Passing a custom conf file to ECS task definition

Question

Actually I have a simple use case, where I have to pass a custom config file in my ECS task definition. Example- Let's suppose I want to run Nginx as a service in ECS cluster and now I have to pass my custom nginx.conf to ECS task definition. I am not able to figure out any possible way to do so. I was doing the same kind of thing in kubernetes using config maps and secrets, and after that mounting them to docker containers. How can I achieve the same in ECS?

Glyceryl

Answer 1

You can't pass any custom configuration via task definition. However, I can think of two different approaches below, pick one that fits your bill:

1 - Bake the custom configuration inside your image via Dockerfile. This is comparatively cost-effective. 2- Use docker volume to mount the configuration from the host into the container. Now that both EC2 and Fargate launch types support EFS, you can use EFS volume if you want to have one volume mounted on to multiple containers on multiple hosts. Here's a step-by-step guide from AWS documentation.

Philipson

Answer 2

Disclaimer: I am the author or UDL.

The Ultimate Docker Launcher was created to support exactly this scenario. It will modify or write files based on environment variables, which avoids the need to mount any external file systems. For example, this Dockerfile will overwrite the contents of /etc/nginx/nginx.conf with your own contents (which is base64 encoded):

FROM nginx

RUN apt-get update; apt-get install -y jq curl

# Download the latest version of udl
RUN curl -s https://api.github.com/repos/mcasperson/UltimateDockerLauncher/releases/latest | \
    jq '.assets[] | select(.name|match("udl$")) | .browser_download_url' | \
    xargs -I {} curl -L -o /opt/udl {}
RUN chmod +x /opt/udl

# UDL_WRITEFILE_X environment variables are used to save files
ENV UDL_WRITEB64FILE_1='[/etc/nginx/nginx.conf]base64encodedconfigfilegoeshere'

# Here we use bash to call UDL before calling the main application
CMD [ "/bin/bash", "-c", "/opt/udl; nginx -g 'daemon off;'" ]

Engobe