sz4kerto on Docker 1.10.0 is out

I'd really-really need DNS for non-running containers, somehow. Nginx can't start if an upstream container is down, as its name won't be resolved.

bmelton 10y

I've had that problem too, and found that you can implement a "wait" command.

If you're using Docker Compose, add this to your environment: environment: - WAIT_COMMAND=[ $(curl --write-out %{http_code} --silent --output /dev/null http://elastic:9200/_cat/health?h=st) = 200 ] - WAIT_START_CMD=python /code/lytten/main.py - WAIT_SLEEP=2 - WAIT_LOOPS=10

Then, create a 'wait' bash script in your app's source code that looks like this: !/bin/bash echo $WAIT_COMMAND echo $WAIT_START_CMD

    is_ready() {
        eval "$WAIT_COMMAND"
    }

    # wait until is ready
    i=0
    while ! is_ready; do
        i=`expr $i + 1`
        if [ $i -ge $WAIT_LOOPS ]; then
            echo "$(date) - still not ready, giving up"
            exit 1
        fi  
        echo "$(date) - waiting to be ready"
        sleep 10
    done

    #start the script
    exec $WAIT_START_CMD

Then, finally, for your nginx container, add: command: sh /code/wait_to_start.sh

to its specification

Myrmornis 10y

Just in case a shorter version appeals to you, I think you could rewrite it like this:

  timeout 60 bash -c 'until is_ready; do sleep 10; done'

You'll need to `export -f is_ready` if it's a shell function. That's assuming you can use a timeout instead of number-of-retries.

http://man7.org/linux/man-pages/man1/timeout.1.html

bmelton 10y

I was trying to find the source of where I got that bash script from, but couldn't, and then forgot about it within the editing window.

I'll try to find it and provide that feedback. Thanks!

baq 10y

we've got consul set up in a way that points names to a known 503 service if its containers are not up.

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