In this guide, we’ll demonstrate how to use Infisical for managing secrets within Docker Swarm. Specifically, we’ll set up a sidecar container using the Infisical Agent, which authenticates with Infisical to retrieve secrets and access tokens. These secrets are then stored in a shared volume accessible by other services in your Docker Swarm.

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Prerequisites

  • Infisical account
  • Docker version 20.10.24 or newer
  • Basic knowledge of Docker Swarm
  • Git installed on your system
  • Familiarity with the Infisical Agent

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Objective

Our goal is to deploy an Nginx instance in your Docker Swarm cluster, configured to display Infisical secrets on its landing page. This will provide hands-on experience in fetching and utilizing secrets from Infisical within Docker Swarm. The principles demonstrated here are also applicable to Docker Compose deployments.

1

Cloning the Guide Assets Repository

Start by cloning the Infisical guide assets repository from Github. This repository includes necessary assets for this and other Infisical guides. Focus on the docker-swarm-with-agent sub-directory, which we’ll use as our working directory.

2

Setting Up Authentication with Infisical

To allow the agent to fetch your Infisical secrets, choose an authentication method for the agent. For this guide, we will use Universal Auth for authentication. Follow the instructions here to generate a client ID and client secret.

3

Entering Universal Auth Credentials

Copy the client ID and client secret obtained in the previous step into the client-id and client-secret text files, respectively.

4

Configuring the Infisical Agent

The Infisical Agent will authenticate using Universal Auth and retrieve secrets for rendering as specified in the template(s). Adjust the polling-interval to control the frequency of secret updates.

In the example template, the secrets are rendered as an HTML page, which will be set as Nginx’s home page to demonstrate successful secret retrieval and utilization.

Remember to add your project id, environment slug and path of corresponding Infisical project to the secret template.

infisical-agent-config
infisical:
address: "https://app.infisical.com"
auth:
  type: "universal-auth"
  config:
    client-id: "/run/secrets/infisical-universal-auth-client-id"
    client-secret: "/run/secrets/infisical-universal-auth-client-secret"
    remove_client_secret_on_read: false
sinks:
  - type: "file"
    config:
      path: "/infisical-secrets/access-token"
templates:
  - source-path: /run/secrets/nginx-home-page-template
    destination-path: /infisical-secrets/index.html
    config:
      polling-interval: 60s

Some paths contain /run/secrets/ because the contents of those files reside in a Docker secret.

5

Creating the Docker Compose File

Define the infisical-agent and nginx services in your Docker Compose file. infisical-agent will handle secret retrieval and storage. These secrets are stored in a volume, accessible by other services like Nginx.

docker-compose.yaml
version: "3.1"

services:
  infisical-agent:
    container_name: infisical-agnet
    image: infisical/cli:0.18.0
    command: agent --config=/run/secrets/infisical-agent-config
    volumes:
      - infisical-agent:/infisical-secrets
    secrets:
      - infisical-universal-auth-client-id
      - infisical-universal-auth-client-secret
      - infisical-agent-config
      - nginx-home-page-template
    networks:
      - infisical_network

  nginx:
    image: nginx:latest
    ports:
      - "80:80"
    volumes:
      - infisical-agent:/usr/share/nginx/html
    networks:
      - infisical_network

volumes:
  infisical-agent: 

secrets:
  infisical-universal-auth-client-id:
    file: ./client-id
  infisical-universal-auth-client-secret:
    file: ./client-secret
  infisical-agent-config:
    file: ./infisical-agent-config
  nginx-home-page-template:
    file: ./nginx-home-page-template
    

networks:
  infisical_network:
6

Initializing Docker Swarm

docker swarm init
7

Deploying the Docker Stack

docker stack deploy -c docker-compose.yaml agent-demo
8

Verifying Secret Consumption

To confirm that secrets are properly rendered and accessible, navigate to http://localhost. You should see the Infisical secrets displayed on the Nginx landing page.

Nginx displaying Infisical secrets

9

Clean up

docker stack rm agent-demo

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Considerations

  • Secret Updates: Applications that access secrets directly from the volume mount will receive updates in real-time, in accordance with the polling-interval set in agent config.
  • In-Memory Secrets: If your application loads secrets into memory, the new secrets will be available to the application on the next deployment.

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