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Ask HN: Why use Docker and what are the business cases for using it?

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Re: Ask HN: Why use Docker and what are the business cases for using it?

#61

Post by justincormack »

falcolas wrote: post #46
bacheson1293 wrote: post #41

Earlier quoted context omitted.

Absolutely. This situation is handled by using Environment variables. Depending on the environment, I use environment variables to point services at different places (ie dedicated production database server vs my micro dev mysql container).

Remember that environment variables are visible to processes outside the container (i.e. users), if they have the same or higher privileged user. They are not a great place to store passwords or any other confidential information.

The environment of a process is only available to root or the same uid.

Re: Ask HN: Why use Docker and what are the business cases for using it?

#63

Post by vezzy-fnord »

davexunit wrote: post #47
jgrowl wrote: post #34

Besides just actually running software, I also find it really neat when projects use docker to build their entire application. It provides an effective means of documenting all of your dependencies and making reproducible builds. Take the docker-compose for example. You can just check the code out, run a single script that builds the project for your environment and everything is pretty much self contained in the doc…

>making reproducible builds. Docker builds actually aren't reproducible. There are many sources of non-determinism that Docker cannot address. Do you use the base images from DockerHub as-is or do you run 'apt-get upgrade' or whatever for security patches? If you do, the result you get from building that image (as opposed to using what's in a cache) is different depending on the time it was built. The same goes for a…

Don't know why you were downvoted. Docker doesn't give you reproducible builds because you're still running in a raw host OS environment with all its state, but simply the subsystems partitioned into their own namespaces. Docker is more akin to a snapshot than reproducible.

Re: Ask HN: Why use Docker and what are the business cases for using it?

#64

Post by lastofus »

Does Docker provide anything useful to someone who develops on OS X and deploys to Linux VMs (Digital Ocean, Linode, AWS)?

Current setup is something like:

- Develop locally (OS X) - Test deploy to local Vagrant Linux VM (provisioned by Ansible) - Deploy to staging/live Linux VM w/ Ansible (or Fabric if I'm being lazy)

I've been following the Docker hype for some time now, but ever time I look into it, I couldn't find any info on how Docker could make my life simpler or easier. If anything, it would just add another complex abstraction layer to have to deal with.

What am I missing?

Re: Ask HN: Why use Docker and what are the business cases for using it?

#65

Post by fragmede »

rubiquity wrote: post #18
rehevkor5 wrote: post #7

Have you ever used provisioning software like Chef to prepare a server to run your software? Have you ever used that in conjunction with Vagrant in order to test out your provisioning and software deployment locally? Docker replaces (or can replace) all of that.

Docker does NOT replace configuration management tools like Chef, Puppet and Ansible. Those are still necessary for preparing the host machine which Docker containers will run on. Where Docker does alleviate/reallocate some things is in the configuration of the containers that run on those hosts. Instead of configuring the host for Ruby/Python/etc. you would move that configuration to your Dockerfile. But I think CM…

> Docker does NOT replace configuration management tools

You're right, for now, but hopefully not forever.

Docker, the company, has got an insane valuation, so is monetize anything and everything in sight to validate that valuation. But trying to give away tools to developers is an uphill battle on a good day, never mind selling to developers. So Docker is pursuing the end of the market that's likely to pay off - the data center, and that's why there's such a huge push behind putting Docker into production.

Now, my experience with current CM tools is that it's still easier to boot a VM and tinker with it to get it working 'normally' (ie, bash + editing config files directly), and then throw that VM away and play with my chosen CM tool to get it working there instead.

Dockerfiles do a good job of bridging that divide, out of the box. On a fresh machine, I install the base OS, and then install docker, and I'm up and running Dockerfiles, albiet with a cold (docker build) cache.

Hopefully the next generation of CM tools can blend the both so setting up a local target is easy as 'docker build' and ongoing maintenance of deployed machines is as easy as 'puppet agent --onetime'.

Re: Ask HN: Why use Docker and what are the business cases for using it?

#66

Post by MalcolmDiggs »

In my experience, if you start hearing: "I don't know what's wrong, it works fine on my localhost!" a lot, then it may be time to think about Docker.

In more general terms: more the complex the environment, the more moving pieces, the more developers on the team, the more servers in production, the more likely there's going be a discrepancy between what Developer-A has running on his machine, and what Developer-B has running on theirs. Docker helps keep everybody on the same page.

For me personally: I'm a dev on a number of projects, and Docker helps me keep my dependencies straight. I no longer have to change things around locally just to work on Project-A, I just get their latest Docker image, and I'm good to go.

Re: Ask HN: Why use Docker and what are the business cases for using it?

#67

Post by notwedtm »

osipov wrote: post #35
takeda wrote: post #23

Earlier quoted context omitted.

Great, but what are the benefits of running Docker in AWS? You are still running VMs and you are being charged for running them. With Docker you are simply putting yet another layer of complexity, because now you have to run more beefier VMs, you now have problem with network communication between containers running on different hosts. So you will most likely need to use overlay network. You also decrease resiliency,…

>what are the benefits of running Docker in AWS? I don't see benefits to running Docker in AWS. In my opinion, AWS implemented its Docker-based Container Service very poorly. I advise my customers against using AWS when want to use Docker. There are many bare metal as a service providers out in the marketplace. >the argument about running the same container in dev/test/prod Is this issue really caused by Docker becau…

Can you name a few bare metal as a service providers?

Re: Ask HN: Why use Docker and what are the business cases for using it?

#68

Post by bri3d »

takeda wrote: post #23
osipov wrote: post #3

There are many ways of using Docker and obviously different companies could come up with their own business cases for adopting the technology. So let me focus on one scenario and we can talk about whether it makes sense for your environment. Software engineering is often difficult because programmers have to deal with inconsistent environments for development and for production execution of their products. Due to mis…

Great, but what are the benefits of running Docker in AWS? You are still running VMs and you are being charged for running them. With Docker you are simply putting yet another layer of complexity, because now you have to run more beefier VMs, you now have problem with network communication between containers running on different hosts. So you will most likely need to use overlay network. You also decrease resiliency,…

Robust composition. Instead of needing a separate database, message queue, app server VM, you can run all 3 containers together on one omnibus machine, or separated as scalability needs demand.

Yes, you can achieve something similar using multiple layers in OpsWorks or different deployment schemes with normal Chef, but IMO containers make provisioning and deploying combinations of components easier than most other provisioning and deployment solutions. There's less opportunity for unexpected version collisions and because the network infrastructure is virtual, you can move containers between underlying VMs, allowing capacity planning without substantial reconfiguration.

Re: Ask HN: Why use Docker and what are the business cases for using it?

#69

Post by distracteddev90 »

vruiz wrote: post #15

Side question. I'm well aware of the benefits of docker but, has anybody measured performance degradation due to lack of machine specialization? Back in the web 1.0 days it was common knowledge that you start in 1 server, then you split into 1 app server and 1 database server and you can get 4x the capacity. Did we lose all that with the docker way? Is it not so relevant anymore with modern multicore CPUs?

Docker doesn't force you to put your app and your db on the same image. That is up to you. Most have "App" images and "DB" images separate.

If we want to get really specific, Its also common to see the "DB" image split up between the image of the disk where the data is actually persisted, and the image of the actual DB process. This makes it easy to play around with your data under different versions of your DB.

Re: Ask HN: Why use Docker and what are the business cases for using it?

#70

Post by justizin »

lastofus wrote: post #64

Does Docker provide anything useful to someone who develops on OS X and deploys to Linux VMs (Digital Ocean, Linode, AWS)? Current setup is something like: - Develop locally (OS X) - Test deploy to local Vagrant Linux VM (provisioned by Ansible) - Deploy to staging/live Linux VM w/ Ansible (or Fabric if I'm being lazy) I've been following the Docker hype for some time now, but ever time I look into it, I couldn't fin…

You can build a docker image in a vagrant VM on OSX and deploy that exact docker image to production.

If your vagrant image resembles production, it's probably fine, but there's a level of confidence to be reached from deploying the exact entire self-contained binary, shipping it through QA and staging, and eventually promoting it to production.

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