Support for envvar-based config (closes #1)

Dockerfile

@@ -52,4 +52,8 @@ ENV LANGUAGE en_US:en
 ENV LC_ALL en_US.UTF-8
 RUN locale-gen en_US.UTF-8
 
+# copy in the entrypoint script
+COPY entrypoint /
+RUN chmod +x /entrypoint
+
 VOLUME ["/etc/gitlab-runner", "/home/gitlab-runner", "/output"]

entrypoint

@@ -26,5 +26,15 @@ if [ -f "${CA_CERTIFICATES_PATH}" ]; then
   cmp --silent "${CA_CERTIFICATES_PATH}" "${LOCAL_CA_PATH}" || update_ca
 fi
 
+# if we don't have a config file...
+if [[ ! -e ${CONFIG_FILE} ]]; then
+  # ...but we do have config vars...
+  if [[ -n ${CI_SERVER_URL} && -n ${RUNNER_TOKEN} && -n ${RUNNER_DESCRIPTION} && -n ${RUNNER_EXECUTOR} ]]; then
+    # register the runner
+    su gitlab-runner -c \
+      "gitlab-runner register --non-interactive --config '${CONFIG_FILE}' --url '${CI_SERVER_URL}' --registration-token '${RUNNER_TOKEN}' --description '${RUNNER_DESCRIPTION}' --executor '${RUNNER_EXECUTOR}'"
+  fi
+fi
+
 # launch gitlab-runner passing all arguments
 exec gitlab-runner "$@"