Creating Docker Images

In this part, we’ll create our first Pulumi resource. Resources in Pulumi are the basic building blocks of your infrastructure, whether that’s a database instance or a compute instance or a specific storage bucket. In Pulumi, resource providers manage your resources. You can group those resources to abstract them (such as a group of compute instances that all have the same configuration and implementation) via component resources.

In this case, our resources are going to be Docker containers and images that we build locally using infrastructure as code. Our resource provider is Docker, and we’re using Node.js Node.js Python Go .NET .NET .NET as our language host, or the executor that compiles the code we write and interprets it for Pulumi.

Verify your application

Let’s explore what app we’re deploying on the infrastructure we’re creating. Open up the pulumi/tutorial-pulumi-fundamentals repo. Let’s explore the contents of the app/ directory. There is a backend, a frontend, and a data directory. All three directories contain a Dockerfile that builds the application images.

Let’s examine the backend Dockerfile in app/backend/Dockerfile:

FROM node:14

# Create app directory
WORKDIR /usr/src/app

COPY ./src/package*.json ./
RUN npm install
COPY ./src .
RUN npm build
EXPOSE 3000

CMD [ "npm", "start" ]

This Dockerfile copies the REST backend into the Docker filesystem, installs the dependencies, and builds the image. Note that port 3000 must be open on your host machine.

Build your Docker Image with Pulumi

Before we start writing our Pulumi program, we need to install the right provider. In this case, we want to use the @pulumi/docker provider for Node.js, our language host. Let’s to install the provider now:

cd ../
npm install @pulumi/docker

Before we start writing our Pulumi program, we need to install the right provider. In this case, we want to use the pulumi_docker provider for Python, our language host. It’s always good practice for Python to work inside a virtual environment, or venv, so let’s activate our venv and use pip to install the provider along with the main Pulumi package:

cd ../
source venv/bin/activate
pip3 install pulumi_docker

You should see output showing the provider package being installed, just like for any Python package install. Add the package to the requirements.txt file by adding pulumi_docker on a new line at the end of the file.

Before we start writing our Pulumi program, we need to install the right providers. In this case, we want to use the com.pulumi:docker provider for Java, our language host. Since we’re using Gradle, we’ll add it to our build file, and it will get added at build time. Let’s modify our build.gradle file in the app/ directory:

plugins {
    id 'application'
}

repositories {
    maven { // The google mirror is less flaky than mavenCentral()
        url("https://maven-central.storage-download.googleapis.com/maven2/")
    }
    mavenCentral()
    mavenLocal()
}

var pulumiJavaSdkVersion = System.getenv("PULUMI_JAVA_SDK_VERSION") ?: "0.1.0"
var pulumiDockerSdkVersion = System.getenv("PULUMI_DOCKER_PROVIDER_SDK_VERSION") ?: "3.2.0"

dependencies {
    implementation "com.pulumi:pulumi:$pulumiJavaSdkVersion"
    implementation "com.pulumi:docker:$pulumiDockerSdkVersion"
}

application {
    mainClass = project.hasProperty("mainClass")
            ? project.getProperty("mainClass")
            : 'my_first_app.App'
}

Back inside your Pulumi program, let’s build your first Docker image. Remember that a Pulumi program is the code that defines the desired state of your infrastructure using a general-purpose programming language. In this case, we’re using Node.js Node.js Python Go .NET .NET .NET , so our main file is index.js index.ts __main__.py main.go Program.cs Program.fs Program.vb App.java Pulumi.yaml . Inside your program’s index.js index.ts __main__.py main.go Program.cs Program.fs Program.vb App.java Pulumi.yaml file, use any editor to add the following code:

import * as pulumi from "@pulumi/pulumi";
import * as docker from "@pulumi/docker";

const stack = pulumi.getStack();

const backendImageName = "backend";
const backend = new docker.RemoteImage(`${backendImageName}`, {
    name: "pulumi/tutorial-pulumi-fundamentals-backend:latest",
});
import os
import pulumi
import pulumi_docker as docker

stack = pulumi.get_stack()

# build our backend image!
backend_image_name = "backend"
backend = docker.RemoteImage("backend",
                             name="pulumi/tutorial-pulumi-fundamentals-backend:latest"
                            )
package my_first_app;

import com.pulumi.Context;
import com.pulumi.Pulumi;
import com.pulumi.docker.RemoteImage;
import com.pulumi.docker.RemoteImageArgs;

import java.util.List;

public class App {
    public static void main(String[] args) {
        Pulumi.run(App::stack);
    }

    private static void stack(Context ctx) {

        final var stackName = ctx.stackName();

        final String backendImageName = "backend";
        final var backendImage = new RemoteImage(
                backendImageName,
                RemoteImageArgs.builder()
                        .name(String.format("pulumi/tutorial-pulumi-fundamentals-%s:latest",backendImageName))
                        .build()
        );
    }
}
name: my_first_app
runtime: yaml
description: A minimal Pulumi YAML program

configuration: {}
variables:     {}
resources:
  backend-image:
    type: docker:index:RemoteImage
    properties:
      name: pulumi/tutorial-pulumi-fundamentals-backend:latest
outputs:       {}

In this file, we import the main Pulumi package and the Docker provider. Then, we figure out which stack we’re operating against, and populate the stack variable for later use. When we build our backend image, we give it a name in our stack as “backend” before passing some arguments to the Docker provider. The Docker provider uses the name argument to pull a remote image for us to use.

Notice that we’re mixing in some language constructs in here like process.cwd(). With Pulumi, we have access to the full language ecosystem, including built-ins and third-party libraries. Pulumi also has typing support, so you can use the tools in your favorite IDE, like completion, to verify that you’re using the correct types for any inputs you’re using. Pretty cool!

In this file, we import the main Pulumi package and the Docker provider. Then, we figure out which stack we’re operating against, and populate the stack variable for later use. When we build our backend image, we give it a name in our stack as “backend” before passing some arguments to the Docker provider. The Docker provider uses the name argument to pull a remote image for us to use.

Notice that we’re mixing in some language constructs in here like os.getcwd(). With Pulumi, we have access to the full language ecosystem, including third-party libraries. Pulumi also has typing support, so you can use the tools in your favorite IDE, like completion, to verify that you’re using the correct types for any inputs you’re using. Pretty cool!

In this file, we import the main Pulumi package and the Docker provider. Then, we figure out which stack we’re operating against, and populate the stackName variable for later use. When we build our backend image, we give it a name in our stack as “backend” before passing some arguments to the Docker provider. The Docker provider uses the name argument to pull a remote image for us to use.

Notice that we’re mixing in some language constructs in here like String.format. With Pulumi, we have access to the full language ecosystem, including third-party libraries. Pulumi also has typing support, so you can use the tools in your favorite IDE, like completion, to verify that you’re using the correct types for any inputs you’re using. Pretty cool!

In this file, we’re defining a RemoteImage resource using the Docker provider. The properties are the arguments (or inputs in Pulumi terms) that the resource takes. The Docker provider uses the name input to pull a remote image for us to use.

Run pulumi up.

Pulumi should build your Docker image. First, though, it gives you a preview of the changes you’ll be making to the stack and asks if the changes appear okay to you. You’ll need to reply “yes” to the prompt to actually build the image. After the command finishes, you will see your image if you run the command docker images or docker image ls (depending on your preference).

Let’s dig a bit deeper into the code and explore the various Pulumi concepts. Every resource has inputs and outputs. Inputs are values that are provided to the resource. Outputs are the resource’s properties. Note that Pulumi can’t know the output until the resource has completed provisioning as some of those outputs are provided by the provider after everything has loaded, booted, or otherwise has come online. More on outputs later.

In our case here, the Docker RemoteImage resource takes the following inputs:

  • an unnamed string: a name for the resource we are creating
  • name: the name of the remote image to pull down
  • an unnamed string: a name for the resource we are creating
  • name: the name of the remote image to pull down
  • an unnamed string: a name for the resource we are creating
  • name: the name of the remote image to pull down
  • name: the name of the remote image to pull down

Now that we’ve provisioned our first piece of infrastructure, let’s add the other pieces of our application.

Add the frontend client and MongoDB

Our application includes a frontend client and MongoDB. We’ll add them to the program, so add this code after the previous fragment.

// build our frontend image!
const frontendImageName = "frontend";
const frontend = new docker.RemoteImage(`${frontendImageName}`, {
    name: "pulumi/tutorial-pulumi-fundamentals-frontend:latest",
});

// build our mongodb image!
const mongoImage = new docker.RemoteImage("mongo", {
    name: "pulumi/tutorial-pulumi-fundamentals-database-local:latest",
});
# build our frontend image!
frontend_image_name = "frontend"
frontend = docker.RemoteImage("frontend",
                              name="pulumi/tutorial-pulumi-fundamentals-frontend:latest"
                             )

# build our mongodb image!
mongo_image = docker.RemoteImage("mongo",
                                 name="pulumi/tutorial-pulumi-fundamentals-database-local:latest"
                                )
final String frontendImageName = "frontend";
final var frontendImage = new RemoteImage(
        frontendImageName,
        RemoteImageArgs.builder()
                .name(String.format("pulumi/tutorial-pulumi-fundamentals-%s:latest",frontendImageName))
                .build()
);

final var mongoImage = new RemoteImage(
        "mongoImage",
        RemoteImageArgs.builder()
                .name("pulumi/tutorial-pulumi-fundamentals-database-local:latest")
                .build()
);
  frontend-image:
    type: docker:index:RemoteImage
    properties:
      name: pulumi/tutorial-pulumi-fundamentals-frontend:latest

We build the frontend client and the populated MongoDB database image the same way we built the backend.

Compare your program now to this complete program before we move forward:

import * as pulumi from "@pulumi/pulumi";
import * as docker from "@pulumi/docker";

const stack = pulumi.getStack();

const backendImageName = "backend";
const backend = new docker.RemoteImage(`${backendImageName}`, {
    name: "pulumi/tutorial-pulumi-fundamentals-backend:latest",
});

// build our frontend image!
const frontendImageName = "frontend";
const frontend = new docker.RemoteImage(`${frontendImageName}`, {
    name: "pulumi/tutorial-pulumi-fundamentals-frontend:latest",
});

// build our mongodb image!
const mongoImage = new docker.RemoteImage("mongo", {
    name: "pulumi/tutorial-pulumi-fundamentals-database-local:latest",
});
import os
import pulumi
import pulumi_docker as docker

stack = pulumi.get_stack()

# build our backend image!
backend_image_name = "backend"
backend = docker.RemoteImage("backend",
                             name="pulumi/tutorial-pulumi-fundamentals-backend:latest"
                            )

# build our frontend image!
frontend_image_name = "frontend"
frontend = docker.RemoteImage("frontend",
                              name="pulumi/tutorial-pulumi-fundamentals-frontend:latest"
                             )

# build our mongodb image!
mongo_image = docker.RemoteImage("mongo",
                                 name="pulumi/tutorial-pulumi-fundamentals-database-local:latest"
                                )
package my_first_app;

import com.pulumi.Context;
import com.pulumi.Pulumi;
import com.pulumi.docker.RemoteImage;
import com.pulumi.docker.RemoteImageArgs;

import java.util.List;

public class App {
    public static void main(String[] args) {
        Pulumi.run(App::stack);
    }

    private static void stack(Context ctx) {

        final var stackName = ctx.stackName();

        final String backendImageName = "backend";
        final var backendImage = new RemoteImage(
                backendImageName,
                RemoteImageArgs.builder()
                        .name(String.format("pulumi/tutorial-pulumi-fundamentals-%s:latest",backendImageName))
                        .build()
        );

        final String frontendImageName = "frontend";
        final var frontendImage = new RemoteImage(
                frontendImageName,
                RemoteImageArgs.builder()
                        .name(String.format("pulumi/tutorial-pulumi-fundamentals-%s:latest",frontendImageName))
                        .build()
        );

        final var mongoImage = new RemoteImage(
                "mongoImage",
                RemoteImageArgs.builder()
                        .name("pulumi/tutorial-pulumi-fundamentals-database-local:latest")
                        .build()
        );
    }
}
name: my_first_app
runtime: yaml
description: A minimal Pulumi YAML program

configuration: {}
variables:     {}
resources:
  backend-image:
    type: docker:index:RemoteImage
    properties:
      name: pulumi/tutorial-pulumi-fundamentals-backend:latest
  frontend-image:
    type: docker:index:RemoteImage
    properties:
      name: pulumi/tutorial-pulumi-fundamentals-frontend:latest
outputs:       {}

If your code looks the same, great! Otherwise, update yours to match this code.

Now, run pulumi up to build all of the images that we’ll need.

From here, we can move on to configuring and provisioning our containers.

Onward!