Add docker-build template to coder-labs namespace (#235)

This template builds Docker containers from a Dockerfile, rather than
using a pre-built image, allowing for more customization of the
development environment.

Based on the docker template that was removed in coder/coder#15504.

---------

Co-authored-by: blink-so[bot] <211532188+blink-so[bot]@users.noreply.github.com>

registry/coder-labs/templates/docker-build/README.md

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+---
+display_name: Docker Build
+description: Build Docker containers from Dockerfile as Coder workspaces
+icon: ../../../../.icons/docker.svg
+verified: true
+tags: [docker, container, dockerfile]
+---
+
+# Remote Development on Docker Containers (Build from Dockerfile)
+
+Build and provision Docker containers from a Dockerfile as [Coder workspaces](https://coder.com/docs/workspaces) with this example template.
+
+This template builds a custom Docker image from the included Dockerfile, allowing you to customize the development environment by modifying the Dockerfile rather than using a pre-built image.
+
+<!-- TODO: Add screenshot -->
+
+## Prerequisites
+
+### Infrastructure
+
+The VM you run Coder on must have a running Docker socket and the `coder` user must be added to the Docker group:
+
+```sh
+# Add coder user to Docker group
+sudo adduser coder docker
+
+# Restart Coder server
+sudo systemctl restart coder
+
+# Test Docker
+sudo -u coder docker ps
+```
+
+## Architecture
+
+This template provisions the following resources:
+
+- Docker image (built from Dockerfile and kept locally)
+- Docker container pod (ephemeral)
+- Docker volume (persistent on `/home/coder`)
+
+This means, when the workspace restarts, any tools or files outside of the home directory are not persisted. To pre-bake tools into the workspace (e.g. `python3`), modify the `build/Dockerfile`. Alternatively, individual developers can [personalize](https://coder.com/docs/dotfiles) their workspaces with dotfiles.
+
+> [!NOTE]
+> This template is designed to be a starting point! Edit the Terraform and Dockerfile to extend the template to support your use case.
+
+### Editing the image
+
+Edit the `build/Dockerfile` and run `coder templates push` to update workspaces. The image will be rebuilt automatically when the Dockerfile changes.
+
+## Difference from the standard Docker template
+
+The main difference between this template and the standard Docker template is:
+
+- **Standard Docker template**: Uses a pre-built image (e.g., `codercom/enterprise-base:ubuntu`)
+- **Docker Build template**: Builds a custom image from the included `build/Dockerfile`
+
+This allows for more customization of the development environment while maintaining the same workspace functionality.

registry/coder-labs/templates/docker-build/build/Dockerfile

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+FROM ubuntu
+
+RUN apt-get update \
+	&& apt-get install -y \
+	curl \
+	git \
+	golang \
+	sudo \
+	vim \
+	wget \
+	&& rm -rf /var/lib/apt/lists/*
+
+ARG USER=coder
+RUN useradd --groups sudo --no-create-home --shell /bin/bash ${USER} \
+	&& echo "${USER} ALL=(ALL) NOPASSWD:ALL" >/etc/sudoers.d/${USER} \
+	&& chmod 0440 /etc/sudoers.d/${USER}
+USER ${USER}
+WORKDIR /home/${USER}

registry/coder-labs/templates/docker-build/main.tf

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+terraform {
+  required_providers {
+    coder = {
+      source = "coder/coder"
+    }
+    docker = {
+      source = "kreuzwerker/docker"
+    }
+  }
+}
+
+locals {
+  username = data.coder_workspace_owner.me.name
+}
+
+variable "docker_socket" {
+  default     = ""
+  description = "(Optional) Docker socket URI"
+  type        = string
+}
+
+provider "docker" {
+  # Defaulting to null if the variable is an empty string lets us have an optional variable without having to set our own default
+  host = var.docker_socket != "" ? var.docker_socket : null
+}
+
+data "coder_provisioner" "me" {}
+data "coder_workspace" "me" {}
+data "coder_workspace_owner" "me" {}
+
+resource "coder_agent" "main" {
+  arch           = data.coder_provisioner.me.arch
+  os             = "linux"
+  startup_script = <<-EOT
+    set -e
+
+    # Prepare user home with default files on first start.
+    if [ ! -f ~/.init_done ]; then
+      cp -rT /etc/skel ~
+      touch ~/.init_done
+    fi
+
+    # Install the latest code-server.
+    # Append "--version x.x.x" to install a specific version of code-server.
+    curl -fsSL https://code-server.dev/install.sh | sh -s -- --method=standalone --prefix=/tmp/code-server
+
+    # Start code-server in the background.
+    /tmp/code-server/bin/code-server --auth none --port 13337 >/tmp/code-server.log 2>&1 &
+  EOT
+
+  # These environment variables allow you to make Git commits right away after creating a
+  # workspace. Note that they take precedence over configuration defined in ~/.gitconfig!
+  # You can remove this block if you'd prefer to configure Git manually or using
+  # dotfiles. (see docs/dotfiles.md)
+  env = {
+    GIT_AUTHOR_NAME     = coalesce(data.coder_workspace_owner.me.full_name, data.coder_workspace_owner.me.name)
+    GIT_AUTHOR_EMAIL    = "${data.coder_workspace_owner.me.email}"
+    GIT_COMMITTER_NAME  = coalesce(data.coder_workspace_owner.me.full_name, data.coder_workspace_owner.me.name)
+    GIT_COMMITTER_EMAIL = "${data.coder_workspace_owner.me.email}"
+  }
+
+  # The following metadata blocks are optional. They are used to display
+  # information about your workspace in the dashboard. You can remove them
+  # if you don't want to display any information.
+  # For basic resources, you can use the `coder stat` command.
+  # If you need more control, you can write your own script.
+  metadata {
+    display_name = "CPU Usage"
+    key          = "0_cpu_usage"
+    script       = "coder stat cpu"
+    interval     = 10
+    timeout      = 1
+  }
+
+  metadata {
+    display_name = "RAM Usage"
+    key          = "1_ram_usage"
+    script       = "coder stat mem"
+    interval     = 10
+    timeout      = 1
+  }
+
+  metadata {
+    display_name = "Home Disk"
+    key          = "3_home_disk"
+    script       = "coder stat disk --path $${HOME}"
+    interval     = 60
+    timeout      = 1
+  }
+
+  metadata {
+    display_name = "CPU Usage (Host)"
+    key          = "4_cpu_usage_host"
+    script       = "coder stat cpu --host"
+    interval     = 10
+    timeout      = 1
+  }
+
+  metadata {
+    display_name = "Memory Usage (Host)"
+    key          = "5_mem_usage_host"
+    script       = "coder stat mem --host"
+    interval     = 10
+    timeout      = 1
+  }
+
+  metadata {
+    display_name = "Load Average (Host)"
+    key          = "6_load_host"
+    # get load avg scaled by number of cores
+    script   = <<EOT
+      echo "`cat /proc/loadavg | awk '{ print $1 }'` `nproc`" | awk '{ printf "%0.2f", $1/$2 }'
+    EOT
+    interval = 60
+    timeout  = 1
+  }
+
+  metadata {
+    display_name = "Swap Usage (Host)"
+    key          = "7_swap_host"
+    script       = <<EOT
+      free -b | awk '/^Swap/ { printf("%.1f/%.1f", $3/1024.0/1024.0/1024.0, $2/1024.0/1024.0/1024.0) }'
+    EOT
+    interval     = 10
+    timeout      = 1
+  }
+}
+
+resource "coder_app" "code-server" {
+  agent_id     = coder_agent.main.id
+  slug         = "code-server"
+  display_name = "code-server"
+  url          = "http://localhost:13337/?folder=/home/${local.username}"
+  icon         = "/icon/code.svg"
+  subdomain    = false
+  share        = "owner"
+
+  healthcheck {
+    url       = "http://localhost:13337/healthz"
+    interval  = 5
+    threshold = 6
+  }
+}
+
+resource "docker_volume" "home_volume" {
+  name = "coder-${data.coder_workspace.me.id}-home"
+  # Protect the volume from being deleted due to changes in attributes.
+  lifecycle {
+    ignore_changes = all
+  }
+  # Add labels in Docker to keep track of orphan resources.
+  labels {
+    label = "coder.owner"
+    value = data.coder_workspace_owner.me.name
+  }
+  labels {
+    label = "coder.owner_id"
+    value = data.coder_workspace_owner.me.id
+  }
+  labels {
+    label = "coder.workspace_id"
+    value = data.coder_workspace.me.id
+  }
+  # This field becomes outdated if the workspace is renamed but can
+  # be useful for debugging or cleaning out dangling volumes.
+  labels {
+    label = "coder.workspace_name_at_creation"
+    value = data.coder_workspace.me.name
+  }
+}
+
+resource "docker_image" "main" {
+  name = "coder-${data.coder_workspace.me.id}"
+  build {
+    context = "./build"
+    build_args = {
+      USER = local.username
+    }
+  }
+  triggers = {
+    dir_sha1 = sha1(join("", [for f in fileset(path.module, "build/*") : filesha1(f)]))
+  }
+}
+
+resource "docker_container" "workspace" {
+  count = data.coder_workspace.me.start_count
+  image = docker_image.main.name
+  # Uses lower() to avoid Docker restriction on container names.
+  name = "coder-${data.coder_workspace_owner.me.name}-${lower(data.coder_workspace.me.name)}"
+  # Hostname makes the shell more user friendly: coder@my-workspace:~$
+  hostname = data.coder_workspace.me.name
+  # Use the docker gateway if the access URL is 127.0.0.1
+  entrypoint = ["sh", "-c", replace(coder_agent.main.init_script, "/localhost|127\\.0\\.0\\.1/", "host.docker.internal")]
+  env        = ["CODER_AGENT_TOKEN=${coder_agent.main.token}"]
+  host {
+    host = "host.docker.internal"
+    ip   = "host-gateway"
+  }
+  volumes {
+    container_path = "/home/${local.username}"
+    volume_name    = docker_volume.home_volume.name
+    read_only      = false
+  }
+
+  # Add labels in Docker to keep track of orphan resources.
+  labels {
+    label = "coder.owner"
+    value = data.coder_workspace_owner.me.name
+  }
+  labels {
+    label = "coder.owner_id"
+    value = data.coder_workspace_owner.me.id
+  }
+  labels {
+    label = "coder.workspace_id"
+    value = data.coder_workspace.me.id
+  }
+  labels {
+    label = "coder.workspace_name"
+    value = data.coder_workspace.me.name
+  }
+}