Oliver Davies
5eba6de81a
This is a follow-up to commit 3be9031de8
as each daily email has a `permalink` value that overrides the default
content type permalink.
76 lines
3.4 KiB
Markdown
76 lines
3.4 KiB
Markdown
---
|
|
permalink: daily/2022/08/12/git-worktrees-docker-compose
|
|
title: Git Worktrees and Docker Compose
|
|
pubDate: 2022-08-12
|
|
---
|
|
|
|
I've recently started trialing Git worktrees again as part of my development workflow.
|
|
|
|
If you are unfamiliar with Git worktrees, they allow you to have muliple branches of a repository checked out at the same time in different directories.
|
|
|
|
For example, this is what I see within my local checkout of my website repository:
|
|
|
|
```
|
|
.
|
|
├── config
|
|
├── HEAD
|
|
├── main
|
|
│ ├── ansible
|
|
│ ├── nginx
|
|
│ ├── README.md
|
|
│ └── website
|
|
├── new-post
|
|
│ ├── ansible
|
|
│ ├── nginx
|
|
│ ├── README.md
|
|
│ └── website
|
|
├── objects
|
|
│ ├── info
|
|
│ └── pack
|
|
├── packed-refs
|
|
├── refs
|
|
│ ├── heads
|
|
│ └── tags
|
|
└── worktrees
|
|
├── main
|
|
└── new-post
|
|
```
|
|
|
|
The first thing that you'll notice is, because it's a bare clone, it looks a little different to a what you usually see in a Git repository.
|
|
|
|
Each worktree has it's own directory, so my "main" branch inside the `main` directory.
|
|
|
|
If I need to work on a different branch, such as `new-post`, then I can create a new worktree, move into that directory and start working. I don't need to commit or stash any in-progress work and switch branches.
|
|
|
|
## Complications with Docker Compose
|
|
|
|
I use Docker and Docker Compose for my projects, and this caused some issues for me the last time that I tried using worktrees.
|
|
|
|
By default, Docker Compose will use the name of the directory that the Compose file is in to name its containers. If the directory name is "oliverdavies-uk", then the containers will be `oliverdavies-uk-web_1`, `oliverdavies-uk-db_1` etc.
|
|
|
|
This doesn't work so well if the directory is a worktree called "main" or "master" as you'll have containers called `main_web_1` or `master_db_1`.
|
|
|
|
The way to solve this is to use the `COMPOSE_PROJECT_NAME` environment variable.
|
|
|
|
If you prefix Docker Compose commands with `COMPOSE_PROJECT_NAME=your-project`, or add it to an `.env` file (Docker Compose will load this automatically), then this will override the prefix in the container names to be `your-project-{service}`.
|
|
|
|
## Container names per worktree
|
|
|
|
Whilst you could use the same Compose project name within all of your worktrees, I prefer to include the worktree name as a suffix - something like `my-project-main` or `my-project-staging` - and keep these stored in an `.env` file in each worktree's directory.
|
|
|
|
As each worktree now has unique container names, I can have multiple instances of a project running at the same time, and each worktree will have it's own separate data - meaning that I can make changes and test something in one worktree without affecting any others.
|
|
|
|
You can also use the `COMPOSE_PROJECT_NAME` variable inside Docker Compose files.
|
|
|
|
For example, if you use Traefik and needed to override the host URL for a service, the string will be interpolated and the project name would be injected as you'd expect.
|
|
|
|
```language-yaml
|
|
labels:
|
|
- "traefik.http.routers.${COMPOSE_PROJECT_NAME}.rule=Host(
|
|
`${COMPOSE_PROJECT_NAME}.docker.localhost`,
|
|
`admin.${COMPOSE_PROJECT_NAME}.docker.localhost`
|
|
)"
|
|
```
|
|
|
|
This means that Traefik would continue to use a different URL for each worktree without you needing to make any changes to your Docker Compose file.
|