61a234d562
When we see an `ECONNREFUSED` (or equivalent) from an attempted `HEAD` on the
`/_ping` endpoint there is no point in trying again with `GET` since the server
is not responding/available at all.
Once vendored into the cli this will partially mitigate https://github.com/docker/cli/issues/1739
("Docker commands take 1 minute to timeout if context endpoint is unreachable")
by cutting the effective timeout in half.
Signed-off-by: Ian Campbell <ijc@docker.com>
(cherry picked from commit 8c8457b0f2)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
66 lines
2.1 KiB
Go
66 lines
2.1 KiB
Go
package client // import "github.com/docker/docker/client"
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import (
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"context"
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"net/http"
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"path"
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"github.com/docker/docker/api/types"
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"github.com/docker/docker/errdefs"
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)
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// Ping pings the server and returns the value of the "Docker-Experimental",
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// "Builder-Version", "OS-Type" & "API-Version" headers. It attempts to use
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// a HEAD request on the endpoint, but falls back to GET if HEAD is not supported
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// by the daemon.
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func (cli *Client) Ping(ctx context.Context) (types.Ping, error) {
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var ping types.Ping
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// Using cli.buildRequest() + cli.doRequest() instead of cli.sendRequest()
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// because ping requests are used during API version negotiation, so we want
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// to hit the non-versioned /_ping endpoint, not /v1.xx/_ping
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req, err := cli.buildRequest("HEAD", path.Join(cli.basePath, "/_ping"), nil, nil)
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if err != nil {
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return ping, err
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}
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serverResp, err := cli.doRequest(ctx, req)
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if err == nil {
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defer ensureReaderClosed(serverResp)
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switch serverResp.statusCode {
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case http.StatusOK, http.StatusInternalServerError:
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// Server handled the request, so parse the response
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return parsePingResponse(cli, serverResp)
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}
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} else if IsErrConnectionFailed(err) {
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return ping, err
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}
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req, err = cli.buildRequest("GET", path.Join(cli.basePath, "/_ping"), nil, nil)
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if err != nil {
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return ping, err
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}
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serverResp, err = cli.doRequest(ctx, req)
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defer ensureReaderClosed(serverResp)
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if err != nil {
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return ping, err
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}
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return parsePingResponse(cli, serverResp)
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}
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func parsePingResponse(cli *Client, resp serverResponse) (types.Ping, error) {
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var ping types.Ping
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if resp.header == nil {
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err := cli.checkResponseErr(resp)
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return ping, errdefs.FromStatusCode(err, resp.statusCode)
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}
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ping.APIVersion = resp.header.Get("API-Version")
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ping.OSType = resp.header.Get("OSType")
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if resp.header.Get("Docker-Experimental") == "true" {
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ping.Experimental = true
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}
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if bv := resp.header.Get("Builder-Version"); bv != "" {
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ping.BuilderVersion = types.BuilderVersion(bv)
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}
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err := cli.checkResponseErr(resp)
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return ping, errdefs.FromStatusCode(err, resp.statusCode)
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}
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