Struct: credentials.ChainProvider

import "../ibm-cos-sdk-go/aws/credentials"

Overview

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,
})))

Implemented Interfaces

s3crypto.Cipher, credentials.Provider, s3manager.ReadSeekerWriteTo, s3manager.WriterReadFrom

Structure Field Summary collapse

Method Summary collapse

Structure Field Details

Providers []Provider

VerboseErrors bool

Method Details

func (c *ChainProvider) IsExpired() bool

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.



92
93
94
95
96
97
98
 
// File 'aws/credentials/chain_provider.go', line 92


func (c *ChainProvider) IsExpired() bool {
	if c.curr != nil {
		return c.curr.IsExpired()
	}

	return true
}

func (c *ChainProvider) Retrieve() (Value, error)

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.



70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
 
// File 'aws/credentials/chain_provider.go', line 70


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
}