% CONTAINERS-REGISTRIES.D(5) Registries.d Man Page % Miloslav Trmač % August 2016
containers-registries.d - Directory for various registries configurations
The registries configuration directory contains configuration for various registries (servers storing remote container images), and for content stored in them, so that the configuration does not have to be provided in command-line options over and over for every command, and so that it can be shared by all users of containers/image.
By default (unless overridden at compile-time), the registries configuration directory is
applications may allow using a different directory instead.
The directory may contain any number of files with the extension
each using the YAML format. Other than the mandatory extension, names of the files
The contents of these files are merged together; to have a well-defined and easy to understand
behavior, there can be only one configuration section describing a single namespace within a registry
(in particular there can be at most one one
default-docker section across all files,
and there can be at most one instance of any key under the the
these sections are documented later).
Thus, it is forbidden to have two conflicting configurations for a single registry or scope, and it is also forbidden to split a configuration for a single registry or scope across more than one file (even if they are not semantically in conflict).
Each YAML file must contain a “YAML mapping” (key-value pairs). Two top-level keys are defined:
default-dockeris the configuration section (as documented below) for registries implementing "Docker Registry HTTP API V2".
This key is optional.
dockeris a mapping, using individual registries implementing "Docker Registry HTTP API V2", or namespaces and individual images within these registries, as keys; the value assigned to any such key is a configuration section.
This key is optional.
Scopes matching individual images are named Docker references in the fully expanded form, either
using a tag or digest. For example,
More general scopes are prefixes of individual-image scopes, and specify a repository (by omitting the tag or digest), a repository namespace, or a registry host (and a port if it differs from the default).
Note that if a registry is accessed using a hostname+port configuration, the port-less hostname is not used as parent scope.
When searching for a configuration to apply for an individual container image, only
the configuration for the most-precisely matching scope is used; configuration using
more general scopes is ignored. For example, if any configuration exists for
docker.io/library/busybox, the configuration for
docker.io is ignored
(even if some element of the configuration is defined for
docker.io and not for
A single configuration section is selected for a container image using the process described above. The configuration section is a YAML mapping, with the following keys:
sigstore-stagingdefines an URL of of the signature storage, used for editing it (adding or deleting signatures).
This key is optional; if it is missing,
sigstore below is used.
sigstoredefines an URL of the signature storage. This URL is used for reading existing signatures, and if
sigstore-stagingdoes not exist, also for adding or removing them.
This key is optional; if it is missing, no signature storage is defined (no signatures
are download along with images, adding new signatures is possible only if
sigstore-staging is defined).
The following demonstrates how to to consume and run images from various registries and namespaces:
docker: registry.database-supplier.com: sigstore: https://sigstore.database-supplier.com distribution.great-middleware.org: sigstore: https://security-team.great-middleware.org/sigstore docker.io/web-framework: sigstore: https://sigstore.web-framework.io:8080
For developers in
docker: registry.example.com: sigstore: https://registry-sigstore.example.com registry.example.com/mydepartment: sigstore: https://sigstore.mydepartment.example.com sigstore-staging: file:///mnt/mydepartment/sigstore-staging registry.example.com/mydepartment/myproject:mybranch: sigstore: http://localhost:4242/sigstore sigstore-staging: file:///home/useraccount/webroot/sigstore
If a company publishes its products using a different domain, and different registry hostname for each of them, it is still possible to use a single signature storage server without listing each domain individually. This is expected to rarely happen, usually only for staging new signatures.
default-docker: sigstore-staging: file:///mnt/company/common-sigstore-staging
Miloslav Trmač email@example.com