Extend hoster to get paths from environment.

Dockerfile

@@ -1,11 +1,8 @@
-FROM frolvlad/alpine-python3
+FROM python:3.10.6-alpine3.16
 
 RUN pip3 install docker
 RUN mkdir /hoster
 WORKDIR /hoster
 ADD hoster.py /hoster/
 
-CMD ["python3", "-u", "hoster.py"]
-
-
-
+CMD ["python3", "-u", "hoster.py"]

README.md

@@ -1,14 +1,25 @@
 # Hoster
 
+## Mount hosts file directyly
 A simple "etc/hosts" file injection tool to resolve names of local Docker containers on the host.
 
 hoster is intended to run in a Docker container:
 
     docker run -d \
-        -v /var/run/docker.sock:/tmp/docker.sock \
-        -v /etc/hosts:/tmp/hosts \
+        --mount type=bind,source=/var/run/docker.sock,target=/tmp/docker.sock \
+        --mount type=bind,source=/etc/hosts,target=/tmp/hosts \
         dvdarias/docker-hoster
 
+## Mount directory containing hosts file
+In some cases there is a problem while rewriting hosts file. This can be prevent with mapping/mounting complete directory and point to the hosts file with environment variable.
+
+    docker run -d \
+        -e HOST_PATH=/tmp/etc/hosts -e SOCK_PATH=tmp/docker.sock \
+        --mount type=bind,source=/etc,target=/tmp/etc \
+        --mount type=bind,source=/var/run/docker.sock,target=/tmp/docker.sock \
+        dvdarias/docker-hoster
+
+
 The `docker.sock` is mounted to allow hoster to listen for Docker events and automatically register containers IP.
 
 Hoster inserts into the host's `/etc/hosts` file an entry per running container and keeps the file updated with any started/stoped container.

hoster.py

@@ -129,9 +129,11 @@ def update_hosts_file():
 
 
 def parse_args():
+    hostPath = os.getenv('HOST_PATH', "/tmp/hosts")
+    sockPath = os.getenv('SOCK_PATH', "tmp/docker.sock")
     parser = argparse.ArgumentParser(description='Synchronize running docker container IPs with host /etc/hosts file.')
-    parser.add_argument('socket', type=str, nargs="?", default="tmp/docker.sock", help='The docker socket to listen for docker events.')
-    parser.add_argument('file', type=str, nargs="?", default="/tmp/hosts", help='The /etc/hosts file to sync the containers with.')
+    parser.add_argument('socket', type=str, nargs="?", default=sockPath, help='The docker socket to listen for docker events.')
+    parser.add_argument('file', type=str, nargs="?", default=hostPath, help='The /etc/hosts file to sync the containers with.')
     return parser.parse_args()
 
 if __name__ == '__main__':