DOP-C02 imagedefinitions.json Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  A Docker image pushed to Amazon ECR.

  Why it's wrong here

  Pushing the Docker image to Amazon ECR is a necessary prerequisite but not the output artifact that the ECS deploy action consumes. CodeBuild must also write an image definitions file (imagedefinitions.json) containing the container name and the exact image URI in ECR; the ECS deploy action reads that JSON, not the image itself, to register a new task definition and update the service. Without the JSON mapping, the ECS service has no way to know which image tag corresponds to the new deployment.

• ✗

  A zip file containing the application source code.

  Why it's wrong here

  A zip file containing the application source code is incorrect because the CodePipeline ECS deploy action is not designed to ingest source code or build context. It expects a structured artifact that lists the container name and the ECR image URI so it can prepare the task definition for deployment. A source-code zip contains no image metadata, and even if it included a Dockerfile or buildspec, the deploy action would not inspect or build anything at that stage — it only parses the image details JSON.

• ✗

  A tarball stored in Amazon S3.

  Why it's wrong here

  A tarball stored in Amazon S3 is wrong because the deploy action does not accept arbitrary archives. Even if the tarball contains the source code, a Docker image, or a nested imagedefinitions.json, the ECS deploy action expects the image details JSON to be a standalone artifact in its extracted form, not embedded inside a compressed archive. The platform cannot unpack arbitrary tar files to discover the file, so the deployment would fail or be skipped unless the pipeline first extracts the tarball and republishes the JSON as a separate artifact.

• ✓

  A JSON file with the image details.

  Why this is correct

  This is correct because the ECS deploy action in CodePipeline consumes an image definitions file, typically named imagedefinitions.json, formatted as a JSON array mapping each ECS container name to its image URI (for example, [{"name":"web","imageUri":"123456789012.dkr.ecr.us-east-1.amazonaws.com/my-app:latest"}]). CodeBuild generates this file as a pipeline artifact after pushing the image to ECR, and CodePipeline uses it to create/update the task definition and trigger the deployment. The file must be at the artifact root with the recognized name; any other JSON structure or filename will cause the deploy action to fail.

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