69 lines
1.6 KiB
Go
69 lines
1.6 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package prober
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"net/http"
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)
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const maxHTTPBody = 4 << 20 // MiB
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// HTTP returns a ProbeClass that healthchecks an HTTP URL.
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//
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// The probe function sends a GET request for url, expects an HTTP 200
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// response, and verifies that want is present in the response
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// body.
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func HTTP(url, wantText string) ProbeClass {
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return ProbeClass{
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Probe: func(ctx context.Context) error {
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return probeHTTP(ctx, url, []byte(wantText))
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},
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Class: "http",
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}
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}
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func probeHTTP(ctx context.Context, url string, want []byte) error {
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req, err := http.NewRequestWithContext(ctx, "GET", url, nil)
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if err != nil {
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return fmt.Errorf("constructing request: %w", err)
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}
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// Get a completely new transport each time, so we don't reuse a
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// past connection.
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tr := http.DefaultTransport.(*http.Transport).Clone()
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defer tr.CloseIdleConnections()
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c := &http.Client{
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Transport: tr,
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}
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resp, err := c.Do(req)
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if err != nil {
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return fmt.Errorf("fetching %q: %w", url, err)
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}
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defer resp.Body.Close()
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if resp.StatusCode != 200 {
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return fmt.Errorf("fetching %q: status code %d, want 200", url, resp.StatusCode)
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}
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bs, err := io.ReadAll(io.LimitReader(resp.Body, maxHTTPBody))
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if err != nil {
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return fmt.Errorf("reading body of %q: %w", url, err)
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}
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if !bytes.Contains(bs, want) {
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// Log response body, but truncate it if it's too large; the limit
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// has been chosen arbitrarily.
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if maxlen := 300; len(bs) > maxlen {
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bs = bs[:maxlen]
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}
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return fmt.Errorf("body of %q does not contain %q (got: %q)", url, want, string(bs))
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}
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return nil
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}
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