CODEWITHSUNDEEP
dockerboot2dockerfig
Dima
Dima

Reputation: 6741

Fig doesn't link two containers

Long story short: fig up doesn't link 2 containers properly when docker rundoes.

Scenario:

There are 2 containers: one with Cassandra, another with client service. When containers start Client expects to have cassandra hostname in hosts file and be able to reach it's 9042 port.

I use docker's links to tight containers together. Here is a fig.yml:

cassandra:
  image: "myrepo/cassandra"
  ports:
    - "7199:7199"
    - "9042:9042"
    - "9160:9160"
    - "61621:61621"
    - "2222:22"
  hostname: cassandra

client:
  image: myrepo/client
  links:
    - cassandra
  ports:
    - "8098:8098"
    - "8099:8099"
  hostname: client

When I do fig up client, fig starts cassandra, then client but client cannot reach the cassandra container (it can ping it, but cannot reach the 9042 port).

However, if I start cassandra with fig up cassandra and then run:

docker run --link tramm_cassandra_1:cassandra --link tramm_cassandra_1:cassandra_1 --link tramm_cassandra_1:tramm_cassandra_1 -p 8098:8098 -p 8099:8099 myrepo/client

then client can communicate with cassandra without a problem.

I've inspected containers and here are the output:
- cassandra inspect
- fig up client inspect
- docker run client inspect

The only difference I can find is in HostConfig -> Devices and HostConfig -> LxcConf. In fig-up version they are equal to null, in docker-run version - to [].

Can somebody explain a difference between fig up and docker run and why it works in 'native' docker scenario and doesn't in fig.

Upvotes: 0

Views: 339

Answers (1)

semekh
semekh

Reputation: 3917

It's probably because cassandra takes a lot of time to actually start listening on the port. Try fig up cassandra, wait for a while, and then fig up --no-recreate client.

See also:

Proposal: Containers should not be considered started until the TCP ports they expose are open

Is there a way to delay container startup to support dependant services with a longer startup time

Upvotes: 2

Related Questions