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DCA · Question #14

When using the Docker client to push an image to a registry, what environment variable is used to instruct the client to perform signing of the image?

The correct answer is A. DOCKER_CONTENT_TRUST=1. To enable Docker Content Trust for signing images when pushing to a registry, the DOCKER_CONTENT_TRUST environment variable must be set to 1.

Submitted by naveen.iyer· Apr 18, 2026Image Creation, Management, and Registry

Question

When using the Docker client to push an image to a registry, what environment variable is used to instruct the client to perform signing of the image?

Options

  • ADOCKER_CONTENT_TRUST=1
  • BDOCKER_IMAGE_SIGN=1
  • CDOCKER_PUSH_SIGN=1
  • DNOTARY_ENABLE=1

How the community answered

(25 responses)
  • A
    92% (23)
  • C
    4% (1)
  • D
    4% (1)

Why each option

To enable Docker Content Trust for signing images when pushing to a registry, the `DOCKER_CONTENT_TRUST` environment variable must be set to `1`.

ADOCKER_CONTENT_TRUST=1Correct

Setting the `DOCKER_CONTENT_TRUST` environment variable to `1` explicitly activates Docker Content Trust, which then prompts the Docker client to cryptographically sign images before pushing them to a registry, ensuring integrity and authenticity.

BDOCKER_IMAGE_SIGN=1

`DOCKER_IMAGE_SIGN` is not a recognized or standard environment variable for enabling Docker Content Trust.

CDOCKER_PUSH_SIGN=1

`DOCKER_PUSH_SIGN` is not a recognized or standard environment variable for enabling Docker Content Trust.

DNOTARY_ENABLE=1

While Notary is the underlying technology for Docker Content Trust, `NOTARY_ENABLE` is not the correct environment variable for activating it in the Docker client.

Concept tested: Docker Content Trust environment variable

Source: https://docs.docker.com/engine/security/trust/content_trust/#enable-content-trust-for-pushes

Topics

#Docker Content Trust#Image Signing#Registry Push#Environment Variables

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