Installing with limited connectivity

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Installing with limited connectivity

Many playbooks and roles in OpenStack-Ansible retrieve dependencies from the public Internet by default. The example configurations assume that the deployer provides good quality Internet connectivity via a router on the OpenStack management network.

Deployments may encounter limited external connectivity for a number of reasons:

  • Unreliable or low bandwidth external connectivity

  • Firewall rules which block external connectivity

  • External connectivity required to be via HTTP or SOCKS proxies

  • Architectural decisions by the deployer to isolate the OpenStack networks

  • High security environments where no external connectivity is permitted

We recommend a set of practices and configuration overrides deployers can use when running OpenStack-Ansible in network environments that block Internet connectivity.

The options below are not mutually exclusive and may be combined if desired.

Example internet dependencies

  • Python packages

  • Distribution specific packages

  • LXC container images

  • Source code repositories

  • GPG keys for package validation

Practice A: Mirror internet resources locally

You may choose to operate and maintain mirrors of OpenStack-Ansible and OpenStack dependencies. Mirrors often provide a great deal of risk mitigation by reducing dependencies on resources and systems outside of your direct control. Mirrors can also provide greater stability, performance and security.

Python package repositories

Many packages used to run OpenStack are installed using pip. We advise mirroring the PyPi package index used by pip. A deployer can choose to actively mirror the entire upstream PyPi repository but this may require a significant amount of storage. Alternatively a caching pip proxy can be used to retain local copies of only those packages which are required.

In order to configure the build to use an alternative index, create the file /etc/pip.conf with the following content and ensure that it is placed on all hosts in the environment.

[global]
index-url = http://pip.example.org/simple

Then, in /etc/openstack_deploy/user_variables.yml, inform the deployment that it needs to copy that file from the host into the container cache image.

# Copy these files from the host into the containers
lxc_container_cache_files_from_host:
  - /etc/pip.conf

Distribution specific packages

Many software packages are installed on Ubuntu hosts using .deb packages. Similar packaging mechanisms exist for other Linux distributions. We advise mirroring the repositories that host these packages.

Upstream Ubuntu repositories to mirror for Ubuntu 18.04 LTS:

  • bionic

  • bionic-updates

OpenStack-Ansible requires several other repositories to install specific components such as Galera and Ceph.

Example repositories to mirror (Ubuntu target hosts):

These lists are intentionally not exhaustive and equivalents will be required for other Linux distributions. Consult the OpenStack-Ansible playbooks and role documentation for further repositories and the variables that may be used to override the repository location.

LXC container images

OpenStack-Ansible relies upon community built LXC images when building containers for OpenStack services. Deployers may choose to create, maintain, and host their own container images. Consult the openstack-ansible-lxc_container_create role for details on configuration overrides for this scenario.

Source code repositories

OpenStack-Ansible relies upon Ansible Galaxy to download Ansible roles when bootstrapping a deployment host. Deployers may wish to mirror the dependencies that are downloaded by the bootstrap-ansible.sh script.

Deployers can configure the script to source Ansible from an alternate Git repository by setting the environment variable ANSIBLE_GIT_REPO.

Deployers can configure the script to source Ansible role dependencies from alternate locations by providing a custom role requirements file and specifying the path to that file using the environment variable ANSIBLE_ROLE_FILE.

Practice B: Proxy access to internet resources

Some networks have no routed access to the Internet, or require certain traffic to use application specific gateways such as HTTP or SOCKS proxy servers.

Configuration can be applied to target and deployment hosts to reach public internet resources via HTTP or SOCKS proxy server(s). OpenStack-Ansible may be used to configure target hosts to use the proxy server(s). OpenStack-Ansible does not provide automation for creating the proxy server(s).

Initial host deployment is outside the scope of OpenStack-Ansible and the deployer must ensure a minimum set of proxy configuration is in place, in particular for the system package manager.

apt-get proxy configuration

See Setting up apt-get to use a http-proxy

Other proxy configuration

Further to this basic configuration, there are other network clients on the target hosts which may be configured to connect via a proxy. For example:

  • Most Python network modules

  • curl

  • wget

  • openstack

These tools and their underlying libraries are used by Ansible itself and the OpenStack-Ansible playbooks, so there must be a proxy configuration in place for the playbooks to successfully access external resources.

Typically these tools read environment variables containing proxy server settings. These environment variables can be configured in /etc/environment if required.

It is important to note that the proxy server should only be used to access external resources, and communication between the internal components of the OpenStack deployment should be direct, without going through the proxy. The no_proxy environment variable is used to specify hosts that should be reached directly without going through the proxy. These often are the hosts in the management network.

OpenStack-Ansible provides two distinct mechanisms for configuring proxy server settings:

#. The default configuration file suggests setting a persistent proxy configuration on all target hosts and defines a persistent no_proxy environment variable which lists all hosts/containers’ management addresses as well as the load balancer internal/external addresses.

#. An alternative method applies proxy configuration in a transient manner during the execution of Ansible playbooks and defines a minimum set of management network IP addresses for no_proxy that are required for the playbooks to succeed. These proxy settings do not persist after an Ansible playbook run and the completed deployment does not require them in order to be functional.

The deployer must decide which of these approaches is more suitable for the target hosts, taking into account the following guidance:

#. Persistent proxy configuration is a standard practice and network clients on the target hosts will be able to access external resources after deployment.

#. The deployer must ensure that a persistent proxy configuration has complete coverage of all OpenStack management network host/containers’ IP addresses in the no_proxy environment variable. It is necessary to use a list of IP addresses, CIDR notation is not valid for no_proxy.

#. Transient proxy configuration guarantees that proxy environment variables will not persist, ensuring direct communication between services on the OpenStack management network after deployment. Target host network clients such as wget will not be able to access external resources after deployment.

#. The maximum length of no_proxy should not exceed 1024 characters due to a fixed size buffer in the pam_env PAM module. Longer environment variables will be truncated during deployment operations and this will lead to unpredictable errors during or after deployment.

Once the number of hosts/containers in a deployment reaches a certain size the length of no_proxy will exceed 1024 characters. It is then mandatory to use the transient proxy settings which only requires a subset of the management network IP addresses to be present in no_proxy at deployment time.

Refer to global_environment_variables: and deployment_environment_variables: in the example user_variables.yml for details of configuring persistent and transient proxy environment variables.

Deployment host proxy configuration for bootstrapping Ansible

Configure the bootstrap-ansible.sh script used to install Ansible and Ansible role dependencies on the deployment host to use a proxy by setting the environment variables HTTPS_PROXY or HTTP_PROXY.

Note

We recommend you set your /etc/environment variables with proxy settings before launching any scripts or playbooks to avoid failure.

For larger or complex environments a dedicated deployment host allows the most suitable proxy configuration to be applied to both deployment and target hosts.

Considerations when proxying TLS traffic

Proxying TLS traffic often interferes with the clients ability to perform successful validation of the certificate chain. Various configuration variables exist within the OpenStack-Ansible playbooks and roles that allow a deployer to ignore these validation failures. Find an example /etc/openstack_deploy/user_variables.yml configuration below:

pip_validate_certs: false
galera_package_download_validate_certs: false

The list above is intentionally not exhaustive. Additional variables may exist within the project and will be named using the *_validate_certs pattern. Disable certificate chain validation on a case by case basis and only after encountering failures that are known to only be caused by the proxy server(s).

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