39 lines
1.9 KiB
Markdown
39 lines
1.9 KiB
Markdown
## Design
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### YAML Configuration
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The main file that is handled by this program is the **Configuration File**.
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## Validation
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There are three types of validation: _schema_ which ensures that the input YAML has the correct
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fields of well known types, _semantic_ which ensures that the configuration doesn't violate
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semantic constraints and _runtime_ which ensures that the configuration can be applied to the
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VPP daemon.
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### Schema Validators
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First the configuration file is held against a structural validator, provided by [Yamale](https://github.com/23andMe/Yamale/).
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Based on a validation schema in `schema.yaml`, the input file is checked for syntax correctness.
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For example, a `dot1q` field must be an integer between 1 and 4095, wile an `lcp` string must
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match a certain regular expression. After this first pass of syntax validation, I'm certain that
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_if_ a field is set, it is of the right type (ie. string, int, enum).
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### Semantic Validators
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A set of semantic validators, each with a unique name, ensure that the _semantics_ of the YAML
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are correct. For example, a physical interface cannot have an LCP, addresses or sub-interfaces,
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if it is to be a member of a BondEthernet.
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Validators are expected to return a tuple of (bool,[string]) where the boolean signals success
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(False meaning the validator rejected the configuration file, True meaning it is known to be
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correct), and a list of zero or more strings which contain messages meant for human consumption.
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### Runtime Validators
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After the configuration file is considered syntax and semanticly valid, there is one more set of
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checks to perform -- runtime validators ensure that the configuration elements such as physical
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network devices (ie. `HundredGigabitEthernet12/0/0` or plugin `lcpng` are present on the system.
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It does this by connecting to VPP and querying the runtime state to ensure that what is modeled
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in the configuration file is able to be committed.
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