From 4c2b3dff18d504276ffc14cf39313b3e12d5d4d7 Mon Sep 17 00:00:00 2001 From: ktyl Date: Tue, 27 Sep 2022 00:42:05 +0100 Subject: [PATCH] add drone ci --- blogs/2022/10/17/drone-ci.md | 116 +++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+) create mode 100644 blogs/2022/10/17/drone-ci.md diff --git a/blogs/2022/10/17/drone-ci.md b/blogs/2022/10/17/drone-ci.md new file mode 100644 index 0000000..153c1d4 --- /dev/null +++ b/blogs/2022/10/17/drone-ci.md @@ -0,0 +1,116 @@ +# Drone CI + +When it comes to automation, [GitLab CI](https://gitlab.com) has been my go-to for running builds, tests and deployments of projects from static websites to 3D open-world games. +This has generally been on a self-hosted installation, and often makes use of physical runners. +However, I have some gripes: I mostly only use it for the CI, but it comes with an issue tracker and Git hosting solution too - great for some cases, but overkill in so many others. +Because it's such a complete solution, GitLab is a bit of a resource hog, and can often run frustratingly slowly. + +Recently I've been playing with a friend's self-hosted instance of [Drone CI](https://drone.io/) as a lightweight alternative, and I much prefer it. +I didn't set up the instance, so that part is out of scope for this post, but in case it's relevant, we're using a self-hosted [Gitea](gitea.io) instance to host the source. +You can find out about configuring Drone with Gitea [here](https://docs.drone.io/server/provider/gitea/). + + +## Yet Another Yaml Config + +Like GitLab, Drone is configured via a YAML file at the project root, called `.drone.yml`. +Drone is configured by creating 'steps' to the pipeline, where GitLab uses 'jobs'. + +My first project's automation requirements were small - all I needed for a deployment was to copy all the files in a directory on every push to the `main` branch. +This means I needed secure access to the host, and the ability to copy files to it. +I didn't want to dedicate any permanent resources to such a small project, so opted for the `docker` pipeline option. + +My pipeline would contain a single `deploy` step which would configure SSH access to the host, and then use it to copy the relevant files from the checked out version of the project. +I decided to use `ubuntu` as the Docker image for familiarity and accessibility - there are probably better options. +Drone widely supports Docker image registries; I have not used Docker much, but would like to get more experience with it. + +```yml +kind: pipeline +type: docker +name: deploy + +steps: +- name: deploy + image: ubuntu + when: + branch: + - main + + commands: + - echo hello world +``` + +## Secrets + +A hugely important aspect of automation is ensuring the security of one's pipelines. +Automated access between pipelines is a big risk, and should be locked down as much as possible. +For passing around secrets such as passwords and SSH keys, Drone has a concept of secrets. +I created a private key on my local machine for the runner's access to the remote host, and added a [per-repository secret](https://docs.drone.io/secret/repository/) to contain the value. +This is a named string value which can be accessed from within the context of a single pipeline step. + +I also created secrets to contain values for the remote host address and the user to login as. +These are less of a security concern than the private SSH key, but we should obfuscate them anyway. +It's also a useful step towards generalising the pipeline for other projects: I can use the same set of commands in multiple CI configurations, and just update the secrets from the project page. + +This block was placed in the same step definition as above, below the `image:` entry: + +``` +environment: + HOST: + from_secret: host + USER: + from_secret: user + SSH_KEY: + from_secret: ssh_key +``` + +## Connecting + +To use the SSH key, we need to spin up `ssh-agent` and load our key into it. +Since it's passed into the job as an environment variable, this involves first writing it to a file. +We also need to disable host key checking (the bit that asks if you're sure you want to connect to a new host) as we're making an automated SSH connection, and therefore won't be there to type 'yes'. + +```yml +# configure ssh +- eval $(ssh-agent -s) +- mkdir -p ~/.ssh +- echo "$SSH_KEY" > ~/.ssh/id_rsa +- chmod 600 ~/.ssh/id_rsa +- ssh-add +- echo "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config +``` + +Finally, it's time to run some SSH commands. +I had a bit of trouble getting the hang of variable templating here - it took some trial and error to figure out what variables would get expanded and when. +Since my `HOST` and `USER` values are defined in secrets, I had to get them from my evironment variables and into a correctly formatted string for the SSH target. +As I would be running multiple commands, I also wanted to store this in a variable to keep the SSH commands short in the Drone config. + +What ended up working for me was this: + +```yml +# environment variables get expanded (twice?) +- host="$${USER}@$${HOST}" +# running 'hostname' on the deploy target +- ssh $host "hostname" +``` + +## Images + +It's pretty cool to be able to pass a repository through several Docker images through the pipeline. +I have my website's Makefile set up to build off my local machine, which is on Arch. +It therefore depends on Arch-specific package names. +I didn't want to have to hack around my existing build configuration just to build it automatically, but I also found that the deploy steps I'd already written worked best on Ubuntu. + +For Drone, this is no problem - I can simply specify `image: archlinux` in the build stage, and `image: ubuntu` for the deploy step. +My Makefile and local workflow requires no changes at all, but I can still use the more robust deploy steps from Ubuntu. + +## Final thoughts + +I like Drone's minimalist approach to CI. +There isn't much in terms of configuration, and the interface is much snappier than Gitlab's. +It will take a bit more work to get a full workflow - Gitlab basically has one out the box - but working with more separate components should provide flexibility and resilience in the long run. + +I'd like to explore some more features, like [templates](https://docs.drone.io/template/yaml/) for steps shared between repositories, and spend more time tuning exactly when pipelines run. +I also want to try building some more complex projects, such as those using game engines like Godot, and those targeting multiple target platforms. +Those are adventures for another day, though. + +That's all for now, thanks for reading and see you next time!