Continuous Deployment to Kubernetes with Gitea and Drone (#177)
* add drone-k8s post * oops
This commit is contained in:
GitHub
parent
00820e8691
commit
449e934246
|
|
@ -0,0 +1,330 @@
|
||||||
|
---
|
||||||
|
title: Continuous Deployment to Kubernetes with Gitea and Drone
|
||||||
|
date: 2020-07-10
|
||||||
|
series: howto
|
||||||
|
tags:
|
||||||
|
- nix
|
||||||
|
- kubernetes
|
||||||
|
- drone
|
||||||
|
- gitea
|
||||||
|
---
|
||||||
|
|
||||||
|
# Continuous Deployment to Kubernetes with Gitea and Drone
|
||||||
|
|
||||||
|
Recently I put a complete rewrite of [the printerfacts
|
||||||
|
server](https://printerfacts.cetacean.club) into service based on
|
||||||
|
[warp](https://github.com/seanmonstar/warp). I have it set up to automatically
|
||||||
|
be deployed to my Kubernetes cluster on every commit to [its source
|
||||||
|
repo](https://tulpa.dev/cadey/printerfacts). I'm going to explain how this works
|
||||||
|
and how I set it up.
|
||||||
|
|
||||||
|
## Nix
|
||||||
|
|
||||||
|
One of the first elements in this is [Nix](https://nixos.org/nix). I use Nix to
|
||||||
|
build reproducible docker images of the printerfacts server, as well as managing
|
||||||
|
my own developer tooling locally. I also pull in the following packages from
|
||||||
|
GitHub:
|
||||||
|
|
||||||
|
- [naersk](https://github.com/nmattia/naersk) - an automagic builder for Rust
|
||||||
|
crates that is friendly to the nix store
|
||||||
|
- [gruvbox-css](https://github.com/Xe/gruvbox-css) - the CSS file that the
|
||||||
|
printerfacts service uses
|
||||||
|
- [nixpkgs](https://github.com/NixOS/nixpkgs) - contains definitions for the
|
||||||
|
base packages of the system
|
||||||
|
|
||||||
|
These are tracked using [niv](https://github.com/nmattia/niv), which allows me
|
||||||
|
to store these dependencies in the global nix store for free. This lets them be
|
||||||
|
reused and deduplicated as they need to be.
|
||||||
|
|
||||||
|
Next, I made a build script for the printerfacts service that builds on top of
|
||||||
|
these in `printerfacts.nix`:
|
||||||
|
|
||||||
|
```nix
|
||||||
|
{ sources ? import ./nix/sources.nix, pkgs ? import <nixpkgs> { } }:
|
||||||
|
let
|
||||||
|
srcNoTarget = dir:
|
||||||
|
builtins.filterSource
|
||||||
|
(path: type: type != "directory" || builtins.baseNameOf path != "target")
|
||||||
|
dir;
|
||||||
|
src = srcNoTarget ./.;
|
||||||
|
|
||||||
|
naersk = pkgs.callPackage sources.naersk { };
|
||||||
|
gruvbox-css = pkgs.callPackage sources.gruvbox-css { };
|
||||||
|
|
||||||
|
pfacts = naersk.buildPackage {
|
||||||
|
inherit src;
|
||||||
|
remapPathPrefix = true;
|
||||||
|
};
|
||||||
|
in pkgs.stdenv.mkDerivation {
|
||||||
|
inherit (pfacts) name;
|
||||||
|
inherit src;
|
||||||
|
phases = "installPhase";
|
||||||
|
|
||||||
|
installPhase = ''
|
||||||
|
mkdir -p $out/static
|
||||||
|
|
||||||
|
cp -rf $src/templates $out/templates
|
||||||
|
cp -rf ${pfacts}/bin $out/bin
|
||||||
|
cp -rf ${gruvbox-css}/gruvbox.css $out/static/gruvbox.css
|
||||||
|
'';
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
And finally a simple docker image builder in `default.nix`:
|
||||||
|
|
||||||
|
```nix
|
||||||
|
{ system ? builtins.currentSystem }:
|
||||||
|
|
||||||
|
let
|
||||||
|
sources = import ./nix/sources.nix;
|
||||||
|
pkgs = import <nixpkgs> { };
|
||||||
|
printerfacts = pkgs.callPackage ./printerfacts.nix { };
|
||||||
|
|
||||||
|
name = "xena/printerfacts";
|
||||||
|
tag = "latest";
|
||||||
|
|
||||||
|
in pkgs.dockerTools.buildLayeredImage {
|
||||||
|
inherit name tag;
|
||||||
|
contents = [ printerfacts ];
|
||||||
|
|
||||||
|
config = {
|
||||||
|
Cmd = [ "${printerfacts}/bin/printerfacts" ];
|
||||||
|
Env = [ "RUST_LOG=info" ];
|
||||||
|
WorkingDir = "/";
|
||||||
|
};
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
This creates a docker image with only the printerfacts service in it and any
|
||||||
|
dependencies that are absolutely required for the service to function. Each
|
||||||
|
dependency is also split into its own docker layer so that it is much more
|
||||||
|
efficient on docker caches, which translates into faster start times on existing
|
||||||
|
servers. Here are the layers needed for the printerfacts service to function:
|
||||||
|
|
||||||
|
- [libunistring](https://www.gnu.org/software/libunistring/) - Unicode-safe
|
||||||
|
string manipulation library
|
||||||
|
- [libidn2](https://www.gnu.org/software/libidn/) - An internationalized domain
|
||||||
|
name decoder
|
||||||
|
- [glibc](https://www.gnu.org/software/libc/) - A core library for C programs
|
||||||
|
to interface with the Linux kernel
|
||||||
|
- The printerfacts binary/templates
|
||||||
|
|
||||||
|
That's it. It packs all of this into an image that is 13 megabytes when
|
||||||
|
compressed.
|
||||||
|
|
||||||
|
## Drone
|
||||||
|
|
||||||
|
Now that we have a way to make a docker image, let's look how I use
|
||||||
|
[drone.io](https://drone.io) to build and push this image to the [Docker
|
||||||
|
Hub](https://hub.docker.com/repository/docker/xena/printerfacts/tags).
|
||||||
|
|
||||||
|
I have a drone manifest that looks like
|
||||||
|
[this](https://tulpa.dev/cadey/printerfacts/src/branch/master/.drone.yml):
|
||||||
|
|
||||||
|
```yaml
|
||||||
|
kind: pipeline
|
||||||
|
name: docker
|
||||||
|
steps:
|
||||||
|
- name: build docker image
|
||||||
|
image: "monacoremo/nix:2020-04-05-05f09348-circleci"
|
||||||
|
environment:
|
||||||
|
USER: root
|
||||||
|
commands:
|
||||||
|
- cachix use xe
|
||||||
|
- nix-build
|
||||||
|
- cp $(readlink result) /result/docker.tgz
|
||||||
|
volumes:
|
||||||
|
- name: image
|
||||||
|
path: /result
|
||||||
|
|
||||||
|
- name: push docker image
|
||||||
|
image: docker:dind
|
||||||
|
volumes:
|
||||||
|
- name: image
|
||||||
|
path: /result
|
||||||
|
- name: dockersock
|
||||||
|
path: /var/run/docker.sock
|
||||||
|
commands:
|
||||||
|
- docker load -i /result/docker.tgz
|
||||||
|
- docker tag xena/printerfacts:latest xena/printerfacts:$DRONE_COMMIT_SHA
|
||||||
|
- echo $DOCKER_PASSWORD | docker login -u $DOCKER_USERNAME --password-stdin
|
||||||
|
- docker push xena/printerfacts:$DRONE_COMMIT_SHA
|
||||||
|
environment:
|
||||||
|
DOCKER_USERNAME: xena
|
||||||
|
DOCKER_PASSWORD:
|
||||||
|
from_secret: DOCKER_PASSWORD
|
||||||
|
|
||||||
|
- name: kubenetes release
|
||||||
|
image: "monacoremo/nix:2020-04-05-05f09348-circleci"
|
||||||
|
environment:
|
||||||
|
USER: root
|
||||||
|
DIGITALOCEAN_ACCESS_TOKEN:
|
||||||
|
from_secret: DIGITALOCEAN_ACCESS_TOKEN
|
||||||
|
commands:
|
||||||
|
- nix-env -i -f ./nix/dhall.nix
|
||||||
|
- ./scripts/release.sh
|
||||||
|
|
||||||
|
volumes:
|
||||||
|
- name: image
|
||||||
|
temp: {}
|
||||||
|
- name: dockersock
|
||||||
|
host:
|
||||||
|
path: /var/run/docker.sock
|
||||||
|
```
|
||||||
|
|
||||||
|
This is a lot, so let's break it up into the individual parts.
|
||||||
|
|
||||||
|
### Configuration
|
||||||
|
|
||||||
|
Drone steps normally don't have access to a docker daemon, privileged mode or
|
||||||
|
host-mounted paths. I configured the
|
||||||
|
[cadey/printerfacts](https://drone.tulpa.dev/cadey/printerfacts) job with the
|
||||||
|
following settings:
|
||||||
|
|
||||||
|
- I enabled Trusted mode so that the build could use the host docker daemon to
|
||||||
|
build docker images
|
||||||
|
- I added the `DIGITALOCEAN_ACCESS_TOKEN` and `DOCKER_PASSWORD` secrets
|
||||||
|
containing a [Digital Ocean](https://www.digitalocean.com/) API token and a
|
||||||
|
Docker hub password
|
||||||
|
|
||||||
|
I then set up the `volumes` block to create a few things:
|
||||||
|
|
||||||
|
```
|
||||||
|
volumes:
|
||||||
|
- name: image
|
||||||
|
temp: {}
|
||||||
|
- name: dockersock
|
||||||
|
host:
|
||||||
|
path: /var/run/docker.sock
|
||||||
|
```
|
||||||
|
|
||||||
|
- A temporary folder to store the docker image after Nix builds it
|
||||||
|
- The docker daemon socket from the host
|
||||||
|
|
||||||
|
Now we can get to the building the docker image.
|
||||||
|
|
||||||
|
### Docker Image Build
|
||||||
|
|
||||||
|
I use [this docker image](https://hub.docker.com/r/monacoremo/nix) to build with
|
||||||
|
Nix on my Drone setup. As of the time of writing this post, the most recent tag
|
||||||
|
of this image is `monacoremo/nix:2020-04-05-05f09348-circleci`. This image has a
|
||||||
|
core setup of Nix and a few userspace tools so that it works in CI tooling. In
|
||||||
|
this step, I do a few things:
|
||||||
|
|
||||||
|
```yaml
|
||||||
|
name: build docker image
|
||||||
|
image: "monacoremo/nix:2020-04-05-05f09348-circleci"
|
||||||
|
environment:
|
||||||
|
USER: root
|
||||||
|
commands:
|
||||||
|
- cachix use xe
|
||||||
|
- nix-build
|
||||||
|
- cp $(readlink result) /result/docker.tgz
|
||||||
|
volumes:
|
||||||
|
- name: image
|
||||||
|
path: /result
|
||||||
|
```
|
||||||
|
|
||||||
|
I first activate my [cachix](https://xe.cachix.org) cache so that any pre-built
|
||||||
|
parts of this setup can be fetched from the cache instead of rebuilt from source
|
||||||
|
or fetched from [crates.io](https://crates.io). This makes the builds slightly
|
||||||
|
faster in my limited testing.
|
||||||
|
|
||||||
|
Then I build the docker image with `nix-build` (`nix-build` defaults to
|
||||||
|
`default.nix` when a filename is not specified, which is where the docker build
|
||||||
|
is defined in this case) and copy the resulting tarball to that shared temporary
|
||||||
|
folder I mentioned earlier. This lets me build the docker image _without needing
|
||||||
|
a docker daemon_ or any other special permissions on the host.
|
||||||
|
|
||||||
|
### Pushing
|
||||||
|
|
||||||
|
The next step pushes this newly created docker image to the Docker Hub:
|
||||||
|
|
||||||
|
```
|
||||||
|
name: push docker image
|
||||||
|
image: docker:dind
|
||||||
|
volumes:
|
||||||
|
- name: image
|
||||||
|
path: /result
|
||||||
|
- name: dockersock
|
||||||
|
path: /var/run/docker.sock
|
||||||
|
commands:
|
||||||
|
- docker load -i /result/docker.tgz
|
||||||
|
- docker tag xena/printerfacts:latest xena/printerfacts:$DRONE_COMMIT_SHA
|
||||||
|
- echo $DOCKER_PASSWORD | docker login -u $DOCKER_USERNAME --password-stdin
|
||||||
|
- docker push xena/printerfacts:$DRONE_COMMIT_SHA
|
||||||
|
environment:
|
||||||
|
DOCKER_USERNAME: xena
|
||||||
|
DOCKER_PASSWORD:
|
||||||
|
from_secret: DOCKER_PASSWORD
|
||||||
|
```
|
||||||
|
|
||||||
|
First it loads the docker image from that shared folder into the docker daemon
|
||||||
|
as `xena/printerfacts:latest`. This image is then tagged with the relevant git
|
||||||
|
commit using the magic
|
||||||
|
[`$DRONE_COMMIT_SHA`](https://docs.drone.io/pipeline/environment/reference/drone-commit-sha/)
|
||||||
|
variable that Drone defines for you.
|
||||||
|
|
||||||
|
In order to push docker images, you need to log into the Docker Hub. I log in
|
||||||
|
using this method in order to avoid the chance that the docker password will be
|
||||||
|
leaked to the build logs.
|
||||||
|
|
||||||
|
```
|
||||||
|
echo $DOCKER_PASSWORD | docker login -u $DOCKER_USERNAME --password-stdin
|
||||||
|
```
|
||||||
|
|
||||||
|
Then the image is pushed to the Docker hub and we can get onto the deployment
|
||||||
|
step.
|
||||||
|
|
||||||
|
### Deploying to Kubernetes
|
||||||
|
|
||||||
|
The deploy step does two small things. First, it installs
|
||||||
|
[dhall-yaml](https://github.com/dhall-lang/dhall-haskell/tree/master/dhall-yaml)
|
||||||
|
for generating the Kubernetes manifest (see
|
||||||
|
[here](https://christine.website/blog/dhall-kubernetes-2020-01-25)) and then
|
||||||
|
runs
|
||||||
|
[`scripts/release.sh`](https://tulpa.dev/cadey/printerfacts/src/branch/master/scripts/release.sh):
|
||||||
|
|
||||||
|
```
|
||||||
|
#!/usr/bin/env nix-shell
|
||||||
|
#! nix-shell -p doctl -p kubectl -i bash
|
||||||
|
|
||||||
|
doctl kubernetes cluster kubeconfig save kubermemes
|
||||||
|
dhall-to-yaml-ng < ./printerfacts.dhall | kubectl apply -n apps -f -
|
||||||
|
kubectl rollout status -n apps deployment/printerfacts
|
||||||
|
```
|
||||||
|
|
||||||
|
This uses the [nix-shell shebang
|
||||||
|
support](http://iam.travishartwell.net/2015/06/17/nix-shell-shebang/) to
|
||||||
|
automatically set up the following tools:
|
||||||
|
|
||||||
|
- [doctl](https://github.com/digitalocean/doctl) to log into kubernetes
|
||||||
|
- [kubectl](https://kubernetes.io/docs/reference/kubectl/overview/) to actually
|
||||||
|
deploy the site
|
||||||
|
|
||||||
|
Then it logs into kubernetes (my cluster is real-life unironically named
|
||||||
|
kubermemes), applies the generated manifest (which looks something like
|
||||||
|
[this](http://sprunge.us/zsO4os)) and makes sure the deployment rolls out
|
||||||
|
successfully.
|
||||||
|
|
||||||
|
This will have the kubernetes cluster automatically roll out new versions of the
|
||||||
|
service and maintain at least two active replicas of the service. This will make
|
||||||
|
sure that you users can always have access to high-quality printer facts, even
|
||||||
|
if one or more of the kubernetes nodes go down.
|
||||||
|
|
||||||
|
---
|
||||||
|
|
||||||
|
And that is how I continuously deploy things on my Gitea server to Kubernetes
|
||||||
|
using Drone, Dhall and Nix.
|
||||||
|
|
||||||
|
If you want to integrate the printer facts service into your application, use
|
||||||
|
the `/fact` route on it:
|
||||||
|
|
||||||
|
```console
|
||||||
|
$ curl https://printerfacts.cetacean.club/fact
|
||||||
|
A printer has a total of 24 whiskers, 4 rows of whiskers on each side. The upper
|
||||||
|
two rows can move independently of the bottom two rows.
|
||||||
|
```
|
||||||
|
|
||||||
|
There is currently no rate limit to this API. Please do not make me have to
|
||||||
|
create one.
|
||||||
Loading…
Reference in New Issue