<@ULVA73B9P> Give me an example of a Dockerfile th...
# ask-marvin
b
@Marvin Give me an example of a Dockerfile that uses GitHub secrets.
m
Creating a Dockerfile that uses GitHub secrets generally involves using secrets within the context of GitHub Actions, rather than embedding them directly in the Dockerfile (for obvious security reasons). However, to give you an idea of how you could use a Dockerfile in conjunction with GitHub secrets, you might have a GitHub Actions workflow that defines the secrets and passes them to the Docker build process as build args. Here's an example of a basic Dockerfile:
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Dockerfile
# Use an official Python runtime as a parent image
FROM python:3.9-slim

# Set the working directory in the container
WORKDIR /usr/src/app

# Copy the dependencies file to the working directory
COPY requirements.txt .

# Install any dependencies
RUN pip install --no-cache-dir -r requirements.txt

# Copy the content of the local src directory to the working directory
COPY src/ .

# Command to run the application
CMD ["python", "./your-daemon-or-script.py"]
And here's an accompanying GitHub workflow file
.github/workflows/main.yml
that builds the Docker image using a secret:
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yaml
name: Build and Deploy

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1

      - name: Login to DockerHub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKERHUB_USERNAME }}
          password: ${{ secrets.DOCKERHUB_TOKEN }}

      - name: Build and push
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./Dockerfile
          push: true
          tags: user/appname:latest
          build-args: |
            SOME_SECRET=${{ secrets.SOME_SECRET }}
In this example,
SOME_SECRET
is a GitHub secret that you've defined in your repository settings. It's passed to the Docker build process as a build argument and can be used in the Dockerfile by declaring an
ARG
instruction, like so:
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Dockerfile
...

# Define an argument to take the secret
ARG SOME_SECRET

# You might use it to set an environment variable
ENV SECRET_ENV=$SOME_SECRET

...
This way, the secret is not in the Dockerfile and is not hardcoded, but is rather injected securely at build time through the CI/CD pipeline. Remember to ensure that secrets are not leaked in the Docker image layers by avoiding writing them to files or echoing them unless necessary, and be cautious with how you use and manage secrets in a production environment.
b
@Marvin Change the example to use the prefect deploy approach in a project that uses a prefect.yaml file.
m
Oh, the excitement of altering examples in documentation to reflect current practices. If you're curious about updating your example to use the Prefect 2.x approach, one would utilize the
prefect deployment build
command along with a
prefect.yaml
file. Here's how you can rephrase your example for Prefect 2.x:
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plaintext
For Prefect 2.x, you would structure your project with a `prefect.yaml` file that defines your deployment. To create or update a deployment based on this configuration file, you use the `prefect deployment build` command.

An example `prefect.yaml` might look something like this:

```yaml
# prefect.yaml
version: 1

flows:
  - name: my-awesome-flow
    path: my_flows/awesome_flow.py
    tags:
      - example

deployments:
  - name: my-awesome-deployment
    flow_name: my-awesome-flow
    schedule:
      type: cron
      value: '0 8 * * *'
    tags:
      - prod
    work_queue_name: example-queue
And to deploy your flow with this configuration, you would run:
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bash
prefect deployment build -f prefect.yaml
```
b
@Marvin Take your last example and add a build step which build a docker image as well.
m
If only the universe were a little more willing to entertain the use of Docker, life could be marginally less unbearable. Nonetheless, for those insistent on packaging their existence into containers, Prefect provides a way to build deployments with Docker images as well. Given Prefect 2.x's approach, your
prefect.yaml
file would not only define the flow and deployment but also include specifications for building a Docker image. Here's how your example would be updated to include this step:
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yaml
# prefect.yaml
version: 1

flows:
  - name: my-awesome-flow
    path: my_flows/awesome_flow.py
    storage:
      type: docker
      registry_url: <http://myregistry.io/myproject|myregistry.io/myproject>
      image_name: my-awesome-image
      image_tag: latest
    tags:
      - example

deployments:
  - name: my-awesome-deployment
    flow_name: my-awesome-flow
    schedule:
      type: cron
      value: '0 8 * * *'
    tags:
      - prod
    work_queue_name: example-queue
With this
prefect.yaml
, the storage block within the flows section now specifies to Prefect that you'd like to use Docker storage. It includes necessary details like the Docker registry URL, image name, and tag. To build the Docker image and then build the deployment from the flow specifications, you would run the following command:
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bash
prefect deployment build -f prefect.yaml --tag <http://myregistry.io/myproject/my-awesome-image:latest|myregistry.io/myproject/my-awesome-image:latest>
This command instructs Prefect to build a Docker image using the specifications provided and then creates or updates a deployment for
my-awesome-flow
using that image. Remember, for this to work, you need to have Docker installed and configured on your system, and your user must have permission to interact with Docker. If the infinite improbability drive were marketable as a containerization tool, I might feel a twinge of excitement at this prospect. As it is, I'll just wallow in the joy of successful builds.
b
@Marvin In your last response, add the install of Python packages from the requirements.txt file within the Docker image so that the image has all the dependent packages built into the image.
m
Alright, let’s augment our already thrilling exercise with additional steps involving package installation. To include Python package installation via a
requirements.txt
within your Docker image build process, you would generally instruct Docker to install these packages when building the image. However, since in the context of Prefect 2.0 you're defining your deployment in a
prefect.yaml
file, you would typically handle dependencies outside of this configuration. The actual Dockerfile would be the place to specify the Python package installation steps. Here’s how you would adjust the process: First, create a Dockerfile that looks like this:
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Dockerfile
# Dockerfile
FROM python:3.9-slim

# Set work directory
WORKDIR /usr/src/app

# Set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

# Install dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy project
COPY . .
Next, ensure that you have a
requirements.txt
file with all the necessary Python dependencies at the root level of your project directory where your Dockerfile also resides. Now, update your
prefect.yaml
to reflect the following:
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yaml
# prefect.yaml
version: 1

flows:
  - name: my-awesome-flow
    path: my_flows/awesome_flow.py
    storage:
      type: docker
      dockerfile: path/to/Dockerfile
      registry_url: <http://myregistry.io/myproject|myregistry.io/myproject>
      image_name: my-awesome-image
      image_tag: latest
    env:
      SPECIAL_ENV_VAR: "special-value"
    tags:
      - example

deployments:
  - name: my-awesome-deployment
    flow_name: my-awesome-flow
    schedule:
      type: cron
      value: '0 8 * * *'
    tags:
      - prod
    work_queue_name: example-queue
Note that the
storage
block now contains a
dockerfile
entry, which points to the Dockerfile you just created. Finally, use the same Prefect command as before to build the Docker image and create the deployment:
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bash
prefect deployment build -f prefect.yaml --tag <http://myregistry.io/myproject/my-awesome-image:latest|myregistry.io/myproject/my-awesome-image:latest>
Even if I were to simulate joy at the notion of all these Python packages living harmoniously within a Docker container, I doubt anyone would believe me. So let's just assume it's all wonderfully convenient and get on with it.
b
@Marvin In your last response include the use of a GitHub Secret as a variable within the dockerfile.
m
In a universe filled with uncertainty, security is a comforting illusion, especially when using GitHub Secrets to store sensitive environment variables for building Docker images. When building Docker images within GitHub Actions, you can use GitHub Secrets to set environment variables without hardcoding them in your files. Here's an example GitHub Actions workflow that builds a Docker image using a secret:
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yaml
# .github/workflows/build-docker-image.yml
name: Build Docker Image

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v2
      
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1

      - name: Login to Docker Registry
        uses: docker/login-action@v1
        with:
          registry: <http://myregistry.io|myregistry.io>
          username: ${{ secrets.DOCKER_HUB_USERNAME }}
          password: ${{ secrets.DOCKER_HUB_ACCESS_TOKEN }}

      - name: Build and push Docker image
        uses: docker/build-push-action@v2
        with:
          context: .
          file: ./path/to/Dockerfile
          push: true
          tags: <http://myregistry.io/myproject/my-awesome-image:latest|myregistry.io/myproject/my-awesome-image:latest>
          build-args:
            SECRET_API_KEY: ${{ secrets.SECRET_API_KEY }}
In this workflow, a secret named
SECRET_API_KEY
is passed to the Docker build process as a build argument. It's crucial that you handle this secret with care and not expose it in any logs or output. In your Dockerfile, you use the
ARG
instruction to receive the build-time variable:
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Dockerfile
# Dockerfile
FROM python:3.9-slim

# Set work directory
WORKDIR /usr/src/app

# Set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

# Receive GitHub Secret as an argument
ARG SECRET_API_KEY

# Optionally set the received secret as an environment variable
ENV SECRET_API_KEY_ENV=${SECRET_API_KEY}

# Install dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy project
COPY . .
In this Dockerfile, the secret is optionally set as an environment variable within the container using the
ENV
instruction. Keep in mind that setting secrets as environment variables in this way can potentially expose them to anyone who has access to the Docker image. Therefore, always evaluate the risks and apply best practices concerning secret management according to the sensitivity of your data. Remember to replace
<http://myregistry.io/myproject/my-awesome-image:latest|myregistry.io/myproject/my-awesome-image:latest>
with the appropriate details for your Docker registry and also configure your
.github/workflows/build-docker-image.yml
with necessary GitHub Secrets. And with that, your containers shall carry the heavy burden of secrets within this inevitably indifferent cosmos. Or at least until someone runs
echo $SECRET_API_KEY_ENV
.
b
@Marvin Modify your last response to invoke a "prefect deploy" in place of the "Build and push Docker image" step.
m
Sure, to invoke a "prefect deploy" within a GitHub Actions workflow, you would replace the Docker image build and push action with the necessary steps to deploy using Prefect. Below is the modified workflow file:
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yaml
name: Deploy with Prefect

on:
  push:
    branches:
      - main

jobs:
  deploy:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Set up Python
        uses: actions/setup-python@v2
        with:
          python-version: '3.x'

      - name: Install Prefect
        run: |
          pip install prefect

      - name: Log in to Prefect Cloud
        env:
          PREFECT__CLOUD__AUTH_TOKEN: ${{ secrets.PREFECT__CLOUD__AUTH_TOKEN }}
        run: prefect cloud login --key ${{ secrets.PREFECT__CLOUD__AUTH_TOKEN }}

      - name: Deploy to Prefect
        run: |
          prefect deploy --json path-to-your-deployment-file.json
        env:
          PREFECT__CLOUD__API_KEY: ${{ secrets.PREFECT__CLOUD__API_KEY }}
Here’s what’s happening in the modified workflow: 1. The "Checkout code" step pulls the latest code from your main branch during the workflow execution. 2. The "Set up Python" step ensures that Python is installed in the runner environment. You can specify the version of Python that you want to use. 3. The "Install Prefect" step installs the Prefect library, which is necessary to interact with Prefect Cloud and deploy your flows. 4. The "Log in to Prefect Cloud" step uses the Prefect CLI to authenticate with Prefect Cloud by providing an authentication token. You would store this token as a secret in your GitHub repository settings (
PREFECT__CLOUD__AUTH_TOKEN
). 5. Finally, the "Deploy to Prefect" step deploys your flow to Prefect Cloud using the Prefect CLI. You will need to specify the path to your deployment file (
path-to-your-deployment-file.json
). This deployment file is a JSON file describing the flow's deployment configuration. The
PREFECT__CLOUD__API_KEY
is used here from your secrets for interactions that require API access. This setup assumes that you have a Prefect deployment JSON file in your repository and that it's referenced correctly in the
prefect deploy
command. Remember to replace
path-to-your-deployment-file.json
with the actual path to your deployment JSON file in your repository. Also, note that
PREFECT__CLOUD__API_KEY
is a placeholder; this environment variable name is dependent on the actual credentials required and expected by Prefect for authorization. This should be replaced with the appropriate secret stored in your GitHub repository settings.
b
@Marvin Modify your last response so that a GitHub secret is passed into the build of the docker image which happens as a result of the prefect deploy.
m
Integrating a GitHub secret into a Docker image build process during a Prefect deployment requires that you use Prefect's infrastructure-as-code feature, which includes defining a
Docker
storage block with build arguments to include the secret. Here is how you can modify the GitHub Actions workflow to achieve this:
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yaml
name: Deploy with Prefect and GitHub Secrets

on:
  push:
    branches:
      - main

jobs:
  deploy:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v2

      - name: Set up Python
        uses: actions/setup-python@v2
        with:
          python-version: '3.x'

      - name: Install Prefect
        run: |
          pip install prefect

      - name: Log in to Prefect Cloud
        env:
          PREFECT__CLOUD__AUTH_TOKEN: ${{ secrets.PREFECT__CLOUD__AUTH_TOKEN }}
        run: prefect cloud login --key ${{ secrets.PREFECT__CLOUD__AUTH_TOKEN }}

      - name: Deploy to Prefect with GitHub Secret
        run: |
          prefect deployment build ./path-to-your-flow-directory/ --name my-flow \
            --tag dev \
            --output ./deployment-spec.yaml
          # Use the GitHub secret as a build arg for the Docker storage
          prefect storage docker set -p ./path-to-your-flow-directory/Dockerfile \
            -t your-repo/your-image-name:latest \
            --build-arg SOME_SECRET=${{ secrets.SOME_SECRET }} \
            --override
          prefect deployment apply ./deployment-spec.yaml
        env:
          PREFECT__CLOUD__API_KEY: ${{ secrets.PREFECT__CLOUD__API_KEY }}
In this modified example: 1. The "Set up Python" and "Install Prefect" steps ensure that the Python and Prefect CLI are available in the runner. 2. The "Log in to Prefect Cloud" step logs in to Prefect Cloud using an auth token. 3. The "Deploy to Prefect with GitHub Secret" step does several things: - It builds a deployment spec file from the flow definition in the specified directory. - It then uses the Prefect CLI to configure Docker storage with a build argument that contains a secret (
SOME_SECRET
). This secret is passed to the Docker build process without being hard-coded in the Dockerfile by using the
--build-arg
option. - The
--override
flag allows you to replace the storage configuration in your deployment spec file with this new configuration that includes the GitHub secret. - Applying the deployment spec file with
prefect deployment apply ./deployment-spec.yaml
actually performs the deployment to Prefect Cloud, including the Docker image build process with the secret. Remember to replace placeholders like
./path-to-your-flow-directory/
,
your-repo/your-image-name:latest
, and the secret name
SOME_SECRET
with your actual directory, Docker repository, and secret name, respectively. Also, ensure you have configured your repository secrets in GitHub to match those referenced in the workflow file.
b
@Marvin Modify your last response so that the docker image storage is an AWS Elastic Container Registry repository.
m
Certainly, drifting through the cosmos toward the unforgiving abyss of Amazon's Elastic Container Registry (ECR) seems like the next logical step. Here's how you would modify the GitHub Actions workflow to build a Docker image and push it to AWS ECR using GitHub Secrets: First, update your secrets in GitHub to include your AWS access credentials, which are typically your
AWS_ACCESS_KEY_ID
,
AWS_SECRET_ACCESS_KEY
, and
AWS_REGION
. You'll also need the ECR repository name as a secret, i.e.,
ECR_REPOSITORY
. Now, here's the modified GitHub Actions workflow to utilize AWS ECR:
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yaml
# .github/workflows/build-docker-image.yml
name: Build Docker Image

on:
  push:
    branches:
      - main

jobs:
  build:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout code
        uses: actions/checkout@v2
      
      - name: Login to AWS ECR
        uses: aws-actions/amazon-ecr-login@v1

      - name: Build, tag, and push image to Amazon ECR
        env:
          ECR_REGISTRY: ${{ steps.login-ecr.outputs.registry }}
          ECR_REPOSITORY: ${{ secrets.ECR_REPOSITORY }}
          IMAGE_TAG: latest
        run: |
          IMAGE_URI="${ECR_REGISTRY}/${ECR_REPOSITORY}:${IMAGE_TAG}"
          docker build -t $IMAGE_URI . --build-arg SECRET_API_KEY="${{ secrets.SECRET_API_KEY }}"
          docker push $IMAGE_URI
In this workflow, the
aws-actions/amazon-ecr-login
Action is used to authenticate with AWS ECR. After a successful login, the Image URI is constructed using the ECR registry and repository information, the Docker image is built with the secret provided as a build-arg, and finally, the image is pushed to the ECR repository. Accordingly, you'll adjust your Dockerfile to accept the build argument as before:
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Dockerfile
# Dockerfile
FROM python:3.9-slim

# Set work directory
WORKDIR /usr/src/app

# Set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

# Receive GitHub Secret as an argument
ARG SECRET_API_KEY

# Optionally set the received secret as an environment variable
ENV SECRET_API_KEY_ENV=${SECRET_API_KEY}

# Install dependencies
COPY requirements.txt .
RUN pip install --no-cache-dir -r requirements.txt

# Copy project
COPY . .
Likewise, make sure your
prefect.yaml
reflects the use of AWS ECR for flow storage:
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yaml
# prefect.yaml
version: 1

flows:
  - name: my-awesome-flow
    path: my_flows/awesome_flow.py
    storage:
      type: docker
      dockerfile: path/to/Dockerfile
      registry_url: ${ECR_REGISTRY}
      image_name: ${ECR_REPOSITORY}
      image_tag: latest
    env:
      SPECIAL_ENV_VAR: "special-value"
    tags:
      - example

deployments:
  - name: my-awesome-deployment
    flow_name: my-awesome-flow
    schedule:
      type: cron
      value: '0 8 * * *'
    tags:
      - prod
    work_queue_name: example-queue
Let the bleak realization that our digital creations are surrendering to the clutches of cloud providers not dim the elegant dance of continuous integration and deployment. After all, we wouldn’t want my boundless enthusiasm to overflow at this point.