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>
The execdriver pipes setup uses OS pipes with fds so that they can be
chown'ed to the remapped root user for proper access. Recent flakiness
in certain short-lived tests (usually via the "exec" path) reveals that
the copy routines are not completing before exit/tear-down.
This fix adds synchronization and proper closure such that these
routines exit successfully.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Because devices will be bind-mounted instead of using `mknod`, we need
to make sure the source exists and filter the list by only those whose
source is a valid path/current device entry.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Add `--restart` flag for `update` command, so we can change restart
policy for a container no matter it's running or stopped.
Signed-off-by: Zhang Wei <zhangwei555@huawei.com>
If user specifies --read-only flag it should not effect /dev/mqueue.
This is causing SELinux issues in docker-1.10. --read-only blows up
on SELinux enabled machines. Mounting /dev/mqueue read/only would also
blow up any tool that was going to use /dev/mqueue.
Signed-off-by: Dan Walsh <dwalsh@redhat.com>
mqueue can not be mounted on the host os and then shared into the container.
There is only one mqueue per mount namespace, so current code ends up leaking
the /dev/mqueue from the host into ALL containers. Since SELinux changes the
label of the mqueue, only the last container is able to use the mqueue, all
other containers will get a permission denied. If you don't have SELinux protections
sharing of the /dev/mqueue allows one container to interact in potentially hostile
ways with other containers.
Signed-off-by: Dan Walsh <dwalsh@redhat.com>
We cannot rely on the tar command for this type of operation because tar
versions, flags, and functionality can very from distro to distro.
Since this is in the container execution path it is not safe to have
this as a dependency from dockers POV where the user cannot change the
fact that docker is adding these pre and post mount commands.
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
dockerinit has been around for a very long time. It was originally used
as a way for us to do configuration for LXC containers once the
container had started. LXC is no longer supported, and /.dockerinit has
been dead code for quite a while. This removes all code and references
in code to dockerinit.
Signed-off-by: Aleksa Sarai <asarai@suse.com>
In the default seccomp rule, allow use of 32 bit syscalls on
64 bit architectures, so you can run x86 Linux images on x86_64
without disabling seccomp or using a custom rule.
Signed-off-by: Justin Cormack <justin.cormack@unikernel.com>
Being able to obtain a file handle is no use as we cannot perform
any operation in it, and it may leak kernel state.
Signed-off-by: Justin Cormack <justin.cormack@unikernel.com>
David Calavera
Alexander Morozov
Phil Estes
Brian Goff
Zhang Wei
Jessica Frazelle
Dan Walsh
Victor Vieux
John Howard
Tonis Tiigi
Fangyuan Gao
Joey Geiger
Arnaud Porterie
Michael Crosby
Aleksa Sarai
Phil Estes
Jess Frazelle
Sebastiaan van Stijn
Justin Cormack
Alexander Morozov
Srini Brahmaroutu
Justin Cormack