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dnswatcher/internal/notify/export_test.go
clawbot 23f115053b
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feat: add retry with exponential backoff for notification delivery (#87)
## Summary

Notifications were fire-and-forget: if Slack, Mattermost, or ntfy was temporarily down, changes were silently lost. This adds automatic retry with exponential backoff and jitter to all notification endpoints.

## Changes

### New file: `internal/notify/retry.go`
- `RetryConfig` struct with configurable max retries, base delay, max delay
- `backoff()` computes delay as `BaseDelay * 2^attempt`, capped at `MaxDelay`, with ±25% jitter
- `deliverWithRetry()` wraps any send function with the retry loop
- Defaults: 3 retries (4 total attempts), 1s base delay, 10s max delay
- Context-aware: respects cancellation during retry sleep
- Injectable `sleepFn` for test determinism

### Modified: `internal/notify/notify.go`
- Added `retryConfig` and `sleepFn` fields to `Service`
- Updated `dispatchNtfy`, `dispatchSlack`, `dispatchMattermost` to wrap sends in `deliverWithRetry`
- Structured logging: warns on each retry, logs error only after all retries exhausted, logs info on success after retry

### Modified: `internal/notify/export_test.go`
- Added test helpers: `SetRetryConfig`, `SetSleepFunc`, `DeliverWithRetry`, `BackoffDuration`

### New file: `internal/notify/retry_test.go`
- Backoff calculation tests (exponential increase, max cap with jitter)
- `deliverWithRetry` unit tests: first-attempt success, transient failure recovery, exhausted retries, context cancellation
- Integration tests via `SendNotification`: transient failure retries, all-endpoints retry independently, permanent failure exhausts retries

## Verification
- `make fmt` 
- `make check` (format + lint + tests + build) 
- `docker build .` 
- All existing tests continue to pass unchanged
- No DNS client mocking — notification tests use `httptest` servers

closes #62

Co-authored-by: clawbot <clawbot@noreply.git.eeqj.de>
Reviewed-on: #87
Co-authored-by: clawbot <clawbot@noreply.example.org>
Co-committed-by: clawbot <clawbot@noreply.example.org>
2026-03-22 07:14:59 +01:00

106 lines
2.4 KiB
Go

package notify
import (
"context"
"io"
"log/slog"
"net/http"
"net/url"
"time"
)
// NtfyPriority exports ntfyPriority for testing.
func NtfyPriority(priority string) string {
return ntfyPriority(priority)
}
// SlackColor exports slackColor for testing.
func SlackColor(priority string) string {
return slackColor(priority)
}
// NewRequestForTest exports newRequest for testing.
func NewRequestForTest(
ctx context.Context,
method string,
target *url.URL,
body io.Reader,
) *http.Request {
return newRequest(ctx, method, target, body)
}
// NewTestService creates a Service suitable for unit testing.
// It discards log output and uses the given transport.
func NewTestService(transport http.RoundTripper) *Service {
return &Service{
log: slog.New(slog.DiscardHandler),
transport: transport,
history: NewAlertHistory(),
}
}
// SetNtfyURL sets the ntfy URL on a Service for testing.
func (svc *Service) SetNtfyURL(u *url.URL) {
svc.ntfyURL = u
}
// SetSlackWebhookURL sets the Slack webhook URL on a
// Service for testing.
func (svc *Service) SetSlackWebhookURL(u *url.URL) {
svc.slackWebhookURL = u
}
// SetMattermostWebhookURL sets the Mattermost webhook URL on
// a Service for testing.
func (svc *Service) SetMattermostWebhookURL(u *url.URL) {
svc.mattermostWebhookURL = u
}
// SendNtfy exports sendNtfy for testing.
func (svc *Service) SendNtfy(
ctx context.Context,
topicURL *url.URL,
title, message, priority string,
) error {
return svc.sendNtfy(ctx, topicURL, title, message, priority)
}
// SendSlack exports sendSlack for testing.
func (svc *Service) SendSlack(
ctx context.Context,
webhookURL *url.URL,
title, message, priority string,
) error {
return svc.sendSlack(
ctx, webhookURL, title, message, priority,
)
}
// SetRetryConfig overrides the retry configuration for
// testing.
func (svc *Service) SetRetryConfig(cfg RetryConfig) {
svc.retryConfig = cfg
}
// SetSleepFunc overrides the sleep function so tests can
// eliminate real delays.
func (svc *Service) SetSleepFunc(
fn func(time.Duration) <-chan time.Time,
) {
svc.sleepFn = fn
}
// DeliverWithRetry exports deliverWithRetry for testing.
func (svc *Service) DeliverWithRetry(
ctx context.Context,
endpoint string,
fn func(context.Context) error,
) error {
return svc.deliverWithRetry(ctx, endpoint, fn)
}
// BackoffDuration exports RetryConfig.backoff for testing.
func (rc RetryConfig) BackoffDuration(attempt int) time.Duration {
return rc.defaults().backoff(attempt)
}