cmd/swarm: add config file (#15548)

This commit adds a TOML configuration option to swarm. It reuses
the TOML configuration structure used in geth with swarm
customized items.

The commit:

* Adds a "dumpconfig" command to the swarm executable which
  allows printing the (default) configuration to stdout, which
  then can be redirected to a file in order to customize it.
* Adds a "--config <file>" option to the swarm executable which will
  allow to load a configuration file in TOML format from the
  specified location in order to initialize the Swarm node The
  override priorities are like follows: environment variables
  override command line arguments override config file override
  default config.

4 files changed, 22 insertions, 11 deletions

diff --git a/swarm/network/hive.go b/swarm/network/hive.go
index d37b7e400..2504a4610 100644
--- a/swarm/network/hive.go
+++ b/swarm/network/hive.go
@@ -70,19 +70,25 @@ type HiveParams struct {
 	*kademlia.KadParams
 }
 
-func NewHiveParams(path string) *HiveParams {
-	kad := kademlia.NewKadParams()
+//create default params
+func NewDefaultHiveParams() *HiveParams {
+	kad := kademlia.NewDefaultKadParams()
 	// kad.BucketSize = bucketSize
 	// kad.MaxProx = maxProx
 	// kad.ProxBinSize = proxBinSize
 
 	return &HiveParams{
 		CallInterval: callInterval,
-		KadDbPath:    filepath.Join(path, "bzz-peers.json"),
 		KadParams:    kad,
 	}
 }
 
+//this can only finally be set after all config options (file, cmd line, env vars)
+//have been evaluated
+func (self *HiveParams) Init(path string) {
+	self.KadDbPath = filepath.Join(path, "bzz-peers.json")
+}
+
 func NewHive(addr common.Hash, params *HiveParams, swapEnabled, syncEnabled bool) *Hive {
 	kad := kademlia.New(kademlia.Address(addr), params.KadParams)
 	return &Hive{
diff --git a/swarm/network/kademlia/kademlia.go b/swarm/network/kademlia/kademlia.go
index bf976a3e1..0abc42a19 100644
--- a/swarm/network/kademlia/kademlia.go
+++ b/swarm/network/kademlia/kademlia.go
@@ -52,7 +52,7 @@ type KadParams struct {
 	ConnRetryExp         int
 }
 
-func NewKadParams() *KadParams {
+func NewDefaultKadParams() *KadParams {
 	return &KadParams{
 		MaxProx:              maxProx,
 		ProxBinSize:          proxBinSize,
diff --git a/swarm/network/kademlia/kademlia_test.go b/swarm/network/kademlia/kademlia_test.go
index 417ccecae..88858908a 100644
--- a/swarm/network/kademlia/kademlia_test.go
+++ b/swarm/network/kademlia/kademlia_test.go
@@ -63,7 +63,7 @@ func TestOn(t *testing.T) {
 	if !ok1 || !ok2 {
 		t.Errorf("oops")
 	}
-	kad := New(addr, NewKadParams())
+	kad := New(addr, NewDefaultKadParams())
 	err := kad.On(&testNode{addr: other}, nil)
 	_ = err
 }
@@ -72,7 +72,7 @@ func TestBootstrap(t *testing.T) {
 
 	test := func(test *bootstrapTest) bool {
 		// for any node kad.le, Target and N
-		params := NewKadParams()
+		params := NewDefaultKadParams()
 		params.MaxProx = test.MaxProx
 		params.BucketSize = test.BucketSize
 		params.ProxBinSize = test.BucketSize
@@ -127,7 +127,7 @@ func TestFindClosest(t *testing.T) {
 
 	test := func(test *FindClosestTest) bool {
 		// for any node kad.le, Target and N
-		params := NewKadParams()
+		params := NewDefaultKadParams()
 		params.MaxProx = 7
 		kad := New(test.Self, params)
 		var err error
@@ -198,7 +198,7 @@ var (
 func TestProxAdjust(t *testing.T) {
 	r := rand.New(rand.NewSource(time.Now().UnixNano()))
 	self := gen(Address{}, r).(Address)
-	params := NewKadParams()
+	params := NewDefaultKadParams()
 	params.MaxProx = 7
 	kad := New(self, params)
 
@@ -232,7 +232,7 @@ func TestSaveLoad(t *testing.T) {
 	r := rand.New(rand.NewSource(time.Now().UnixNano()))
 	addresses := gen([]Address{}, r).([]Address)
 	self := RandomAddress()
-	params := NewKadParams()
+	params := NewDefaultKadParams()
 	params.MaxProx = 7
 	kad := New(self, params)
 
diff --git a/swarm/network/syncer.go b/swarm/network/syncer.go
index d76af022c..6d729fcb9 100644
--- a/swarm/network/syncer.go
+++ b/swarm/network/syncer.go
@@ -131,9 +131,8 @@ type SyncParams struct {
 }
 
 // constructor with default values
-func NewSyncParams(bzzdir string) *SyncParams {
+func NewDefaultSyncParams() *SyncParams {
 	return &SyncParams{
-		RequestDbPath:      filepath.Join(bzzdir, "requests"),
 		RequestDbBatchSize: requestDbBatchSize,
 		KeyBufferSize:      keyBufferSize,
 		SyncBufferSize:     syncBufferSize,
@@ -144,6 +143,12 @@ func NewSyncParams(bzzdir string) *SyncParams {
 	}
 }
 
+//this can only finally be set after all config options (file, cmd line, env vars)
+//have been evaluated
+func (self *SyncParams) Init(path string) {
+	self.RequestDbPath = filepath.Join(path, "requests")
+}
+
 // syncer is the agent that manages content distribution/storage replication/chunk storeRequest forwarding
 type syncer struct {
 	*SyncParams                     // sync parameters