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Deploy a Docker Image to Amazon ECS

Amazon Elastic Container Service is an AWS offering for those looking to run containerized workloads. Define an ECS Task Definition describing your workload and a Service Definition where you want to run your workload and you are all set. A Continuous Delivery Pipeline is an excellent spot to orchestrate a deployment to Amazon ECS. In this example, we will go through deploying an image with Amazon ECS inside a Harness Continuous Delivery Pipeline.


There are a few AWS Items to setup, such as the ECS Cluster itself, which we will go through configuring. If you have not signed up for Harness CD, sign up now before diving in.

Create Your First Amazon ECS Cluster

You need access to an AWS Account to create an ECS cluster. After that there are a few items to create ahead of ECS Cluster Creation or can leverage the AWS ECS Cluster Creation Wizard to create. Amazon ECS creates EC2 instances on your behalf to run your workloads. So if you have used EC2 in the past, some of these items will not be too foreign.

Create/Validate Ahead of Time

ECS Instance Role - IAM

The ECS Instance Role will allow the running containers to call underlying ECS API commands. If you do not have an ecsInstanceRole, AWS Provides documentation to create one. Make sure to set up the Trust relationships per the AWS documentation so your user can eventually assume the Role.

ECS Instance Role

ECS Managed Policy - IAM

The next is to choose or set up a Managed Policy which will allow Harness to call ECS. Just as an example to not set up a more specific Harness Centric Managed Policy, you can use the generic AmazonECS_FullAccess [not recommended in production].

ECS Full Access Policy

Attach the Managed Policy to your IAM User

Lastly, the ECS Managed Policy will need to be attached [Add permission] to your user that you will have Harness connect to AWS with.

Attach Policy

VPC/Subnet(s)/Security Group

If this is your first time using ECS or have an account that is a sandbox environment, leveraging the AWS Default VPC and subsequent subnets [e.g one each for each availability zone in a Region] is fine. Depending on your traffic, you would want to create a Security Group to allow that traffic in. In this example, we will be handling traffic over TCP port 80 with an example image. For the future steps of wiring in the ECS Service Definition, make sure to have the subnet and Security Group IDs handy.

Creating an ECS Cluster

With the above items created/validated, you are now ready to create an ECS Cluster. You can pick your flavor of ECS. In this example we will deploy to EC2 Linux + Networking.

AWS Console -> ECS -> Clusters -> Create Cluster

Create ECS Cluster

When filling out the wizard, here are a few prudent details:

  • Cluster Name: harness-ecs
  • Instance Type: A medium instance type e.g m5-medium
  • VPC: existing VPC, e.g your default.
  • Subnets: select the subnets in your VPC. Note: Regions can sometimes have networking exhaustion, for the example better to select multiple subnets that represent each availability zone.
  • Security Group: Security Group that was created before / one that can handle inbound TCP 80. Will need to reference the Security Group ID later, so creating one ahead of time allows the ID to be visible via the UI to reference.

Once set up, you will have an ECS Cluster that is ready to accept workload.

ECS Ready

Now you are ready to wire Harness to deploy on your behalf.

Initial Harness Setup

If you do not have a Harness Account, sign up for a Harness Account for access to the Continuous Delivery Module. a default Harness Project will be created for you automatically. Projects are logical groupings of resources. The generated default project is perfect for the first time deployment.

When navigating back to Deployments, can set the project context to the Default Project by clicking on the blue chevrons >> and selecting Default Project.

Default Project

With the Default Project selected, clicking on Overview will bring up a wizard to create your first Pipeline/Deployment.

First Pipeline

There are a few Harness entities that will need to be created in Harness. The needed objects are a Harness Delegate and an AWS Connector for your user credentials.

Install a Delegate

If you do not have a Delegate installed, follow the steps below to get one installed either in Docker or Kubernetes.

Install Delegate

The Harness Delegate is a lightweight worker process that is installed on your infrastructure and communicates only via outbound HTTP/HTTPS to the Harness Platform. This enables the Harness Platform to leverage the delegate to execute the CI/CD and other tasks on your behalf, without any of your secrets leaving your network.

You can install the Harness Delegate on either Docker or Kubernetes.


You might need additional permissions to execute commands in delegate scripts and create Harness users.

Install the default Harness Delegate

Create a new delegate token

You can install delegates from the Account, Project, or Org scope. In this example, we'll install create a new token in the Account scope.

To create a new delegate token, do the following:

  1. In Harness, select Account Settings, then select Account Resources. The Account Resources page opens.

  2. Select Delegates. The Delegates list page opens.

  3. Select the Tokens tab, then select +New Token. The New Token dialog opens.

  4. Enter a token name, for example firstdeltoken.

  5. Select Apply. Harness generates a new token for you.

  6. Select Copy to copy and store the token in a temporary file.

    You will provide this token as an input parameter in the next installation step. The delegate will use this token to authenticate with the Harness Platform.

Get your Harness account ID

Along with the delegate token, you will also need to provide your Harness accountId as an input parameter during delegate installation. This accountId is present in every Harness URL. For example, in the following URL:

6_vVHzo9Qeu9fXvj-AcQCb is the accountId.


When you install a delegate via the Harness UI, several dependencies in this topic are prefilled for your convenience. This topic explains where to find the required information for CLI-based installation.

For more information, go to View account info and subscribe to downtime alerts.


Ensure that you have access to a Kubernetes cluster. For the purposes of this tutorial, we will use minikube.


Harness supports Kubernetes versions 1.25.16, 1.26.10, and 1.27.8 for delegate installation.

Install minikube

  • On Windows

    choco install minikube

    For Chocolatey installation instructions, go to Installing Chocolatey in the Chocolatey documentation.

    For additional options to install minikube on Windows, go to minikube start in the minikube documentation.

  • On macOS:

    brew install minikube

    For Homebrew installation instructions, go to Installation in the Homebrew documentation.

Now start minikube with the following config.

minikube start --memory 4g --cpus 4

Validate that you have kubectl access to your cluster.

kubectl get pods -A

Now that you have access to a Kubernetes cluster, you can install the delegate using any of the options below.

Install the Helm chart

As a prerequisite, you must have Helm v3 installed on the machine from which you connect to your Kubernetes cluster.

You can now install the delegate using the delegate Helm chart. First, add the harness-delegate Helm chart repo to your local Helm registry.

helm repo add harness-delegate
helm repo update
helm search repo harness-delegate

We will use the harness-delegate/harness-delegate-ng chart in this tutorial.

NAME                                	CHART VERSION	APP VERSION	DESCRIPTION
harness-delegate/harness-delegate-ng 1.0.8 1.16.0 A Helm chart for deploying harness-delegate

Now we are ready to install the delegate. The following example installs/upgrades firstk8sdel delegate (which is a Kubernetes workload) in the harness-delegate-ng namespace using the harness-delegate/harness-delegate-ng Helm chart.

You can install delegates from the Account, Project, or Org scope. In this example, we'll install a delegate in the Account scope.

To install a delegate, do the following:

  1. In Harness, select Account Settings, then select Account Resources. The Account Resources page opens.

  2. Select Delegates. The Delegates list page opens.

  3. Select New Delegate. The New Delegate dialog opens.

  4. Under Select where you want to install your Delegate, select Kubernetes.

  5. Under Install your Delegate, select Helm Chart.

  6. Copy the helm upgrade command.

    The command uses the default values.yaml file located in the delegate Helm chart GitHub repo. To make persistent changes to one or more values, you can download and update the values.yaml file according to your requirements. Once you have updated the file, you can use it by running the upgrade command below.

       helm upgrade -i firstk8sdel --namespace harness-delegate-ng --create-namespace \
    harness-delegate/harness-delegate-ng \
    -f values.yaml \
    --set delegateName=firstk8sdel \
    --set delegateToken=PUT_YOUR_DELEGATE_TOKEN_HERE \
    --set managerEndpoint=PUT_YOUR_MANAGER_HOST_AND_PORT_HERE \
    --set delegateDockerImage=harness/ \
    --set replicas=1 --set upgrader.enabled=true

To install a Helm delegate for Harness Self-Managed Enterprise Edition in an air-gapped environment, you must pass your certificate when you add the Helm repo.

helm repo add harness-delegate --ca-file <.PEM_FILE_PATH> <HELM_CHART_URL_FROM_UI>

For more information on requirements for air-gapped environments, go to Install in an air-gapped environment.

  1. Run the command.

Deploy using a custom role

During delegate installation, you have the option to deploy using a custom role. To use a custom role, you must edit the delegate YAML file.

Harness supports the following custom roles:

  • cluster-admin
  • cluster-viewer
  • namespace-admin
  • custom cluster roles

To deploy using a custom cluster role, do the following:

  1. Open the delegate YAML file in your text editor.

  2. Add the custom cluster role to the roleRef field in the delegate YAML.

    kind: ClusterRoleBinding
    name: harness-delegate-cluster-admin
    - kind: ServiceAccount
    name: default
    namespace: harness-delegate-ng
    kind: ClusterRole
    name: cluster-admin

    In this example, the cluster-admin role is defined.

  3. Save the delegate YAML file.

Verify delegate connectivity

Select Continue. After the health checks pass, your delegate is available for you to use. Select Done and verify your new delegate is listed.

Helm chart & Terraform Helm provider

Delegate Available

Kubernetes manifest

Delegate Available


Delegate Available

You can now route communication to external systems in Harness connectors and pipelines by selecting this delegate via a delegate selector.

Delegate selectors do not override service infrastructure connectors. Delegate selectors only determine the delegate that executes the operations of your pipeline.


The delegate installer provides troubleshooting information for each installation process. If the delegate cannot be verified, select Troubleshoot for steps you can use to resolve the problem. This section includes the same information.

Harness asks for feedback after the troubleshooting steps. You are asked, Did the delegate come up?

If the steps did not resolve the problem, select No, and use the form to describe the issue. You'll also find links to Harness Support and to Delegate docs.

Use the following steps to troubleshoot your installation of the delegate using Helm.

  1. Verify that Helm is correctly installed:

    Check for Helm:


    And then check for the installed version of Helm:

    helm version

    If you receive the message Error: rendered manifests contain a resource that already exists..., delete the existing namespace, and retry the Helm upgrade command to deploy the delegate.

    For further instructions on troubleshooting your Helm installation, go to Helm troubleshooting guide.

  2. Check the status of the delegate on your cluster:

    kubectl describe pods -n <NAMESPACE>
  3. If the pod did not start, check the delegate logs:

    kubectl logs -f <DELEGATE_NAME> -n <NAMESPACE>

    If the state of the delegate pod is CrashLoopBackOff, check your allocation of compute resources (CPU and memory) to the cluster. A state of CrashLoopBackOff indicates insufficient Kubernetes cluster resources.

  4. If the delegate pod is not healthy, use the kubectl describe command to get more information:

    kubectl describe <POD_NAME> -n <NAMESPACE>

Configure Your AWS Credentials and Docker Endpoint in Harness

Especially with a private registry/repository, credentials for the repository are usually scattered around a few scripts or prompted by a system to enter before deployment. Harness has a concept of a Cloud Connector so this will manage the persistence of your cloud provider credentials and use them on your behalf.

To get started with creating an AWS Cloud Provider connector, head to Account Settings -> Account Resources -> Connectors + New Connector -> AWS

Name: my_aws_connector

My AWS Connector

Click Continue and pick your authentication mechanism. If you have an AWS Access Key and Secret, can enter those as encrypted credentials which gets stored in the Harness Secrets Manager.

For example, you can create “my_aws_access” for your Access Key and “my_aws_secret” for the Secret.

AWS Creds

Click continue and select how you will like to connect. You can leverage the Harness Platform or a Delegate to connect. In this example, connecting through Harness is fine.

AWS Connect Harness

Click Save and Continue and your credentials will be tested. Once successful, you can modify one last item so you can pull images from public Docker Hub in the example.

Configure Harness Docker Connector

By default, Harness is wired to the public Docker Hub. Though depending on the image, the API endpoint can be different. The endpoint for us to hit in this example is

Harness -> Account Settings -> Account Connectors -> Harness Docker Connector then Edit.

Edit Harness Docker Connector

Modify the endpoint if not already to

Docker Hub Details

Click Continue to save. Running this Connector through the Harness Platform is fine. Then when saved and validated, you will be wired to that API Endpoint.

Updated Docker Hub

With those wirings out of the way, you are now ready to create an ECS Pipeline. To expedite the creation, we can wire in a pair of configuration files.

Creating Harness Hosted Configuration Files

Harness will execute your configuration files for you. For this example, we will wire two configuration files, an ECS Task Definition JSON and an ECS Service Definition JSON. These manifests can be linked to source control or stored in Harness itself. For ease of use, you can wire and modify these files to fit your ECS Role and Security Group/subnet items inside Harness.


Service Definition JSON:

To Create a manifest hosted by Harness, can add these at the Account Level.

Harness -> Account Settings -> Account Resources -> File Store + New.

Can create two new files, one called ecs_task.json and one called service_definition.json based on the above files in GitHub. Copy and paste the contents into each respective file and save each.

Harness File Store

ECS Task JSON: On lines 3 and 53, replace the value of the executionRoleArn with your ecsInstanceRole.

Service Definition JSON: On line 8, replace the Security Group with your applicable Security Group. On lines 11, 12, and 13 replace the subnets with your subnet IDs for the availability zones selected when the ECS Cluster was created. You can add or subtract items in the subnet array depending on the number of subnets you have.

With those manifests out of the way, creating the ECS Pipeline will be very speedy.

Creating an ECS Harness Pipeline

With the Delegate, ECS Cluster, and manifests created, creating a Harness Pipeline is simple. Leveraging the Default Harness Project is fine for the example.

  • Deployments -> Pipelines + Create new Pipeline
  • Name: my-first-ecs-pipeline
  • Setup: in-line

New Pipeline

Once you click Start, you can add an ECS Deployment Stage. Click in + Add Stage then Deployment and select Amazon ECS.

Stage Name: deploy-to-ecs

Deploy to ECS

Then click Setup Stage. The next step is to create a Harness Service which will represent the ECS Configurations and Artifact that need to be deployed.

In the Service Configuration, click + New Service.

New Service

In the New Service UI, name the new service sample-container and add get ready to add the Task and Service Definitions.

Sample Container Service

To add the Task Definition, click + Add Task Definition. Select Harness as the Task Definition Store.

Task Definition

Select and name the ecs_task.json that was created before.

Manifest Name: Task Def

Task Definition Path

Repeat the same process for the Service Definition once saved. + Add Service Definition.

Name: Service Def

Service Definition

Now both are wired. The next step would be to wire in an artifact/image that you want to deploy.

Manifests Wired

Lastly will wire an artifact to deploy. In the Task Definition, we have added a variable [if you copied from source control] to take in an input from Harness on an image to deploy.

Input Variable

We can specify that image via the Harness by adding an Artifact Source. + Add Artifact Source.

Select Docker Registry, we will select the Public Docker Hub Connector we re-wired before.

Docker Artifact Source

Click Continue. Nginx can be used as an example to start.

  • Artifact Source Name: nginx
  • Image Path: library/nginx

Docker Artifact Source

Click Submit and the Artifact will be wired in. Then click Save.

Artifact Wired

Click Continue to point Harness to your ECS Cluster.

Sample Container Complete

Pointing Harness to ECS

Harness has a concept of Environments which is the target infrastructure where you want to deploy. In this case, we will be deploying to the ECS Cluster that was created.

Specifiy Environment

Click + New Environment

  • Name: my-aws-environment
  • Environment Type: Pre-Production

New Environment

Click Save and next you will point to your specific ECS Cluster by adding that as a piece of Infrastructure. + New Infrastructure

New Infrastructure

  • Name: my-ecs-instance
  • Connector: Your AWS Connector
  • Region: Your AWS Region where the ECS Cluster lives
  • Cluster: harness-ecs

New Infrastructure

Click Save then Continue to define the Execution Strategy.

My ECS Instance

In the Execution Strategy, there are several options on how to deploy to ECS. For the example we will leverage a Rolling Deploying strategy.

Execution Strategy

Once selected, click Use Strategy. Your Pipeline is now ready to be saved. Click on the Save button in the top right.

Save Pipeline

Now you are ready to execute.

Running Your First Harness ECS Deployment

Selecting your Pipeline from Deployments -> Pipelines, can click on the Run Button to execute.

  • Primary Artifact: nginx
  • Tag: stable

Run Pipeline

Click Run Pipeline and your Pipeline will be executed.

After a few moments, your Pipeline will be successfully deployed to ECS.


To see your workload in action, head back to the AWS Console and dive into the Task for the public IP.

AWS Console -> ECS -> Clusters -> harness-ecs -> Tasks -> Task UID -> Public IP

ECS Network

Head to the Public IP e.g and you will see a welcome message.


Congratulations on your ECS deployment! This was a vanilla deployment to ECS. Harness has the ability to orchestrate confidence building steps. We used a pre-packaged image, but Harness CI can execute a Docker Build for you and create a custom image which you can then deploy with similar into Amazon ECS.