# Copy your repositories from Nexus

> Copy your Nexus 3 repositories into Telesphorepo, keep them in sync, then switch over.

Source: https://docs.telesphorepo.com/move-from-nexus/

The move from Nexus has three parts. First, Telesphorepo copies the repositories of a Nexus 3 server and keeps them in sync: this page. Then you move each project, [by hand](/move-projects-by-hand/) or [with an AI agent](/move-projects-with-an-agent/). Last, you switch over, and your builds publish to Telesphorepo.

Your builds keep using Nexus during the copy.

Moving off Nexus has three stages. Before: builds publish to Nexus. During: Telesphorepo copies new uploads from Nexus, and builds still publish to Nexus. After: builds publish to Telesphorepo.

Telesphorepo only reads from Nexus. It never changes Nexus.

1. Add the Nexus server. Open **Settings**, then **Nexus migration**, and click **Add a Nexus server**.

   - **Name:** a short name, for example `old-nexus`
   - **Address:** the address of Nexus, for example `https://nexus.example.com`
   - **Username** and **Password:** a Nexus account that can read every repository that you copy

   Click **Add server**.

2. Choose the repositories. On the page of the Nexus server, under **Repositories to copy**, tick each repository. In **Name here**, enter the name that the repository gets in Telesphorepo.

3. Click the **Copy** button. It shows the number of repositories that you ticked, for example **Copy 3 repositories**. The first sync copies every file. The page shows the progress.

   Telesphorepo then checks Nexus every 15 minutes and copies new files. Click **Sync now** to check at once.

4. Point your builds at Telesphorepo to download. The copied repositories are read only until you switch over, but you can read from them now. Change the repository addresses:

   | Nexus                                                          | Telesphorepo                                             |
   | -------------------------------------------------------------- | -------------------------------------------------------- |
   | `https://nexus.example.com/repository/maven-releases/`         | `https://repo.example.com/maven/maven-releases`          |
   | `https://nexus.example.com/repository/apt-hosted/`             | `https://repo.example.com/debian/apt-hosted`             |
   | `https://nexus.example.com/repository/raw-files/`              | `https://repo.example.com/raw/raw-files`                 |
   | `https://nexus.example.com/repository/npm-hosted/`             | `https://repo.example.com/npm/npm-hosted/`               |
   | `https://nexus.example.com/repository/pypi-hosted/simple/`     | `https://repo.example.com/pypi/pypi-hosted/simple/`      |
   | `https://nexus.example.com/repository/nuget-hosted/index.json` | `https://repo.example.com/nuget/nuget-hosted/index.json` |

   A Cargo repository becomes `sparse+https://repo.example.com/cargo/<name>/index/`, and a Docker repository `repo.example.com/<name>/IMAGE:TAG`. See [Repository addresses](/commands-and-settings/#repository-addresses).

   [Move your projects by hand](/move-projects-by-hand/) lists the files and the addresses for each ecosystem. With a prompt of [Move your projects with an AI agent](/move-projects-with-an-agent/), a coding agent changes every address in a project with you.

5. Prepare publishing. Set up each project as in [Move publishing](/move-projects-by-hand/#move-publishing), and keep publishing to Nexus for now. With a prompt of [Move your projects with an AI agent](/move-projects-with-an-agent/) for the full switch-over, a coding agent does this step and the next with you.

6. Rehearse publishing on a test repository: the copies take uploads only after the switch-over. See [Rehearse publishing](/move-projects-by-hand/#rehearse-publishing).

7. Stop all publishing to Nexus. A file that reaches Nexus after the final sync does not get copied.

8. Switch over. On the page of the Nexus server, click **Switch over**. Read the count of failed files, then click **Run the final sync and switch over**.

   Telesphorepo runs one final sync. Then the repositories accept uploads, and Telesphorepo forgets the Nexus password.

9. Point each project at its real repository: set `repo` in its `telesphorepo.toml`, and publish. See [After the switch-over](/move-projects-by-hand/#after-the-switch-over).

> Caution
>
> Back up the data of Telesphorepo before the first sync. See [Back up](/run-the-server/#back-up).

What Telesphorepo copies

| Nexus repository                                         | Telesphorepo repository                                                                           |
| -------------------------------------------------------- | ------------------------------------------------------------------------------------------------- |
| Maven hosted (`maven2`)                                  | Maven, every file at its path                                                                     |
| npm hosted                                               | npm. Each tarball becomes a version, with the dist-tags of Nexus                                  |
| PyPI hosted                                              | Python (PyPI). Each wheel and sdist, with its metadata                                            |
| Cargo hosted                                             | Cargo (Rust). Each `.crate`, with the index entry from its `Cargo.toml`                           |
| NuGet hosted                                             | NuGet. Each `.nupkg`, as a push                                                                   |
| Docker hosted                                            | Docker. Each tag and manifest, with the layers that it names                                      |
| Raw hosted                                               | Raw, every file at its path                                                                       |
| Apt hosted                                               | Debian. Telesphorepo copies the `.deb` files into the component `main` and builds its own indexes |
| A proxy of Maven, npm, PyPI, Cargo, NuGet, Docker or apt | A proxy of the same remote                                                                        |
| A group of Maven, npm, PyPI, Cargo, NuGet or Docker      | A group of the copied members                                                                     |

The table of repositories marks each repository that Telesphorepo cannot copy, with the reason. A repository that is offline in Nexus cannot be copied.

For an apt repository, choose its signing key in the **Signing key** column. Choose the Nexus key to keep the key that your apt clients already trust. Nexus does not give the passphrase of its key, so enter it when the page asks.

Failed files

A sync continues when one file fails. The page lists each failed file with the reason. A common reason is a release file with the same path but other bytes than the copy in Telesphorepo.

The switch-over also finishes when some files failed. After the switch-over, Telesphorepo cannot read Nexus again. Fix the failed files before you switch over, while Nexus still runs.

If a whole repository fails during the final sync, for example because Nexus does not answer, the switch-over stops. The repositories stay read only. Fix the cause and click **Switch over** again.

Change the sync interval

Open **Settings**, then **General**, and change **Nexus sync interval**. The default is 15 minutes. The shortest is 1 minute.

Remove the Nexus server

After the switch-over, you can delete the Nexus server on its page. The repositories and their files stay.