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//
// Copyright 2021 The Sigstore Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package providers
import (
"context"
"errors"
"fmt"
"sync"
)
var (
m sync.Mutex
providers []ProviderEntry
)
type ProviderEntry struct {
Name string
Provider Interface
}
// Interface is what providers need to implement to participate in furnishing OIDC tokens.
type Interface interface {
// Enabled returns true if the provider is enabled.
Enabled(ctx context.Context) bool
// Provide returns an OIDC token scoped to the provided audience.
Provide(ctx context.Context, audience string) (string, error)
}
// Register is used by providers to participate in furnishing OIDC tokens.
func Register(name string, p Interface) {
m.Lock()
defer m.Unlock()
for _, pe := range providers {
if pe.Name == name {
panic(fmt.Sprintf("duplicate provider for name %q, %T and %T", name, pe.Provider, p))
}
}
providers = append(providers, ProviderEntry{Name: name, Provider: p})
}
// Enabled checks whether any of the registered providers are enabled in this execution context.
func Enabled(ctx context.Context) bool {
m.Lock()
defer m.Unlock()
for _, pe := range providers {
if pe.Provider.Enabled(ctx) {
return true
}
}
return false
}
// Provide fetches an OIDC token from one of the active providers.
func Provide(ctx context.Context, audience string) (string, error) {
m.Lock()
defer m.Unlock()
var id string
var err error
for _, pe := range providers {
p := pe.Provider
if !p.Enabled(ctx) {
continue
}
id, err = p.Provide(ctx, audience)
if err == nil {
return id, nil
}
}
// return the last id/err combo, unless there wasn't an error in
// which case provider.Enabled() wasn't checked.
if err == nil {
err = errors.New("no providers are enabled, check providers.Enabled() before providers.Provide()")
}
return id, err
}
// ProvideFrom fetches the specified provider
func ProvideFrom(_ context.Context, provider string) (Interface, error) {
m.Lock()
defer m.Unlock()
for _, p := range providers {
if p.Name == provider {
return p.Provider, nil
}
}
return nil, fmt.Errorf("%s is not a valid provider", provider)
}
func Providers() []ProviderEntry {
m.Lock()
defer m.Unlock()
return providers
}
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