After review, there are cases where having common requirements for
namespaces and identifiers creates contention between applications. One
example is that it is nice to have namespaces comply with domain name
requirement, but that does not allow underscores, which are required for
certain identifiers.
The namespaces validation has been reverted to be in line with RFC 1035.
Existing identifiers has been modified to allow simply alpha-numeric
identifiers, while limiting adjacent separators.
We may follow up tweaks for the identifier charset but this split should
remove the hard decisions.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
A few days ago, we added validation for namespaces. We've decided to
expand these naming rules to include containers. To facilitate this, a
common package `identifiers` now provides a common validation area.
These rules will be extended to apply to task identifiers, snapshot keys
and other areas where user-provided identifiers may be used.
Signed-off-by: Stephen J Day <stephen.day@docker.com>
