109 lines
3.8 KiB
Go
109 lines
3.8 KiB
Go
/*
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Copyright © 2020 Chris Mellard chris.mellard@icloud.com
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package token
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import (
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"fmt"
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"os"
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"github.com/Azure/go-autorest/autorest/adal"
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"github.com/Azure/go-autorest/autorest/azure/auth"
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)
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func GetServicePrincipalTokenFromEnvironment() (*adal.ServicePrincipalToken, auth.EnvironmentSettings, error) {
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settings, err := auth.GetSettingsFromEnvironment()
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if err != nil {
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return &adal.ServicePrincipalToken{}, auth.EnvironmentSettings{}, fmt.Errorf("failed to get auth settings from environment - %w", err)
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}
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spToken, err := getServicePrincipalToken(settings, settings.Environment.ResourceManagerEndpoint)
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if err != nil {
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return &adal.ServicePrincipalToken{}, auth.EnvironmentSettings{}, fmt.Errorf("failed to initialise sp token config %w", err)
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}
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return spToken, settings, nil
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}
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// getServicePrincipalToken retrieves an Azure AD OAuth2 token from the supplied environment settings for the specified resource
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func getServicePrincipalToken(settings auth.EnvironmentSettings, resource string) (*adal.ServicePrincipalToken, error) {
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//1.Client Credentials
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if _, e := settings.GetClientCredentials(); e == nil {
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clientCredentialsConfig, err := settings.GetClientCredentials()
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if err != nil {
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return &adal.ServicePrincipalToken{}, fmt.Errorf("failed to get client credentials settings from environment - %w", err)
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}
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oAuthConfig, err := adal.NewOAuthConfig(settings.Environment.ActiveDirectoryEndpoint, clientCredentialsConfig.TenantID)
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if err != nil {
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return &adal.ServicePrincipalToken{}, fmt.Errorf("failed to initialise OAuthConfig - %w", err)
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}
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return adal.NewServicePrincipalToken(*oAuthConfig, clientCredentialsConfig.ClientID, clientCredentialsConfig.ClientSecret, clientCredentialsConfig.Resource)
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}
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//2. Client Certificate
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if _, e := settings.GetClientCertificate(); e == nil {
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return &adal.ServicePrincipalToken{}, fmt.Errorf("authentication method currently unsupported")
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}
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//3. Username Password
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if _, e := settings.GetUsernamePassword(); e == nil {
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return &adal.ServicePrincipalToken{}, fmt.Errorf("authentication method currently unsupported")
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}
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// federated OIDC JWT assertion
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jwt, err := jwtLookup()
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if err == nil {
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clientID, isPresent := os.LookupEnv("AZURE_CLIENT_ID")
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if !isPresent {
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return &adal.ServicePrincipalToken{}, fmt.Errorf("failed to get client id from environment")
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}
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tenantID, isPresent := os.LookupEnv("AZURE_TENANT_ID")
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if !isPresent {
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return &adal.ServicePrincipalToken{}, fmt.Errorf("failed to get client id from environment")
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}
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oAuthConfig, err := adal.NewOAuthConfig(settings.Environment.ActiveDirectoryEndpoint, tenantID)
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if err != nil {
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return &adal.ServicePrincipalToken{}, fmt.Errorf("failed to initialise OAuthConfig - %w", err)
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}
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return adal.NewServicePrincipalTokenFromFederatedToken(*oAuthConfig, clientID, *jwt, resource)
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}
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// 4. MSI
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return adal.NewServicePrincipalTokenFromManagedIdentity(resource, &adal.ManagedIdentityOptions{
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ClientID: os.Getenv("AZURE_CLIENT_ID"),
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})
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}
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func jwtLookup() (*string, error) {
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jwt, isPresent := os.LookupEnv("AZURE_FEDERATED_TOKEN")
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if isPresent {
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return &jwt, nil
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}
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if jwtFile, isPresent := os.LookupEnv("AZURE_FEDERATED_TOKEN_FILE"); isPresent {
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jwtBytes, err := os.ReadFile(jwtFile)
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if err != nil {
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return nil, err
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}
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jwt = string(jwtBytes)
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return &jwt, nil
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}
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return nil, fmt.Errorf("no JWT found")
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}
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