docker: general improvements

* rename set_env->set_default
* fix bug with return from bash func
* make '--miningaddr' optional

docker/btcd/start-btcctl.sh

@@ -1,32 +1,46 @@
 #!/usr/bin/env bash
 
-# Check env variable and in case of empty value and default value specified
-# returns default value, in case of non-empty value returns value.
-set_env() {
+# exit from script if error was raised.
+set -e
+
+# error function is used within a bash function in order to send the error
+# message directly to the stderr output and exit.
+error() {
+    echo "$1" > /dev/stderr
+    exit 0
+}
+
+# return is used within bash function in order to return the value.
+return() {
+    echo "$1"
+}
+
+# set_default function gives the ability to move the setting of default
+# env variable from docker file to the script thereby giving the ability to the
+# user override it durin container start.
+set_default() {
     # docker initialized env variables with blank string and we can't just
     # use -z flag as usually.
     BLANK_STRING='""'
 
     VARIABLE="$1"
-    NAME="$2"
-    DEFAULT="$3"
+    DEFAULT="$2"
 
     if [[ -z "$VARIABLE" || "$VARIABLE" == "$BLANK_STRING" ]]; then
 
         if [ -z "$DEFAULT" ]; then
-            echo "You should specify '$NAME' env variable"
-            exit 0
+            error "You should specify default variable"
         else
             VARIABLE="$DEFAULT"
         fi
     fi
 
-    # echo is used as return in case if string values
-    echo "$VARIABLE"
+   return "$VARIABLE"
 }
 
-RPCUSER=$(set_env "$RPCUSER" "RPCUSER")
-RPCPASS=$(set_env "$RPCPASS" "RPCPASS")
+# Set default variables if needed.
+RPCUSER=$(set_default "$RPCUSER" "devuser")
+RPCPASS=$(set_default "$RPCPASS" "devpass")
 
 btcctl \
     --simnet \

docker/btcd/start-btcd.sh

@@ -1,47 +1,69 @@
 #!/usr/bin/env bash
 
-# Check env variable and in case of empty value and default value specified
-# returns default value, in case of non-empty value returns value.
-set_env() {
+# exit from script if error was raised.
+set -e
+
+# error function is used within a bash function in order to send the error
+# message directly to the stderr output and exit.
+error() {
+    echo "$1" > /dev/stderr
+    exit 0
+}
+
+# return is used within bash function in order to return the value.
+return() {
+    echo "$1"
+}
+
+# set_default function gives the ability to move the setting of default
+# env variable from docker file to the script thereby giving the ability to the
+# user override it durin container start.
+set_default() {
     # docker initialized env variables with blank string and we can't just
     # use -z flag as usually.
     BLANK_STRING='""'
 
     VARIABLE="$1"
-    NAME="$2"
-    DEFAULT="$3"
+    DEFAULT="$2"
 
     if [[ -z "$VARIABLE" || "$VARIABLE" == "$BLANK_STRING" ]]; then
 
         if [ -z "$DEFAULT" ]; then
-            echo "You should specify '$NAME' env variable"
-            exit 0
+            error "You should specify default variable"
         else
             VARIABLE="$DEFAULT"
         fi
     fi
 
-    # echo is used as return in case if string values
-    echo "$VARIABLE"
+   return "$VARIABLE"
 }
 
-RPCUSER=$(set_env "$RPCUSER" "RPCUSER")
-RPCPASS=$(set_env "$RPCPASS" "RPCPASS")
+# Set default variables if needed.
+RPCUSER=$(set_default "$RPCUSER" "devuser")
+RPCPASS=$(set_default "$RPCPASS" "devpass")
+DEBUG=$(set_default "$DEBUG" "info")
 
-DEBUG=$(set_env "$DEBUG" "DEBUG")
+PARAMS=$(echo \
+    "--simnet" \
+    "--debuglevel=$DEBUG" \
+    "--rpcuser=$RPCUSER" \
+    "--rpcpass=$RPCPASS" \
+    "--datadir=/data" \
+    "--logdir=/data" \
+    "--rpccert=/rpc/rpc.cert" \
+    "--rpckey=/rpc/rpc.key" \
+    "--rpclisten=0.0.0.0"
+)
 
-MINING_ADDRESS=$(set_env "$MINING_ADDRESS" "MINING_ADDRESS" "ScoDuqH7kYA9nvxuRg4Xk7E31AhsSc5zxp")
+# Set the mining flag only if address is non empty.
+if [[ -n "$MINING_ADDRESS" ]]; then
+    PARAMS="$PARAMS --miningaddr=$MINING_ADDRESS"
+fi
 
-btcd \
-    --debuglevel="$DEBUG" \
-    --datadir="/data" \
-    --logdir="/data" \
-    --simnet \
-    --rpccert="/rpc/rpc.cert" \
-    --rpckey="/rpc/rpc.key" \
-    --rpcuser="$RPCUSER" \
-    --rpcpass="$RPCPASS" \
-    --miningaddr="$MINING_ADDRESS" \
-    --rpclisten="0.0.0.0" \
-    "$@"
+# Add user parameters to command.
+PARAMS="$PARAMS $@"
+
+# Print command and start bitcoin node.
+echo "Command: btcd $PARAMS"
+btcd $PARAMS