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Getting Started with Docker
51–60 of 78 posts
Re: Getting Started with Docker
#52This skips over the hard part: managing docker containers. Poking a hole directly to the container is a leaky abstraction. A reverse proxy like HAProxy or Varnish should be sitting in front of the container. Once you have the reverse proxy setup the next problem that arises is routing to containers based on the domain. Now your HAProxy or Varnish config is going to get bloated and every time you deploy a container th…
This is a great point. The initial Docker examples make everything seem easy, but we blew way past our estimated time in integrating docker into our workflow because of the points you mention. I am still happy with the choice to use docker though and our team will be better at server administration in the future. One thing about this getting started guide is that it recommends the Phusion base image which boots init.…
the comment below by user:
pg_fukd_mydog
Pointed out that FreeBSD jails do this right.
Re: Getting Started with Docker
#53Earlier quoted context omitted.
> ObRelated: Varnish is a beast that few people can configure easily. I'd love to work on a caching reverse proxy that was simple, extensible, and fast. It doesn't have as many caching-specific bells and whistles as Varnish, but nginx is an excellent reverse proxy with some caching abilities (and simple configuration).
The biggest problem is you cannot use `proxy_cache_purge` unless you pay for the commercial version/fork of nginx. That means you can't expire the cached content by URL.
Doesn't this open-source module do the same thing: http://labs.frickle.com/nginx_ngx_cache_purge/
It seems odd for nginx to try to commercialise such basic parts of the stack where 3rd parties can easily write such functionality.
Re: Getting Started with Docker
#54Earlier quoted context omitted.
Update etcd with connection details on container start/stop. Then use a script to watch the appropriate directory in etcd for changes and regenerate the config. Look at "fleet" from CoreOS, and especially their "sidekick" example that uses systemd dependencies to trigger etcd updates: https://coreos.com/docs/launching-containers/launching/launc... though you can certainly do this without fleet too. Then on the haprox…
This is what DNS is for. If you specify your backends by hostname instead of IP, then each time the load-balancer tries to connect to the backend, it'll get a list of A records from its DNS resolver and pick one in a round-robin fashion. Thus, if you have a dynamic DNS server that queries your presence service, it can return exactly the hosts that are up right now as the round-robin set. Right now, if you use SkyDNS[…
SkyDNS looks interesting, but it doesn't appear to do any heath checks on the endpoint. I don't want clients to receive an answer to an A record query that contains the IP address of an endpoint that is down.
Am I mistaken?
Re: Getting Started with Docker
#55Can someone tell me what's the point of this? (I seriously love to know, not criticizing it.) Why would I need to have docker containers to install stuff on them instead of just installing stuff directly on host?
Let's say I develop a new web app, I would install NodeJS, PostgreSQL and such on my machine. Before I deploy the app for the first time, I'll install them in the necessary servers. Now, it looks like I would need to do the same, except adding the step of building Docker containers.
I think I must miss something important here because the number of GitHub stars for Docker is impressive and this is usually a good indication of the usefulness of the project.
Re: Getting Started with Docker
#56Can someone tell me what's the point of this? (I seriously love to know, not criticizing it.) Why would I need to have docker containers to install stuff on them instead of just installing stuff directly on host? Let's say I develop a new web app, I would install NodeJS, PostgreSQL and such on my machine. Before I deploy the app for the first time, I'll install them in the necessary servers. Now, it looks like I woul…
Imagine you wanted to run two apps on the same host, and they depended on different versions of those components, and you wanted to be able to install the app and its dependencies on a new machine really quickly for scaling reasons, and you wanted an exploit on one of the apps to be difficult to escalate over to the other app from, and you'll start understanding some of the pain points Docker solves. :)
Re: Getting Started with Docker
#57Can someone tell me what's the point of this? (I seriously love to know, not criticizing it.) Why would I need to have docker containers to install stuff on them instead of just installing stuff directly on host? Let's say I develop a new web app, I would install NodeJS, PostgreSQL and such on my machine. Before I deploy the app for the first time, I'll install them in the necessary servers. Now, it looks like I woul…
Docker containers let you isolate the entire environment for your app. Let's say your running an app on CoreOS in a container that needs python 1.2.3.
On your laptop you can build and test the new version of the app that needs python 1.2.4. Once you decide that's ready to go, you can push the new container onto the same CoreOS machine, so it's running both containers. Without the containers, running two versions of python on the same box isn't possible. If you had a chef script that updated to 1.2.4, you'd possibly break every other app on the box.
Containers also let you do some cool things like sign and verify a container before it's launched on the box. It should be bit for bit the same on your laptop as it is on the remote machine. Containers also boot within seconds, much faster than a VM. There have been a few tech demos running around that actually spin up a new container with a web server to service every web request, just to show how fast you can boot them. 300ms is pretty long for a web request, but it's the idea that counts.
Re: Getting Started with Docker
#58Shouldn't "setting up a correct init process" be part of every "getting started with docker?" http://phusion.github.io/baseimage-docker/
Wow thanks! I didn't know about the init process and the zombies.
Re: Getting Started with Docker
#59Earlier quoted context omitted.
This is a great point. The initial Docker examples make everything seem easy, but we blew way past our estimated time in integrating docker into our workflow because of the points you mention. I am still happy with the choice to use docker though and our team will be better at server administration in the future. One thing about this getting started guide is that it recommends the Phusion base image which boots init.…
the comment below by user: pg_fukd_mydog Pointed out that FreeBSD jails do this right.
What is that username, something from reddit? I really have no interest in FreeBSD.
Re: Getting Started with Docker
#60Can someone tell me what's the point of this? (I seriously love to know, not criticizing it.) Why would I need to have docker containers to install stuff on them instead of just installing stuff directly on host? Let's say I develop a new web app, I would install NodeJS, PostgreSQL and such on my machine. Before I deploy the app for the first time, I'll install them in the necessary servers. Now, it looks like I woul…
Docker containers let you isolate the entire environment for your app. Let's say your running an app on CoreOS in a container that needs python 1.2.3. On your laptop you can build and test the new version of the app that needs python 1.2.4. Once you decide that's ready to go, you can push the new container onto the same CoreOS machine, so it's running both containers. Without the containers, running two versions of p…
Thanks, this is good info. For NodeJS and Rails, I use nvm and rvm, so didn't have any problem with multiple environments. But yeah, I see your point that Docker can help in such scenario or when there's no equivalent of nvm/rvm.