Docker Compose wait for container X before starting Y

Question

I am using rabbitmq and a simple python sample from here together with docker-compose  My problem is that I need to wait for rabbitmq to be fully started  From what I searched so far  I don t know how to wait with container x  in my case worker  until y  rabbitmq  is started  I found this blog post where he checks if the other host is online  I also found this docker command   wait Usage  docker wait CONTAINER  CONTAINER     Block until a container stops  then print its exit code   Waiting for a container to stop is maybe not what I am looking for but if it is  is it possible to use that command inside the docker-compose yml  My solution so far is to wait some seconds and check the port  but is this the way to achieve this  If I don t wait  I get an error  docker-compose yml worker      build  myapp       volumes      - myapp    usr src app ro      links      - rabbitmq rabbitmq      image  rabbitmq 3-management  python hello sample  rabbit py   import pika import time  import socket  pingcounter   0 isreachable   False while isreachable is False and pingcounter  lt  5      s   socket socket socket AF INET  socket SOCK STREAM      try          s connect   rabbitmq   5672           isreachable   True     except socket error as e          time sleep 2          pingcounter    1     s close    if isreachable      connection   pika BlockingConnection pika ConnectionParameters              host  quot rabbitmq quot        channel   connection channel        channel queue declare queue  hello        channel basic publish exchange                               routing key  hello                             body  Hello World        print   quot   x  Sent  Hello World   quot       connection close    Dockerfile for worker  FROM python 2-onbuild RUN   quot pip quot    quot install quot    quot pika quot    CMD   quot python quot   quot rabbit py quot    Update Nov 2015  A shell script or waiting inside your program is maybe a possible solution  But after seeing this Issue I am looking for a command or feature of docker docker-compose itself  They mention a  solution for implementing a health check  which may be the best option  A open tcp connection does not mean your service is ready or may remain ready  In addition to that I need to change my entrypoint in my dockerfile  So I am hoping for an answer with docker-compose on board commands  which will hopefully the case if they finish this issue  Update March 2016 There is a proposal for providing a built-in way to determine if a container is  quot alive quot   So docker-compose can maybe make use of it in near future  Update June 2016 It seems that the healthcheck will be integrated into docker in Version 1 12 0 Update January 2017 I found a docker-compose solution see  Docker Compose wait for container X before starting Y

User · Answer

Natively that is not possible  yet  See also this feature request   So far you need to do that in your containers CMD to wait until all required services are there   In the Dockerfiles CMD you could refer to your own start script that wraps starting up your container service  Before you start it  you wait for a depending one like   Dockerfile  FROM python 2-onbuild RUN   pip    install    pika   ADD start sh  start sh CMD    start sh     start sh     bin bash while   nc -z rabbitmq 5672  do sleep 3  done python rabbit py   Probably you need to install netcat in your Dockerfile as well  I do not know what is pre-installed on the python image   There are a few tools out there that provide easy to use waiting logic  for simple tcp port checks    wait-for-it  dockerize   For more complex waits    goss - Explanation blog

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Finally found a solution with a docker-compose method  Since docker-compose file format 2 1 you can define healthchecks  I did it in a example project you need to install at least docker 1 12 0   I also needed to extend the rabbitmq-management Dockerfile  because curl isn t installed on the official image  Now I test if the management page of the rabbitmq-container is available  If curl finishes with exitcode 0 the container app  python pika  will be started and publish a message to hello queue  Its now working  output   docker-compose  version 2 1   version   2 1   services    app      build  app       depends on        rabbit          condition  service healthy     links           - rabbit    rabbit      build  rabbitmq       ports           -  quot 15672 15672 quot          -  quot 5672 5672 quot      healthcheck          test    quot CMD quot    quot curl quot    quot -f quot    quot http   localhost 15672 quot           interval  30s         timeout  10s         retries  5  output  rabbit 1     INFO REPORT     25-Jan-2017  14 44 21     rabbit 1    closing AMQP connection  lt 0 718 0 gt   172 18 0 3 36590 - gt  172 18 0 2 5672  app 1         x  Sent  Hello World   healthcheckcompose app 1 exited with code 0  Dockerfile  rabbitmq   curl   FROM rabbitmq 3-management RUN apt-get update RUN apt-get install -y curl  EXPOSE 4369 5671 5672 25672 15671 15672  Version 3 no longer supports the condition form of depends on  So i moved from depends on to restart on-failure  Now my app container will restart 2-3 times until it is working  but it is still a docker-compose feature without overwriting the entrypoint  docker-compose  version 3   version   quot 3 quot   services     rabbitmq    login guest guest     image  rabbitmq management     ports      -  quot 4369 4369 quot      -  quot 5671 5671 quot      -  quot 5672 5672 quot      -  quot 25672 25672 quot      -  quot 15671 15671 quot      -  quot 15672 15672 quot      healthcheck          test    quot CMD quot    quot curl quot    quot -f quot    quot http   localhost 15672 quot           interval  30s         timeout  10s         retries  5    app      build    app      environment        - HOSTNAMERABBIT rabbitmq     restart  on-failure     depends on        - rabbitmq     links           - rabbitmq

User · Answer

Quite recently they ve added the depends on feature  Edit  As of compose version 2 1  till version 3 you can use depends on in conjunction with healthcheck to achieve this  From the docs  version   2 1  services    web      build        depends on        db          condition  service healthy       redis          condition  service started   redis      image  redis   db      image  redis     healthcheck        test   quot exit 0 quot   Before version 2 1 You can still use depends on  but it only effects the order in which services are started - not if they are ready before the dependant service is started  It seems to require at least version 1 6 0  Usage would look something like this  version   2  services    web      build        depends on        - db       - redis   redis      image  redis   db      image  postgres   From the docs   Express dependency between services  which has two effects   docker-compose up will start services in dependency order  In the following example  db and redis will be started before web  docker-compose up SERVICE will automatically include SERVICE   s dependencies  In the following example  docker-compose up web will also create and start db and redis    Note  As I understand it  although this does set the order in which containers are loaded  It does not guarantee that the service inside the container has actually loaded  For example  you postgres container might be up  But the postgres service itself might still be initializing within the container

User · Answer

For container start ordering use  depends on    For waiting previous container start use script  entrypoint    wait-for-it sh db 5432   This article will help you https   docs docker com compose startup-order

User · Answer

Here is the example where main container waits for worker when it start responding for pings   version   3  services    main      image  bash     depends on       - worker     command  bash -c  sleep 2  amp  amp  until ping -qc1 worker  do sleep 1  done  amp  gt  dev null      networks        intra          ipv4 address  172 10 0 254   worker      image  bash     hostname  test01     command  bash -c  ip route  amp  amp  sleep 10      networks        intra          ipv4 address  172 10 0 11 networks    intra      driver  bridge     ipam        config        - subnet  172 10 0 0 24   However  the proper way is to use healthcheck    2 1

User · Answer

I just have 2 compose files and start one first and second one later  My script looks like that      bin bash  before i build my docker files  when done i start my build docker-compose docker-compose -f docker-compose build yaml up  now i start other docker-compose which needs the image of the first docker-compose -f docker-compose prod yml up

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Not recommended for serious deployments  but here is essentially a  wait x seconds  command   With docker-compose version 3 4 a start period instruction has been added to healthcheck  This means we can do the following   docker-compose yml   version   3 4  services      your server docker container   zmq server      build        context    server router router       dockerfile  Dockerfile      container that has to wait   zmq client      build        context    client dealer        dockerfile  Dockerfile     depends on        - zmq server     healthcheck        test   sh status sh        start period  5s   status sh      bin sh  exit 0   What happens here is that the healthcheck is invoked after 5 seconds  This calls the status sh script  which always returns  No problem   We just made zmq client container wait 5 seconds before starting   Note  It s important that you have version   3 4   If the  4 is not there  docker-compose complains

User · Answer

Tried many different ways  but liked the simplicity of this  https   github com ufoscout docker-compose-wait  The idea that you can use ENV vars in the docker compose file to submit a list of services hosts  with ports  which should be  awaited  like this  WAIT HOSTS  postgres 5432  mysql 3306  mongo 27017   So let s say you have the following docker-compose yml file  copy past from repo README    version   3   services     mongo      image  mongo 3 4     hostname  mongo     ports        -  27017 27017     postgres      image   postgres 9 4      hostname  postgres     ports        -  5432 5432     mysql      image   mysql 5 7      hostname  mysql     ports        -  3306 3306     mySuperApp      image   mySuperApp latest      hostname  mySuperApp     environment        WAIT HOSTS  postgres 5432  mysql 3306  mongo 27017   Next  in order for services to wait  you need to add the following two lines to your Dockerfiles  into Dockerfile of the services which should await other services to start    ADD https   github com ufoscout docker-compose-wait releases download 2 5 0 wait  wait RUN chmod  x  wait   The complete example of such sample Dockerfile  again from the project repo README     FROM alpine     Add your application to the docker image ADD MySuperApp sh  MySuperApp sh     Add the wait script to the image ADD https   github com ufoscout docker-compose-wait releases download 2 5 0 wait  wait RUN chmod  x  wait     Launch the wait tool and then your application CMD  wait  amp  amp   MySuperApp sh   For other details about possible usage see README

User · Answer

restart  on-failure did the trick for me  see below  --- version   2 1  services    consumer      image  golang alpine     volumes        -     go src srv-consumer     working dir   go src srv-consumer     environment        AMQP DSN   amqp   guest guest rabbitmq 5672      command  go run cmd main go     links            - rabbitmq     restart  on-failure    rabbitmq      image  rabbitmq 3 7-management-alpine     ports        -  15672 15672        -  5672 5672

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basing on this blog post https   8thlight com blog dariusz-pasciak 2016 10 17 docker-compose-wait-for-dependencies html  I configured my docker-compose yml as shown below   version   3 1   services    rabbitmq      image  rabbitmq 3 7 2-management-alpine     restart  always     environment        RABBITMQ HIPE COMPILE  1       RABBITMQ MANAGEMENT  1       RABBITMQ VM MEMORY HIGH WATERMARK  0 2       RABBITMQ DEFAULT USER   rabbitmq        RABBITMQ DEFAULT PASS   rabbitmq      ports        -  15672 15672        -  5672 5672      volumes        - data  var lib rabbitmq rw    start dependencies      image  alpine latest     links        - rabbitmq     command   gt         bin sh -c           echo Waiting for rabbitmq service start             while   nc -z rabbitmq 5672          do           sleep 1          done          echo Connected            volumes    data       Then I do for run      docker-compose up start dependencies  rabbitmq service will start in daemon mode  start dependencies will finish the work

User · Answer

There is a ready to use utility called  docker-wait  that can be used for waiting

User · Answer

Using restart  unless-stopped or restart  always may solve this problem   If worker container stops when rabbitMQ is not ready  it will be restarted until it is

User · Answer

you can also just add it to the command option eg   command  bash -c  sleep 5  start sh    https   github com docker compose issues 374 issuecomment-156546513  to wait on a port you can also use something like this  command  bash -c  while   curl -s rabbitmq 5672  gt   dev null  do echo waiting for xxx  sleep 3  done  start sh    to increment the waiting time you can hack a bit more   command  bash -c  for i in  1  100    do if   curl -s rabbitmq 5672  gt   dev null   then echo waiting on rabbitmq for  i seconds  sleep  i  fi  done  start sh

User · Answer

In version 3 of a Docker Compose file  you can use RESTART   For example   docker-compose yml  worker      build  myapp       volumes      - myapp    usr src app ro     restart  on-failure     depends on      - rabbitmq rabbitmq      image  rabbitmq 3-management   Note that I used depends on instead of links since the latter is deprecated in version 3   Even though it works  it might not be the ideal solution since you restart the docker container at every failure   Have a look to RESTART POLICY as well  it let you fine tune the restart policy   When you use Compose in production  it is actually best practice to use the restart policy       Specifying a restart policy like restart  always to avoid downtime

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You can also solve this by setting an endpoint which waits for the service to be up by using netcat  using the docker-wait script   I like this approach as you still have a clean command section in your docker-compose yml and you don t need to add docker specific code to your application   version   2  services    db      image  postgres   django      build        command  python manage py runserver 0 0 0 0 8000     entrypoint    docker-entrypoint sh db 5432     volumes        -    code     ports        -  8000 8000      depends on        - db   Then your docker-entrypoint sh      bin sh  postgres host  1 postgres port  2 shift 2 cmd         wait for the postgres docker to be running while   nc  postgres host  postgres port  do    gt  amp 2 echo  Postgres is unavailable - sleeping    sleep 1 done   gt  amp 2 echo  Postgres is up - executing command     run the command exec  cmd   This is nowadays documented in the official docker documentation   PS  You should install netcat in your docker instance if this is not available  To do so add this to your Docker file    RUN apt-get update  amp  amp  apt-get install netcat-openbsd -y

User · Answer

I currently also have that requirement of waiting for some services to be up and running before others start  Also read the suggestions here and on some other places  But most of them require that the docker-compose yml some how has to be changed a bit  So I started working on a solution which I consider to be an orchestration layer around docker-compose itself and I finally came up with a shell script which I called docker-compose-profile  It can wait for tcp connection to a certain container even if the service does not expose any port to the host directy  The trick I am using is to start another docker container inside the stack and from there I can  usually  connect to every service  as long no other network configuration is applied   There is also waiting method to watch out for a certain log message  Services can be grouped together to be started in a single step before another step will be triggered to start  You can also exclude some services without listing all other services to start  like a collection of available services minus some excluded services   This kind of configuration can be bundled to a profile  There is a yaml configuration file called dcp yml which  for now  has to be placed aside your docker-compose yml file  For your question this would look like  command    aliases      upd        command   quot up -d quot        description            Create and start container  Detach afterword   profiles    default      description          Wait for rabbitmq before starting worker      command  upd     steps        - label  only-rabbitmq         only    rabbitmq           wait            - 5 tcp   rabbitmq 5432       - label  all-others  You could now start your stack by invoking dcp -p default upd  or even simply by dcp  as there is only a default profile to run up -d on  There is a tiny problem  My current version does not  yet  support special waiting condition like the ony You actually need  So there is no test to send a message to rabbit  I have been already thinking about a further waiting method to run a certain command on host or as a docker container  Than we could extend that tool by something like             wait            - service  rabbitmq             method  container             timeout  5             image  python-test-rabbit      having a docker image called python-test-rabbit that does your check  The benefit then would be that there is no need anymore to bring the waiting part to your worker  It would be isolated and stay inside the orchestration layer  May be someone finds this helpful to use  Any suggestions are very welcome  You can find this tool at https   gitlab com michapoe docker-compose-profile

User · Answer

One of the alternative solution is to use a container orchestration solution like Kubernetes  Kubernetes has support for init containers which run to completion before other containers can start  You can find an example here with SQL Server 2017 Linux container where API container uses init container to initialise a database   https   www handsonarchitect com 2018 08 understand-kubernetes-object-init html

[docker-compose] Docker Compose wait for container X before starting Y

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