oliverdavies.uk/content/node.5c793601-f8ea-470d-8c64-3e669226e651.yml

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<p>I've recently started trialing Git worktrees again as part of my development workflow.</p>
<p>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.</p>
<p>For example, this is what I see within my local checkout of my website repository:</p>
<pre><code>.
├── 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
</code></pre>
<p>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.</p>
<p>Each worktree has it's own directory, so my "main" branch inside the <code>main</code> directory.</p>
<p>If I need to work on a different branch, such as <code>new-post</code>, 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.</p>
<h2 id="complications-with-docker-compose">Complications with Docker Compose</h2>
<p>I use Docker and Docker Compose for my projects, and this caused some issues for me the last time that I tried using worktrees.</p>
<p>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 <code>oliverdavies-uk-web_1</code>, <code>oliverdavies-uk-db_1</code> etc.</p>
<p>This doesn't work so well if the directory is a worktree called "main" or "master" as you'll have containers called <code>main_web_1</code> or <code>master_db_1</code>.</p>
<p>The way to solve this is to use the <code>COMPOSE_PROJECT_NAME</code> environment variable.</p>
<p>If you prefix Docker Compose commands with <code>COMPOSE_PROJECT_NAME=your-project</code>, or add it to an <code>.env</code> file (Docker Compose will load this automatically), then this will override the prefix in the container names to be <code>your-project-{service}</code>.</p>
<h2 id="container-names-per-worktree">Container names per worktree</h2>
<p>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 <code>my-project-main</code> or <code>my-project-staging</code> - and keep these stored in an <code>.env</code> file in each worktree's directory.</p>
<p>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.</p>
<p>You can also use the <code>COMPOSE_PROJECT_NAME</code> variable inside Docker Compose files.</p>
<p>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.</p>
<pre><code class="language-yaml">labels:
- "traefik.http.routers.${COMPOSE_PROJECT_NAME}.rule=Host(
`${COMPOSE_PROJECT_NAME}.docker.localhost`,
`admin.${COMPOSE_PROJECT_NAME}.docker.localhost`
)"
</code></pre>
<p>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.</p>
format: full_html
processed: |
<p>I've recently started trialing Git worktrees again as part of my development workflow.</p>
<p>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.</p>
<p>For example, this is what I see within my local checkout of my website repository:</p>
<pre><code>.
├── config
├── HEAD
├── main
│&nbsp;&nbsp; ├── ansible
│&nbsp;&nbsp; ├── nginx
│&nbsp;&nbsp; ├── README.md
│&nbsp;&nbsp; └── website
├── new-post
│&nbsp;&nbsp; ├── ansible
│&nbsp;&nbsp; ├── nginx
│&nbsp;&nbsp; ├── README.md
│&nbsp;&nbsp; └── website
├── objects
│&nbsp;&nbsp; ├── info
│&nbsp;&nbsp; └── pack
├── packed-refs
├── refs
│&nbsp;&nbsp; ├── heads
│&nbsp;&nbsp; └── tags
└── worktrees
├── main
└── new-post
</code></pre>
<p>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.</p>
<p>Each worktree has it's own directory, so my "main" branch inside the <code>main</code> directory.</p>
<p>If I need to work on a different branch, such as <code>new-post</code>, 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.</p>
<h2 id="complications-with-docker-compose">Complications with Docker Compose</h2>
<p>I use Docker and Docker Compose for my projects, and this caused some issues for me the last time that I tried using worktrees.</p>
<p>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 <code>oliverdavies-uk-web_1</code>, <code>oliverdavies-uk-db_1</code> etc.</p>
<p>This doesn't work so well if the directory is a worktree called "main" or "master" as you'll have containers called <code>main_web_1</code> or <code>master_db_1</code>.</p>
<p>The way to solve this is to use the <code>COMPOSE_PROJECT_NAME</code> environment variable.</p>
<p>If you prefix Docker Compose commands with <code>COMPOSE_PROJECT_NAME=your-project</code>, or add it to an <code>.env</code> file (Docker Compose will load this automatically), then this will override the prefix in the container names to be <code>your-project-{service}</code>.</p>
<h2 id="container-names-per-worktree">Container names per worktree</h2>
<p>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 <code>my-project-main</code> or <code>my-project-staging</code> - and keep these stored in an <code>.env</code> file in each worktree's directory.</p>
<p>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.</p>
<p>You can also use the <code>COMPOSE_PROJECT_NAME</code> variable inside Docker Compose files.</p>
<p>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.</p>
<pre><code class="language-yaml">labels:
- "traefik.http.routers.${COMPOSE_PROJECT_NAME}.rule=Host(
`${COMPOSE_PROJECT_NAME}.docker.localhost`,
`admin.${COMPOSE_PROJECT_NAME}.docker.localhost`
)"
</code></pre>
<p>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.</p>
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