2018-02-05 21:05:59 +00:00
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package daemon // import "github.com/docker/docker/daemon"
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2014-07-31 20:48:23 +00:00
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2015-09-18 17:48:16 +00:00
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import (
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2021-08-20 22:23:26 +00:00
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"context"
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Remove static errors from errors package.
Moving all strings to the errors package wasn't a good idea after all.
Our custom implementation of Go errors predates everything that's nice
and good about working with errors in Go. Take as an example what we
have to do to get an error message:
```go
func GetErrorMessage(err error) string {
switch err.(type) {
case errcode.Error:
e, _ := err.(errcode.Error)
return e.Message
case errcode.ErrorCode:
ec, _ := err.(errcode.ErrorCode)
return ec.Message()
default:
return err.Error()
}
}
```
This goes against every good practice for Go development. The language already provides a simple, intuitive and standard way to get error messages, that is calling the `Error()` method from an error. Reinventing the error interface is a mistake.
Our custom implementation also makes very hard to reason about errors, another nice thing about Go. I found several (>10) error declarations that we don't use anywhere. This is a clear sign about how little we know about the errors we return. I also found several error usages where the number of arguments was different than the parameters declared in the error, another clear example of how difficult is to reason about errors.
Moreover, our custom implementation didn't really make easier for people to return custom HTTP status code depending on the errors. Again, it's hard to reason about when to set custom codes and how. Take an example what we have to do to extract the message and status code from an error before returning a response from the API:
```go
switch err.(type) {
case errcode.ErrorCode:
daError, _ := err.(errcode.ErrorCode)
statusCode = daError.Descriptor().HTTPStatusCode
errMsg = daError.Message()
case errcode.Error:
// For reference, if you're looking for a particular error
// then you can do something like :
// import ( derr "github.com/docker/docker/errors" )
// if daError.ErrorCode() == derr.ErrorCodeNoSuchContainer { ... }
daError, _ := err.(errcode.Error)
statusCode = daError.ErrorCode().Descriptor().HTTPStatusCode
errMsg = daError.Message
default:
// This part of will be removed once we've
// converted everything over to use the errcode package
// FIXME: this is brittle and should not be necessary.
// If we need to differentiate between different possible error types,
// we should create appropriate error types with clearly defined meaning
errStr := strings.ToLower(err.Error())
for keyword, status := range map[string]int{
"not found": http.StatusNotFound,
"no such": http.StatusNotFound,
"bad parameter": http.StatusBadRequest,
"conflict": http.StatusConflict,
"impossible": http.StatusNotAcceptable,
"wrong login/password": http.StatusUnauthorized,
"hasn't been activated": http.StatusForbidden,
} {
if strings.Contains(errStr, keyword) {
statusCode = status
break
}
}
}
```
You can notice two things in that code:
1. We have to explain how errors work, because our implementation goes against how easy to use Go errors are.
2. At no moment we arrived to remove that `switch` statement that was the original reason to use our custom implementation.
This change removes all our status errors from the errors package and puts them back in their specific contexts.
IT puts the messages back with their contexts. That way, we know right away when errors used and how to generate their messages.
It uses custom interfaces to reason about errors. Errors that need to response with a custom status code MUST implementent this simple interface:
```go
type errorWithStatus interface {
HTTPErrorStatusCode() int
}
```
This interface is very straightforward to implement. It also preserves Go errors real behavior, getting the message is as simple as using the `Error()` method.
I included helper functions to generate errors that use custom status code in `errors/errors.go`.
By doing this, we remove the hard dependency we have eeverywhere to our custom errors package. Yes, you can use it as a helper to generate error, but it's still very easy to generate errors without it.
Please, read this fantastic blog post about errors in Go: http://dave.cheney.net/2014/12/24/inspecting-errors
Signed-off-by: David Calavera <david.calavera@gmail.com>
2016-02-25 15:53:35 +00:00
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"fmt"
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2019-02-12 00:24:09 +00:00
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containertypes "github.com/docker/docker/api/types/container"
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2023-08-26 13:24:46 +00:00
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"github.com/docker/docker/api/types/events"
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2015-11-12 19:55:17 +00:00
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"github.com/docker/docker/container"
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daemon: daemon.containerRestart: don't cancel restart on context cancel
commit def549c8f6716507ee9175fe9d798a42df89e27d passed through the context
to the daemon.ContainerStart function. As a result, restarting containers
no longer is an atomic operation, because a context cancellation could
interrupt the restart (between "stopping" and "(re)starting"), resulting
in the container being stopped, but not restarted.
Restarting a container, or more factually; making a successful request on
the `/containers/{id]/restart` endpoint, should be an atomic operation.
This patch uses a context.WithoutCancel for restart requests.
It's worth noting that daemon.containerStop already uses context.WithoutCancel,
so in that function, we'll be wrapping the context twice, but this should
likely not cause issues (just redundant for this code-path).
Before this patch, starting a container that bind-mounts the docker socket,
then restarting itself from within the container would cancel the restart
operation. The container would be stopped, but not started after that:
docker run -dit --name myself -v /var/run/docker.sock:/var/run/docker.sock docker:cli sh
docker exec myself sh -c 'docker restart myself'
docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
3a2a741c65ff docker:cli "docker-entrypoint.s…" 26 seconds ago Exited (128) 7 seconds ago myself
With this patch: the stop still cancels the exec, but does not cancel the
restart operation, and the container is started again:
docker run -dit --name myself -v /var/run/docker.sock:/var/run/docker.sock docker:cli sh
docker exec myself sh -c 'docker restart myself'
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4393a01f7c75 docker:cli "docker-entrypoint.s…" About a minute ago Up 4 seconds myself
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2023-10-20 16:00:16 +00:00
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"github.com/docker/docker/internal/compatcontext"
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2015-09-18 17:48:16 +00:00
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)
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2015-03-25 07:44:12 +00:00
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2015-07-30 21:01:53 +00:00
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// ContainerRestart stops and starts a container. It attempts to
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// gracefully stop the container within the given timeout, forcefully
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// stopping it if the timeout is exceeded. If given a negative
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// timeout, ContainerRestart will wait forever until a graceful
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// stop. Returns an error if the container cannot be found, or if
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// there is an underlying error at any stage of the restart.
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2021-08-20 22:23:26 +00:00
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func (daemon *Daemon) ContainerRestart(ctx context.Context, name string, options containertypes.StopOptions) error {
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2019-08-09 12:10:07 +00:00
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ctr, err := daemon.GetContainer(name)
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2014-12-16 23:06:35 +00:00
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if err != nil {
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2015-03-25 07:44:12 +00:00
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return err
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2014-07-31 20:48:23 +00:00
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}
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2022-08-17 21:13:49 +00:00
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err = daemon.containerRestart(ctx, daemon.config(), ctr, options)
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2021-08-20 20:43:13 +00:00
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if err != nil {
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Remove static errors from errors package.
Moving all strings to the errors package wasn't a good idea after all.
Our custom implementation of Go errors predates everything that's nice
and good about working with errors in Go. Take as an example what we
have to do to get an error message:
```go
func GetErrorMessage(err error) string {
switch err.(type) {
case errcode.Error:
e, _ := err.(errcode.Error)
return e.Message
case errcode.ErrorCode:
ec, _ := err.(errcode.ErrorCode)
return ec.Message()
default:
return err.Error()
}
}
```
This goes against every good practice for Go development. The language already provides a simple, intuitive and standard way to get error messages, that is calling the `Error()` method from an error. Reinventing the error interface is a mistake.
Our custom implementation also makes very hard to reason about errors, another nice thing about Go. I found several (>10) error declarations that we don't use anywhere. This is a clear sign about how little we know about the errors we return. I also found several error usages where the number of arguments was different than the parameters declared in the error, another clear example of how difficult is to reason about errors.
Moreover, our custom implementation didn't really make easier for people to return custom HTTP status code depending on the errors. Again, it's hard to reason about when to set custom codes and how. Take an example what we have to do to extract the message and status code from an error before returning a response from the API:
```go
switch err.(type) {
case errcode.ErrorCode:
daError, _ := err.(errcode.ErrorCode)
statusCode = daError.Descriptor().HTTPStatusCode
errMsg = daError.Message()
case errcode.Error:
// For reference, if you're looking for a particular error
// then you can do something like :
// import ( derr "github.com/docker/docker/errors" )
// if daError.ErrorCode() == derr.ErrorCodeNoSuchContainer { ... }
daError, _ := err.(errcode.Error)
statusCode = daError.ErrorCode().Descriptor().HTTPStatusCode
errMsg = daError.Message
default:
// This part of will be removed once we've
// converted everything over to use the errcode package
// FIXME: this is brittle and should not be necessary.
// If we need to differentiate between different possible error types,
// we should create appropriate error types with clearly defined meaning
errStr := strings.ToLower(err.Error())
for keyword, status := range map[string]int{
"not found": http.StatusNotFound,
"no such": http.StatusNotFound,
"bad parameter": http.StatusBadRequest,
"conflict": http.StatusConflict,
"impossible": http.StatusNotAcceptable,
"wrong login/password": http.StatusUnauthorized,
"hasn't been activated": http.StatusForbidden,
} {
if strings.Contains(errStr, keyword) {
statusCode = status
break
}
}
}
```
You can notice two things in that code:
1. We have to explain how errors work, because our implementation goes against how easy to use Go errors are.
2. At no moment we arrived to remove that `switch` statement that was the original reason to use our custom implementation.
This change removes all our status errors from the errors package and puts them back in their specific contexts.
IT puts the messages back with their contexts. That way, we know right away when errors used and how to generate their messages.
It uses custom interfaces to reason about errors. Errors that need to response with a custom status code MUST implementent this simple interface:
```go
type errorWithStatus interface {
HTTPErrorStatusCode() int
}
```
This interface is very straightforward to implement. It also preserves Go errors real behavior, getting the message is as simple as using the `Error()` method.
I included helper functions to generate errors that use custom status code in `errors/errors.go`.
By doing this, we remove the hard dependency we have eeverywhere to our custom errors package. Yes, you can use it as a helper to generate error, but it's still very easy to generate errors without it.
Please, read this fantastic blog post about errors in Go: http://dave.cheney.net/2014/12/24/inspecting-errors
Signed-off-by: David Calavera <david.calavera@gmail.com>
2016-02-25 15:53:35 +00:00
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return fmt.Errorf("Cannot restart container %s: %v", name, err)
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2014-12-16 23:06:35 +00:00
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}
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2015-03-25 07:44:12 +00:00
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return nil
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2014-07-31 20:48:23 +00:00
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}
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2015-11-02 23:25:26 +00:00
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// containerRestart attempts to gracefully stop and then start the
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// container. When stopping, wait for the given duration in seconds to
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// gracefully stop, before forcefully terminating the container. If
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// given a negative duration, wait forever for a graceful stop.
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2022-08-31 20:12:30 +00:00
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func (daemon *Daemon) containerRestart(ctx context.Context, daemonCfg *configStore, container *container.Container, options containertypes.StopOptions) error {
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daemon: daemon.containerRestart: don't cancel restart on context cancel
commit def549c8f6716507ee9175fe9d798a42df89e27d passed through the context
to the daemon.ContainerStart function. As a result, restarting containers
no longer is an atomic operation, because a context cancellation could
interrupt the restart (between "stopping" and "(re)starting"), resulting
in the container being stopped, but not restarted.
Restarting a container, or more factually; making a successful request on
the `/containers/{id]/restart` endpoint, should be an atomic operation.
This patch uses a context.WithoutCancel for restart requests.
It's worth noting that daemon.containerStop already uses context.WithoutCancel,
so in that function, we'll be wrapping the context twice, but this should
likely not cause issues (just redundant for this code-path).
Before this patch, starting a container that bind-mounts the docker socket,
then restarting itself from within the container would cancel the restart
operation. The container would be stopped, but not started after that:
docker run -dit --name myself -v /var/run/docker.sock:/var/run/docker.sock docker:cli sh
docker exec myself sh -c 'docker restart myself'
docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
3a2a741c65ff docker:cli "docker-entrypoint.s…" 26 seconds ago Exited (128) 7 seconds ago myself
With this patch: the stop still cancels the exec, but does not cancel the
restart operation, and the container is started again:
docker run -dit --name myself -v /var/run/docker.sock:/var/run/docker.sock docker:cli sh
docker exec myself sh -c 'docker restart myself'
docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
4393a01f7c75 docker:cli "docker-entrypoint.s…" About a minute ago Up 4 seconds myself
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2023-10-20 16:00:16 +00:00
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// Restarting is expected to be an atomic operation, and cancelling
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// the request should not cancel the stop -> start sequence.
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ctx = compatcontext.WithoutCancel(ctx)
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2019-02-12 00:24:09 +00:00
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// Determine isolation. If not specified in the hostconfig, use daemon default.
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actualIsolation := container.HostConfig.Isolation
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if containertypes.Isolation.IsDefault(actualIsolation) {
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actualIsolation = daemon.defaultIsolation
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}
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2015-11-02 23:25:26 +00:00
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// Avoid unnecessarily unmounting and then directly mounting
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// the container when the container stops and then starts
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2019-02-12 00:24:09 +00:00
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// again. We do not do this for Hyper-V isolated containers
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// (implying also on Windows) as the HCS must have exclusive
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// access to mount the containers filesystem inside the utility
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// VM.
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if !containertypes.Isolation.IsHyperV(actualIsolation) {
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if err := daemon.Mount(container); err == nil {
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defer daemon.Unmount(container)
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}
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2015-11-02 23:25:26 +00:00
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}
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2016-08-25 07:54:49 +00:00
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if container.IsRunning() {
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2022-07-19 10:17:08 +00:00
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container.Lock()
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container.HasBeenManuallyRestarted = true
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container.Unlock()
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2016-03-01 16:30:27 +00:00
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2021-08-20 22:23:26 +00:00
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err := daemon.containerStop(ctx, container, options)
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2016-08-25 07:54:49 +00:00
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if err != nil {
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return err
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}
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2015-11-02 23:25:26 +00:00
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}
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2022-08-17 21:13:49 +00:00
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if err := daemon.containerStart(ctx, daemonCfg, container, "", "", true); err != nil {
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2015-11-02 23:25:26 +00:00
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return err
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}
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2023-08-26 13:24:46 +00:00
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daemon.LogContainerEvent(container, events.ActionRestart)
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2015-11-02 23:25:26 +00:00
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return nil
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}
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