User context manager

examples/scala_container.py

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+#!/usr/bin/env python3
+# Copyright (C) 2025 Antonio Paolillo. All rights reserved.
+# SPDX-License-Identifier: MIT
+
+"""
+SCALA Docker Image Builder Script.
+
+This script uses the `pythainer` framework to build a Docker image containing
+a specified version of SCALA installed from binaries. It creates a development
+environment with a custom non-root user, installs necessary dependencies
+
+Example:
+    $ python3 scala_container.py
+
+Main Steps:
+    1. Create a base image with required dependencies.
+    2. Add a non-root user and configure the workspace.
+    3. Download and install Java 11
+    4. Download and install Scala
+    5. Build the Docker image
+    6. Run the Docker image
+"""
+
+from pythainer.builders import PartialDockerBuilder, UserManager
+from pythainer.examples.builders import get_user_builder
+
+
+def java_builder(version: str | None, user_manager: UserManager) -> PartialDockerBuilder:
+    """
+    Builds a partial container to extend a base container with Java
+
+    Parameters:
+        version (str): The Java version to install
+        user_manager (UserManager): The docker image user_manager
+
+    Returns:
+        PartialDockerBuilder: A partial builder to extend a docker image with Java
+    """
+    builder = PartialDockerBuilder()
+    builder.user_manager = user_manager
+
+    # run the commands in the context as root
+    with builder.as_root() as root_builder:
+        root_builder.add_packages(
+            packages=[f"openjdk-{version}-jre" if version != None else "default-jre"]
+        )
+
+        version = "21" if version == None else version
+        root_builder.env(name="JAVA_HOME", value=f"/usr/lib/jvm/java-{version}-openjdk-amd64")
+    # go back to user before becoming root
+
+    return builder
+
+
+def scala_builder(user: str, user_manager: UserManager) -> PartialDockerBuilder:
+    """
+    Scala container builder
+
+    Parameters:
+        user (str): The user for whom to install Scala
+        user_manager (UserManager): The docker image user_manager
+
+    Returns:
+        PartialDockerBuilder: A partial builder to extend a docker image with Java
+    """
+
+    builder = PartialDockerBuilder()
+    builder.user_manager = user_manager
+
+    with builder.as_user(username=user):
+        # the java builder should be called outside but, this is a great example to show that the
+        # execution will be returned to the user space after exiting the user context
+        builder |= java_builder(version="11", user_manager=user_manager)
+
+        archive_base = "cs-x86_64-pc-linux"
+        archive = f"{archive_base}.gz"
+
+        # this is dependent on the home existing
+        builder.run(
+            "cd ~;"
+            f"curl -fL https://github.com/coursier/coursier/releases/latest/download/{archive} -o {archive};"
+            f"gunzip {archive};"
+            f"chmod +x {archive_base};"
+            f"./{archive_base} setup -y"
+        )
+
+        builder.env(name="PATH", value=f"$PATH:/home/{user}/.local/share/coursier/bin")
+
+    return builder
+
+
+def main():
+    """
+    Build and run a Docker image containing Java and Scala.
+
+    Steps:
+        1. Create a base image with required dependencies.
+        2. Add a non-root user and configure the workspace.
+        3. Download and install Java 11
+        4. Download and install Scala
+        5. Build the Docker image
+        6. Run the Docker image
+    """
+    user_name = "user"
+    docker_workdir = f"/home/{user_name}/workspace"
+
+    builder = get_user_builder(
+        image_name="scala_container",
+        base_ubuntu_image="ubuntu:24.04",
+        user_name=user_name,
+    )
+
+    builder.workdir(path=docker_workdir)
+
+    builder |= scala_builder(user=user_name, user_manager=builder.user_manager)
+
+    builder.build()
+
+    runner = builder.get_runner()
+
+    cmd = runner.get_command()
+    print(" ".join(cmd))
+    runner.generate_script()
+
+    runner.run()
+
+
+if __name__ == "__main__":
+    main()