docs: simplify Docker quickstart (#4257)

examples/templates/docker/README.md

@@ -9,39 +9,9 @@ tags: [local, docker]
 To get started, run `coder templates init`. When prompted, select this template.
 Follow the on-screen instructions to proceed.
 
-## Adding/removing images
+## Editing the image
 
-After building and pushing an image to an image registry (e.g., DockerHub), edit
-the template to make the image available to users:
-
-```sh
-# Open the template
-vim main.tf
-```
-
-Modify your file to match the following:
-
-```diff
-variable "docker_image" {
-  description = "What Docker image would you like to use for your workspace?"
-  default     = "codercom/enterprise-base:ubuntu"
-  validation {
-    condition     = contains(["codercom/enterprise-base:ubuntu", "codercom/enterprise-node:ubuntu",
--                              "codercom/enterprise-intellij:ubuntu"], var.docker_image)
-+                              "codercom/enterprise-intellij:ubuntu", "codercom/enterprise-golang:ubuntu"], var.docker_image)
-    error_message = "Invalid Docker image!"
-  }
-}
-```
-
-Update the template:
-
-```sh
-coder template push docker
-```
-
-You can also remove images from the validation list. Workspaces using older template versions will continue using
-the removed image until you update the workspace to the latest version.
+Edit the `Dockerfile` and run `coder templates push` to update workspaces.
 
 ## code-server
 
@@ -49,30 +19,6 @@ the removed image until you update the workspace to the latest version.
 resource block. The `coder_app` resource is defined to access `code-server` through
 the dashboard UI over `localhost:13337`.
 
-## Updating images
-
-To reduce drift, we recommend versioning images in your registry by creating tags. To update the image tag in the template:
-
-```sh
-variable "docker_image" {
-  description = "What Docker image would you like to use for your workspace?"
-  default     = "codercom/enterprise-base:ubuntu"
-  validation {
--    condition     = contains(["my-org/base-development:v1.1", "myorg-java-development:v1.1"], var.docker_image)
-+    condition     = contains(["my-org/base-development:v1.1", "myorg-java-development:v1.2"], var.docker_image)
-
-    error_message = "Invalid Docker image!"
-  }
-}
-```
-
-Optional: Update workspaces to the latest template version:
-
-```sh
-coder ls
-coder update [workspace name]
-```
-
 ## Extending this template
 
 See the [kreuzwerker/docker](https://registry.terraform.io/providers/kreuzwerker/docker) Terraform provider documentation to

examples/templates/docker/build/Dockerfile

@@ -0,0 +1,3 @@
+FROM ubuntu
+
+RUN apt-get update && apt-get install -y curl wget git vim golang

examples/templates/docker/main.tf

@@ -6,7 +6,7 @@ terraform {
     }
     docker = {
       source  = "kreuzwerker/docker"
-      version = "~> 2.20.2"
+      version = "~> 2.22"
     }
   }
 }
@@ -55,24 +55,24 @@ resource "coder_app" "code-server" {
 }
 
 
-variable "docker_image" {
-  description = "Which Docker image would you like to use for your workspace?"
-  # The codercom/enterprise-* images are only built for amd64
-  default = "codercom/enterprise-base:ubuntu"
-  validation {
-    condition = contains(["codercom/enterprise-base:ubuntu", "codercom/enterprise-node:ubuntu",
-    "codercom/enterprise-intellij:ubuntu", "codercom/enterprise-golang:ubuntu"], var.docker_image)
-    error_message = "Invalid Docker image!"
-  }
-}
-
 resource "docker_volume" "home_volume" {
   name = "coder-${data.coder_workspace.me.owner}-${lower(data.coder_workspace.me.name)}-home"
 }
 
+
+resource "docker_image" "main" {
+  name = "coder-${data.coder_workspace.me.id}"
+  build {
+    path = "./build"
+  }
+  triggers = {
+    dir_sha1 = sha1(join("", [for f in fileset(path.module, "build/*") : filesha1(f)]))
+  }
+}
+
 resource "docker_container" "workspace" {
   count = data.coder_workspace.me.start_count
-  image = var.docker_image
+  image = docker_image.main.name
   # Uses lower() to avoid Docker restriction on container names.
   name = "coder-${data.coder_workspace.me.owner}-${lower(data.coder_workspace.me.name)}"
   # Hostname makes the shell more user friendly: coder@my-workspace:~$
@@ -80,7 +80,12 @@ resource "docker_container" "workspace" {
   dns      = ["1.1.1.1"]
   # Use the docker gateway if the access URL is 127.0.0.1
   command = [
-  "sh", "-c", replace(coder_agent.main.init_script, "localhost", "host.docker.internal")]
+    "sh", "-c",
+    <<EOT
+    trap '[ $? -ne 0 ] && echo === Agent script exited with non-zero code. Sleeping infinitely to preserve logs... && sleep infinity' EXIT
+    ${replace(coder_agent.main.init_script, "localhost", "host.docker.internal")}
+    EOT
+  ]
   env = ["CODER_AGENT_TOKEN=${coder_agent.main.token}"]
   host {
     host = "host.docker.internal"
@@ -92,13 +97,3 @@ resource "docker_container" "workspace" {
     read_only      = false
   }
 }
-
-resource "coder_metadata" "container_info" {
-  count       = data.coder_workspace.me.start_count
-  resource_id = docker_container.workspace[0].id
-
-  item {
-    key   = "image"
-    value = var.docker_image
-  }
-}