120 lines
3.7 KiB
Go
120 lines
3.7 KiB
Go
package tracer
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import (
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"fmt"
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"net"
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"net/http"
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"runtime"
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"strconv"
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"strings"
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"time"
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)
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var tracerVersion = "v1.0"
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const (
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defaultHostname = "localhost"
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defaultPort = "8126"
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defaultAddress = defaultHostname + ":" + defaultPort
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defaultHTTPTimeout = time.Second // defines the current timeout before giving up with the send process
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traceCountHeader = "X-Datadog-Trace-Count" // header containing the number of traces in the payload
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)
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// Transport is an interface for span submission to the agent.
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type transport interface {
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send(p *payload) error
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}
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// newTransport returns a new Transport implementation that sends traces to a
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// trace agent running on the given hostname and port. If the zero values for
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// hostname and port are provided, the default values will be used ("localhost"
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// for hostname, and "8126" for port).
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//
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// In general, using this method is only necessary if you have a trace agent
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// running on a non-default port or if it's located on another machine.
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func newTransport(addr string) transport {
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return newHTTPTransport(addr)
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}
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// newDefaultTransport return a default transport for this tracing client
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func newDefaultTransport() transport {
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return newHTTPTransport(defaultAddress)
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}
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type httpTransport struct {
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traceURL string // the delivery URL for traces
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client *http.Client // the HTTP client used in the POST
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headers map[string]string // the Transport headers
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}
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// newHTTPTransport returns an httpTransport for the given endpoint
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func newHTTPTransport(addr string) *httpTransport {
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// initialize the default EncoderPool with Encoder headers
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defaultHeaders := map[string]string{
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"Datadog-Meta-Lang": "go",
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"Datadog-Meta-Lang-Version": strings.TrimPrefix(runtime.Version(), "go"),
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"Datadog-Meta-Lang-Interpreter": runtime.Compiler + "-" + runtime.GOARCH + "-" + runtime.GOOS,
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"Datadog-Meta-Tracer-Version": tracerVersion,
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"Content-Type": "application/msgpack",
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}
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host, port, _ := net.SplitHostPort(addr)
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if host == "" {
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host = defaultHostname
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}
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if port == "" {
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port = defaultPort
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}
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addr = fmt.Sprintf("%s:%s", host, port)
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return &httpTransport{
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traceURL: fmt.Sprintf("http://%s/v0.3/traces", addr),
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client: &http.Client{
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// We copy the transport to avoid using the default one, as it might be
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// augmented with tracing and we don't want these calls to be recorded.
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// See https://golang.org/pkg/net/http/#DefaultTransport .
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Transport: &http.Transport{
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Proxy: http.ProxyFromEnvironment,
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DialContext: (&net.Dialer{
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Timeout: 30 * time.Second,
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KeepAlive: 30 * time.Second,
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DualStack: true,
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}).DialContext,
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MaxIdleConns: 100,
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IdleConnTimeout: 90 * time.Second,
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TLSHandshakeTimeout: 10 * time.Second,
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ExpectContinueTimeout: 1 * time.Second,
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},
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Timeout: defaultHTTPTimeout,
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},
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headers: defaultHeaders,
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}
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}
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func (t *httpTransport) send(p *payload) error {
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// prepare the client and send the payload
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req, err := http.NewRequest("POST", t.traceURL, p)
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if err != nil {
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return fmt.Errorf("cannot create http request: %v", err)
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}
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for header, value := range t.headers {
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req.Header.Set(header, value)
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}
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req.Header.Set(traceCountHeader, strconv.Itoa(p.itemCount()))
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req.Header.Set("Content-Length", strconv.Itoa(p.size()))
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response, err := t.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 response.Body.Close()
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if code := response.StatusCode; code >= 400 {
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// error, check the body for context information and
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// return a nice error.
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msg := make([]byte, 1000)
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n, _ := response.Body.Read(msg)
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txt := http.StatusText(code)
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if n > 0 {
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return fmt.Errorf("%s (Status: %s)", msg[:n], txt)
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}
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return fmt.Errorf("%s", txt)
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}
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return nil
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}
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