[docker] Run as non-root user, fixes permissions. (#5702)

docker-entrypoint.sh

@@ -14,7 +14,7 @@ pattern="@Command(name = \"$1\""
 if expr "x$1" : 'x[a-z][a-z-]*$' > /dev/null && fgrep -qe "$pattern" "$cmdsrc"/*.java; then
     # If ${GEN_DIR} has been mapped elsewhere from default, and that location has not been built
     if [[ ! -f "${codegen}" ]]; then
-        (cd "${GEN_DIR}" && exec mvn -am -pl "modules/swagger-codegen-cli" package)
+        (cd "${GEN_DIR}" && exec mvn -am -pl "modules/swagger-codegen-cli" -Duser.home=$(dirname MAVEN_CONFIG) package)
     fi
     command=$1
     shift

run-in-docker.sh

@@ -10,7 +10,9 @@ mkdir -p "${maven_cache_repo}"
 docker run --rm -it \
         -w /gen \
         -e GEN_DIR=/gen \
+        -e MAVEN_CONFIG=/var/maven/.m2 \
+        -u "$(id -u):$(id -u)" \
         -v "${PWD}:/gen" \
-        -v "${maven_cache_repo}:/root/.m2/repository" \
+        -v "${maven_cache_repo}:/var/maven/.m2/repository" \
         --entrypoint /gen/docker-entrypoint.sh \
         maven:3-jdk-7 "$@"