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) }