Remove string checking in API error handling

Use strongly typed errors to set HTTP status codes.
Error interfaces are defined in the api/errors package and errors
returned from controllers are checked against these interfaces.

Errors can be wraeped in a pkg/errors.Causer, as long as somewhere in the
line of causes one of the interfaces is implemented. The special error
interfaces take precedence over Causer, meaning if both Causer and one
of the new error interfaces are implemented, the Causer is not
traversed.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>

container/container.go

@@ -43,6 +43,7 @@ import (
 	"github.com/docker/libnetwork/options"
 	"github.com/docker/libnetwork/types"
 	agentexec "github.com/docker/swarmkit/agent/exec"
+	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"golang.org/x/net/context"
 )
@@ -55,8 +56,8 @@ const (
 )
 
 var (
-	errInvalidEndpoint = fmt.Errorf("invalid endpoint while building port map info")
-	errInvalidNetwork  = fmt.Errorf("invalid network settings while building port map info")
+	errInvalidEndpoint = errors.New("invalid endpoint while building port map info")
+	errInvalidNetwork  = errors.New("invalid network settings while building port map info")
 )
 
 // Container holds the structure defining a container object.
@@ -274,7 +275,7 @@ func (container *Container) SetupWorkingDirectory(rootIDs idtools.IDPair) error
 	if err := idtools.MkdirAllAndChownNew(pth, 0755, rootIDs); err != nil {
 		pthInfo, err2 := os.Stat(pth)
 		if err2 == nil && pthInfo != nil && !pthInfo.IsDir() {
-			return fmt.Errorf("Cannot mkdir: %s is not a directory", container.Config.WorkingDir)
+			return errors.Errorf("Cannot mkdir: %s is not a directory", container.Config.WorkingDir)
 		}
 
 		return err
@@ -357,7 +358,7 @@ func (container *Container) StartLogger() (logger.Logger, error) {
 	cfg := container.HostConfig.LogConfig
 	initDriver, err := logger.GetLogDriver(cfg.Type)
 	if err != nil {
-		return nil, fmt.Errorf("failed to get logging factory: %v", err)
+		return nil, errors.Wrap(err, "failed to get logging factory")
 	}
 	info := logger.Info{
 		Config:              cfg.Config,
@@ -723,18 +724,18 @@ func (container *Container) BuildCreateEndpointOptions(n libnetwork.Network, epC
 
 			for _, ips := range ipam.LinkLocalIPs {
 				if linkip = net.ParseIP(ips); linkip == nil && ips != "" {
-					return nil, fmt.Errorf("Invalid link-local IP address:%s", ipam.LinkLocalIPs)
+					return nil, errors.Errorf("Invalid link-local IP address: %s", ipam.LinkLocalIPs)
 				}
 				ipList = append(ipList, linkip)
 
 			}
 
 			if ip = net.ParseIP(ipam.IPv4Address); ip == nil && ipam.IPv4Address != "" {
-				return nil, fmt.Errorf("Invalid IPv4 address:%s)", ipam.IPv4Address)
+				return nil, errors.Errorf("Invalid IPv4 address: %s)", ipam.IPv4Address)
 			}
 
 			if ip6 = net.ParseIP(ipam.IPv6Address); ip6 == nil && ipam.IPv6Address != "" {
-				return nil, fmt.Errorf("Invalid IPv6 address:%s)", ipam.IPv6Address)
+				return nil, errors.Errorf("Invalid IPv6 address: %s)", ipam.IPv6Address)
 			}
 
 			createOptions = append(createOptions,
@@ -838,7 +839,7 @@ func (container *Container) BuildCreateEndpointOptions(n libnetwork.Network, epC
 				portStart, portEnd, err = newP.Range()
 			}
 			if err != nil {
-				return nil, fmt.Errorf("Error parsing HostPort value(%s):%v", binding[i].HostPort, err)
+				return nil, errors.Wrapf(err, "Error parsing HostPort value (%s)", binding[i].HostPort)
 			}
 			pbCopy.HostPort = uint16(portStart)
 			pbCopy.HostPortEnd = uint16(portEnd)

container/container_unix.go

@@ -3,7 +3,6 @@
 package container
 
 import (
-	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -262,6 +261,14 @@ func (container *Container) ConfigMounts() []Mount {
 	return mounts
 }
 
+type conflictingUpdateOptions string
+
+func (e conflictingUpdateOptions) Error() string {
+	return string(e)
+}
+
+func (e conflictingUpdateOptions) Conflict() {}
+
 // UpdateContainer updates configuration of a container. Callers must hold a Lock on the Container.
 func (container *Container) UpdateContainer(hostConfig *containertypes.HostConfig) error {
 	// update resources of container
@@ -273,16 +280,16 @@ func (container *Container) UpdateContainer(hostConfig *containertypes.HostConfi
 	// once NanoCPU is already set, updating CPUPeriod/CPUQuota will be blocked, and vice versa.
 	// In the following we make sure the intended update (resources) does not conflict with the existing (cResource).
 	if resources.NanoCPUs > 0 && cResources.CPUPeriod > 0 {
-		return fmt.Errorf("Conflicting options: Nano CPUs cannot be updated as CPU Period has already been set")
+		return conflictingUpdateOptions("Conflicting options: Nano CPUs cannot be updated as CPU Period has already been set")
 	}
 	if resources.NanoCPUs > 0 && cResources.CPUQuota > 0 {
-		return fmt.Errorf("Conflicting options: Nano CPUs cannot be updated as CPU Quota has already been set")
+		return conflictingUpdateOptions("Conflicting options: Nano CPUs cannot be updated as CPU Quota has already been set")
 	}
 	if resources.CPUPeriod > 0 && cResources.NanoCPUs > 0 {
-		return fmt.Errorf("Conflicting options: CPU Period cannot be updated as NanoCPUs has already been set")
+		return conflictingUpdateOptions("Conflicting options: CPU Period cannot be updated as NanoCPUs has already been set")
 	}
 	if resources.CPUQuota > 0 && cResources.NanoCPUs > 0 {
-		return fmt.Errorf("Conflicting options: CPU Quota cannot be updated as NanoCPUs has already been set")
+		return conflictingUpdateOptions("Conflicting options: CPU Quota cannot be updated as NanoCPUs has already been set")
 	}
 
 	if resources.BlkioWeight != 0 {
@@ -310,7 +317,7 @@ func (container *Container) UpdateContainer(hostConfig *containertypes.HostConfi
 		// if memory limit smaller than already set memoryswap limit and doesn't
 		// update the memoryswap limit, then error out.
 		if resources.Memory > cResources.MemorySwap && resources.MemorySwap == 0 {
-			return fmt.Errorf("Memory limit should be smaller than already set memoryswap limit, update the memoryswap at the same time")
+			return conflictingUpdateOptions("Memory limit should be smaller than already set memoryswap limit, update the memoryswap at the same time")
 		}
 		cResources.Memory = resources.Memory
 	}
@@ -327,7 +334,7 @@ func (container *Container) UpdateContainer(hostConfig *containertypes.HostConfi
 	// update HostConfig of container
 	if hostConfig.RestartPolicy.Name != "" {
 		if container.HostConfig.AutoRemove && !hostConfig.RestartPolicy.IsNone() {
-			return fmt.Errorf("Restart policy cannot be updated because AutoRemove is enabled for the container")
+			return conflictingUpdateOptions("Restart policy cannot be updated because AutoRemove is enabled for the container")
 		}
 		container.HostConfig.RestartPolicy = hostConfig.RestartPolicy
 	}