Correct logic handling a server resource update

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/asaskevich/govalidator v0.0.0-20190424111038-f61b66f89f4a
 	github.com/buger/jsonparser v0.0.0-20181115193947-bf1c66bbce23
 	github.com/containerd/fifo v0.0.0-20190226154929-a9fb20d87448 // indirect
+	github.com/creasty/defaults v1.3.0 // indirect
 	github.com/docker/distribution v2.7.1+incompatible // indirect
 	github.com/docker/docker v0.0.0-20180422163414-57142e89befe
 	github.com/docker/go-connections v0.4.0

go.sum

@@ -10,6 +10,8 @@ github.com/buger/jsonparser v0.0.0-20181115193947-bf1c66bbce23 h1:D21IyuvjDCshj1
 github.com/buger/jsonparser v0.0.0-20181115193947-bf1c66bbce23/go.mod h1:bbYlZJ7hK1yFx9hf58LP0zeX7UjIGs20ufpu3evjr+s=
 github.com/containerd/fifo v0.0.0-20190226154929-a9fb20d87448 h1:PUD50EuOMkXVcpBIA/R95d56duJR9VxhwncsFbNnxW4=
 github.com/containerd/fifo v0.0.0-20190226154929-a9fb20d87448/go.mod h1:ODA38xgv3Kuk8dQz2ZQXpnv/UZZUHUCL7pnLehbXgQI=
+github.com/creasty/defaults v1.3.0 h1:uG+RAxYbJgOPCOdKEcec9ZJXeva7Y6mj/8egdzwmLtw=
+github.com/creasty/defaults v1.3.0/go.mod h1:CIEEvs7oIVZm30R8VxtFJs+4k201gReYyuYHJxZc68I=
 github.com/docker/distribution v2.7.1+incompatible h1:a5mlkVzth6W5A4fOsS3D2EO5BUmsJpcB+cRlLU7cSug=
 github.com/docker/distribution v2.7.1+incompatible/go.mod h1:J2gT2udsDAN96Uj4KfcMRqY0/ypR+oyYUYmja8H+y+w=
 github.com/docker/docker v0.0.0-20180422163414-57142e89befe h1:VW8TnWi0CZgg7oCv0wH6evNwkzcJg/emnw4HrVIWws4=

server/environment_docker.go

@@ -696,13 +696,6 @@ func (d *DockerEnvironment) exposedPorts() nat.PortSet {
 // Formats the resources available to a server instance in such as way that Docker will
 // generate a matching environment in the container.
 func (d *DockerEnvironment) getResourcesForServer() container.Resources {
-	b := true
-	oomDisabled := d.Server.Container.OomDisabled
-
-	if oomDisabled == nil {
-		oomDisabled = &b
-	}
-
 	return container.Resources{
 		// @todo memory limit should be slightly higher than the reservation
 		Memory:            d.Server.Build.MemoryLimit * 1000000,
@@ -712,6 +705,6 @@ func (d *DockerEnvironment) getResourcesForServer() container.Resources {
 		CPUPeriod:         100000,
 		CPUShares:         1024,
 		BlkioWeight:       d.Server.Build.IoWeight,
-		OomKillDisable: oomDisabled,
+		OomKillDisable:    &d.Server.Container.OomDisabled,
 	}
 }

server/server.go

@@ -46,16 +46,16 @@ type Server struct {
 		Image string `json:"image,omitempty"`
 		// If set to true, OOM killer will be disabled on the server's Docker container.
 		// If not present (nil) we will default to disabling it.
-		OomDisabled *bool `json:"oom_disabled,omitempty"`
+		OomDisabled bool `default:"false" json:"oom_disabled" yaml:"oom_disabled"`
 		// Defines if the container needs to be rebuilt on the next boot.
-		RebuildRequired bool `json:"rebuild_required,omitempty"`
+		RebuildRequired bool `default:"false" json:"rebuild_required,omitempty" yaml:"rebuild_required"`
 	} `json:"container,omitempty"`
 
 	Environment Environment `json:"-" yaml:"-"`
 
 	Filesystem *Filesystem `json:"-" yaml:"-"`
 
-	Resources *ResourceUsage `json:"resources"`
+	Resources *ResourceUsage `json:"resources" yaml:"-"`
 
 	// Server cache used to store frequently requested information in memory and make
 	// certain long operations return faster. For example, FS disk space usage.

server/update.go

@@ -2,6 +2,7 @@ package server
 
 import (
 	"encoding/json"
+	"github.com/buger/jsonparser"
 	"github.com/imdario/mergo"
 	"github.com/pkg/errors"
 )
@@ -19,12 +20,30 @@ func (s *Server) UpdateDataStructure(data []byte) error {
 		return errors.WithStack(err)
 	}
 
+	// Don't allow obviously corrupted data to pass through into this function. If the UUID
+	// doesn't match something has gone wrong and the API is attempting to meld this server
+	// instance into a totally different one, which would be bad.
+	if src.Uuid != s.Uuid {
+		return errors.New("attempting to merge a data stack with an invalid UUID")
+	}
+
 	// Merge the new data object that we have received with the existing server data object
 	// and then save it to the disk so it is persistent.
-	if err := mergo.Merge(&s, src); err != nil {
+	if err := mergo.Merge(s, src, mergo.WithOverride); err != nil {
 		return errors.WithStack(err)
 	}
 
+	// Mergo can't quite handle this boolean value correctly, so for now we'll just
+	// handle this edge case manually since none of the other data passed through in this
+	// request is going to be boolean. Allegedly.
+	if v, err := jsonparser.GetBoolean(data, "container", "oom_disabled"); err != nil {
+		if err != jsonparser.KeyPathNotFoundError {
+			return errors.WithStack(err)
+		}
+	} else {
+		s.Container.OomDisabled = v
+	}
+
 	s.Container.RebuildRequired = true
 	if _, err := s.WriteConfigurationToDisk(); err != nil {
 		return errors.WithStack(err)