DehU

Docker /etc/hosts Updater is a project made for populating your /etc/hosts file with aliases of current running Docker containers.

Installation

Go to this directory, activate your venv and then type:

pip install .

Usage

To populate your /etc/hosts file, run (as root):

dehu populate

A new section starting with ### Start of DehU entries and ending with ### End of DehU entries will be added to your /etc/hosts file.

You can ask DehU to print the content of the /etc/hosts file afterwards with the -v option.

To cleanup your /etc/hosts file, run (as root):

dehu clear

Examples

The compose.yml file in the tests directory contains a simple container architecture with:

• A first container with the aliases:

  • alias1.local
  • alias2.local

• A second container with the aliases:

  • alias2.local
  • alias3.local

You can start those containers by running:

cd tests
docker compose up -d 

Then, run dehu to populate your /etc/hosts file

sudo dehu populate

You should have an output like this:

The following aliases have been ignored as they are shared by multiple containers:
  - alias2.local

This alias being shared by two containers, it is ignored by dehu. Moreover, your /etc/hosts file now contains this section:

### Start of DehU entries
tests-service_2-1 172.18.0.2
service_2 172.18.0.2
alias3.local  172.18.0.2
tests-service_1-1 172.19.0.2
service_1 172.19.0.2
alias1.local  172.19.0.2
### End of DehU entries

Where you can find the aliases manually set in the compose.yml file as well as the aliases Docker compose automatically creates.

Now if you stop a container and rerun DehU:

docker compose down service_2
sudo dehu populate

You now have the following section in /etc/hosts:

### Start of DehU entries
tests-service_1-1 172.19.0.2
service_1 172.19.0.2
alias1.local  172.19.0.2
alias2.local  172.19.0.2
### End of DehU entries

Since there are no more conflicts, you find the alias2.local alias.

Finally, you can clear your /etc/hosts file by running:

sudo dehu clear