Files
moby/client/container_wait.go
Sebastiaan van Stijn 29ad05b130 client: ContainerWaitResult: use singular for channels
These channels should ever only return a single result, so rename
them to match that expectation.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2025-10-29 12:37:46 +01:00

93 lines
2.8 KiB
Go

package client
import (
"bytes"
"context"
"encoding/json"
"errors"
"io"
"net/url"
"github.com/moby/moby/api/types/container"
)
const containerWaitErrorMsgLimit = 2 * 1024 /* Max: 2KiB */
// ContainerWaitOptions holds options for [Client.ContainerWait].
type ContainerWaitOptions struct {
Condition container.WaitCondition
}
// ContainerWaitResult defines the result from the [Client.ContainerWait] method.
type ContainerWaitResult struct {
Result <-chan container.WaitResponse
Error <-chan error
}
// ContainerWait waits until the specified container is in a certain state
// indicated by the given condition, either;
//
// - "not-running" ([container.WaitConditionNotRunning]) (default)
// - "next-exit" ([container.WaitConditionNextExit])
// - "removed" ([container.WaitConditionRemoved])
//
// ContainerWait blocks until the request has been acknowledged by the server
// (with a response header), then returns two channels on which the caller can
// wait for the exit status of the container or an error if there was a problem
// either beginning the wait request or in getting the response. This allows the
// caller to synchronize ContainerWait with other calls, such as specifying a
// "next-exit" condition ([container.WaitConditionNextExit]) before issuing a
// [Client.ContainerStart] request.
func (cli *Client) ContainerWait(ctx context.Context, containerID string, options ContainerWaitOptions) ContainerWaitResult {
resultC := make(chan container.WaitResponse)
errC := make(chan error, 1)
containerID, err := trimID("container", containerID)
if err != nil {
errC <- err
return ContainerWaitResult{Result: resultC, Error: errC}
}
query := url.Values{}
if options.Condition != "" {
query.Set("condition", string(options.Condition))
}
resp, err := cli.post(ctx, "/containers/"+containerID+"/wait", query, nil, nil)
if err != nil {
defer ensureReaderClosed(resp)
errC <- err
return ContainerWaitResult{Result: resultC, Error: errC}
}
go func() {
defer ensureReaderClosed(resp)
responseText := bytes.NewBuffer(nil)
stream := io.TeeReader(resp.Body, responseText)
var res container.WaitResponse
if err := json.NewDecoder(stream).Decode(&res); err != nil {
// NOTE(nicks): The /wait API does not work well with HTTP proxies.
// At any time, the proxy could cut off the response stream.
//
// But because the HTTP status has already been written, the proxy's
// only option is to write a plaintext error message.
//
// If there's a JSON parsing error, read the real error message
// off the body and send it to the client.
if errors.As(err, new(*json.SyntaxError)) {
_, _ = io.ReadAll(io.LimitReader(stream, containerWaitErrorMsgLimit))
errC <- errors.New(responseText.String())
} else {
errC <- err
}
return
}
resultC <- res
}()
return ContainerWaitResult{Result: resultC, Error: errC}
}