Documentation
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Overview ¶
Package http is the HTTP backend of the Prometheus querier: instant queries reduced to one sample, and range queries reduced to one series, over a Prometheus server's HTTP query API. Both fail closed: a result that is not exactly one finite value (or one series of them) is an error, never a silent zero.
Index ¶
Constants ¶
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Variables ¶
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Functions ¶
This section is empty.
Types ¶
type Client ¶
type Client struct {
// contains filtered or unexported fields
}
Client queries the Prometheus server at its base URL.
func New ¶
New builds the client for the Prometheus server at baseURL (e.g. the in-cluster service address), sending requests through doer.
func (*Client) Query ¶
Query evaluates promql as an instant query and returns its single sample value. No sample, several series, or a NaN or infinite value is an error: a value that can't be measured is never reported as 0.
func (*Client) QueryRange ¶
func (c *Client) QueryRange( ctx context.Context, promql string, start, end time.Time, step time.Duration, ) ([]Sample, error)
QueryRange evaluates promql over [start, end] at step and returns its single series. No series is an empty series (nothing was recorded in the window); several series or a NaN or infinite sample is an error.
type Config ¶
type Config struct {
// BaseURL is the Prometheus server root (e.g. its in-cluster service address);
// required.
BaseURL string `yaml:"base_url" mapstructure:"base_url"`
// Timeout is the http.Client timeout: it bounds each HTTP attempt, response body
// included, even with the client resilience disabled; zero means no transport
// bound.
Timeout time.Duration `yaml:"timeout" mapstructure:"timeout"`
// MaxBodyBytes caps a response body the backend buffers; a larger one is
// CodeInvalidInput. Zero or less means no cap.
MaxBodyBytes int64 `yaml:"max_body_bytes" mapstructure:"max_body_bytes"`
}
Config configures the HTTP backend.
type HTTPDoer ¶
type HTTPDoer interface {
// Do sends req and returns its response (the caller closes its body).
Do(req *nethttp.Request) (*nethttp.Response, error)
}
HTTPDoer is the HTTP boundary the client sends its requests through.
SDK seam — matches *nethttp.Client's Do, the stdlib HTTP transport boundary; it types the wire call, not a port, so it cannot compose with a core interface.
func DecorateDoer ¶
DecorateDoer runs every request inner sends through the client tier (c), as the operation "prometheus.<last path segment>" (prometheus.query, prometheus.query_range).
Each attempt reads the whole response body before the tier's per-attempt timeout ends, so the returned body is buffered and the deadline cannot cut a read short. A body larger than maxBodyBytes is CodeInvalidInput (narrow the query); zero or less means no limit.
Query requests are GETs, so every attempt is retryable. A transport error keeps a code it already carries; otherwise the caller's deadline is CodeTimeout, its cancellation CodeCanceled, and any other failure CodeUnavailable. A throttling or unavailable status (429, 502, 503, 504) is a CodeUnavailable error, so the tier retries it and its breaker counts it. Any other status passes through for the client to code.
Source Files