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package credentials
import (
"github.com/aws/aws-sdk-go/aws/awserr"
)
var (
// ErrNoValidProvidersFoundInChain Is returned when there are no valid
// providers in the ChainProvider.
//
// This has been deprecated. For verbose error messaging set
// aws.Config.CredentialsChainVerboseErrors to true.
ErrNoValidProvidersFoundInChain = awserr.New("NoCredentialProviders",
`no valid providers in chain. Deprecated.
For verbose messaging see aws.Config.CredentialsChainVerboseErrors`,
nil)
)
// A ChainProvider will search for a provider which returns credentials
// and cache that provider until Retrieve is called again.
//
// The ChainProvider provides a way of chaining multiple providers together
// which will pick the first available using priority order of the Providers
// in the list.
//
// If none of the Providers retrieve valid credentials Value, ChainProvider's
// Retrieve() will return the error ErrNoValidProvidersFoundInChain.
//
// If a Provider is found which returns valid credentials Value ChainProvider
// will cache that Provider for all calls to IsExpired(), until Retrieve is
// called again.
//
// Example of ChainProvider to be used with an EnvProvider and EC2RoleProvider.
// In this example EnvProvider will first check if any credentials are available
// via the environment variables. If there are none ChainProvider will check
// the next Provider in the list, EC2RoleProvider in this case. If EC2RoleProvider
// does not return any credentials ChainProvider will return the error
// ErrNoValidProvidersFoundInChain
//
// creds := credentials.NewChainCredentials(
// []credentials.Provider{
// &credentials.EnvProvider{},
// &ec2rolecreds.EC2RoleProvider{
// Client: ec2metadata.New(sess),
// },
// })
//
// // Usage of ChainCredentials with aws.Config
// svc := ec2.New(session.Must(session.NewSession(&aws.Config{
// Credentials: creds,
// })))
//
type ChainProvider struct {
Providers []Provider
curr Provider
VerboseErrors bool
}
// NewChainCredentials returns a pointer to a new Credentials object
// wrapping a chain of providers.
func NewChainCredentials(providers []Provider) *Credentials {
return NewCredentials(&ChainProvider{
Providers: append([]Provider{}, providers...),
})
}
// Retrieve returns the credentials value or error if no provider returned
// without error.
//
// If a provider is found it will be cached and any calls to IsExpired()
// will return the expired state of the cached provider.
func (c *ChainProvider) Retrieve() (Value, error) {
var errs []error
for _, p := range c.Providers {
creds, err := p.Retrieve()
if err == nil {
c.curr = p
return creds, nil
}
errs = append(errs, err)
}
c.curr = nil
var err error
err = ErrNoValidProvidersFoundInChain
if c.VerboseErrors {
err = awserr.NewBatchError("NoCredentialProviders", "no valid providers in chain", errs)
}
return Value{}, err
}
// IsExpired will returned the expired state of the currently cached provider
// if there is one. If there is no current provider, true will be returned.
func (c *ChainProvider) IsExpired() bool {
if c.curr != nil {
return c.curr.IsExpired()
}
return true
}
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