How to pass Deployment Variables to deployed Docker images in ECS?

Question

We have a simple pipeline that builds a Docker image with our app, pushes it to DockerHub, and finally deploys it to an ECS cluster.

Each cluster runs to a different environment (e.g. Development, Staging, Production), and we need to pass different environment variables for our application in each of these deployed environments. For example, the Google Analytics Tracker ID is different in Development and in Production.

We are using Deployment Variables in Bitbucket Pipelines to achieve this. For example:

* Test Deployment* GOOGLE_ANALYTICS_ID = myDevId

* Production Deployemtn* GOOGLE_ANALYTICS_ID = myProductionId

But we can't figure out this...

How do we take these values (e.g. $GOOGLE_ANALYTICS_ID) in the bitbucket-pipelines.yml file and pass them all the way through to our deployed Docker containers in ECS? What is the best practice approach?

We're new to CI/CD, so trying to figure out what the right approach is.

Do we need to build and deploy separate Docker images for each environment? Or is there a way to pass in these environment variables to ECS as part of deploying the Docker image?

Any help, reference articles, etc, is really appreciated. Thanks

Ralph_6vkqjr · Answer

Hi @Philip Hodder

Thanks for your reply. We ended up resolving this a few weeks ago, by passing in the Bitbucket Deployment variables into ECS as part of the TaskDefinition.

So the Docker images don't have any environment variables baked in -- otherwise we'd need to be building different images for each environment. They are specified at the time the container is spun up.

We're using the AWS CLI in our pipeline, but all ECS config is handled via CloudFormation templates.

Best,

Ralph

Philip Hodder · Answer

Hello,

With Docker, you have two options for adding these environment variables.

* Build and deploy the separate Docker images with the different environment variables.
* Or create a single Dockerfile without the variable defined (or an empty value). And then pass in the environment specific variable at container startup time. You may need some ECS specific settings here that I'm not familiar with.

How do you normally deploy these images? There might be a field on the relevant deploy API that lets you set runtime environment variables at container startup.

Thanks,

Phil