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>
This makes it so when calling `docker run --rm`, or `docker rm -v`, only
volumes specified without a name, e.g. `docker run -v /foo` instead of
`docker run -v awesome:/foo` are removed.
Note that all volumes are named, some are named by the user, some get a
generated name. This is specifically about how the volume was specified
on `run`, assuming that if the user specified it with a name they expect
it to persist after the container is cleaned up.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Makes `docker volume ls` and `docker volume inspect` ask the volume
drivers rather than only using what is cached locally.
Previously in order to use a volume from an external driver, one would
either have to use `docker volume create` or have a container that is
already using that volume for it to be visible to the other volume
API's.
For keeping uniqueness of volume names in the daemon, names are bound to
a driver on a first come first serve basis. If two drivers have a volume
with the same name, the first one is chosen, and a warning is logged
about the second one.
Adds 2 new methods to the plugin API, `List` and `Get`.
If a plugin does not implement these endpoints, a user will not be able
to find the specified volumes as well requests go through the drivers.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Allow passing mount propagation option shared, slave, or private as volume
property.
For example.
docker run -ti -v /root/mnt-source:/root/mnt-dest:slave fedora bash
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
1. rename it from ValidateMountMode to ValidMountMode
Because it's a function simply check mount mode is valid or not.
2. remove the rw check return value
It's not supposed to be combined into this function, and we already
have a function for that check.
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
- comments on exported values
- constant string replaced by constant reference
- unexport implementation details of VolumeDriver 'local'
- add fixed packages to linter list
Signed-off-by: Morgan Bauer <mbauer@us.ibm.com>
- Refactor opts.ValidatePath and add an opts.ValidateDevice
ValidePath will now accept : containerPath:mode, hostPath:containerPath:mode
and hostPath:containerPath.
ValidateDevice will have the same behavior as current.
- Refactor opts.ValidateEnv, opts.ParseEnvFile
Environment variables will now be validated with the following
definition :
> Environment variables set by the user must have a name consisting
> solely of alphabetics, numerics, and underscores - the first of
> which must not be numeric.
Signed-off-by: Vincent Demeester <vincent@sbr.pm>
Signed by all authors:
Signed-off-by: Michael Crosby <crosbymichael@gmail.com>
Signed-off-by: Arnaud Porterie <arnaud.porterie@docker.com>
Signed-off-by: David Calavera <david.calavera@gmail.com>
Signed-off-by: Jeff Lindsay <progrium@gmail.com>
Signed-off-by: Alexander Morozov <lk4d4@docker.com>
Signed-off-by: Luke Marsden <luke@clusterhq.com>
Signed-off-by: David Calavera <david.calavera@gmail.com>
