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Rails on Docker

fly.io

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Re: Rails on Docker

#11

Post by jchw »

emerongi wrote: post #7
jchw wrote: post #2

> Everything after that removes the manifest files and any temporary files downloaded during this command. It's necessary to remove all these files in this command to keep the size of the Docker image to a minimum. Smaller Dockerfiles mean faster deployments. It isn't explicitly explained, but the reason why it must be in this command and not separated out is because each command in a dockerfile creates a new "layer"…

If you only care about the final image size, then `docker build --squash` squashes the layers for you as well.

Definitely, although it's worth noting that while the image size will be smaller, it will get rid of the benefits of sharing base layers. Having less redundant layers lets you save most of the space without losing any of the benefits of sharing slices. I think that is the main reason why this is not usually done.

Re: Rails on Docker

#12

Post by grk »

agtorre wrote: post #5

This is really cool. Is the Rails server production ready? I was always under the impression you had to run it with Uvicorn or similar, although I haven't been following Rails development recently.

The default Gemfile now bundles Puma in, so yeah it's production ready

Re: Rails on Docker

#13

Post by [deleted] »

MuffinFlavored wrote: post #6
brundolf wrote: post #4

I used to think I hated Docker, but I think what I actually hate is using Docker locally (building/rebuilding/cache-busting images, spinning containers up and down, the extra memory usage on macOS, etc etc). I don't need all that for development, I just want to run my dang code But I've been really enjoying it as a way of just telling a PaaS "hey here's the compiler/runtime my code needs to run", and then mostly not…

> I don't need all that for development, I just want to run the dang code Have you ever worked somewhere where in order to run the code locally on your machine, it's a blend of "install RabbitMQ on your machine, connect to MS-SQL in dev, use a local Redis, connect to Cassandra in dev, run 1 service that this service routes through/calls to locally, but then that service will call to 2 services in dev", etc?

[deleted]

Re: Rails on Docker

#14

Post by gkfasdfasdf »

emerongi wrote: post #7
jchw wrote: post #2

> Everything after that removes the manifest files and any temporary files downloaded during this command. It's necessary to remove all these files in this command to keep the size of the Docker image to a minimum. Smaller Dockerfiles mean faster deployments. It isn't explicitly explained, but the reason why it must be in this command and not separated out is because each command in a dockerfile creates a new "layer"…

If you only care about the final image size, then `docker build --squash` squashes the layers for you as well.

--squash is still experimental, I believe multi-stage images are the new best practice here.

Re: Rails on Docker

#15

Post by toastercat »

MuffinFlavored wrote: post #6
brundolf wrote: post #4

I used to think I hated Docker, but I think what I actually hate is using Docker locally (building/rebuilding/cache-busting images, spinning containers up and down, the extra memory usage on macOS, etc etc). I don't need all that for development, I just want to run my dang code But I've been really enjoying it as a way of just telling a PaaS "hey here's the compiler/runtime my code needs to run", and then mostly not…

> I don't need all that for development, I just want to run the dang code Have you ever worked somewhere where in order to run the code locally on your machine, it's a blend of "install RabbitMQ on your machine, connect to MS-SQL in dev, use a local Redis, connect to Cassandra in dev, run 1 service that this service routes through/calls to locally, but then that service will call to 2 services in dev", etc?

I certainly have. And there is often a Dockerfile or a docker-compose file. And the docs will say "just run docker-compose up, and you should be good to go."

And 50% of the time it actually works. The other 50% of the time, it doesn't, and I spend a week talking to other engineers and ops trying to figure out why.

Not a jab at Docker, btw.

Re: Rails on Docker

#16

Post by brundolf »

toastercat wrote: post #15
MuffinFlavored wrote: post #6

Earlier quoted context omitted.

> I don't need all that for development, I just want to run the dang code Have you ever worked somewhere where in order to run the code locally on your machine, it's a blend of "install RabbitMQ on your machine, connect to MS-SQL in dev, use a local Redis, connect to Cassandra in dev, run 1 service that this service routes through/calls to locally, but then that service will call to 2 services in dev", etc?

I certainly have. And there is often a Dockerfile or a docker-compose file. And the docs will say "just run docker-compose up, and you should be good to go." And 50% of the time it actually works. The other 50% of the time, it doesn't, and I spend a week talking to other engineers and ops trying to figure out why. Not a jab at Docker, btw.

And to borrow from the classic regex saying: "Now you have two problems"

Re: Rails on Docker

#17

Post by jayd16 »

toastercat wrote: post #15
MuffinFlavored wrote: post #6

Earlier quoted context omitted.

> I don't need all that for development, I just want to run the dang code Have you ever worked somewhere where in order to run the code locally on your machine, it's a blend of "install RabbitMQ on your machine, connect to MS-SQL in dev, use a local Redis, connect to Cassandra in dev, run 1 service that this service routes through/calls to locally, but then that service will call to 2 services in dev", etc?

I certainly have. And there is often a Dockerfile or a docker-compose file. And the docs will say "just run docker-compose up, and you should be good to go." And 50% of the time it actually works. The other 50% of the time, it doesn't, and I spend a week talking to other engineers and ops trying to figure out why. Not a jab at Docker, btw.

What are some common error cases you see this way?

Re: Rails on Docker

#18

Post by brightball »

MuffinFlavored wrote: post #6
brundolf wrote: post #4

I used to think I hated Docker, but I think what I actually hate is using Docker locally (building/rebuilding/cache-busting images, spinning containers up and down, the extra memory usage on macOS, etc etc). I don't need all that for development, I just want to run my dang code But I've been really enjoying it as a way of just telling a PaaS "hey here's the compiler/runtime my code needs to run", and then mostly not…

> I don't need all that for development, I just want to run the dang code Have you ever worked somewhere where in order to run the code locally on your machine, it's a blend of "install RabbitMQ on your machine, connect to MS-SQL in dev, use a local Redis, connect to Cassandra in dev, run 1 service that this service routes through/calls to locally, but then that service will call to 2 services in dev", etc?

Docker compose for those services while the language itself runs natively has been the best solution to this problem for me in the past. Docker compose for redis, postgres, elastic, etc.

IMO Docker for local dev is most beneficial for python where local installs are so all over the place.

Re: Rails on Docker

#19

Post by 411111111111111 »

gkfasdfasdf wrote: post #14
emerongi wrote: post #7

Earlier quoted context omitted.

If you only care about the final image size, then `docker build --squash` squashes the layers for you as well.

--squash is still experimental, I believe multi-stage images are the new best practice here.

in case anyone doesn't know what that means, its basically this kind of dockerfile

  FROM the_source_image as builder
  RUN build.sh

  FROM the_source_image
  COPY --from=builder /app/artifacts /app/
  CMD ....
i'm not sure if you can really call it the new best practice though, its been the default for ... a very long time at this point.

Re: Rails on Docker

#20

Post by brundolf »

brightball wrote: post #18
MuffinFlavored wrote: post #6

Earlier quoted context omitted.

> I don't need all that for development, I just want to run the dang code Have you ever worked somewhere where in order to run the code locally on your machine, it's a blend of "install RabbitMQ on your machine, connect to MS-SQL in dev, use a local Redis, connect to Cassandra in dev, run 1 service that this service routes through/calls to locally, but then that service will call to 2 services in dev", etc?

Docker compose for those services while the language itself runs natively has been the best solution to this problem for me in the past. Docker compose for redis, postgres, elastic, etc. IMO Docker for local dev is most beneficial for python where local installs are so all over the place.

Yeah, and python has been most of my exposure to local Docker, so that may be coloring my experience here. Running a couple off-the-shelf applications in the background with Docker isn't too bad, but having it at the center of your dev workflow where you're constantly rebuilding a container around your own code is just awful in my experience
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