how to check if container is up to date

Question

I'm using docker-compose to mange my container 'abc' in a linux server (centos).

my steps that I want to perofrm:

1) docker compose pull 'abc' in order to pull my latest image

docker-compose --file docker-compose.yml pull

2) docker command to check if my container 'abc' need to be updated (possible???)

3) if my container 'abc' I will perform docker-compose up -d

docker-compose --file docker-compose.yml up -d

Remark: I know that step 3 is checking and than update the container if necessary but I need to perform pre tasks if step 2 return True

This seems related:https://stackoverflow.com/questions/37685581/how-to-get-docker-compose-to-use-the-latest-image-from-repository — TheGameiswar, Nov 14 '17 at 14:43
thanks @TheGameiswar for your messgae but I didn't find there any command for my step 2 — dsaydon, Nov 14 '17 at 14:46
AS per this ,it is not implemented..:https://github.com/docker/compose/issues/3574 — TheGameiswar, Nov 14 '17 at 14:49
What kind of pre-task do you want to do? That sounds wrong somehow... — Jonas Heinisch, Nov 14 '17 at 14:52
@TheGameiswar - I didn't find any mention there for what i'm looking for — dsaydon, Nov 14 '17 at 15:06
@jonasheinisch - several pre tasks such as: disable the host in my f5 pool load balancer, run a script and more... — dsaydon, Nov 14 '17 at 15:07
You could do something like this to check the if the container is using the latest image id. ```CONTAINER_IMAGE_SHA=docker container inspect $CONTAINER_NAME -f "{{ .Image }}" LATEST_IMAGE_SHA=docker image inspect $IMAGE_NAME -f "{{ .Id }}"``` — Bill Cheng, Nov 14 '17 at 20:39

score 3 · Answer 1 · answered Nov 14 '17 at 15:03

To restate your question as I read it:

Prior to updating a container, do X

Changes Include:

Image changes
Environment changes for containers
Networking changes
..etc

TLDR; What you want is a dry-run feature of docker-compose. You are not alone: https://github.com/docker/compose/issues/1203

More; I think you are out of luck trying to use docker-compose itself for this purpose until this issue is tackled by the developer community. To be completely safe you would want to perform your pre-flight action when anything affecting the running container is about to change.

Potential Direction: If we were to wish for this, we'd build a shell script that does the examination for us, as simple as a diff on the compose file, or more complex as locating each image e.g., grep image docker-compose.yml | sed "s/^.*\: $.*$,$/\1/g" ... etc and so forth.

Jan Gassen · Accepted Answer · 2020-12-29T15:00:36.080

I'm not entirely sure if this will do exactly what you need, but you can try to check if your container needs updating like this:

docker-compose puts a label with a hash of the current configuration into the container config. You can get the configuration hash like this:

docker inspect my-container -f '{{index .Config.Labels "com.docker.compose.config-hash"}}'

You can then compare this hash to the hash of your current docker compose file:

docker-compose config --hash="my-container"

If those hashes differ, the containers probably needs to be rebuild as the configuration has changed.

This will however probably not work if you're using the latest tag and the image itself needs updating. To account for that, you could additionally try How do I check if my local docker image is outdated, without pushing from somewhere else? or Bash parse docker status to check if local image is up to date

how to check if container is up to date

2 Answers2