Python/Linux Distribution Notes

Updated: 10 Nov 2017 23:30 GMT

This document exists to help bridge the gap between the Conductor python package and any downstream distribution. The steps outlined herein may be taken into consideration when creating an AT&T SWM package, Ubuntu/Debian package, Chef cookbook, or Ansible playbook.

Components

Conductor consists of five services that work together:

  • ``conductor-api``: An HTTP REST API
  • ``conductor-controller``: Validation, translation, and status/results
  • ``conductor-data``: Inventory provider and service controller gateway
  • ``conductor-solver``: Processing and solution calculation
  • ``conductor-reservation``: Reserves the suggested solution solved by Solver component.

Workflow

  • Deployment plans are created, viewed, and deleted via conductor-api and its REST API.
  • Included within each conductor-api plan request is a Homing Template.
  • Homing Templates describe a set of inventory demands and constraints to be solved against.
  • conductor-api hands off all API requests to conductor-controller for handling.
  • All deployment plans are assigned a unique identifier (UUID-4), which can be used to check for solution status asynchronously. (Conductor does not support callbacks at this time.)
  • conductor-controller ensures templates are well-formed and valid. Errors and remediation are made visible through conductor-api. When running in debug mode, the API will also include a python traceback in the response body, if available.
  • conductor-controller uses conductor-data to resolve demands against a particular inventory provider (e.g., A&AI).
  • conductor-controller translates the template into a format suitable for solving.
  • As each template is translated, conductor-solver begins working on it.
  • conductor-solver uses conductor-data to resolve constraints against a particular service controller (e.g., SDN-C).
  • conductor-solver determines the most suitable inventory to recommend.
  • conductor-reservation attempts to reserve the solved solution in SDN-GC

NOTE: There is no Command Line Interface or Python API Library at this time.

Pre-Flight and Pre-Installation Considerations

AT&T Application Identifiers and Roles

  • App/Tool Name: ECOMP Conductor
  • MOTS Application ID: 26213
  • MechID: m04308
  • ECOMP Feature ID: F13704
  • PMT: 461306
  • UAM Role Name: Conductor Production Support
  • UAM Role id: 0000025248

Root

Be aware that some commands may require sudo, depending on the account being used to perform the installation.

Proxy

If line-of-sight to internet-facing repositories is permitted and available, set the following shell environment variables if AT&T proxy services are required:

$ export http_proxy="http://one.proxy.att.com:8080/"
$ export https_proxy="http://one.proxy.att.com:8080/"

Requirements

Conductor is officially supported on Ubuntu 14.04 LTS (Trusty Tahr), though it should also work on newer releases.

Ensure the following Ubuntu packages are present, as they may not be included by default:

conductor-api may be run as-is for development and test purposes. When used in a production environment, it is recommended that conductor-api run under a multithreaded httpd service supporting WSGI, tuned as appropriate.

Configuration instructions for apache2 httpd and nginx are included herein. Respective package requirements are:

All Conductor services use AT&T Music for data storage/persistence and/or as a RPC transport mechanism. Consult the Music Local Installation Guide for installation/configuration steps.

Networking

All conductor services require line-of-sight access to all Music servers/ports.

The conductor-api service uses TCP port 8091.

Security

conductor-api is accessed via HTTP. SSL/TLS certificates and AuthN/AuthZ (e.g., AAF) are not supported at this time.

Conductor makes use of plugins that act as gateways to inventory providers and service controllers. At present, two plugins are supported out-of-the-box: A&AI and SDN-C, respectively.

A&AI requires two-way SSL/TLS. Certificates must be registered and whitelisted with A&AI. SDN-C uses HTTP Basic Authentication. Consult with each respective service for official information on how to obtain access.

Storage

For a cloud environment in particular, it may be desirable to use a separate block storage device (e.g., an OpenStack Cinder volume) for logs, configuration, and other data persistence. In this way, it becomes a trivial matter to replace the entire VM if necessary, followed by reinstallation of the app and any supplemental configuration. Take this into consideration when setting various Conductor config options.

Python Virtual Environments

At present, Conductor installation is only supported at the (upstream) python package level and not the (downstream) Ubuntu distribution or SWM package levels.

To mitigate/eliminate the risk of introducing conflicts with other python applications or Ubuntu/SWM package dependencies, consider installing Conductor in a python virtual environment (or venv for short).

Example venv-aware WSGI app configurations, sysvinit scripts, and upstart scripts can be found in the Conductor repository under examples.

Python Package Dependencies

Conductor is installed using the python pip command. pip uses a python project’s requirements manifest to install all python module dependencies.

NOTE: When line-of-sight access to a PyPI-compatible package index is not available, advance installation of Conductor’s python package dependencies is required before installation.

Other Production Environment Considerations

TBD. :)

Over time, considerations may include services such as:

  • AAF
  • AppMetrics
  • Introscope
  • Nagios
  • Splunk
  • UAM

Installation and Configuration

IMPORTANT: Perform the steps in this section after optionally configuring and activating a python virtual environment.

Installing From a PyPI Repository

In ONAP, the conductor package can be found on ````.

Installation is via the pip command. Here is an example pip.conf file that uses both the internet and intranet-facing PyPI repositories:

[global]
index = https://pypi.python.org/pypi
index-url = https://pypi.python.org/simple
extra-index-url =
trusted-host =

Once the configuration is in place, installation is simple:

$ pip install of-has

To upgrade or downgrade, simply re-run pip install using the appropriate pip command line options.

NOTE: Be sure proxy settings are in place if they’re required to access pypi.python.org.

Installing From Source

Conductor source in ONAP is maintained in https://gerrit.onap.org/r/optf/has.

Clone the git repository, and then install from within the conductor directory:

$ git clone https://gerrit.onap.org/r/optf/has
Cloning into 'conductor'...
remote: Counting objects: 2291, done.
remote: Compressing objects:  88% (1918/2179)
remote: Compressing objects: 100% (2179/2179), done.
remote: Total 2291 (delta 1422), reused 0 (delta 0)
Receiving objects: 100% (2291/2291), 477.59 KiB | 0 bytes/s, done.
Resolving deltas: 100% (1422/1422), done.
$ cd conductor
$ pip install .

The latest source can be pulled from ONAP at any time and reinstalled:

$ git pull
$ pip install .

Verifying Installation

Each of the five Conductor services may be invoked with the --help option:

$ conductor-api -- --help
$ conductor-controller --help
$ conductor-data --help
$ conductor-solver --help
$ conductor-reservation --help

NOTE: The conductor-api command is deliberate. -- is used as as separator between the arguments used to start the WSGI server and the arguments passed to the WSGI application.

Post-Flight and Post-Installation Considerations

User and Group

It’s good practice to create an unprivileged account (e.g., a user/group named conductor) and run all Conductor services as that user:

$ sudo addgroup --system conductor
$ sudo adduser --system --home /var/lib/conductor --ingroup conductor --no-create-home --shell /bin/false conductor

SSL/TLS Certificates

The A&AI Inventory Provider Plugin requiries two-way SSL/TLS. After provisioning a certificate per A&AI guidelines, it will be necessary to securely install the certificate, key, and certificate authority bundle.

When running conductor services as conductor:conductor (recommended), consider co-locating all of these files under the configuration directory. For example, when using /etc/conductor:

$ # Certificate files (crt extension, 644 permissions)
$ sudo mkdir /etc/conductor/ssl/certs
$ # Private Certificate Key files (key extension, 640 permissions)
$ sudo mkdir /etc/conductor/ssl/private
$ # Certificate Authority (CA) Bundles (crt extension, 644 permissions)
$ sudo mkdir /etc/conductor/ssl/ca-certificates
$ # Add files to newly created directories, then set ownership
$ sudo chmod -R conductor:conductor /etc/conductor/ssl

For a hypothetical domain name imacculate.client.research.att.com, example filenames could be as follows:

$ find ssl -type f -printf '%M %u:%g %f\n'
-rw-r----- conductor:conductor imacculate.client.research.att.com.key
-rw-r--r-- conductor:conductor Symantec_Class_3_Secure_Server_CA.crt
-rw-r--r-- conductor:conductor imacculate.client.research.att.com.crt

When running conductor services as root, consider these existing Ubuntu filesystem locations for SSL/TLS files:

Certificate files (crt extension) are typically stored in /etc/ssl/certs with root:root ownership and 644 permissions.

Private Certificate Key files (key extension) are typically stored in /etc/ssl/private with root:root ownership and 640 permissions.

Certificate Authority (CA) Bundles (crt extension) are typically stored in /usr/share/ca-certificates/conductor with root:root ownership, and 644 permissions. These Bundle files are then symlinked within /etc/ssl/certs using equivalent filenames, a pem extension, and root:root ownership.

NOTE: LUKS (Linux Unified Key Setup) is not supported by Conductor at this time.

Configuration

Configuration files are located in etc/conductor relative to the python environment Conductor is installed in.

To generate a sample configuration file, change to the directory just above where etc/conductor is located (e.g., / for the default environment, or the virtual environment root directory). Then:

$ oslo-config-generator --config-file=etc/conductor/conductor-config-generator.conf

This will generate etc/conductor/conductor.conf.sample.

Because the configuration directory and files will include credentials, consider removing world permissions:

$ find etc/conductor -type f -exec chmod 640 {} +
$ find etc/conductor -type d -exec chmod 750 {} +

The sample config may then be copied and edited. Be sure to backup any previous conductor.conf if necessary.

$ cd etc/conductor
$ cp -p conductor.conf.sample conductor.conf

conductor.conf is fully annotated with descriptions of all options. Defaults are included, with all options commented out. Conductor will use defaults even if an option is not present in the file. To change an option, simply uncomment it and edit its value.

With the exception of the DEFAULT section, it’s best to restart the Conductor services after making any config changes. In some cases, only one particular service actually needs to be restarted. When in doubt, however, it’s best to restart all of them.

A few options in particular warrant special attention:

[DEFAULT]

# If set to true, the logging level will be set to DEBUG instead of the default
# INFO level. (boolean value)
# Note: This option can be changed without restarting.
#debug = false

For more verbose logging across all Conductor services, set debug to true.

[aai]

# Base URL for A&AI, up to and not including the version, and without a
# trailing slash. (string value)
#server_url = https://controller:8443/aai

# SSL/TLS certificate file in pem format. This certificate must be registered
# with the A&AI endpoint. (string value)
#certificate_file = certificate.pem

# Private Certificate Key file in pem format. (string value)
#certificate_key_file = certificate_key.pem

# Certificate Authority Bundle file in pem format. Must contain the appropriate
# trust chain for the Certificate file. (string value)
#certificate_authority_bundle_file = certificate_authority_bundle.pem

Set server_url to the A&AI server URL, to but not including the version, omitting any trailing slash. Conductor supports A&AI API v9 at a minimum.

Set the certificate prefixed keys to the appropriate SSL/TLS-related files.

IMPORTANT: The A&AI server may have a mismatched host/domain name and SSL/TLS certificate. In such cases, certificate verification will fail. To mitigate this, certificate_authority_bundle_file may be set to an empty value. While Conductor normally requires a CA Bundle (otherwise why bother using SSL/TLS), this requirement has been temporarily relaxed so that development and testing may continue.

[messaging_server]

# Log debug messages. Default value is False. (boolean value)
#debug = false

When the DEFAULT section’s debug option is true, set this section’s debug option to true to enable detailed Conductor-side RPC-over-Music debug messages.

Be aware, it is voluminous. “You have been warned.” :)

[music_api]

# List of hostnames (round-robin access) (list value)
#hostnames = localhost

# Log debug messages. Default value is False. (boolean value)
#debug = false

Set hostnames to match wherever the Music REST API is being hosted (wherever Apache Tomcat and MUSIC.war are located).

When the DEFAULT section’s debug option is true, set this section’s debug option to true to enable detailed Conductor-side MUSIC API debug messages.

The previous comment around the volume of log lines applies even more so here. (Srsly. We’re not kidding.)

IMPORTANT: Conductor does not presently use Music’s atomic consistency features due to concern around lock creation/acquisition. Instead, Conductor uses eventual consistency. For this reason, consistency issues may occur when using Music in a multi-server, High Availability configuration.

[sdnc]

# Base URL for SDN-C. (string value)
#server_url = https://controller:8443/restconf

# Basic Authentication Username (string value)
#username = <None>

# Basic Authentication Password (string value)
#password = <None>

Set server_url to the SDN-C server URL, omitting any trailing slash.

Set username and password to the appropriate values as directed by SDN-C.

Running for the First Time

Each Conductor component may be run interactively. In this case, the user does not necessarily matter.

When running interactively, it is suggested to run each command in a separate terminal session and in the following order:

conductor-data --config-file=/etc/conductor/conductor.conf
conductor-controller --config-file=/etc/conductor/conductor.conf
conductor-solver --config-file=/etc/conductor/conductor.conf
conductor-reservation --config-file=/etc/conductor/conductor.conf
conductor-api --port=8091 -- --config-file=/etc/conductor/conductor.conf

Optionally, use an application like screen to nest all five terminal sessions within one detachable session. (This is also the same package used by DevStack.)

To verify that conductor-api can be reached, browse to http://HOST:8091/, where HOST is the hostname conductor-api is running on. No AuthN/AuthZ is required at this time. Depending on network considerations, it may be necessary to use a command like wget instead of a desktop browser.

The response should look similar to:

{
  "versions": {
    "values": [
      {
        "status": "development",
        "updated": "2016-11-01T00:00:00Z",
        "media-types": [
          {
            "base": "application/json",
            "type": "application/vnd.ecomp.homing-v1+json"
          }
        ],
        "id": "v1",
        "links": [
          {
            "href": "http://127.0.0.1:8091/v1",
            "rel": "self"
          },
          {
            "href": "http://conductor.research.att.com/",
            "type": "text/html",
            "rel": "describedby"
          }
        ]
      }
    ]
  }
}

Sample API Calls and Homing Templates

A Postman collection illustrating sample requests is available upon request. The collection will also be added in a future revision.

Sample homing templates are also available.

Ubuntu Service Scripts

Ubuntu sysvinit (init.d) and upstart (init) scripts are typically installed at the Ubuntu package level. Since there is no such packaging at this time, example scripts have been provided in the repository.

To install, place all Conductor sysvinit scripts in /etc/init.d, and all upstart scripts in /etc/init.

Set file permissions:

$ sudo chmod 644 /etc/init/conductor*
$ sudo chmod 755 /etc/init.d/conductor*

If a python virtual environment is being used, edit each /etc/init/conductor* and /etc/init.d/conductor* prefixed file so that PYTHON_HOME is set to the python virtual environment root directory.

Next, enable the scripts:

$ sudo update-rc.d conductor-api defaults
$ sudo update-rc.d conductor-controller defaults
$ sudo update-rc.d conductor-data defaults
$ sudo update-rc.d conductor-solver defaults
$ sudo update-rc.d conductor-reservation defaults
$ sudo initctl reload-configuration

Conductor components may now be started/stopped like any other Ubuntu service, for example:

$ sudo service conductor-api start
$ sudo service conductor-api status
$ sudo service conductor-api restart
$ sudo service conductor-api stop

Conductor service scripts automatically create directories for log, lock, run, lib, and log files, e.g., /var/log/conductor and so on.

Log File Rotation

Sample logrotate.d configuration files have been provided in the repository.

To install, place all Conductor logrotate files in /etc/logrotate.d.

Set file ownership and permissions:

$ sudo chown root:root /etc/logrotate.d/conductor*
$ sudo chmod 644 /etc/logrotate.d/conductor*

logrotate.d automatically recognizes new files at the next log rotation opportunity and does not require restarting.

Running conductor-api Under apache2 httpd and mod_wsgi

Sample configuration files have been provided in the repository.

These instructions presume a conductor user exists. See the Service Scripts section for details.

First, set up a few directories:

$ sudo mkdir -p /var/www/conductor
$ sudo mkdir /var/log/apache2/conductor

To install, place the Conductor WSGI application file in /var/www/conductor.

Set the owner/group of both directories/files to conductor:

$ sudo chown -R conductor:conductor /var/log/apache2/conductor /var/www/conductor

Next, place the Conductor apache2 httpd site config file in /etc/apache2/sites-available.

Set the owner/group to root:

$ sudo chown -R root:root /etc/apache2/sites-available/conductor.conf

If Conductor was installed in a python virtual environment, append python-home=VENV to WSGIDaemonProcess, where VENV is the python virtual environment root directory.

IMPORTANT: Before proceeding, disable the conductor-api sysvinit and upstart services, as the REST API will now be handled by apache2 httpd. Otherwise there will be a port conflict, and you will be sad.

Enable the Conductor site, ensure the configuration syntax is valid, and gracefully restart apache2 httpd.

$ sudo a2ensite conductor
$ sudo apachectl -t
Syntax OK
$ sudo apachectl graceful

To disable the Conductor site, run sudo a2dissite conductor, then gracefully restart once again. Optionally, re-enable the conductor-api sysvinit and upstart services.

Running conductor-api Under nginx and uWSGI

Sample configuration files have been provided in the repository.

These instructions presume a conductor user exists. See the Service Scripts section for details.

To install, place the Conductor nginx config files and WSGI application file in /etc/nginx (taking care to backup any prior configuration files). It may be desirable to incorporate Conductor’s nginx.conf into the existing config.

Rename app.wsgi to conductor.wsgi:

$ cd /etc/nginx
$ sudo mv app.wsgi conductor.wsgi

In nginx.conf, set CONDUCTOR_API_FQDN to the server name.

IMPORTANT: Before proceeding, disable the conductor-api sysvinit and upstart services, as the REST API will now be handled by nginx. Otherwise there will be a port conflict, and you will be sad.

Restart nginx:

$ sudo service nginx restart

Then, run conductor-api under nginx using uWSGI:

$ sudo uwsgi -s /tmp/uwsgi.sock --chmod-socket=777 --wsgi-file /etc/nginx/conductor.wsgi --callable application --set port=8091

To use a python virtual environment, add --venv VENV to the uwsgi command, where VENV is the python virtual environment root directory.

Uninstallation

Activate a virtual environment (venv) first, if necessary, then uninstall with:

$ pip uninstall ecomp-conductor

Remove any previously made configuration file changes, user accounts, Ubuntu/SWM packages, and other settings as needed.

Bug Reporting and Feedback

… is encouraged. Please raise an issue at: https://jira.onap.org/projects/OPTFRA/summary