---
title: Building Flink from Source
weight: 21
type: docs
aliases:
  - /flinkDev/building.html
  - /start/building.html
---
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# Building Flink from Source

This page covers how to build Flink {{< version >}} from sources.

## Build Flink

In order to build Flink you need the source code. Either [download the source of a release]({{< downloads >}}) or [clone the git repository]({{< github_repo >}}).

In addition you need **Maven 3.8.6** and a **JDK** (Java Development Kit). Flink requires **Java 11** to build.

To clone from git, enter:

```bash
git clone {{< github_repo >}}
```

The simplest way of building Flink is by running:

```bash
mvn clean install -DskipTests
```

This instructs [Maven](http://maven.apache.org) (`mvn`) to first remove all existing builds (`clean`) and then create a new Flink binary (`install`).

To speed up the build you can:
- skip tests by using ' -DskipTests'
- skip QA plugins and javadoc generation by using the `fast` Maven profile
- skip the WebUI compilation by using the `skip-webui-build` Maven profile
- use Maven's parallel build feature, e.g., 'mvn package -T 1C' will attempt to build 1 module for each CPU core in parallel.
  {{< hint warning >}}
  Parallel builds may deadlock due to a bug in the maven-shade-plugin. It is recommended to only use it as a 2 steps process, where you first run `mvn validate/test-compile/test` in parallel, and then run `mvn package/verify/install` with a single thread.
  {{< /hint >}}

The build script will be:
```bash
mvn clean install -DskipTests -Dfast -Pskip-webui-build -T 1C
```
The `fast` and `skip-webui-build` profiles have a significant impact on the build time, particularly on slower storage devices, due to them reading/writing many small files.

## Build PyFlink

#### Prerequisites

1. Building Flink

    If you want to build a PyFlink package that can be used for pip installation, you need to build the Flink project first, as described in [Build Flink](#build-flink).

2. Python version(3.9, 3.10, 3.11 or 3.12) is required

    ```shell
    $ python --version
    # the version printed here must be 3.9, 3.10, 3.11 or 3.12
    ```

3. Build PyFlink with Cython extension support (optional)

    To build PyFlink with Cython extension support, you’ll need a C compiler. It's a little different on how to install the C compiler on different operating systems:

    * **Linux** Linux operating systems usually come with GCC pre-installed. Otherwise, you need to install it manually. For example, you can install it with command `sudo apt-get install build-essential` On Ubuntu or Debian.

    * **Mac OS X** To install GCC on Mac OS X, you need to download and install "[Command Line Tools for Xcode](https://developer.apple.com/downloads/index.action)", which is available in Apple’s developer page.

    You also need to install the dependencies with following command:

    ```shell
    $ python -m pip install --group flink-python/pyproject.toml:dev
    ```

#### Installation

Then go to the root directory of flink source code and run this command to build the sdist package and wheel package of `apache-flink` and `apache-flink-libraries`:

```bash
cd flink-python; python setup.py sdist bdist_wheel; cd apache-flink-libraries; python setup.py sdist; cd ..;
```

The sdist package of `apache-flink-libraries` will be found under `./flink-python/apache-flink-libraries/dist/`. It could be installed as following:

```bash
python -m pip install apache-flink-libraries/dist/*.tar.gz
```

The sdist and wheel packages of `apache-flink` will be found under `./flink-python/dist/`. Either of them could be used for installation, such as:

```bash
python -m pip install dist/*.whl
```

## Scala Versions

{{< hint info >}}
Users that purely use the Java APIs and libraries can *ignore* this section.
{{< /hint >}}

Flink has APIs, libraries, and runtime modules written in [Scala](http://scala-lang.org). Users of the Scala API and libraries may have to match the Scala version of Flink with the Scala version of their projects (because Scala is not strictly backwards compatible).

Since version 1.15 Flink dropped the support of Scala 2.11 and it will use Scala 2.12 to build by default.

To build against a specific binary Scala version you can use:
```bash
mvn clean install -DskipTests -Dscala.version=<scala version>
```


{{< top >}}

## Encrypted File Systems

If your home directory is encrypted you might encounter a `java.io.IOException: File name too long` exception. Some encrypted file systems, like encfs used by Ubuntu, do not allow long filenames, which is the cause of this error.

The workaround is to add:

```xml
<args>
    <arg>-Xmax-classfile-name</arg>
    <arg>128</arg>
</args>
```

in the compiler configuration of the `pom.xml` file of the module causing the error. For example, if the error appears in the `flink-yarn` module, the above code should be added under the `<configuration>` tag of `scala-maven-plugin`. See [this issue](https://issues.apache.org/jira/browse/FLINK-2003) for more information.

{{< top >}}

