Which command only updates the Docker image?

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1

Which command is used to update only the Docker image?

/var/discourse# ./launcher -h
Usage: launcher COMMAND CONFIG [--skip-prereqs] [--docker-args STRING]
Commands:
    start:       Start/initialize a container
    stop:        Stop a running container
    restart:     Restart a container
    destroy:     Stop and remove a container
    enter:       Open a shell to run commands inside the container
    logs:        View the Docker logs for a container
    bootstrap:   Bootstrap a container for the config based on a template
    run:         Run the given command with the config in the context of the last bootstrapped image
    rebuild:     Rebuild a container (destroy old, bootstrap, start new)
    cleanup:     Remove all containers that have stopped for > 24 hours
    start-cmd:   Generate docker command used to start container

Options:
    --skip-prereqs             Don't check launcher prerequisites
    --docker-args              Extra arguments to pass when running docker
    --skip-mac-address         Don't assign a mac address
    --run-image                Override the image used for running the container

My use case is:
Currently, during the build process, if a Docker image update is required but the server’s network connection is poor, the process gets stuck at the image update step for a very long time. I would like to have a dedicated command for updating the Docker image, so that I can update the image in advance separately and then build the code without any rush. For example:

./launcher pull-docker

I know I can manually create a working version, but I would still prefer if the official team could provide one.

2

hmmm, only way i know is to first update the launcher script:

cd /var/discourse
git pull

then find the default image tag the launcher is using:

grep -m1 '^image=' launcher

the output should look like:

image="discourse/base:2.0.20260915-0028"

then run:

docker pull discourse/base:2.0.20260915-0028

then when you run ./launcher rebuild app it should skip the download i think.

it should say Status: Image is up to date for discourse/base:2.0.20260915-0028 when you run the rebuild…

3

Thanks for the reply. I’m currently updating using a similar method, but it’s quite cumbersome. I’d like to write my own automation script, but I’m worried about potential incompatibility after official updates.

4

you can do it with an executable bash script and even use a cron job to automate it. not sure why it would become incompatible any time soon.

5

What I mean is that it might become incompatible in the future, and I may need to check this script every single time, which undoubtedly adds extra work. I’m just assuming the worst-case scenario :joy:. Of course, when it comes to solving the problem, let’s just get started first and adjust as we go.