---
description: >-
  Use OCI registries as an distribution mechanism for OpenTofu module packages
---

# Module Packages in OCI Registries

OpenTofu supports installing module packages from
[a variety of different sources](/language/modules/sources.mdx), including
from repositories in registries that implement the OCI Distribution protocol.

You can configure OpenTofu to install a module from an OCI repository by
using the `oci:` source address scheme:

```hcl
module "example" {
  source = "oci://example.com/repository-name"
}
```

For more information on how to select OCI artifacts to install, refer to
[the module sources documentation](/language/modules/sources.mdx#oci-distribution-repository).
The remainder of this page focuses on how to construct suitable OCI artifacts
for use as OpenTofu module packages.

## Required OCI Repository Content

The OCI artifact selected by an `oci:` module source address must follow certain
requirements for both its manifest metadata and for the blob representing the
content of the module package.

The chosen tag or digest must correspond to a standard
[OCI Image Manifest](https://github.com/opencontainers/image-spec/blob/v1.1.1/manifest.md)
whose `artifactType` property is set to `"application/vnd.opentofu.modulepkg"`.

The image manifest's `layers` array must include exactly one descriptor
whose `mediaType` is `archive/zip`, referring to a valid `.zip` archive
representing the content of the module package.

The root directory of the `.zip` archive corresponds to the root directory of
the module package, and so contains the `.tf`, `.tofu`, etc configuration files
describing the default module from the module package. The archive may
optionally contain subdirectories representing additional modules, which can
then be selected using the usual syntax for
[Modules in Package Sub-directories](/language/modules/sources.mdx#modules-in-package-sub-directories).

If the specified source address does not include either of the `tag` or `digest` query
string arguments then OpenTofu attempts to resolve a tag named `latest`. OpenTofu makes
no other assumptions about tag naming convention beyond the syntax constraints required
by the OCI Distribution specification.

## Assembling and Pushing Module Package Manifests

### Install and Configure ORAS

We recommend assembling and pushing the manifests and blobs for a module
package using the CLI tool offered by [the ORAS project](https://oras.land/).

If you are installing and using ORAS for the first time, and you intend to
push to an OCI registry that requires authentication, you will need to first
obtain credentials for that repository using [`oras login`](https://oras.land/docs/commands/oras_login).

### Create a `.zip` archive

The actual content of a module package is represented for an OCI artifact as
a single layer using the `.zip` archive format.

You can use any suitable tool to build a `.zip` archive containing the
module source code (`.tf`/`.tofu`/etc files) you intend to distribute.
For example, using the `zip` tool commonly available on Unix systems:

```shell
zip -r ../module-package.zip .
```

This command creates or updates an archive `module-package.zip` in the
parent of the current working directory, containing all of the files
in the current working directory and any of its subdirectories.
Creating the file in the parent directory avoids adding the zip file
into itself if you run the same command again.

The next section will use `module-package.zip` to refer to the `.zip`
archive you've created.

### Push the artifact to a remote repository

The `oras push` command can automatically construct a suitable image manifest,
upload that manifest and the associated `.zip` file to a remote OCI repository,
and create or update one or more tags referring to it in the same repository.

```shell
oras push \
  --artifact-type=application/vnd.opentofu.modulepkg \
  example.com/repository-name:latest \
  module-package.zip:archive/zip
```

`example.com/repository-name` is the address of the repository to push the
artifact into. `latest` is the tag name to use.

`module-package.zip` is the name of the `.zip` archive created in the previous
step. The `:archive/zip` suffix tells ORAS which media type to specify for
this file in the artifact manifest. OpenTofu does not support any other media
types.

The `--artifact-type` option included above must be used _exactly as shown_
to ensure that OpenTofu will recognize this artifact as a module package.

The repository address and tag shown above can be specified in a `module`
block source address as follows:

```hcl
module "example" {
  source = "oci://example.com/repository-name?tag=latest"
}
```

If you chose the tag name `latest` as shown here then you can omit the
`tag` argument, specifying just `oci://example.com/repository-name`,
because "latest" is the tag name OpenTofu uses by default.

