15 ms·

I chose Docker for my project with hope that it would help me create an easily reproducible development environment... And I'm not really sure if it was a good

by d33 10y ago

I chose Docker for my project with hope that it would help me create an easily reproducible development environment... And I'm not really sure if it was a good idea. There's so many moving parts and I can't name one that actually works well. Configuring storage is a hell (running out of disk space can lead to errors that are really difficult to debug), the dance with bridges makes configuring firewall a terrible experience. I definitely wouldn't recommend it as a stable container solution.

gizmodo59 10y ago
Can you briefly describe your environment?
deleted 10y ago
[deleted]
redrummr 10y ago
Why is storage an issue? With databases, for example, you store data upstream (on the host) and keep the dockerised app/thing mostly stateless, or at least capped with regards to storage. More details about your environment would be appreciated.
- jdoliner 10y ago
  Keeping data on the host is exactly the reason that it's an issue. Swarm offers not guarantees that containers will be rescheduled on the same host that it was initially scheduled on and assumes that it can reschedule containers as failures arise... this doesn't work when your database gets rescheduled and emptied along the way.
  - zamalek 10y ago
    > your database gets rescheduled and emptied along the way That's bundling an CP application into seemingly AP infrastructure (from what I gleaned from their docs). Completely the wrong tool for the job. If the application was designed for that it would have recovered. In your defense, they have nothing to warn about that in their documentation.
    - jdoliner 10y ago
      This isn't really a CAP theorem problem and it's certainly not right to describe Docker as "AP infrastructure." What would that mean exactly? Would you expect this problem to go away if I used a database that sacrificed consistency for availability such as Riak?
      - zamalek 10y ago
        Swarm (not the whole of Docker) seems like something designed for databases like Riak, yes. A SQL failover cluster might work, but certainly not a single database container on infrastructure designed for highly available apps.
  - kerr23 10y ago
    In docker 1.12 you can 'tag' a node and tell a 'service' to only run on the tagged nodes. Not saying that's a good idea, but it is getting closer. You could, for example, have a node that's only for DBs that has volumes on it. You could then use DRBD on the host to clone that data to a secondary node. then in the event that node 1 dies swarm would bring the DB up on node2. With the mesh network stuff they've added the endpoint would remain the same, so all your apps would need to do would be re-connect.
    - jdoliner 10y ago
      > Not saying that's a good idea, but it is getting closer. No, that isn't getting closer it's getting farther away. The whole point of containers is that they make the host machine completely fungible. If I can only schedule my DB containers on a specific machine then I might as well just run my DB on that machine and be done with it.
      - kerr23 10y ago
        hmm, your first complaint was that "Swarm offers no guarantees that containers will be rescheduled on the same host". I'm saying that, if you want, you CAN make it guarantee that a container will be rescheduled to the same host. (or a controlled level of hosts). I don't think it's docker's responsibility to solve database clustering. And, as I said, I'm not advocating running a production DB in docker. But I can see a way that you may be able to.
        jdoliner 10y ago
        I see how that was confusing. I meant that the fact that Swarm doesn't offer such a guarantee is the reason that storing the data on the host isn't a solution. My real complaint is that none of these give you a way to do persistence that doesn't destroy some other really nice properties of containers. There's lots of people trying to fix this problem the right way, Kubernetes has made a lot of progress on having volumes follow the containers around from host to host. Torus is a slightly different approach, Flocker is another one. > I don't think it's docker's responsibility to solve database clustering. I don't know if I'd call it a responsibility. But Docker is obviously trying to expand their platform into more and more aspects of containerization. If they figured out persistence that would really set them apart, something that this product doesn't really do. It mostly just keeps them even with Kubernetes at best. And an imitation of it at worst.
- jodok 10y ago
  why not run the database directly in the container as well? we're doing that with https://crate.io https://crate.io - just expose your local instance store as volume, crate will take care of the rest
- jodok 10y ago
  why not run the database directly in the container as well? we're doing that with https://crate.io https://crate.io - just expose your local instance store as volume, crate will take care of the rest
jjtheblunt 10y ago
Did you try rkt or find something else which you liked?
lewisl9029 10y ago
I've been experimenting with Docker for reproducible dev environments as well for a while now, and my biggest issue has been with the app build step, which often requires a specific non-Linux platform (OS X for iOS and Windows for UWP). Back in my previous project using Cordova, I made the Docker workflow work adequately by offloading builds to web-based build services like PhoneGap Build and Ionic Package (building only a thin live-reloading wrapper app that points to a configurable IP:port for development). But my new project uses React Native, and I haven't found any similar build services for React Native apps (or even just regular native apps) yet. Anyone have any suggestions?
- theodorton 10y ago
  Bitrise and Circle CI both support OS X environments for building projects. Combined with fastlane, you'd probably have a good setup for continuous delivery. I've only got experience with running fastlane locally though.
  - nomel 10y ago
    I'm not a web guy, so this question is genuine. How in the world do you keep up/discover all of the different frameworks that seem to pop up daily?
    - skewart 10y ago
      By spending unreasonable amounts of time on HN - at least that's how I rationalize things to myself.
lopatin 10y ago
I totally agree. Docker feels really tidy conceptually. I ended up somehow convincing myself that adding this extra layer of technology into my (relatively tiny) infrastructure will decrease it's complexity. Unsurprisingly, the effect was the exact opposite.
- knz 10y ago
  I feel the exact opposite! The Dockerfile is a simple way to define my environment and it's trivial to run the app in either development, QA, or production. Throw in some of the other functionality such as being able to deploy from an image rather than having to rebuild each time, and it's been a productive addition to my toolset. I'm guessing it depends on how complex your application is, but I've found it fantastic for running Python (Flask), PostgreSQL/PostGIS, MapServer, and some other smaller applications.
  - Annatar 10y ago
    And did you produce OS packages for any of that configuration work, or did you just end up dumping a bunch of files into the "image"?
    - knz 10y ago
      It's not an image in the sense that you can run updates/installs and strip out the crap associated with that but it's so trivial to run "images" that the benefits far outweigh the additional disk space for our use cases.
- codygman 10y ago
  I've been enjoying Nixos[0] and hope to try Nixops[1] soon. The difference between Nixos and docker is that nixos makes it possible to have a truly reproducible environment. See the surprisingly readable paper[2] for more details. 0: http://nixos.org/ http://nixos.org/ 1: http://nixos.org/nixops/ http://nixos.org/nixops/ 2: https://nixos.org/~eelco/pubs/nixos-jfp-final.pdf https://nixos.org/~eelco/pubs/nixos-jfp-final.pdf
ldehaan 10y ago
just a quick tip: check out weave for managing networking, IMO it's much easier and I'm not even talking about the docker plugin. just use weave without the plugin and it works amazingly well. for the configuration aspect, just use dockerfiles and a system like mesos and marathon for deploying production. you can then write simple restful API commands to launch different environments with marathon. build all your docker containers to act as single server instances, i.e., spark on one container, SQL on another. tie in a default install of cadvisor on all mesos clients and you can have easy monitoring as well.
rdtsc 10y ago
You probably want something like NixOS or Guix if you really want to go down that way. Yeah I see where you are coming from. First time I heard about Docker, I thought it did what NixOS does, but it doesn't really.
catmanjan 10y ago
I think Vagrant would be a good replacement for you, it's basically docker but built exactly for reproducible dev environments
Annatar 10y ago
You might want to try out SmartOS: one .json file, vmadm(1M) and imgadm(1M) commands later, you'll have a fully isolated UNIX server, running at the speed of bare metal and residing on ZFS, protecting your data. If you need a more complex network setup, dladm(1M) will enable you to configure virtual switches and routers. The manual pages are really good, too. And there is nothing to install, as SmartOS runs from memory, so that all storage in the system can be used for virtual servers. Upgrades are a breeze by just booting into a new image, either from USB or PXE booting from the network.
fpoling 10y ago
From my experience with Docker one should just avoid docker-supplied volumes and manage the storage oneself using host bind mounts for containers and consistently using --read-only for containers themselves. With that it is really weired to read all complains and issues about volumes management. It seems Docker just picked up wrong model for their storage. Then they try forever to fix impedance mismatch between that model and how people want to use Docker.
- cpuguy83 10y ago
  Care to clarify issues you have with volume management? I think the biggest issue is around the `-v` syntax (and the corrosponding API). In the UX we call things a volume which are actually a mount (which happen to use a volume). I like the way we have implemented this in the new services API.... `docker run --mount type=volume,source=important_data,volume-driver=foo,volume-options=...`
  - fpoling 10y ago
    For me the biggest issue with docker volumes is lack of any notion of subvolumes or volume grouping. Consider an application consisting of few containers communicating over unix sockets each with its own state. Surely I can create a bunch of volumes for the containers, but those would not have any notion of grouping. That complicates administration and development. For example, it is very useful to have a shell view of all volumes for the application to poke inside or debug issues. Surely I can do docker run ubuntu and mount all relevant volumes under /mnt there, but that is not user friendly. Or consider that during development or debugging I want to transfer the state to another machine. Why it is not possible to tar all application volumes with single command and restore them in a new place again with single command? I.e, something similar for docker save/load, but for volumes? All those issues are trivially solvable if I use some directory on a file system for the whole application state and use subdirectories there for individual volumes for the containers and then pass those with -v to relevant containers.
flavioaiello 10y ago
My experience with Docker is kind of ambivalent. We are using docker with docker compose on a legacy vmware stack in a corporate environment. No swarm and no docker overlay network as it does undermine firewalls. It is perfect to apply gitlow and semver to each build of each docker image, so each outcoming application stack is fully determenistic and auditable. Docker storage and network are really simple and docker is the perfect fit. On the other side devs were asking for jenkins for that process. We run also Jenkins on Docker but it's cumbersome as it doesn't allow declarative configuration. There are dozen of plugins out there but it doesn't change the fact that the outcome is ressource hungry and slow. For now we are actually optimizing using Job-DSL plugin. We reached our target, but it was extremly time consuming and pain. For a new project I'm in, maybe we go to replace jenkins with concourseci or drone. Imho a PaaS doesn't solve processual versioning and testing requirements. For that you still need further tools - with or without docker.
- pas 10y ago
  Try Drone CI. It's _very_ Docker friendly.
- jacques_chester 10y ago
  > For a new project I'm in, maybe we go to replace jenkins with concourseci or drone. I love Concourse. Look me up if you have questions.
jondubois 10y ago
I also didn't get the point of Docker until a few months ago when I got acquainted with Kubernetes (K8s) and Rancher. It doesn't really make sense to use Docker without some sort of distributed scheduling/orchestration system like Kubernetes, Docker Swarm or Mesos. I think the first few years of Docker were just pointless but I genuinely feel that it is all starting to come together now. Docker 1.12 looks promising on the orchestration front - Hopefully they will back all these new features with thorough documentation (which I found lacking in Swarm when compared to K8s). It looks like Swarm is just following in K8s' footsteps and maybe even improving things along the way. Based on what I just read, it looks like Docker Swarm might finally be a serious contender to K8s.

by d33 10y ago

gizmodo59 10y ago

Can you briefly describe your environment?

deleted 10y ago

[deleted]

redrummr 10y ago

Why is storage an issue? With databases, for example, you store data upstream (on the host) and keep the dockerised app/thing mostly stateless, or at least capped with regards to storage. More details about your environment would be appreciated.

jdoliner 10y ago
Keeping data on the host is exactly the reason that it's an issue. Swarm offers not guarantees that containers will be rescheduled on the same host that it was initially scheduled on and assumes that it can reschedule containers as failures arise... this doesn't work when your database gets rescheduled and emptied along the way.
- zamalek 10y ago
  > your database gets rescheduled and emptied along the way That's bundling an CP application into seemingly AP infrastructure (from what I gleaned from their docs). Completely the wrong tool for the job. If the application was designed for that it would have recovered. In your defense, they have nothing to warn about that in their documentation.
  - jdoliner 10y ago
    This isn't really a CAP theorem problem and it's certainly not right to describe Docker as "AP infrastructure." What would that mean exactly? Would you expect this problem to go away if I used a database that sacrificed consistency for availability such as Riak?
    - zamalek 10y ago
      Swarm (not the whole of Docker) seems like something designed for databases like Riak, yes. A SQL failover cluster might work, but certainly not a single database container on infrastructure designed for highly available apps.
- kerr23 10y ago
  In docker 1.12 you can 'tag' a node and tell a 'service' to only run on the tagged nodes. Not saying that's a good idea, but it is getting closer. You could, for example, have a node that's only for DBs that has volumes on it. You could then use DRBD on the host to clone that data to a secondary node. then in the event that node 1 dies swarm would bring the DB up on node2. With the mesh network stuff they've added the endpoint would remain the same, so all your apps would need to do would be re-connect.
  - jdoliner 10y ago
    > Not saying that's a good idea, but it is getting closer. No, that isn't getting closer it's getting farther away. The whole point of containers is that they make the host machine completely fungible. If I can only schedule my DB containers on a specific machine then I might as well just run my DB on that machine and be done with it.
    - kerr23 10y ago
      hmm, your first complaint was that "Swarm offers no guarantees that containers will be rescheduled on the same host". I'm saying that, if you want, you CAN make it guarantee that a container will be rescheduled to the same host. (or a controlled level of hosts). I don't think it's docker's responsibility to solve database clustering. And, as I said, I'm not advocating running a production DB in docker. But I can see a way that you may be able to.
      - jdoliner 10y ago
        I see how that was confusing. I meant that the fact that Swarm doesn't offer such a guarantee is the reason that storing the data on the host isn't a solution. My real complaint is that none of these give you a way to do persistence that doesn't destroy some other really nice properties of containers. There's lots of people trying to fix this problem the right way, Kubernetes has made a lot of progress on having volumes follow the containers around from host to host. Torus is a slightly different approach, Flocker is another one. > I don't think it's docker's responsibility to solve database clustering. I don't know if I'd call it a responsibility. But Docker is obviously trying to expand their platform into more and more aspects of containerization. If they figured out persistence that would really set them apart, something that this product doesn't really do. It mostly just keeps them even with Kubernetes at best. And an imitation of it at worst.
jodok 10y ago
why not run the database directly in the container as well? we're doing that with https://crate.io https://crate.io - just expose your local instance store as volume, crate will take care of the rest
jodok 10y ago
why not run the database directly in the container as well? we're doing that with https://crate.io https://crate.io - just expose your local instance store as volume, crate will take care of the rest

jjtheblunt 10y ago

Did you try rkt or find something else which you liked?

lewisl9029 10y ago

I've been experimenting with Docker for reproducible dev environments as well for a while now, and my biggest issue has been with the app build step, which often requires a specific non-Linux platform (OS X for iOS and Windows for UWP). Back in my previous project using Cordova, I made the Docker workflow work adequately by offloading builds to web-based build services like PhoneGap Build and Ionic Package (building only a thin live-reloading wrapper app that points to a configurable IP:port for development). But my new project uses React Native, and I haven't found any similar build services for React Native apps (or even just regular native apps) yet. Anyone have any suggestions?

theodorton 10y ago
Bitrise and Circle CI both support OS X environments for building projects. Combined with fastlane, you'd probably have a good setup for continuous delivery. I've only got experience with running fastlane locally though.
- nomel 10y ago
  I'm not a web guy, so this question is genuine. How in the world do you keep up/discover all of the different frameworks that seem to pop up daily?
  - skewart 10y ago
    By spending unreasonable amounts of time on HN - at least that's how I rationalize things to myself.

lopatin 10y ago

I totally agree. Docker feels really tidy conceptually. I ended up somehow convincing myself that adding this extra layer of technology into my (relatively tiny) infrastructure will decrease it's complexity. Unsurprisingly, the effect was the exact opposite.

knz 10y ago
I feel the exact opposite! The Dockerfile is a simple way to define my environment and it's trivial to run the app in either development, QA, or production. Throw in some of the other functionality such as being able to deploy from an image rather than having to rebuild each time, and it's been a productive addition to my toolset. I'm guessing it depends on how complex your application is, but I've found it fantastic for running Python (Flask), PostgreSQL/PostGIS, MapServer, and some other smaller applications.
- Annatar 10y ago
  And did you produce OS packages for any of that configuration work, or did you just end up dumping a bunch of files into the "image"?
  - knz 10y ago
    It's not an image in the sense that you can run updates/installs and strip out the crap associated with that but it's so trivial to run "images" that the benefits far outweigh the additional disk space for our use cases.
codygman 10y ago
I've been enjoying Nixos[0] and hope to try Nixops[1] soon. The difference between Nixos and docker is that nixos makes it possible to have a truly reproducible environment. See the surprisingly readable paper[2] for more details. 0: http://nixos.org/ http://nixos.org/ 1: http://nixos.org/nixops/ http://nixos.org/nixops/ 2: https://nixos.org/~eelco/pubs/nixos-jfp-final.pdf https://nixos.org/~eelco/pubs/nixos-jfp-final.pdf

ldehaan 10y ago

just a quick tip: check out weave for managing networking, IMO it's much easier and I'm not even talking about the docker plugin. just use weave without the plugin and it works amazingly well. for the configuration aspect, just use dockerfiles and a system like mesos and marathon for deploying production. you can then write simple restful API commands to launch different environments with marathon. build all your docker containers to act as single server instances, i.e., spark on one container, SQL on another. tie in a default install of cadvisor on all mesos clients and you can have easy monitoring as well.

rdtsc 10y ago

You probably want something like NixOS or Guix if you really want to go down that way. Yeah I see where you are coming from. First time I heard about Docker, I thought it did what NixOS does, but it doesn't really.

catmanjan 10y ago

I think Vagrant would be a good replacement for you, it's basically docker but built exactly for reproducible dev environments

Annatar 10y ago

You might want to try out SmartOS: one .json file, vmadm(1M) and imgadm(1M) commands later, you'll have a fully isolated UNIX server, running at the speed of bare metal and residing on ZFS, protecting your data. If you need a more complex network setup, dladm(1M) will enable you to configure virtual switches and routers. The manual pages are really good, too. And there is nothing to install, as SmartOS runs from memory, so that all storage in the system can be used for virtual servers. Upgrades are a breeze by just booting into a new image, either from USB or PXE booting from the network.

fpoling 10y ago

From my experience with Docker one should just avoid docker-supplied volumes and manage the storage oneself using host bind mounts for containers and consistently using --read-only for containers themselves. With that it is really weired to read all complains and issues about volumes management. It seems Docker just picked up wrong model for their storage. Then they try forever to fix impedance mismatch between that model and how people want to use Docker.

cpuguy83 10y ago
Care to clarify issues you have with volume management? I think the biggest issue is around the `-v` syntax (and the corrosponding API). In the UX we call things a volume which are actually a mount (which happen to use a volume). I like the way we have implemented this in the new services API.... `docker run --mount type=volume,source=important_data,volume-driver=foo,volume-options=...`
- fpoling 10y ago
  For me the biggest issue with docker volumes is lack of any notion of subvolumes or volume grouping. Consider an application consisting of few containers communicating over unix sockets each with its own state. Surely I can create a bunch of volumes for the containers, but those would not have any notion of grouping. That complicates administration and development. For example, it is very useful to have a shell view of all volumes for the application to poke inside or debug issues. Surely I can do docker run ubuntu and mount all relevant volumes under /mnt there, but that is not user friendly. Or consider that during development or debugging I want to transfer the state to another machine. Why it is not possible to tar all application volumes with single command and restore them in a new place again with single command? I.e, something similar for docker save/load, but for volumes? All those issues are trivially solvable if I use some directory on a file system for the whole application state and use subdirectories there for individual volumes for the containers and then pass those with -v to relevant containers.

flavioaiello 10y ago

My experience with Docker is kind of ambivalent. We are using docker with docker compose on a legacy vmware stack in a corporate environment. No swarm and no docker overlay network as it does undermine firewalls. It is perfect to apply gitlow and semver to each build of each docker image, so each outcoming application stack is fully determenistic and auditable. Docker storage and network are really simple and docker is the perfect fit. On the other side devs were asking for jenkins for that process. We run also Jenkins on Docker but it's cumbersome as it doesn't allow declarative configuration. There are dozen of plugins out there but it doesn't change the fact that the outcome is ressource hungry and slow. For now we are actually optimizing using Job-DSL plugin. We reached our target, but it was extremly time consuming and pain. For a new project I'm in, maybe we go to replace jenkins with concourseci or drone. Imho a PaaS doesn't solve processual versioning and testing requirements. For that you still need further tools - with or without docker.

pas 10y ago
Try Drone CI. It's _very_ Docker friendly.
jacques_chester 10y ago
> For a new project I'm in, maybe we go to replace jenkins with concourseci or drone. I love Concourse. Look me up if you have questions.

jondubois 10y ago

I also didn't get the point of Docker until a few months ago when I got acquainted with Kubernetes (K8s) and Rancher. It doesn't really make sense to use Docker without some sort of distributed scheduling/orchestration system like Kubernetes, Docker Swarm or Mesos. I think the first few years of Docker were just pointless but I genuinely feel that it is all starting to come together now. Docker 1.12 looks promising on the orchestration front - Hopefully they will back all these new features with thorough documentation (which I found lacking in Swarm when compared to K8s). It looks like Swarm is just following in K8s' footsteps and maybe even improving things along the way. Based on what I just read, it looks like Docker Swarm might finally be a serious contender to K8s.