docker: add ltcd image

Intoduce the Litecoin network daemon, which will be needed in order
to interact with Litecoin blockchain.

docker/ltcd/Dockerfile

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+FROM golang:1.7
+
+MAINTAINER Andrey Samokhvalov <andrew.shvv@gmail.com>
+
+# Expose mainnet ports (server, rpc)
+EXPOSE 8333 8334
+
+# Expose testnet ports (server, rpc)
+EXPOSE 18333 18334
+
+# Expose simnet ports (server, rpc)
+EXPOSE 18555 18556
+
+# Expose segnet ports (server, rpc)
+EXPOSE 28901 28902
+
+# Grab and install the latest version of roasbeef's fork of btcd and all
+# related dependencies.
+WORKDIR $GOPATH/src/github.com/ltcsuite/ltcd
+RUN git clone https://github.com/ltcsuite/ltcd ./
+RUN go get -u github.com/Masterminds/glide
+RUN glide install
+RUN go install . ./cmd/ltcctl ./cmd/gencerts
+
+RUN mkdir "/rpc" "/root/.ltcd" "/root/.ltcctl"
+RUN touch "/root/.ltcd/ltcd.conf"
+
+# Manually generate certificate and add all domains, it is needed to connect
+# "ltcctl" and "lnd" to "ltcd" over docker links.
+RUN "/go/bin/gencerts" --host="*" --directory="/rpc" --force
+
+# Create a volume to house pregenerated RPC credentials. This will be
+# shared with any lnd, btcctl containers so they can securely query btcd's RPC
+# server.
+# You should NOT do this before certificate generation!
+# Otherwise manually generated certificate will be overriden with shared
+# mounted volume! For more info read dockerfile "VOLUME" documentation.
+VOLUME ["/rpc"]
+
+COPY "start-ltcctl.sh" .
+COPY "start-ltcd.sh" .
+
+RUN chmod +x start-ltcctl.sh
+RUN chmod +x start-ltcd.sh
+

docker/ltcd/start-ltcctl.sh

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+#!/usr/bin/env bash
+
+# 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"
+    DEFAULT="$2"
+
+    if [[ -z "$VARIABLE" || "$VARIABLE" == "$BLANK_STRING" ]]; then
+
+        if [ -z "$DEFAULT" ]; then
+            error "You should specify default variable"
+        else
+            VARIABLE="$DEFAULT"
+        fi
+    fi
+
+   return "$VARIABLE"
+}
+
+# Set default variables if needed.
+RPCUSER=$(set_default "$RPCUSER" "devuser")
+RPCPASS=$(set_default "$RPCPASS" "devpass")
+NETWORK=$(set_default "$NETWORK" "simnet")
+
+ltcctl \
+    "--$NETWORK" \
+    --rpccert="/rpc/rpc.cert" \
+    --rpcuser="$RPCUSER" \
+    --rpcpass="$RPCPASS" \
+    --rpcserver="rpcserver" \
+    "$@"

docker/ltcd/start-ltcd.sh

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+#!/usr/bin/env bash
+
+# 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"
+    DEFAULT="$2"
+
+    if [[ -z "$VARIABLE" || "$VARIABLE" == "$BLANK_STRING" ]]; then
+
+        if [ -z "$DEFAULT" ]; then
+            error "You should specify default variable"
+        else
+            VARIABLE="$DEFAULT"
+        fi
+    fi
+
+   return "$VARIABLE"
+}
+
+# Set default variables if needed.
+RPCUSER=$(set_default "$RPCUSER" "devuser")
+RPCPASS=$(set_default "$RPCPASS" "devpass")
+DEBUG=$(set_default "$DEBUG" "info")
+NETWORK=$(set_default "$NETWORK" "simnet")
+
+PARAMS=$(echo \
+    "--$NETWORK" \
+    "--debuglevel=$DEBUG" \
+    "--rpcuser=$RPCUSER" \
+    "--rpcpass=$RPCPASS" \
+    "--datadir=/data" \
+    "--logdir=/data" \
+    "--rpccert=/rpc/rpc.cert" \
+    "--rpckey=/rpc/rpc.key" \
+    "--rpclisten=0.0.0.0"
+)
+
+# Set the mining flag only if address is non empty.
+if [[ -n "$MINING_ADDRESS" ]]; then
+    PARAMS="$PARAMS --miningaddr=$MINING_ADDRESS"
+fi
+
+# Add user parameters to command.
+PARAMS="$PARAMS $@"
+
+# Print command and start bitcoin node.
+echo "Command: ltcd $PARAMS"
+ltcd $PARAMS
+