In my docker compose file there is a dynamic field which I'd like to generate during the running. Actually it is a string template:
environment:
- SERVER_URL:https://0.0.0.0:${PORT}
And I want to configure this PORT parameter dynamically
docker-compose run <service> PORT=443
In documentation there is ARGS parameters set I suppose I can use. But there is no information how can I use those inside compose file
In docker-compose, arguments are available and usefull only in dockerfile. You can specify what you are doing in the level ahead like following:
#dockerfile
ARG PORT
ENV SERVER_URL "https://0.0.0.0:$PORT"
Your port can be set in your docker-compose.yml:
build:
context: .
args:
- PORT=443
It is actually an environment variable in any case. You can pass it through your run command if that fits to you:
PORT=443 docker-compose run <service>
#or
docker-compose run <service> -e PORT=443
PORT=443 docker-compose ... -f bla.yml to pass the port in and then in my YAML file, the line command: bash -c "echo $PORT" successfully displayed 443.
MYARG=123 docker-compose run <service>, it returns "The terum MYARG=12345 is not recognized as a cmdlet name, function, script file or operating program." - When using docker-compose run <service> -e MYARG=123, it returns "Error response from daemon: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: exec: "-e": executable file not found in $PATH: unknown"
You can use the flag when using docker-compose build
docker-compose build --build-arg PRODUCTION=VALUE
In Dockerfile you can get the argument PRODUCTION
# Dockerfile
ARG PRODUCTION
FROM node:latest
This is possible with docker stack deploy
Example Compose File in your environment section:
- MY_VARIABLE_NAME=${MY_VARIABLE_VALUE}
Stack Deploy Command (I ran this from Gitbash in Windows):
MY_VARIABLE_VALUE=some-value docker stack deploy --compose-file compose_file_here stackname
Reference See this Github post here
docker compose up as well
docker-compose up in such a way that the variable would be expanded when "executing" the docker compose, but would NOT be seen by the container. For example, a variable that specifies which version of the image to use to spin up a particular service.Sharing the only way I managed to set a runtime variable with Docker Compose using minimum setup and command changes.
On docker-compose.yml:
services:
my_service:
...
environment:
- MYENVVAR=placeholder_value
On the terminal:
docker-compose run -e MYENVVAR=actual_value my_service
Please pay attention that the "-e" portion of the command line argument must come before the service name.
This is described on the official documentation: Set environment variables with docker compose run
This worked for me and I did not have to touch my Dockerfile:
I used
PORT=443 docker-compose ...(whatever)... -f bla.yml
to pass the port in and then in my YAML file, the line command: bash -c "echo $PORT" successfully displayed 443.
We can pass the argument to docker compose like that:
Run the docker-compose.yaml with this command:
$ ENV=staging docker-compose up
docker-compose.yaml file look like that:
...
go:
container_name: mailavail_go
build:
context: ./go
dockerfile: Dockerfile
args:
ENV: ${ENV} # we can defined arguments like that
ports:
- 8080:8080
...
Dockerfile file look like that:
...
FROM golang:latest
ARG ENV=dev # we can also add a default value
ENV ENV=${ENV} # this will set the value
echo "My ENV is ${ENV}" # This is for testing purpose and it will the ENV value
RUN mkdir /golang
...
This is possible with docker-compose with ARGS inside Dockerfile.
Problem to Solve:
Dockerfile
RUN
ARG CACHEBUST=1 # This will setup a arg called CACHEBUST
RUN git clone
Run the below bash command to build and run. SETTING --build-arg CACHEBUST= random md5sum hash, makes Docker-Compose to rebuild the image, starting the line with ARGS and so on.
docker-compose -f dockerprd.yml build --build-arg CACHEBUST=$(echo $RANDOM | md5sum | head -c 20; echo;) && docker-compose -f dockerprd.yml up -d
To use variables in a docker-compose.yml or compose.yml file you can do this:
docker-compose.yml:# docker-compose.yml
version: '3.8'
name: "my_project"
services:
db:
image: postgres:$docker_image_version # <- this is the variable
restart: always
environment:
POSTGRES_PASSWORD: example
.env file in the same directory as docker-compose.yml:# .env
docker_image_version="16-alpine3.19"
docker compose config
You should see that the variable will be replaced:
name: my_project
services:
db:
environment:
POSTGRES_PASSWORD: example
image: postgres:16-alpine3.19
networks:
default: null
restart: always
networks:
default:
name: my_project_default
docker compose up -d
docker compose ps
You should see something like:
NAME IMAGE COMMAND SERVICE CREATED STATUS PORTS
my_project-db-1 postgres:16-alpine3.19 "docker-entrypoint.sh postgres" db 5 seconds ago Up 5 seconds 5432/tcp
In the output you can see that it is running the version set in the .env file: 16-alpine3.19
Source: Docker compose documentation
The solution that I found for this problem was to dynamically create an env file and pass it as --env-file value.
I created a bash script:
$PROJ=$1
echo "REST_URL=http://$2" > ./docker-env-$PROJ
echo "BRANCH=$3" >> ./docker-env-$PROJ
docker compose \
-p $PROJ \
--env-file ./docker-env-$PROJ \
up -d
rm -f ./docker-env-$PROJ
and run it:
start_all.sh mycont "localhost:8080" master