feat(acrauth): add ACR login helper that writes container auth files #321
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,100 @@ | ||
| // Copyright 2025 Microsoft Corporation | ||
| // | ||
| // 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. | ||
|
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| package acrauth | ||
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| import ( | ||
| "context" | ||
| "errors" | ||
| "fmt" | ||
| "net/url" | ||
| "time" | ||
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| "github.com/Azure/azure-sdk-for-go/sdk/azcore" | ||
| "github.com/Azure/azure-sdk-for-go/sdk/azcore/policy" | ||
| "github.com/Azure/azure-sdk-for-go/sdk/containers/azcontainerregistry" | ||
| ) | ||
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| // NullGUIDUsername is the username ACR expects when the password is a refresh token. | ||
| const NullGUIDUsername = "00000000-0000-0000-0000-000000000000" | ||
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| const armScope = "https://management.azure.com/.default" | ||
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| // ExchangeForRefreshToken trades an Entra token for an ACR refresh token, which is what | ||
| // container tooling stores as the registry password. | ||
| func ExchangeForRefreshToken(ctx context.Context, cred azcore.TokenCredential, acrFQDN string) (string, error) { | ||
| endpoint, err := url.Parse(fmt.Sprintf("https://%s", acrFQDN)) | ||
| if err != nil { | ||
| return "", fmt.Errorf("failed to parse ACR endpoint: %w", err) | ||
| } | ||
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| client, err := azcontainerregistry.NewAuthenticationClient(endpoint.String(), nil) | ||
| if err != nil { | ||
| return "", fmt.Errorf("failed to create ACR authentication client: %w", err) | ||
| } | ||
|
|
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| armToken, err := cred.GetToken(ctx, policy.TokenRequestOptions{Scopes: []string{armScope}}) | ||
| if err != nil { | ||
| return "", fmt.Errorf("failed to get ARM token: %w", err) | ||
| } | ||
|
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| response, err := client.ExchangeAADAccessTokenForACRRefreshToken( | ||
| ctx, | ||
| azcontainerregistry.PostContentSchemaGrantTypeAccessToken, | ||
| endpoint.Hostname(), | ||
| &azcontainerregistry.AuthenticationClientExchangeAADAccessTokenForACRRefreshTokenOptions{ | ||
| AccessToken: &armToken.Token, | ||
| }, | ||
| ) | ||
| if err != nil { | ||
| return "", fmt.Errorf("failed to exchange AAD access token for ACR refresh token: %w", err) | ||
| } | ||
| if response.RefreshToken == nil || *response.RefreshToken == "" { | ||
| return "", errors.New("got an empty response when exchanging AAD access token for ACR refresh token") | ||
| } | ||
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| return *response.RefreshToken, nil | ||
| } | ||
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| const ( | ||
| retryAttempts = 5 | ||
| retryInitial = 2 * time.Second | ||
| retryFactor = 2 | ||
| ) | ||
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| // ExchangeForRefreshTokenWithRetry retries the exchange, which fails transiently while a | ||
| // freshly-granted role assignment propagates. | ||
| func ExchangeForRefreshTokenWithRetry(ctx context.Context, cred azcore.TokenCredential, acrFQDN string) (string, error) { | ||
| var lastErr error | ||
| delay := retryInitial | ||
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| for attempt := range retryAttempts { | ||
|
weherdh marked this conversation as resolved.
|
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| if attempt > 0 { | ||
| select { | ||
| case <-ctx.Done(): | ||
| return "", fmt.Errorf("failed to exchange ACR refresh token: %w: last exchange error: %w", ctx.Err(), lastErr) | ||
| case <-time.After(delay): | ||
| } | ||
| delay *= retryFactor | ||
| } | ||
|
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| token, err := ExchangeForRefreshToken(ctx, cred, acrFQDN) | ||
| if err == nil { | ||
| return token, nil | ||
| } | ||
| lastErr = err | ||
| } | ||
|
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| return "", fmt.Errorf("failed to exchange ACR refresh token after %d attempts: %w", retryAttempts, lastErr) | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,123 @@ | ||
| // Copyright 2025 Microsoft Corporation | ||
| // | ||
| // 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. | ||
|
|
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| package acrauth | ||
|
|
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| import ( | ||
| "encoding/base64" | ||
| "encoding/json" | ||
| "errors" | ||
| "fmt" | ||
| "io/fs" | ||
| "os" | ||
| "path/filepath" | ||
| ) | ||
|
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| // authFileMode keeps the credential readable only by its owner. | ||
| const authFileMode fs.FileMode = 0o600 | ||
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| // UpsertCredential adds or replaces the entry for one registry in a container auth file, | ||
| // leaving every other registry and any fields we don't model untouched. | ||
| func UpsertCredential(path, registry, username, password string) error { | ||
| if registry == "" { | ||
| return errors.New("registry must not be empty") | ||
| } | ||
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| document, err := readAuthFile(path) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| auths, ok := document["auths"].(map[string]any) | ||
| if !ok { | ||
| auths = map[string]any{} | ||
| } | ||
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| entry, ok := auths[registry].(map[string]any) | ||
| if !ok { | ||
| entry = map[string]any{} | ||
| } | ||
| entry["auth"] = base64.StdEncoding.EncodeToString([]byte(username + ":" + password)) | ||
|
Collaborator
There was a problem hiding this comment. This preserves an existing |
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| auths[registry] = entry | ||
| document["auths"] = auths | ||
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| return writeAuthFile(path, document) | ||
| } | ||
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| func readAuthFile(path string) (map[string]any, error) { | ||
| raw, err := os.ReadFile(path) | ||
| if errors.Is(err, fs.ErrNotExist) { | ||
| return map[string]any{}, nil | ||
| } | ||
| if err != nil { | ||
| return nil, fmt.Errorf("failed to read auth file %q: %w", path, err) | ||
| } | ||
| if len(raw) == 0 { | ||
| return map[string]any{}, nil | ||
| } | ||
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| var document map[string]any | ||
| if err := json.Unmarshal(raw, &document); err != nil { | ||
| return nil, fmt.Errorf("failed to parse auth file %q: %w", path, err) | ||
| } | ||
| if document == nil { | ||
| document = map[string]any{} | ||
| } | ||
| return document, nil | ||
| } | ||
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| // writeAuthFile writes through a temporary file in the same directory so a failure part-way | ||
| // through cannot leave the tool holding a truncated credential file. A bind-mounted auth file | ||
| // cannot be renamed over, so that path falls back to a non-atomic in-place write. | ||
| func writeAuthFile(path string, document map[string]any) error { | ||
| raw, err := json.MarshalIndent(document, "", " ") | ||
| if err != nil { | ||
| return fmt.Errorf("failed to serialize auth file: %w", err) | ||
| } | ||
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| dir := filepath.Dir(path) | ||
| if err := os.MkdirAll(dir, 0o755); err != nil { | ||
| return fmt.Errorf("failed to create directory %q: %w", dir, err) | ||
| } | ||
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| // CreateTemp opens with mode 0600, so the credential is never briefly world-readable. | ||
| tmp, err := os.CreateTemp(dir, ".auth-*.json") | ||
| if err != nil { | ||
| return fmt.Errorf("failed to create temporary auth file: %w", err) | ||
| } | ||
| defer func() { | ||
| _ = os.Remove(tmp.Name()) | ||
| }() | ||
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| if _, err := tmp.Write(raw); err != nil { | ||
| _ = tmp.Close() | ||
| return fmt.Errorf("failed to write temporary auth file: %w", err) | ||
| } | ||
| if err := tmp.Close(); err != nil { | ||
| return fmt.Errorf("failed to close temporary auth file: %w", err) | ||
| } | ||
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| if err := os.Rename(tmp.Name(), path); err != nil { | ||
| // A bind-mounted auth file cannot be renamed over (EBUSY), so write through it instead. | ||
| if fallbackErr := os.WriteFile(path, raw, authFileMode); fallbackErr != nil { | ||
| return fmt.Errorf("failed to replace auth file %q: %w: in-place write also failed: %w", path, err, fallbackErr) | ||
| } | ||
| // WriteFile only applies the mode when it creates the file, so an existing one keeps its own. | ||
| if chmodErr := os.Chmod(path, authFileMode); chmodErr != nil { | ||
| return fmt.Errorf("failed to restrict permissions on auth file %q: %w", path, chmodErr) | ||
| } | ||
| } | ||
| return nil | ||
| } | ||
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All five new Go files have CRLF line endings.
gofmt -l tools/acrauth/*.golists every file, andgo tool golangci-lint run ./tools/acrauth/...fails thegciformatter check. Please run the repository formatter and commit the LF-normalized files so the verify job can pass.