Clojurians Log v2

Spectacular

I have question for the group: what’s the smoothest track into production

best options for [ cmd line | web app | event based service | …. others ] ...

web app: heroku

agreed!

what do you mean by cmd line / event based service?

cmd line … some batch or scheduled task

batch: heroku worker I guess.

event based service …. something sitting behind a queue / kafka | kinesis style ingestion system

aws lambda? 🙂

it runs clojure

I read the Lambda Clojure thing … seems awkward 😞

or do you have a better experience?

no experience

since we have so many components in our backend (queues, db's, web api, batch) we are running everything in docker containers on google container engine

before we were running on VMs, with the necessary ceremony with ansible and supervisorctl to keep stuff running

but I wouldn't say it's the smoothest track into production 🙂

although it's a lot better than the VM setup

You have a lot going on .... But let's think hello world in each of these options and then I think it's easy to see how the infra dominates the code

Assuming you want to say hello to everybody at once ;-)

😄

How do you keep your docker resources up to date?

well, event based, if you don't want to use lambda, you're going to need some compute infrastructure that watches for changes

docker resources as in, the VMs, docker, kubernetes?

or as in 'you have nginx running, now upgrade to the next version'?

The latter (nginx, JVM, ...)

yes, that is still a manual work of course

as for the JVM, everytime a component is built it will use the latest version of a major release (now 1.8)

I guess the platform should look after you for the other stuff

other components will get updated manually and go through dev > staging > prod path

So you have some base images with common infra?

obviously there still is configuration management

yes

and try to use as much as possible the official images

That everyone 'uses' in docker speak

yes

Makes a ton of sense

so, e.g. our app docker container is

FROM java:openjdk-8-jre

and then a few lines to copy the uberjar and

ENTRYPOINT exec java $JVM_OPTS -jar /opt/your.jar

docker and kubernetes will watch that it keeps running

Ok so you use openjdk - easiest by far too!

indeed 🙂

and then for some stuff like queues I intend to use Google pub/sub

I wish datomic ran on Google Cloud Datastore

no need to run your own cassandra and stuff

yeah - and it’s annoying that they don’t enable storage extension points

indeed

cos it seems quite simple

I don't think the requirements for the underlying storage are complex indeed

you just need some transactionality to store the pointer to the indexes

I would love them to provide a protocol that could be implemented

anyway, off-topic 🙂

how do you determine the size of the compute resource on the Google engine?

container engine?

we knew what our app was consuming in terms of resources on a VM

so, we took that, increased it a bit and spun up 4 hosts 🙂

you can increase the resources by updating the spec of the 'instance group'

so, you shouldn't be tied to what you have chosen

I think they are also working on a 'mixed' cluster with e.g. CPU heavy and MEM heavy VMs

and you can tie certain components of your app to a specific type of host

that’s nice

and I guess it attaches the equivalent of EBS to the instances so that compute is swappable?

yes

well, the thing is, you should not use the default disks attached to the instances

kubernetes will manage volumes for you. you just specify which container needs which volume mounted where and it will do that on the right host where the container is running

you can use all kind of volumes but google persistent disk is a good choice for not losing data on cluster upgrades

side question - on something else I’m looking at - do you know how easy it is to resize the volumes (it’s a pain on EBS)

I have found a decent example from the uswitch guys to implement AWS Lambda

https://github.com/uswitch/lambada

But when you see their example you see the yuckiness of the AWS Lambda API

I mean holy crap, you have to return the status via this bullshit JSON

I think this example could be wrapped nicer (I will make a PR for that but it doesn’t hide the fact)

resizing a disk is easy, but only possible when the resulting disk is bigger than the old one