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package client // import "github.com/docker/docker/client"
import (
"context"
"net/http"
"path"
"github.com/docker/docker/api/types"
"github.com/docker/docker/errdefs"
)
// Ping pings the server and returns the value of the "Docker-Experimental",
// "Builder-Version", "OS-Type" & "API-Version" headers. It attempts to use
// a HEAD request on the endpoint, but falls back to GET if HEAD is not supported
// by the daemon.
func (cli *Client) Ping(ctx context.Context) (types.Ping, error) {
var ping types.Ping
// Using cli.buildRequest() + cli.doRequest() instead of cli.sendRequest()
// because ping requests are used during API version negotiation, so we want
// to hit the non-versioned /_ping endpoint, not /v1.xx/_ping
req, err := cli.buildRequest(http.MethodHead, path.Join(cli.basePath, "/_ping"), nil, nil)
if err != nil {
return ping, err
}
serverResp, err := cli.doRequest(ctx, req)
if err == nil {
defer ensureReaderClosed(serverResp)
switch serverResp.statusCode {
case http.StatusOK, http.StatusInternalServerError:
// Server handled the request, so parse the response
return parsePingResponse(cli, serverResp)
}
} else if IsErrConnectionFailed(err) {
return ping, err
}
req, err = cli.buildRequest(http.MethodGet, path.Join(cli.basePath, "/_ping"), nil, nil)
if err != nil {
return ping, err
}
serverResp, err = cli.doRequest(ctx, req)
defer ensureReaderClosed(serverResp)
if err != nil {
return ping, err
}
return parsePingResponse(cli, serverResp)
}
func parsePingResponse(cli *Client, resp serverResponse) (types.Ping, error) {
var ping types.Ping
if resp.header == nil {
err := cli.checkResponseErr(resp)
return ping, errdefs.FromStatusCode(err, resp.statusCode)
}
ping.APIVersion = resp.header.Get("API-Version")
ping.OSType = resp.header.Get("OSType")
if resp.header.Get("Docker-Experimental") == "true" {
ping.Experimental = true
}
if bv := resp.header.Get("Builder-Version"); bv != "" {
ping.BuilderVersion = types.BuilderVersion(bv)
}
err := cli.checkResponseErr(resp)
return ping, errdefs.FromStatusCode(err, resp.statusCode)
}
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