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Docker credentials

Let Docker retrieve registry credentials through SecretSpec providers

The Docker credential integration is available in SecretSpec 0.20+. It lets docker pull, docker push, docker build, and Docker Compose retrieve registry credentials from any SecretSpec provider without copying the password or token into Docker’s config.json.

Prerequisites

  • Docker
  • SecretSpec 0.20 or newer, including docker-credential-secretspec on PATH

Quick start

These commands are available in SecretSpec 0.20+.

Configure the registry with its non-secret username:

This changes your Docker configuration

Docker has no repository-local configuration. configure updates $DOCKER_CONFIG/config.json when DOCKER_CONFIG is set, or the user-level ~/.docker/config.json (%USERPROFILE%\.docker\config.json on Windows) otherwise. The change applies to every Docker command using that configuration. SecretSpec preserves unrelated settings and refuses to replace another helper. Undo it with secretspec docker unconfigure --registry ghcr.io.

$ secretspec docker configure --registry ghcr.io --username YOUR_USERNAME

After confirmation, the command prints the matching login command:

Configured Docker credential for ghcr.io.
Docker configuration: /home/you/.docker/config.json
Store the credential with: secretspec docker login 'ghcr.io'
Undo with: secretspec docker unconfigure --registry 'ghcr.io'

Store the password or access token in SecretSpec’s embedded, registry-isolated credential store:

$ secretspec docker login ghcr.io

login prompts securely on a terminal and reads the password or token from standard input when piped.

Use SecretSpec to log in and out

After configuring the helper, use secretspec docker login and secretspec docker logout to manage the stored credential. Docker’s own docker login and docker logout operations try to write or erase through the helper, which is intentionally read-only.

Docker now invokes docker-credential-secretspec get automatically:

$ docker pull ghcr.io/OWNER/IMAGE:TAG
$ docker push ghcr.io/OWNER/IMAGE:TAG

configure does not retrieve or store the credential. It adds the registry’s credHelpers entry and records only the registry, Docker configuration path, username, provider selection, and other value-free metadata. login prompts for the secret and stores it through the selected provider. Each registry and physical Docker configuration pair has a separate SecretSpec project and secret-key identity, so credentials remain isolated even in flat providers that do not namespace keys by project or profile. SecretSpec’s managed state is owner-readable and owner-writable only; Docker’s existing config.json permissions are preserved.

Rerunning configure for the same registry and Docker configuration replaces its SecretSpec metadata and reports that replacement. It does not delete the stored credential.

To use a provider other than your default, pass the same override to both commands. The follow-up command printed by configure includes it automatically:

$ secretspec docker configure \
  --registry ghcr.io \
  --username YOUR_USERNAME \
  --provider onepassword
$ secretspec docker login ghcr.io --provider onepassword

Exported SECRETSPEC_FILE, SECRETSPEC_PROFILE, SECRETSPEC_PROVIDER, and SECRETSPEC_REASON values are not saved as durable Docker helper settings. Pass --file, --profile, --provider, or --reason explicitly when the helper should keep using that selection.

Docker Hub

Docker uses the historical key https://index.docker.io/v1/ for Docker Hub. SecretSpec 0.20+ normalizes the familiar Docker Hub hostnames and URL forms to that key:

$ secretspec docker configure \
  --registry docker.io \
  --username YOUR_DOCKER_ID
$ secretspec docker login docker.io

Registry addresses may contain a port, such as registry.example.com:5000, but not a repository path. Credentials are scoped to the registry rather than an image namespace.

Use a project manifest

Custom Docker credential configuration is available in SecretSpec 0.20+.

For a credential already declared by a project, pass --file to select the advanced custom-manifest mode. In this mode, --token-secret and either --username or --username-secret are required:

[project]
name = "docker-credentials"
revision = "1.0"


[profiles.default]
GHCR_TOKEN = { description = "GitHub Container Registry token" }
$ secretspec set GHCR_TOKEN --file secretspec.toml
$ secretspec --file secretspec.toml docker configure \
  --registry ghcr.io \
  --token-secret GHCR_TOKEN \
  --username YOUR_USERNAME

To resolve the username from SecretSpec too, declare it and replace --username with --username-secret GHCR_USERNAME. Custom-manifest mode also accepts --profile and --provider.

The managed state records the manifest’s absolute path and, when supplied as --profile, that profile; it never records resolved secret values. Without an explicit --profile, the helper resolves the normal profile each time it runs. A symlinked manifest retains its logical path, so relative extends entries resolve beside the symlink. If the manifest moves, rerun configure for the affected registry. Manage custom-manifest values with secretspec set and secretspec delete; secretspec docker login and logout intentionally manage only the embedded store.

Alternate Docker configuration directory

Per-configuration Docker credential isolation is available in SecretSpec 0.20+. SecretSpec and Docker both honor DOCKER_CONFIG when selecting config.json:

$ DOCKER_CONFIG="$HOME/.config/docker-work" \
  secretspec docker configure \
    --registry registry.example.com \
    --username YOUR_USERNAME

The same registry can use different SecretSpec credentials in different Docker configuration directories. Embedded credentials are isolated by both registry and the physical Docker configuration path. Equivalent paths through symlinked directories resolve to the same credential identity. Use the same DOCKER_CONFIG value when logging in, logging out, or unconfiguring entries from that file.

Use DOCKER_CONFIG instead of docker —config

Docker’s --config \<PATH\> flag selects a configuration for the Docker process, but Docker does not pass that path to credential helpers. Export DOCKER_CONFIG=\<PATH\> instead so docker-credential-secretspec can identify the matching managed credential. Using only docker --config \<PATH\> can find the helper registration while leaving the helper unable to select its credential.

Remove credentials and configuration

These removal commands are available in SecretSpec 0.20+.

Remove an embedded secret without changing Docker’s helper configuration:

$ secretspec docker logout ghcr.io

Pass the same --provider used for login when it was explicitly overridden.

Remove one helper registration from the active Docker configuration:

$ secretspec docker unconfigure --registry ghcr.io

Remove every Docker credential helper registration that SecretSpec owns in that file:

$ secretspec docker unconfigure --all

Configuration changes prompt with a default of No. Pass --yes for non-interactive setup or removal. SecretSpec preserves the default credential store, other registry helpers, existing auths, and unrelated Docker options. If a managed entry changes outside SecretSpec, unconfigure refuses to modify another helper’s entry. If the SecretSpec helper entry is already absent, unconfigure safely removes the stale managed state so an interrupted removal can be rerun.

logout and unconfigure are independent: logout deletes the embedded secret, while unconfigure removes Docker’s reference to the helper. This matches the separation between login and configure.

Read-only helper behavior

In SecretSpec 0.20+, docker-credential-secretspec answers Docker’s get operation. It rejects store, erase, and list, so Docker’s own docker login and docker logout cannot overwrite or delete values in a shared provider. Use secretspec docker login and secretspec docker logout for the embedded store, or normal SecretSpec commands for a custom manifest.

Docker may still print Removing login credentials and exit successfully after docker logout even though a read-only helper retained the credential. Use secretspec docker logout to remove the stored value, and secretspec docker unconfigure to stop Docker from invoking the helper.

When no matching configuration or stored value exists, the helper returns Docker’s standard credential-not-found response.

Last updated Oct 11, 2026