1package config
2
3import (
4 "context"
5 "os"
6
7 "github.com/aws/aws-sdk-go-v2/aws"
8)
9
10// defaultAWSConfigResolvers are a slice of functions that will resolve external
11// configuration values into AWS configuration values.
12//
13// This will setup the AWS configuration's Region,
14var defaultAWSConfigResolvers = []awsConfigResolver{
15 // Resolves the default configuration the SDK's aws.Config will be
16 // initialized with.
17 resolveDefaultAWSConfig,
18
19 // Sets the logger to be used. Could be user provided logger, and client
20 // logging mode.
21 resolveLogger,
22 resolveClientLogMode,
23
24 // Sets the HTTP client and configuration to use for making requests using
25 // the HTTP transport.
26 resolveHTTPClient,
27 resolveCustomCABundle,
28
29 // Sets the endpoint resolving behavior the API Clients will use for making
30 // requests to. Clients default to their own clients this allows overrides
31 // to be specified. The resolveEndpointResolver option is deprecated, but
32 // we still need to set it for backwards compatibility on config
33 // construction.
34 resolveEndpointResolver,
35 resolveEndpointResolverWithOptions,
36
37 // Sets the retry behavior API clients will use within their retry attempt
38 // middleware. Defaults to unset, allowing API clients to define their own
39 // retry behavior.
40 resolveRetryer,
41
42 // Sets the region the API Clients should use for making requests to.
43 resolveRegion,
44 resolveEC2IMDSRegion,
45 resolveDefaultRegion,
46
47 // Sets the additional set of middleware stack mutators that will custom
48 // API client request pipeline middleware.
49 resolveAPIOptions,
50
51 // Resolves the DefaultsMode that should be used by SDK clients. If this
52 // mode is set to DefaultsModeAuto.
53 //
54 // Comes after HTTPClient and CustomCABundle to ensure the HTTP client is
55 // configured if provided before invoking IMDS if mode is auto. Comes
56 // before resolving credentials so that those subsequent clients use the
57 // configured auto mode.
58 resolveDefaultsModeOptions,
59
60 // Sets the resolved credentials the API clients will use for
61 // authentication. Provides the SDK's default credential chain.
62 //
63 // Should probably be the last step in the resolve chain to ensure that all
64 // other configurations are resolved first in case downstream credentials
65 // implementations depend on or can be configured with earlier resolved
66 // configuration options.
67 resolveCredentials,
68
69 // Sets the resolved bearer authentication token API clients will use for
70 // httpBearerAuth authentication scheme.
71 resolveBearerAuthToken,
72
73 // Sets the sdk app ID if present in env var or shared config profile
74 resolveAppID,
75
76 resolveBaseEndpoint,
77
78 // Sets the DisableRequestCompression if present in env var or shared config profile
79 resolveDisableRequestCompression,
80
81 // Sets the RequestMinCompressSizeBytes if present in env var or shared config profile
82 resolveRequestMinCompressSizeBytes,
83
84 // Sets the AccountIDEndpointMode if present in env var or shared config profile
85 resolveAccountIDEndpointMode,
86}
87
88// A Config represents a generic configuration value or set of values. This type
89// will be used by the AWSConfigResolvers to extract
90//
91// General the Config type will use type assertion against the Provider interfaces
92// to extract specific data from the Config.
93type Config interface{}
94
95// A loader is used to load external configuration data and returns it as
96// a generic Config type.
97//
98// The loader should return an error if it fails to load the external configuration
99// or the configuration data is malformed, or required components missing.
100type loader func(context.Context, configs) (Config, error)
101
102// An awsConfigResolver will extract configuration data from the configs slice
103// using the provider interfaces to extract specific functionality. The extracted
104// configuration values will be written to the AWS Config value.
105//
106// The resolver should return an error if it it fails to extract the data, the
107// data is malformed, or incomplete.
108type awsConfigResolver func(ctx context.Context, cfg *aws.Config, configs configs) error
109
110// configs is a slice of Config values. These values will be used by the
111// AWSConfigResolvers to extract external configuration values to populate the
112// AWS Config type.
113//
114// Use AppendFromLoaders to add additional external Config values that are
115// loaded from external sources.
116//
117// Use ResolveAWSConfig after external Config values have been added or loaded
118// to extract the loaded configuration values into the AWS Config.
119type configs []Config
120
121// AppendFromLoaders iterates over the slice of loaders passed in calling each
122// loader function in order. The external config value returned by the loader
123// will be added to the returned configs slice.
124//
125// If a loader returns an error this method will stop iterating and return
126// that error.
127func (cs configs) AppendFromLoaders(ctx context.Context, loaders []loader) (configs, error) {
128 for _, fn := range loaders {
129 cfg, err := fn(ctx, cs)
130 if err != nil {
131 return nil, err
132 }
133
134 cs = append(cs, cfg)
135 }
136
137 return cs, nil
138}
139
140// ResolveAWSConfig returns a AWS configuration populated with values by calling
141// the resolvers slice passed in. Each resolver is called in order. Any resolver
142// may overwrite the AWS Configuration value of a previous resolver.
143//
144// If an resolver returns an error this method will return that error, and stop
145// iterating over the resolvers.
146func (cs configs) ResolveAWSConfig(ctx context.Context, resolvers []awsConfigResolver) (aws.Config, error) {
147 var cfg aws.Config
148
149 for _, fn := range resolvers {
150 if err := fn(ctx, &cfg, cs); err != nil {
151 return aws.Config{}, err
152 }
153 }
154
155 return cfg, nil
156}
157
158// ResolveConfig calls the provide function passing slice of configuration sources.
159// This implements the aws.ConfigResolver interface.
160func (cs configs) ResolveConfig(f func(configs []interface{}) error) error {
161 var cfgs []interface{}
162 for i := range cs {
163 cfgs = append(cfgs, cs[i])
164 }
165 return f(cfgs)
166}
167
168// LoadDefaultConfig reads the SDK's default external configurations, and
169// populates an AWS Config with the values from the external configurations.
170//
171// An optional variadic set of additional Config values can be provided as input
172// that will be prepended to the configs slice. Use this to add custom configuration.
173// The custom configurations must satisfy the respective providers for their data
174// or the custom data will be ignored by the resolvers and config loaders.
175//
176// cfg, err := config.LoadDefaultConfig( context.TODO(),
177// config.WithSharedConfigProfile("test-profile"),
178// )
179// if err != nil {
180// panic(fmt.Sprintf("failed loading config, %v", err))
181// }
182//
183// The default configuration sources are:
184// * Environment Variables
185// * Shared Configuration and Shared Credentials files.
186func LoadDefaultConfig(ctx context.Context, optFns ...func(*LoadOptions) error) (cfg aws.Config, err error) {
187 var options LoadOptions
188 for _, optFn := range optFns {
189 if err := optFn(&options); err != nil {
190 return aws.Config{}, err
191 }
192 }
193
194 // assign Load Options to configs
195 var cfgCpy = configs{options}
196
197 cfgCpy, err = cfgCpy.AppendFromLoaders(ctx, resolveConfigLoaders(&options))
198 if err != nil {
199 return aws.Config{}, err
200 }
201
202 cfg, err = cfgCpy.ResolveAWSConfig(ctx, defaultAWSConfigResolvers)
203 if err != nil {
204 return aws.Config{}, err
205 }
206
207 return cfg, nil
208}
209
210func resolveConfigLoaders(options *LoadOptions) []loader {
211 loaders := make([]loader, 2)
212 loaders[0] = loadEnvConfig
213
214 // specification of a profile should cause a load failure if it doesn't exist
215 if os.Getenv(awsProfileEnvVar) != "" || options.SharedConfigProfile != "" {
216 loaders[1] = loadSharedConfig
217 } else {
218 loaders[1] = loadSharedConfigIgnoreNotExist
219 }
220
221 return loaders
222}