github.com/rish1988/moby@v25.0.2+incompatible/client/ping.go (about)

     1  package client // import "github.com/docker/docker/client"
     2  
     3  import (
     4  	"context"
     5  	"net/http"
     6  	"path"
     7  	"strings"
     8  
     9  	"github.com/docker/docker/api/types"
    10  	"github.com/docker/docker/api/types/swarm"
    11  	"github.com/docker/docker/errdefs"
    12  )
    13  
    14  // Ping pings the server and returns the value of the "Docker-Experimental",
    15  // "Builder-Version", "OS-Type" & "API-Version" headers. It attempts to use
    16  // a HEAD request on the endpoint, but falls back to GET if HEAD is not supported
    17  // by the daemon.
    18  func (cli *Client) Ping(ctx context.Context) (types.Ping, error) {
    19  	var ping types.Ping
    20  
    21  	// Using cli.buildRequest() + cli.doRequest() instead of cli.sendRequest()
    22  	// because ping requests are used during API version negotiation, so we want
    23  	// to hit the non-versioned /_ping endpoint, not /v1.xx/_ping
    24  	req, err := cli.buildRequest(ctx, http.MethodHead, path.Join(cli.basePath, "/_ping"), nil, nil)
    25  	if err != nil {
    26  		return ping, err
    27  	}
    28  	serverResp, err := cli.doRequest(req)
    29  	if err == nil {
    30  		defer ensureReaderClosed(serverResp)
    31  		switch serverResp.statusCode {
    32  		case http.StatusOK, http.StatusInternalServerError:
    33  			// Server handled the request, so parse the response
    34  			return parsePingResponse(cli, serverResp)
    35  		}
    36  	} else if IsErrConnectionFailed(err) {
    37  		return ping, err
    38  	}
    39  
    40  	// HEAD failed; fallback to GET.
    41  	req.Method = http.MethodGet
    42  	serverResp, err = cli.doRequest(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  	if si := resp.header.Get("Swarm"); si != "" {
    65  		state, role, _ := strings.Cut(si, "/")
    66  		ping.SwarmStatus = &swarm.Status{
    67  			NodeState:        swarm.LocalNodeState(state),
    68  			ControlAvailable: role == "manager",
    69  		}
    70  	}
    71  	err := cli.checkResponseErr(resp)
    72  	return ping, errdefs.FromStatusCode(err, resp.statusCode)
    73  }