blog, jake.ai-importin

Go is all of the rage, all my friends are doing it so I feel like I have to do it too… So I’ve been playing with Go and Docker a bit recently to try and learn more about go and how I can use it for work and side projects.

I’m enjoying things so far, and I’m finding interesting tidbits as I go. This is one of them.

With go it is easy to build staticly linked binaries which can be distributed. This is awesome by itself, but with docker it is even more awesome.

You can build your go binaries like so:

CGO_ENABLED=0 go build -a ../src/worker.go

Once you’ve built your staticly linked binary you can build a docker image on top of the scratch base image. You can read about the Scratch Image on the docker site, but basically its an empty image that you can drop your binary into that will run as a very minimal container.

FROM scratch
MAINTAINER Jake Dahn <[email protected]>
ADD bin/worker /worker
ENTRYPOINT ["/worker"]

Below is output of some shell output from building and running a docker container that contains a go binary. Notice the image size is 5MB. If I use ubuntu or other distros as a base image my docker image is significanly larger:

[email protected]:/vagrant# docker pull scratch
Pulling repository scratch
511136ea3c5a: Download complete
Status: Image is up to date for scratch:latest

[email protected]:/vagrant$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
scratch             latest              511136ea3c5a        16 months ago       0 B

[email protected]:/vagrant$ docker build -t jake .
Sending build context to Docker daemon 53.73 MB
Sending build context to Docker daemon
Step 0 : FROM scratch
 ---> 511136ea3c5a
Step 1 : MAINTAINER Jake Dahn <[email protected]>
 ---> Running in 27f068468755
 ---> a063241634df
Removing intermediate container 27f068468755
Step 2 : ADD bin/worker /worker
 ---> 5053eed5787c
Removing intermediate container 3a36a6c5e19b
Step 3 : ENTRYPOINT /worker
 ---> Running in 1f8014d919b5
 ---> ae0bd28d3e2e
Removing intermediate container 1f8014d919b5
Successfully built ae0bd28d3e2e

[email protected]:/vagrant$ docker images
REPOSITORY          TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
jake                latest              ae0bd28d3e2e        4 seconds ago       5.191 MB
scratch             latest              511136ea3c5a        16 months ago       0 B

[email protected]:/vagrant$ docker run -t -i jake
2014/10/24 05:40:02  [*] Waiting for messages. To exit press CTRL+C # this is a running go program that is a rabbitmq consumer

This is an interesting way to ship and deploy software.