Rene Nochebuena
caa397591e
Introduces code.nochebuena.dev/einherjar/httpclient — the outbound HTTP client starter for the Einherjar framework. Absorbs the httpclient package from micro-lib, replacing fmt.Errorf wrapping with core/xerrors and adding generic JSON helpers. Interfaces: - Provider — Do(req *http.Request) (*http.Response, error) Implementation: - New(logger, cfg) Provider — configures net.Dialer + retry + circuit breaker - NewWithDefaults(logger) Provider — convenience constructor with default config - Retry: avast/retry-go; configurable MaxRetries and RetryDelay; retries on network errors and 5xx responses; logs each retry attempt at Warn level - Circuit breaker: sony/gobreaker; opens after CBThreshold consecutive failures within CBTimeout window; returns ErrUnavailable when open - DoJSON[T](ctx, client, req) (*T, error) — executes request, decodes JSON body - DoJSONRequest[Req, Resp](ctx, client, method, rawURL, body) (*Resp, error) — marshals body, builds request, executes, decodes response - MapStatusToError(code, msg) error — maps HTTP status codes to xerrors values Config (EINHERJAR_HTTP_* env vars): Name(http), Timeout(30s), DialTimeout(5s), MaxRetries(3), RetryDelay(1s), CBThreshold(10), CBTimeout(1m) - identifiable.go: package-level Module variable (observability.Identifiable) for version identification — httpclient is a stateless provider; not registered with the launcher
134 lines
3.4 KiB
Markdown
134 lines
3.4 KiB
Markdown
# einherjar/httpclient
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[](https://code.nochebuena.dev/einherjar/httpclient)
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[](LICENSE)
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[](https://go.dev)
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> To cross the realms, one must know the road — and how to wait when the bridge is down.
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`code.nochebuena.dev/einherjar/httpclient` is the outbound HTTP client component of the Einherjar framework. It composes retry (via `avast/retry-go`) and a circuit breaker (via `sony/gobreaker`) behind a single `Provider` interface with one method: `Do`. Generic helpers `DoJSON` and `DoJSONRequest` reduce boilerplate for JSON APIs without hiding the underlying client.
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---
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## Usage
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### Setup
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```go
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import "code.nochebuena.dev/einherjar/httpclient"
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// With env-var config
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client := httpclient.New(logger, httpclient.DefaultConfig())
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// Or zero-config with defaults
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client := httpclient.NewWithDefaults(logger)
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```
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`httpclient` is not a `lifecycle.Component` — it is stateless and requires no registration with the launcher.
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### Sending requests
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```go
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, "https://api.example.com/users", nil)
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if err != nil {
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return err
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}
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resp, err := client.Do(req)
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if err != nil {
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return err
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}
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defer resp.Body.Close()
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```
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### JSON GET helper
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```go
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type User struct {
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ID string `json:"id"`
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Name string `json:"name"`
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}
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req, _ := http.NewRequestWithContext(ctx, http.MethodGet, "https://api.example.com/users/123", nil)
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user, err := httpclient.DoJSON[User](ctx, client, req)
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// user is *User on success
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```
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### JSON POST helper
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```go
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type CreateReq struct {
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Name string `json:"name"`
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Email string `json:"email"`
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}
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type CreateResp struct {
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ID string `json:"id"`
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}
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resp, err := httpclient.DoJSONRequest[CreateReq, CreateResp](
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ctx, client,
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http.MethodPost, "https://api.example.com/users",
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CreateReq{Name: "Alice", Email: "alice@example.com"},
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)
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// resp is *CreateResp on success
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```
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### Error mapping
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```go
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// Map HTTP status codes to xerrors for consistent error handling
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err := httpclient.MapStatusToError(resp.StatusCode, "upstream error")
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// 400 → ErrInvalidInput
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// 401 → ErrUnauthorized
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// 403 → ErrPermissionDenied
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// 404 → ErrNotFound
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// 409 → ErrAlreadyExists
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// 429 → ErrRateLimited
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// 503 → ErrUnavailable
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```
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---
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## Environment variables
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| Variable | Required | Default | Description |
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| `EINHERJAR_HTTP_CLIENT_NAME` | No | `http` | Circuit breaker name (appears in logs) |
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| `EINHERJAR_HTTP_TIMEOUT` | No | `30s` | Total request timeout |
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| `EINHERJAR_HTTP_DIAL_TIMEOUT` | No | `5s` | TCP connection timeout |
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| `EINHERJAR_HTTP_MAX_RETRIES` | No | `3` | Maximum retry attempts |
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| `EINHERJAR_HTTP_RETRY_DELAY` | No | `1s` | Delay between retries |
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| `EINHERJAR_HTTP_CB_THRESHOLD` | No | `10` | Consecutive failures before circuit opens |
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| `EINHERJAR_HTTP_CB_TIMEOUT` | No | `1m` | Time before circuit attempts half-open |
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---
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## Dependency graph
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```
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contracts (zero dependencies)
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↑
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core
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↑
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httpclient (contracts, core, retry-go, gobreaker)
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↑
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your app
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```
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---
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## Verification
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```bash
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cd httpclient/
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go build ./...
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go vet ./...
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go test ./...
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gofmt -l .
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```
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---
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> *A warrior who cannot reach the other realm is useless to the battle.*
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> *Build the bridge. Make it resilient. Know when to wait.*
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