[openstack-dev] [Solum] Supporting swift downloads for operator languagepacks

Murali Allada murali.allada at RACKSPACE.COM
Wed Jun 17 16:40:16 UTC 2015

Hello Solum Developers,

When we were designing the operator languagepack feature for Solum, we wanted to make use of public urls to download operator LPs, such as those available for CDN backed swift containers we have at Rackspace, or any publicly accessible url. This would mean that when a user chooses to build applications on to??p of a languagepack provided by the operator, we use a url to 'wget' the LP image.

Recently, we have started noticing a number of failures because of corrupted docker images downloaded using 'wget'. The docker images work fine when we download them manually with a swift client and use them. The corruption seem to be happening when we try to download a large image using 'wget' and there are dropped packets or intermittent network issues.

My thinking is to start using the swift client to download operator LPs by default instead of wget. The swift client already implements retry logic, downloading large images in chunks, etc. This means we would not get the niceties of using publicly accessible urls. However, the feature will be more reliable and robust.

The implementation would be as follows:

  *   ?We'll use the existing service tenant configuration available in the solum config file to authenticate and store operator languagepacks using the swift client. We were using a different tenant to build and host LPs, but now that we require the tenants credentials in the config file, it's best to reuse the existing service tenant creds. Note: If we don't, we'll have 3 separate tenants to maintain.
     *   ?Service tenant
     *   Operator languagepack tenant
     *   Global admin tenant
  *   I'll keep the option to download the operator languagepacks from a publicly available url. I'll allow operators to choose which method they want to use by changing a setting in the solum config file.

FYI: In my tests, I've noticed that downloading an image using the swift client is twice as fast as downloading the same image using 'wget' from a CDN url.


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