The node is back online, but running services arent automatically rebalanced. Want to see a failing health check? AWS ECS. Update the health check and the service. Initialize the Swarm on the manager node: You now have a functional single-node Swarm. This solution is not based on docker swarm: but from documentation it seems able to understand docker-compose version 3 specification. Your costs are based on EC2 instances, so easy to manage (because EC2 cost management is critical for your forecast in a medium sized company), ECS works via ecs tasks syntax: it seems complex to deploy a docker swarm stack without a deep rework of the, ECS need the other AWS resources to work with (like Load balancers and so on). Already on GitHub? Add the service to docker-compose-swarm.yml: Point the Docker daemon at node-1 and update the stack: It could take a minute or two for the visualizer to spin up. Last updated Otherwise, it will equal nay!. Turn back to services/web/project/api/main.py. In a new window open a session to the node running the container and check the filesystem: For a production deployment you would also add healthchecks, update and rollback configuration, security settings (like user IDs for the container processes) and more. This is where Docker Swarm (or "Swarm mode") fits in along with a number of other orchestration tools -- like Kubernetes, ECS, Mesos, and Nomad. Create AWS ECS context using credentials of your choice. It assumes that you have basic working knowledge of Flask, Docker, and container orchestration. Make sure you dive into some of the more advanced topics like logging, monitoring, and using rolling updates to enable zero-downtime deployments before using Docker Swarm in production. You can run all the examples with Docker Desktop, except for the node management section because youll only have a single node. Heres it is on YouTube - ECS-O2: Containers in Production with Docker Swarm, DIAMOL episode 12: Deploying distributed apps as stacks in Docker Swarm, DIAMOL episode 13: Automating releases with upgrades and rollbacks, Pluralsight: Managing Load Balancing and Scale in Docker Swarm Mode Clusters, Pluralsight: Handling Data and Stateful Applications in Docker (includes distributed storage in Swarm clusters), Ongoing support for Docker Swarm from Mirantis. Docker Swarm Visualizer is an open source tool designed to monitor a Docker Swarm cluster. Try this again, but this time scale out. It uses the Docker Compose specification to model applications so its easy for people to transition from Compose on a single machine to a Swarm cluster. With it you can easily distribute sensitive info (like usernames and passwords, SSH keys, SSL certificates, API tokens, etc.) Scale up and more containers will be created - incoming requests get load-balanced between them: Browse to the site and refresh a few times. Copyright 2017 - 2022 TestDriven Labs. You can provision a brand new cluster in about 3 minutes versus the 15 minutes required by a FarGate K8s cluster. It gets deployed as a stack, which is a grouping for services, networks and other resources. Take note of the differences between the two compose files: Sign up for a DigitalOcean account (if you dont already have one), and then generate an access token so you can access the DigitalOcean API. Run the docker swarm join command from the manager node. Anyway seems impossible to define scale factors and replica rules using the version 3 specification (the deploy subsection is unsupported). Elton's Container Show - resources for the YouTube broadcast. This new docker-stack.yml spec models the to-do app with configs and secrets mounted into the container. ECS isnot a docker swarm implementation. It's worth noting that the health check settings defined in a compose file will override the settings from a Dockerfile. This is a bit weird. We've already set up the Docker Swarm Visualizer tool to help with monitoring, but much more can be done. If the secret in the request payload is the same as the SECRET_CODE variable, a message in the response payload will be equal to yay!. Theres some extra production detail in docker-stack-2.yml - adding process constraints to the containers, and running multiple replicas of the web app. The VPC that i mentioned in x-aws-vpc will not appear under cft-output.yaml. Docker can read secrets from either its own database (external mode) or from a local file (file mode). Swarm mode takes the service abstraction from Docker Compose and makes it into a first-class object. You can create services on the Swarm, and the orchestrator schedules containers to run. When working with a distributed system it's important to set up proper logging and monitoring so you can gain insight into what's happening when things go wrong. Make sure all is well before moving on. Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Developed by Check out Docker Swarm instrumentation with Prometheus for more info. Review the secrets configuration reference guide as well as this Stack Overflow answer for more info on both external and file-based secrets. This is beyond the scope of this blog post, but take a look at the following resources for help on this: Finally, Prometheus (along with its de-facto GUI Grafana) is a powerful monitoring solution. Update the web service in docker-compose-swarm.yml like so: Before we can test the health check, we need to add curl to the container. Repeat the swarm leave command on all nodes. That lets you separate configuration management from app management. Additional environment details (AWS ECS, Azure ACI, local, etc. You'll probably want to aggregate log events from each service to help make analysis and visualization easier. Instead the default VPC will appear here. The text was updated successfully, but these errors were encountered: This is actually a bug in github.com/compose-spec/compose-go not merging top-level extensions This is an intermediate-level tutorial. However, x-aws-autoscaling indeed gets appended correctly. Where ECS shines are the following areas: Freedom, Economy and Information Technology, What is the difference between Docker Swarm, Kubernetes, and Amazon ECS, it seems able to understand docker-compose version 3 specification. Lets write a script that will: Add a new file called deploy.sh to the project root: In this post we looked at how to run a Flask app on DigitalOcean via Docker Swarm. Sign in There's also a number of managed Kubernetes-based services on the market: For more, review the Choosing the Right Containerization and Cluster Management Tool blog post. In this course, you'll learn how to set up a development environment with Docker in order to build and deploy a microservice powered by Python and Flask. Swarm can run applications defined for Docker Compose - any parts of the Compose spec which arent relevant in Swarm mode (like depends_on) get ignored. Review the following courses for more info on each of these tools and topics: By the end of this tutorial, you will be able to As you move from deploying containers on a single machine to deploying them across a number of machines, you'll need an orchestration tool to manage (and automate) the arrangement, coordination, and availability of the containers across the entire system. The output shows the command you run on other nodes to join the Swarm. The specifics of the x-aws-vpc and the related subnets should appear in the output. In the services/web/project/api/main.py file, take note of the /secret route. We'll look at the latter. Swarm is an opinionated orchestrator which is simple to work with. In terms of logging, you can run the following command (from the node manager) to access the logs of a service running on multiple nodes: Review the docs to learn more about the logs command as well as how to configure the default logging driver. Update the test command in docker-compose-swarm.yml to ping port 5001 instead of 5000: Just like before, update the service and then find the node and container id that the flask_web service is on. I will describe here the EC2 solution, for sake of simplicity. These machines provide a docker ce container in standard mode (no swarm). as expected. container_id is the ID of the Docker container the app is running in: Take a quick look at the code before moving on: Since Docker Swarm uses multiple Docker engines, we'll need to use a Docker image registry to distribute our three images to each of the engines. Have a question about this project? I am writing this article to stress this, because this point is not very clear digging in the tutorials (it is explained a bit in the question What is the difference between Docker Swarm, Kubernetes, and Amazon ECS but then the tuytorials mix the things up too much). Secrets are encrypted and can only be read inside the container filesystem. Michael Herman. You can even log in on these clones and inspect them a bit. He is the co-founder/author of Real Python. Traffic is re-routed appropriately. The database stores all the app specs and you can use it for configuration objects. Well occasionally send you account related emails. Create another file named docker-compose.prod.yaml . You can find the code in the flask-docker-swarm repo on GitHub. You'll also apply the practices of Test-Driven Development with pytest as you develop a RESTful API. Review the health check instruction from the official docs. One popular approach is to set up an ELK (Elasticsearch, Logstash, and Kibana) stack in the Swarm cluster. Join our mailing list to be notified about updates and new releases. By clicking Sign up for GitHub, you agree to our terms of service and Elastic rescale and resilience: for instance if a EC2 instance goes down, the Amazon infrastructure will bring ti back from death (a manual rescale (ecs-cli scale) anyway will bring down the services, so this operation is not completely hassle-free). This will take a few minutes. Bring down the stack and remove the nodes: Ready to put everything together? Im running Linux VMs for the Swarm cluster using Vagrant. to your account. In a production environment you should use health checks to test whether a specific container is working as expected before routing traffic to it. Clone down the base branch from the flask-docker-swarm repo: Build the images and spin up the containers locally: Create and seed the database users table: Test out the following URLs in your browser of choice. In Swarm mode the default network driver is overlay, which spans all the nodes in the cluster. The cluster has its own HA database, replicated across all the manager nodes (typically 3 in a production cluster). You can add health checks to either a Dockerfile or to a compose file. You must relay on amazon cloud driver to collect logs. Hosted on GitHub Pages Theme by orderedlist, ECS-O2: Containers in Production with Docker Swarm, Pluralsight: Handling Data and Stateful Applications in Docker, ECS-O3: Containers in Production with Kubernetes. ECS create images with fixed EBS disk size of 30GB (reducing this size seems not so easy). Let's look at how to spin up a Docker Swarm cluster on DigitalOcean and then configure a microservice, powered by Flask and Postgres, to run on it. Drained nodes wont schedule any more containers. We'll look at the former. compose-spec/compose-go#102, compose-spec/compose-go#102 has been merged and dependency updated, docker compose overlay not concatenating compose top level extensions (for AWS ECS). Back on the manager node, update the stack: The update happens as a staged rollout. Well deploy the to-do app next using custom config objects: todo-web-config.json and todo-web-secrets.json. Replace 'vpc-0ef709490b6edce0d' with any other VPC in your AWS account. Reset the Docker environment back to localhost: Re-build the image and push the new version to Docker Hub: Point the daemon back at the manager, and then update the service: For more on defining secrets in a compose file, refer to the the Use Secrets in Compose section of the docs. 10% of profits from each of our FastAPI courses and our Flask Web Development course will be donated to the FastAPI and Flask teams, respectively. ECS uses the already known Amazon technology (like Cloud Formation) to deploy a cluster of EC2 machines. This tutorial uses the Docker Hub image registry but feel free to use a different registry service or run your own private registry within Swarm. You signed in with another tab or window. Theres a single container running, but you can browse to port 8080 on any node and the traffic gets routed to the container. Once complete, initialize Swarm mode on node-1: Grab the join token from the output of the previous command, and then add the remaining nodes to the Swarm as workers: Point the Docker daemon at node-1 and deploy the stack: Now, to update the database based on the schema provided in the web service, we first need to point the Docker daemon at the node that flask_web is running on: Assign the container ID for flask_web to a variable: Create the database table and apply the seed: Finally, point the Docker daemon back at node-1 and retrieve the IP associated with the machine that flask_nginx is running on: Let's add another web app to the cluster: Confirm that the service did in fact scale: You should see different container_ids being returned, indicating that requests are being routed appropriately via a round robin algorithm between the two replicas: What happens if we scale in as traffic is hitting the cluster? ECS is based on Amazon Cloud infrastructure, and offers two different implementations: one based on EC2 instances and one on AWS FarGate. Curious about how to add health checks to a Dockerfile? Then, run: The service should be down in the Docker Swarm Visualizer dashboard as well. At this point, you should understand how Docker Swarm works and be able to deploy a cluster with an app running on it. Nodes are top-level objects, but you need to be connected to a manager to work with them. You can create a new VPC in your AWS account using. In this episode we create a Swarm cluster and deploy some applications, showing how the Compose spec can be extended to include production concerns. We can gain access to this secret within the Flask App. Anyone can read the contents of a config object. Start by creating a new secret from the manager node: Next, remove the SECRET_CODE environment variable and add the secrets config to the web service in docker-compose-swarm-yml: At the bottom of the file, define the source of the secret, as external, just below the volumes declaration: That's it. Moving on, let's set up a new Docker Compose file for use with Docker Swarm: Save this file as docker-compose-swarm.yml in the project root. On the following example you can even see a EFS file system mount: The ecs-agent (line 5) is the agent running as docker container, which enable the ECS to work. Looking for a challenge? Remember: The command you use for the health check needs to be available inside the container. For this reason ECS is great for running docker-compose images, but not seem a good fit for docker swarm stacks of services. The orchestration component in Docker Swarm is a separate open-source project called SwarmKit. Standard docker logging is a dead end. Michael is a software engineer and educator who lives and works in the Denver/Boulder area. This simple docker-compose.yml file is perfectly valid to run in the cluster. Its baked into the Docker Engine so when you run in Swarm mode there are no additional components. February 23rd, 2021, APP_SETTINGS=project.config.ProductionConfig, "https://releases.rancher.com/install-docker/19.03.9.sh", [==================================================, "/var/run/docker.sock:/var/run/docker.sock", curl --fail http://localhost:5000/ping || exit 1, " % Total % Received % Xferd Average Speed Time Time Time Current\n Dload Upload Total Spent Left Speed\n\r 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0\r100 69 100 69 0 0 11629 0 --:--:-- --:--:-- --:--:-- 13800\n{\"container_id\":\"a6127b1f469d\",\"message\":\"pong!\",\"status\":\"success\"}\n", curl --fail http://localhost:5001/ping || exit 1, " % Total % Received % Xferd Average Speed Time Time Time Current\n Dload Upload Total Spent Left Speed\n\r 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0curl: (7) Failed to connect to localhost port 5001: Connection refused\n", "Create the DB table and apply the seed", Test-Driven Development with Python, Flask, and Docker, Deploying a Flask and React Microservice to AWS ECS, Choosing the Right Containerization and Cluster Management Tool, Docker Swarm instrumentation with Prometheus, large community, flexible, most features, hip, easy to set up, perfect for smaller clusters, fully-managed service, integrated with AWS, Explain what container orchestration is and why you may need to use an orchestration tool, Discuss the pros and cons of using Docker Swarm over other orchestration tools like Kubernetes and Elastic Container Service (ECS), Spin up a Flask-based microservice locally with Docker Compose, Build Docker images and push them up to the Docker Hub image registry, Provision hosts on Digital Ocean with Docker Machine, Configure a Docker Swarm cluster to run on Digital Ocean, Run Flask, Nginx, and Postgres on Docker Swarm, Use a round robin algorithm to route traffic on a Swarm cluster, Monitor a Swarm cluster with Docker Swarm Visualizer, Use Docker Secrets to manage sensitive information within Docker Swarm, Configure health checks to check the status of a service before it's added to a cluster, Access the logs of a service running on a Swarm cluster, If a single health check takes longer than the time defined in the, Provision the droplets with Docker Machine, Create the database table and apply the seed. Then, find the node that the flask_web service is on: Make sure to replace
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