github.com/kaisenlinux/docker.io@v0.0.0-20230510090727-ea55db55fac7/engine/client/ping.go (about)

     1  package client // import "github.com/docker/docker/client"
     2  
     3  import (
     4  	"context"
     5  	"net/http"
     6  	"path"
     7  
     8  	"github.com/docker/docker/api/types"
     9  	"github.com/docker/docker/errdefs"
    10  )
    11  
    12  // Ping pings the server and returns the value of the "Docker-Experimental",
    13  // "Builder-Version", "OS-Type" & "API-Version" headers. It attempts to use
    14  // a HEAD request on the endpoint, but falls back to GET if HEAD is not supported
    15  // by the daemon.
    16  func (cli *Client) Ping(ctx context.Context) (types.Ping, error) {
    17  	var ping types.Ping
    18  
    19  	// Using cli.buildRequest() + cli.doRequest() instead of cli.sendRequest()
    20  	// because ping requests are used during API version negotiation, so we want
    21  	// to hit the non-versioned /_ping endpoint, not /v1.xx/_ping
    22  	req, err := cli.buildRequest(http.MethodHead, path.Join(cli.basePath, "/_ping"), nil, nil)
    23  	if err != nil {
    24  		return ping, err
    25  	}
    26  	serverResp, err := cli.doRequest(ctx, req)
    27  	if err == nil {
    28  		defer ensureReaderClosed(serverResp)
    29  		switch serverResp.statusCode {
    30  		case http.StatusOK, http.StatusInternalServerError:
    31  			// Server handled the request, so parse the response
    32  			return parsePingResponse(cli, serverResp)
    33  		}
    34  	} else if IsErrConnectionFailed(err) {
    35  		return ping, err
    36  	}
    37  
    38  	req, err = cli.buildRequest(http.MethodGet, path.Join(cli.basePath, "/_ping"), nil, nil)
    39  	if err != nil {
    40  		return ping, err
    41  	}
    42  	serverResp, err = cli.doRequest(ctx, req)
    43  	defer ensureReaderClosed(serverResp)
    44  	if err != nil {
    45  		return ping, err
    46  	}
    47  	return parsePingResponse(cli, serverResp)
    48  }
    49  
    50  func parsePingResponse(cli *Client, resp serverResponse) (types.Ping, error) {
    51  	var ping types.Ping
    52  	if resp.header == nil {
    53  		err := cli.checkResponseErr(resp)
    54  		return ping, errdefs.FromStatusCode(err, resp.statusCode)
    55  	}
    56  	ping.APIVersion = resp.header.Get("API-Version")
    57  	ping.OSType = resp.header.Get("OSType")
    58  	if resp.header.Get("Docker-Experimental") == "true" {
    59  		ping.Experimental = true
    60  	}
    61  	if bv := resp.header.Get("Builder-Version"); bv != "" {
    62  		ping.BuilderVersion = types.BuilderVersion(bv)
    63  	}
    64  	err := cli.checkResponseErr(resp)
    65  	return ping, errdefs.FromStatusCode(err, resp.statusCode)
    66  }