Configure Conda with Nexus

Conda repositories are commonly referred to as channels. A channel is an online location where Conda stores and retrieves packages. Conda clients search one or more channels when resolving packages.

Configure the Conda client to use Nexus before you download or upload packages. Conda uses the optional .condarc runtime configuration file to define settings such as channels and environment directories. Note that a Nexus Conda repository must exist in Nexus before configuring the client.

Conda can be configured in the following methods:

Update the available channels
Set the default channels
Set the channel alias

Update the Available Channels

Listing channel locations in .condarc overrides Conda defaults, so Conda searches only the listed channels in the given order. When using the Conda client with Nexus Repository, add the Nexus Conda repository in .condarc and remove the default channels:

conda config --add channels <protocol>://<authentication>@<hostname>:<port>/repository/<repository_name>
conda config --remove channels defaults

Where:

<protocol> - The protocol used to connect to Nexus Repository; HTTP or HTTPS
<authentication> - See Authentication Methods
<hostname> - The hostname of your Nexus Repository instance
<port> - The port used by your Nexus Repository instance
<repository_name> - The name of your Conda repository in Nexus Repository

See the Conda documentation on managing channels

Set the Default Channels

In a standard Conda configuration, the defaults channel points to multiple channels at repo.anaconda.com. If you define default_channels, Conda uses that list instead of the standard set. This configuration is useful for air-gapped and enterprise environments where clients must connect only to approved repositories.

default_channels:
  - <channel_url>

Where,

<channel_url> - The channel URL that Conda should use instead of the standard default channels.

Example:

default_channels:
  - http://nexus.example.com:8081/repository/conda-proxy

See the documentation on default channels

Set the Channel Alias

When you use the -c or --channel flag with a channel name that is not a URL, Conda prepends the channel_alias value to that name. Set channel_alias to the URL of your Conda repository to direct those requests through Nexus.

channel_alias: <protocol>://<authentication>@<hostname>:<port>/repository/<repository_name>

Where:

Authentication Methods

Nexus Conda repository supports the following authentication methods:

Authentication method	Suitable for	Distinctive Aspects
Basic authentication	Simple configurations using HTTPS or a trusted network.	Easy to set up, but exposes credentials in the URL.
`.netrc` file	Secure and maintainable option for local development or shared configuration patterns.	Recommended method. Keeps credentials separate from the repository URL.
Environment variables	CI/CD or scripted environments.	Useful for automation and secret injection. Keeps credentials out of static configuration files, but still depends on how the runtime environment manages secrets.

Basic Authentication

Note

Use this method only on trusted networks or with HTTPS.

Basic authentication embeds username and password within URL. For example:

https://<username>:<password>@<hostname>:<port>/repository/<repository_name>

Example for setting the channel defaults:

conda config --add channels https://admin:admin123@nexus.example.com:8081/repository/conda-proxy
conda config --remove channels defaults

Example for setting the channel alias

channel_alias: https://admin:admin123@example.nexus.com:8081/repository/conda-proxy

.netrc

This method stores credentials in ~/.netrc on Linux and macOS or %HOME%\_netrc on Windows. It prevents you from exposing the credentials within the URL. Take the following steps to authenticate using .netrc.

Store your credentials to the .netrc file.

machine <hostname>
login <username>
password <password>

On Linux and macOS only, set the file permissions for .condarc to retrieve the credentials. Run:

chmod 600 ~/.netrc

Configure the channel without embedded credentials:

channels:
  - https://<hostname>:<port>/repository/<repository_name>

Example:

Store your credentials in the .netrc file.

machine example.nexus.com
login admin
password admin123

For Linux and macOS, set the file permissions to retrieve the credentials.

chmod 600 ~/.netrc

Add the channel.

conda config --add channels https://example.nexus.com:8081/repository/conda-all
conda config --remove channels defaults

If you want to set the channel alias, run:

channel_alias: https://example.nexus.com:8081/repository/conda-all

Environment Variables

In shell environments, store credentials in environment variables and reference those variables when you define the repository URL.

export CONDA_USERNAME="username"
export CONDA_PASSWORD="password"

Example:

Set the environmental variables.

export CONDA_USERNAME="admin"
export CONDA_PASSWORD="admin123"

Add the channel. Run:

conda config --add channels https://${CONDA_USERNAME}:${CONDA_PASSWORD}@example.nexus.com:8081/repository/conda-all
conda config --remove channels defaults

If you want to set the channel alias, run:

channel_alias: https://${CONDA_USERNAME}:${CONDA_PASSWORD}@example.nexus.com:8081/repository/conda-all