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: https://www.embulk.org/
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
For further details, visit Embulk documentation.
Upgrading to the latest version
Following command updates embulk itself to the specific released version.
embulk selfupdate x.y.z
Embulk Development
Build
./gradlew cli # creates pkg/embulk-VERSION.jar
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
Update JRuby
Modify jrubyVersion in build.gradle to update JRuby of Embulk.
Release
You need to add your bintray account information to ~/.gradle/gradle.properties
bintray_user=(bintray user name)
bintray_api_key=(bintray api key)
Modify version in build.gradle at a detached commit to bump Embulk version up.
git checkout --detach master
(Remove "-SNAPSHOT" in "version" in build.gradle.)
git add build.gradle
git commit -m "Release vX.Y.Z"
git tag -a vX.Y.Z
(Write the release note for vX.Y.Z in the tag annotation.)
./gradlew clean && ./gradlew release
git push -u origin vX.Y.Z
See also:
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