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The ability to deploy a local directory of puppet modules to an overcloud using the OpenStack swift object service.
None of the above mechanisms provides an easy workflow when making minor (ad-hoc) changes to the puppet modules and only distro packages can be used to provide updated puppet modules to an already deployed overcloud. While we do have a way to rsync over updated modules on “firstboot” via rsync this isn’t a useful mechanism for operator who may wish to use heat stack-update to deploy puppet changes without having to build a new RPM/Deb package for each revision.
Create an optional (opt-in) workflow that if enabled will allow an operator to create and deploy a local artifact (tarball, distro package, etc.) of puppet modules to a new or existing overcloud via heat stack-create and stack-update. The mechanism would use the OpenStack object store service (rather than rsync) which we already have available on the undercloud. The new workflow would work like this:
- A puppet modules artifact (tarball, distro package, etc.) would be uploaded into a swift container.
- The container would be configured so that a Swift Temp URL can be generated
- A Swift Temp URL would be generated for the puppet modules URL that is stored in swift
- A heat environment would be generated which sets a DeployArtifactURLs parameter to this swift URL. (the parameter could be a list so that multiple URLs could also be downloaded.)
- The TripleO Heat Templates would be modified so that they include a new ‘script’ step which if it detects a custom DeployArtifactURLs parameter would automatically download the artifact from the provided URL, and deploy it locally on each overcloud role during the deployment workflow. By “deploy locally” we mean a tarball would be extracted, and RPM would get installed, etc. The actual deployment mechanism will be pluggable such that both tarballs and distro packages will be supported and future additions might be added as well so long as they also fit into the generic DeployArtifactURLs abstraction.
- The Operator could then use the generated heat environment to deploy a new set of puppet modules via heat stack-create or heat stack-update.
- TripleO client could be modified so that it automically loads generated heat environments in a convienent location. This (optional) extra step would make enabling the above workflow transparent and only require the operator to run a ‘upload-puppet-modules’ tool to upload and configure new puppet modules for deployment via Swift.
There are many alternatives we could use to obtain a similar workflow that allows the operator to more deploy puppet modules from a local directory:
- Setting up a puppet master would allow a similar workflow. The downside of this approach is that it would require a bit of overhead, and it is puppet specific (the deployment mechanism would need to be re-worked if we ever had other types of on-disk files to update).
- Rsync. We already support rsync for firstboot scripts. The downside of rsync is it requires extra setup, and doesn’t have an API like OpenStack swift does allowing for local or remote management and updates to the puppet modules.
The new deployment would use a Swift Temp URL over HTTP/HTTPS. The duration of the Swift Temp URL’s can be controlled when they are signed via swift-temp-url if extra security is desired. By using a Swift Temp URL we avoid the need to pass the administrators credentials onto each overcloud node for swiftclient and instead can simply use curl (or wget) to download the updated puppet modules. Given we already deploy images over http/https using an undercloud the use of Swift in this manner should pose minimal extra security risks.
The ability to deploy puppet modules via Swift will be opt-in so the impact on end users would be minimal. The heat templates will contain a new script deployment that may take a few extra seconds to deploy on each node (even if the feature is not enabled). We could avoid the extra deployment time perhaps by noop’ing out the heat resource for the new swift puppet module deployment.
Developers and Operators would likely be able to deploy puppet module changes more quickly (without having to create a distro package). The actual deployment of puppet modules via swift (downloading and extracting the tarball) would likely be just as fast as a tarball.
Being able to more easily deploy updated puppet modules to an overcloud would likely speed up the development update and testing cycle of puppet modules.
- Create an upload-puppet-modules script in tripleo-common. Initially this may be a bash script which we ultimately refine into a Python version if it proves useful.
- Modify tripleo-heat-templates so that it supports a DeployArtifactURLs parameter (if the parameter is set) attempt to deploy the list of files from this parameter. The actual contents of the file might be a tarball or a distribution package (RPM).
- Modify tripleoclient so that the workflow around using upload-puppet-modules can be “transparent”. Simply running upload-puppet-modules would not only upload the puppet modules it would also generate a Heat environment that would then automatically configure heat stack-update/create commands to use the new URL via a custom heat environment.
- Update our CI scripts in tripleo-ci and/or tripleo-common so that we make use of the new Puppet modules deployment mechanism.
- Update tripleo-docs to make note of the new feature.
We would likely want to switch to use this feature in our CI because it allows us to avoid git cloning the same puppet modules for both the undercloud and overcloud nodes. Simply calling the extra upload-puppet-modules script on the undercloud as part of our deployment workflow would enable the feature and allow it to be tested.
We would need to document the additional (optional) workflow associated with deploying puppet modules via Swift.