providers: Resolver and Factory types

These new types are adaptations of terraform.ProviderResolver and
terraform.ResourceProviderFactory respectively. In a later commit we will
update users of the old types to use these new types, possibly in a
"gradual repair" sort of fashion by initially using type aliases, though
that won't 100% solve the problem because the types themselves have
changed in this move to return providers.Interface instead of
terraform.ResourceProvider.
This commit is contained in:
Martin Atkins 2018-08-15 12:09:09 -07:00
parent bddfd0412c
commit 594a821ab3
1 changed files with 112 additions and 0 deletions

112
providers/resolver.go Normal file
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package providers
import (
"fmt"
"github.com/hashicorp/terraform/plugin/discovery"
)
// Resolver is an interface implemented by objects that are able to resolve
// a given set of resource provider version constraints into Factory
// callbacks.
type Resolver interface {
// Given a constraint map, return a Factory for each requested provider.
// If some or all of the constraints cannot be satisfied, return a non-nil
// slice of errors describing the problems.
ResolveProviders(reqd discovery.PluginRequirements) (map[string]Factory, []error)
}
// ResolverFunc wraps a callback function and turns it into a Resolver
// implementation, for convenience in situations where a function and its
// associated closure are sufficient as a resolver implementation.
type ResolverFunc func(reqd discovery.PluginRequirements) (map[string]Factory, []error)
// ResolveProviders implements Resolver by calling the
// wrapped function.
func (f ResolverFunc) ResolveProviders(reqd discovery.PluginRequirements) (map[string]Factory, []error) {
return f(reqd)
}
// ResolverFixed returns a Resolver that has a fixed set of provider factories
// provided by the caller. The returned resolver ignores version constraints
// entirely and just returns the given factory for each requested provider
// name.
//
// This function is primarily used in tests, to provide mock providers or
// in-process providers under test.
func ResolverFixed(factories map[string]Factory) Resolver {
return ResolverFunc(func(reqd discovery.PluginRequirements) (map[string]Factory, []error) {
ret := make(map[string]Factory, len(reqd))
var errs []error
for name := range reqd {
if factory, exists := factories[name]; exists {
ret[name] = factory
} else {
errs = append(errs, fmt.Errorf("provider %q is not available", name))
}
}
return ret, errs
})
}
// Factory is a function type that creates a new instance of a resource
// provider, or returns an error if that is impossible.
type Factory func() (Interface, error)
// FactoryFixed is a helper that creates a Factory that just returns some given
// single provider.
//
// Unlike usual factories, the exact same instance is returned for each call
// to the factory and so this must be used in only specialized situations where
// the caller can take care to either not mutate the given provider at all
// or to mutate it in ways that will not cause unexpected behavior for others
// holding the same reference.
func FactoryFixed(p Interface) Factory {
return func() (Interface, error) {
return p, nil
}
}
// ProviderHasResource is a helper that requests schema from the given provider
// and checks if it has a resource type of the given name.
//
// This function is more expensive than it may first appear since it must
// retrieve the entire schema from the underlying provider, and so it should
// be used sparingly and especially not in tight loops.
//
// Since retrieving the provider may fail (e.g. if the provider is accessed
// over an RPC channel that has operational problems), this function will
// return false if the schema cannot be retrieved, under the assumption that
// a subsequent call to do anything with the resource type would fail
// anyway.
func ProviderHasResource(provider Interface, typeName string) bool {
resp := provider.GetSchema()
if resp.Diagnostics.HasErrors() {
return false
}
_, exists := resp.ResourceTypes[typeName]
return exists
}
// ProviderHasDataSource is a helper that requests schema from the given
// provider and checks if it has a data source of the given name.
//
// This function is more expensive than it may first appear since it must
// retrieve the entire schema from the underlying provider, and so it should
// be used sparingly and especially not in tight loops.
//
// Since retrieving the provider may fail (e.g. if the provider is accessed
// over an RPC channel that has operational problems), this function will
// return false if the schema cannot be retrieved, under the assumption that
// a subsequent call to do anything with the data source would fail
// anyway.
func ProviderHasDataSource(provider Interface, dataSourceName string) bool {
resp := provider.GetSchema()
if resp.Diagnostics.HasErrors() {
return false
}
_, exists := resp.DataSources[dataSourceName]
return exists
}