Example project to initialize an etcd docker container on startup with initial key-value pairs from a text file via docker-compose.
- Start etcd container and load initial values:
docker-compose up -d --build - Retrieve all values from etcd container:
docker exec -it etcd-initializer_etcd_1 etcdctl get --prefix "" - Windows users: Be careful to keep the line endings as
LFin load-default-values.sh, otherwise you will get errors on execution.
Starting point of this project is the docker-compose.yml:
Here the main etcd service is set up as well as the etcd-initializer, which is only used to read out the key-value-pairs
from a (in out case) .properties file and write them into the main etcd.
To achieve this, the etcd-initializer gets the content of the etcd directory copied in the container
(done during build of the image as defined in the Dockerfile) and then executes the script load-default-values
with a properties file as parameter.
Since this is its only command the container stops after execution.
Important: After the first build, use docker-compose up -d --build in order to have changes in the properties file
reflected in the container.
The script load-default-values only reads the key-value-pairs from the properties file specified in the docker-compose
and writes the into the main etcd via etcd put <key> <value>.
In a productive setup, you would probably have a separate compose file per environment, where you would specify separate .properties files.
The main etcd container needs to be started in order to run scripts like etcd put <key> <value>.
Etcd itself does not support loading initial values from a file
(see feature request for reference).
To make sure that the main etcd is ready to accept connections, it seemed to be the easiest and most maintainable way
to start a second etcd container, since it is small, fast in startup and already brings all necessary functionality.
Contributions via pull requests are very welcome, e.g. for supporting Json files.