[docker] adding entrypoint and template generation to dockerfile for u18

Signed-off-by: Raphael Defosseux <raphael.defosseux@eurecom.fr>

docker/scripts/enb_entrypoint.sh

@@ -0,0 +1,44 @@
+#!/bin/bash
+
+set -euo pipefail
+
+# Based another env var
+if [[ -v USE_FDD_CU ]]; then ln -s /opt/oai-enb/etc/cu.fdd.conf /opt/oai-enb/etc/enb.conf; fi
+if [[ -v USE_FDD_DU ]]; then ln -s /opt/oai-enb/etc/du.fdd.conf /opt/oai-enb/etc/enb.conf; fi
+if [[ -v USE_FDD_MONO ]]; then ln -s /opt/oai-enb/etc/enb.fdd.conf /opt/oai-enb/etc/enb.conf; fi
+if [[ -v USE_TDD_MONO ]]; then ln -s /opt/oai-enb/etc/enb.tdd.conf /opt/oai-enb/etc/enb.conf; fi
+if [[ -v USE_FDD_RCC ]]; then ln -s /opt/oai-enb/etc/rcc.if4p5.enb.fdd.conf /opt/oai-enb/etc/enb.conf; fi
+if [[ -v USE_FDD_RRU ]]; then ln -s /opt/oai-enb/etc/rru.fdd.conf /opt/oai-enb/etc/enb.conf; fi
+if [[ -v USE_TDD_RRU ]]; then ln -s /opt/oai-enb/etc/rru.tdd.conf /opt/oai-enb/etc/enb.conf; fi
+
+CONFIG_FILES=`ls /opt/oai-enb/etc/enb.conf`
+
+for c in ${CONFIG_FILES}; do
+    # grep variable names (format: ${VAR}) from template to be rendered
+    VARS=$(grep -oP '@[a-zA-Z0-9_]+@' ${c} | sort | uniq | xargs)
+
+    # create sed expressions for substituting each occurrence of ${VAR}
+    # with the value of the environment variable "VAR"
+    EXPRESSIONS=""
+    for v in ${VARS}; do
+	NEW_VAR=`echo $v | sed -e "s#@##g"`
+        if [[ "${!NEW_VAR}x" == "x" ]]; then
+            echo "Error: Environment variable '${NEW_VAR}' is not set." \
+                "Config file '$(basename $c)' requires all of $VARS."
+            exit 1
+        fi
+        EXPRESSIONS="${EXPRESSIONS};s|${v}|${!NEW_VAR}|g"
+    done
+    EXPRESSIONS="${EXPRESSIONS#';'}"
+
+    # render template and inline replace config file
+    sed -i "${EXPRESSIONS}" ${c}
+done
+
+# Later-on, how to add command lines options?
+
+# Load the USRP binaries
+# --> later conditional (when doing simulators)
+/usr/lib/uhd/utils/uhd_images_downloader.py
+
+exec "$@"