Kibana 4 from CSV files

For further details, visit Embulk documentation.

Upgrading to the latest version

Following command updates embulk itself to the latest released version.

embulk selfupdate

Following command updates embulk itself to the specific released version.

embulk selfupdate x.y.z

Older versions are available at dl.embulk.org.

Embulk Development

Build

./gradlew cli  # creates pkg/embulk-VERSION.jar
./gradlew gem  # creates pkg/embulk-VERSION.gem

You can see JaCoCo's test coverage report at ${project}/build/reports/tests/index.html You can see Findbug's report at ${project}/build/reports/findbug/main.html # FIXME coverage information is not included somehow

You can use classpath task to use bundle exec ./bin/embulk for development:

./gradlew -t classpath  # -x test: skip test
./bin/embulk

To deploy artifacts to your local maven repository at ~/.m2/repository/:

./gradlew install

To compile the source code of embulk-core project only:

./gradlew :embulk-core:compileJava

Task dependencies shows dependency tree of embulk-core project:

./gradlew :embulk-core:dependencies

Documents

Embulk uses Sphinx, YARD (Ruby API) and JavaDoc (Java API) for document generation.

brew install python
pip install sphinx
gem install yard
./gradlew site
# documents are: embulk-docs/build/html

Release

You need to add your bintray account information to ~/.gradle/gradle.properties

bintray_user=(bintray user name)
bintray_api_key=(bintray api key)

Run following commands and follow its instruction:

./gradlew set_version -Pto=$VERSION

./gradlew releaseCheck
./gradlew release
git commit -am v$VERSION
git tag v$VERSION

See also:

• Bintray
• How to acquire bintray API Keys