CODEWITHSUNDEEP
docker
shmish111
shmish111

Reputation: 3787

docker containers communication on dev machine

I have a container that runs a simple service that requires a connection to elasticsearch. For this I need to provide my service with the address of elasticsearch. I am confused as to how I can create a container that can be used in production and on my local machine (mac). How are people providing configuration like this these days?

So far I have come up with having my process take environmental variables as arguments which I can pass to the container with docker run -e. It seems unlikely that I would be doing this type of thing in production.

Upvotes: 2

Views: 49

Answers (3)

lingxiao
lingxiao

Reputation: 1224

How about writing it into the configuration file of your application and mount the configuration directory onto your container with -v?

To make it more organized, I use Ansible for orchestration. This way you could have a template of the configuration file for your application while the actually parameters are in the variable file of the corresponding Ansible playbook at a centralized location. Ansible will be in charge of copying the template over to the desired location and do variable substitution for you. It also recently enhanced its Docker support.

Upvotes: 1

VonC
VonC

Reputation: 1323523

I have a container that runs a simple service that requires a connection to elasticsearch. For this I need to provide my service with the address of elasticsearch

If elasticsearch is running in its own container on the same host (managed by the same docker daemon), then you can link it to your own container (at the docker run stage) with the --link option (which sets environment variables)

docker run --link elasticsearch:elasticsearch --name <yourContainer> <yourImage>

See "Linking containers together"

In that case, your container config can be static and known/written in advance, as it will refer to the search machine as 'elasticsearch'.

Upvotes: 3

Software Engineer
Software Engineer

Reputation: 16100

Environment variables are absolutely fine (we use them all the time for this sort of thing) as long as you're using service names, not ip addresses. Even with ip addresses you'd have no problem as long as you only have one ES and you're willing to restart your service every time the ES ip address changes.

You should really ask someone who knows for sure how you resolve these things in your production environments, because you're unlikely to be the only person in your org who has had this problem -- connecting to a database poses the same problem.

If you have no constraints at all then you should check out something like Consul from Hashicorp. It'll help you a lot with this problem; if you are allowed to use it.

Upvotes: 0

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