Merge branch 'project_package_registry_docs' into 'master'

Add Package workflows section to docs

Closes #118657

See merge request gitlab-org/gitlab!21697

doc/user/packages/index.md

@@ -22,3 +22,9 @@ guide you through the process. Or check out how other members of the commmunity
 are adding support for [PHP](https://gitlab.com/gitlab-org/gitlab/merge_requests/17417) or [Terraform](https://gitlab.com/gitlab-org/gitlab/merge_requests/18834).
 
 NOTE: **Note** We are especially interested in adding support for [PyPi](https://gitlab.com/gitlab-org/gitlab/issues/10483), [RubyGems](https://gitlab.com/gitlab-org/gitlab/issues/803), [Debian](https://gitlab.com/gitlab-org/gitlab/issues/5835), and [RPM](https://gitlab.com/gitlab-org/gitlab/issues/5932).
+
+## Package workflows
+
+Learning how to use the GitLab Package Registry will help you build your own custom package workflow.
+
+[Use a project as a package registry](./workflows/project_registry.md) to publish all of your packages to one project.

doc/user/packages/workflows/project_registry.md

+# Project as a package registry
+
+Using the features of the package registry, it is possible to use one project to store all of your packages.
+
+This guide mirrors the creation of [this package registry](https://gitlab.com/sabrams/my-package-registry).
+
+For the video version, see [Single Project Package Registry Demo](https://youtu.be/ui2nNBwN35c).
+
+## How does this work?
+
+You might be wondering "how is it possible to upload two packages from different codebases to the same project on GitLab?".
+
+It is easy to forget that a package on GitLab belongs to a project, but a project does not have to be a code repository.
+The code used to build your packages can be stored anywhere - maybe it is another project on GitLab, or maybe a completely
+different system altogether. All that matters is that when you configure your remote repositories for those packages, you
+point them at the same project on GitLab.
+
+## Why would I do this?
+
+There are a few reasons you might want to publish all your packages to one project on GitLab:
+
+1. You want to publish your packages on GitLab, but to a project that is different from where your code is stored.
+1. You would like to group packages together in ways that make sense for your usage (all NPM packages in one project,
+   all packages being used by a specific department in one project, all private packages in one project, etc.)
+1. You want to use one remote for all of your packages when installing them into other projects.
+1. You would like to migrate your packages to a single place on GitLab from a third-party package registry and do not
+   want to worry about setting up separate projects for each package.
+1. You want to have your CI pipelines build all of your packages to one project so the individual responsible for
+validating packages can manage them all in one place.
+
+## Example walkthrough
+
+There is no functionality specific to this feature. All we are doing is taking advantage of functionality available in each
+of the package management systems to publish packages of different types to the same place.
+
+Let's take a look at how you might create a public place to hold all of your public packages.
+
+### Create a project
+
+First, create a new project on GitLab. It does not have to have any code or content. Make note of the project ID
+displayed on the project overview page, as you will need this later.
+
+### Create an access token
+
+All of the package repositories available on the GitLab package registry are accessible using [GitLab personal access
+tokens](../../profile/personal_access_tokens.md).
+
+While using CI, you can alternatively use CI job tokens (`CI_JOB_TOKEN`) to authenticate.
+
+### Configure your local project for the GitLab registry and upload
+
+There are many ways to use this feature. You can upload all types of packages to the same project,
+split things up based on package type, or package visibility level.
+
+The purpose of this tutorial is to demonstrate the root idea that one project can hold many unrelated
+packages, and to allow you to discover the best way to use this functionality yourself.
+
+#### NPM
+
+If you are using NPM, this involves creating an `.npmrc` file and adding the appropriate URL for uploading packages
+to your project using your project ID, then adding a section to your `package.json` file with a similar URL.
+
+Follow
+the instructions in the [GitLab NPM Registry documentation](../npm_registry/index.md#authenticating-to-the-gitlab-npm-registry). Once
+you do this, you will be able to push your NPM package to your project using `npm publish`, as described in the
+[uploading packages](../npm_registry/index.md#uploading-packages) section of the docs.
+
+#### Maven
+
+If you are using Maven, this involves updating your `pom.xml` file with distribution sections, including the
+appropriate URL for your project, as described in the [GitLab Maven Repository documentation](../maven_repository/index.md#project-level-maven-endpoint).
+Then, you need to add a `settings.xml` file and [include your access token](../maven_repository/index.md#authenticating-with-a-personal-access-token).
+Now you can [deploy Maven packages](../maven_repository/index.md#uploading-packages) to your project.
+
+#### Conan
+
+For Conan, first you need to add GitLab as a Conan registry remote. Follow the instructions in the [GitLab Conan Repository docs](../conan_repository/index.md#setting-the-conan-remote-to-the-gitlab-package-registry)
+to do so. Then, create your package using the plus-separated (`+`) project path as your Conan user. For example,
+if your project is located at `https://gitlab.com/foo/bar/my-proj`, then you can [create your Conan package](../conan_repository/index.md)
+using `conan create . foo+bar+my-proj/channel`, where `channel` is your package channel (`stable`, `beta`, etc.). Once your package
+is created, you are ready to [upload your package](../conan_repository/index.md#uploading-a-package) depending on your final package recipe. For example:
+
+```sh
+CONAN_LOGIN_USERNAME=<gitlab-username> CONAN_PASSWORD=<personal_access_token> conan upload MyPackage/1.0.0@foo+bar+my-proj/channel --all --remote=gitlab
+```