Found a couple of places where pretty low level errors were never being
wrapped with any sort of context.
For example, if you try to create a local volume using some bad mount
options, the kernel will return `invalid argument` when we try to mount
it at container start.
What would happen is a user would `docker run` with this volume and get
an error like `Error response from daemon: invalid argument`.
This uses github.com/pkg/errors to provide some context to the error
message without masking the original error.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
When the daemon is started, it looks at all the volumes and checks to
see if any of them have mount options persisted to disk, and loads them
from disk if it does.
In some cases a volume will be created with an empty map causing the
options file to be persisted and volume options set to a non-nil value
on daemon restart... this causes problems later when the driver checks
for a non-nil value to determine if it should try and mount with the
persisted volume options.
Ensures 2 things:
1. Instead of only checking nilness for the opts map, use `len` to make
sure it is not an empty map, which we don't really need to persit.
2. An empty (or nulled) opts.json will not inadvertnatly set volume
options on daemon restart.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
this improves the error message if a user tries to
create a volume with a single-character name:
Before this change:
docker volume create --name a
Error response from daemon: create a: "a" includes invalid characters for a local volume name, only "[a-zA-Z0-9][a-zA-Z0-9_.-]" are allowed
After this change:
docker volume create --name a
Error response from daemon: create a: volume name is too short, names should be at least two alphanumeric characters
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
On daemon restart the local volume driver will read options that it
persisted to disk, however it was reading an incorrect path, causing
volume options to be silently ignored after a daemon restart.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
This is similar to network scopes where a volume can either be `local`
or `global`. A `global` volume is one that exists across the entire
cluster where as a `local` volume exists on a single engine.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
This generates an ID string for calls to Mount/Unmount, allowing drivers
to differentiate between two callers of `Mount` and `Unmount`.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
The `Status` field is a `map[string]interface{}` which allows the driver to pass
back low-level details about the underlying volume.
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
Allows users to submit options similar to the `mount` command when
creating a volume with the `local` volume driver.
For example:
```go
$ docker volume create -d local --opt type=nfs --opt device=myNfsServer:/data --opt o=noatime,nosuid
```
Signed-off-by: Brian Goff <cpuguy83@gmail.com>
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>
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>
Delegate validation tasks to the volume drivers. It's up to them
to decide whether a name is valid or not.
Restrict volume names for the local driver to prevent creating
mount points outside docker's volumes directory.
Signed-off-by: David Calavera <david.calavera@gmail.com>
Adds support for the daemon to handle user namespace maps as a
per-daemon setting.
Support for handling uid/gid mapping is added to the builder,
archive/unarchive packages and functions, all graphdrivers (except
Windows), and the test suite is updated to handle user namespace daemon
rootgraph changes.
Docker-DCO-1.1-Signed-off-by: Phil Estes <estesp@linux.vnet.ibm.com> (github: estesp)
Underlying volume data may have been removed by some other tool.
Ignore and remove the reference in this case.
Signed-off-by: Brian Goff <cpuguy83@gmail.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>
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>
