Add Coder template for jail development

Creates a comprehensive Coder template specifically designed for developing
the jail network isolation tool. The template provisions AWS EC2 VMs with:

- Ubuntu 22.04 LTS for modern kernel namespace support
- Go 1.24+ development environment
- Network tools (iptables, netfilter, tcpdump) for jail functionality
- Pre-installed jail binary built from source
- Code Server and JetBrains IDE support
- Proper network configuration for namespace operations

The template is optimized for jail's requirements including:
- Linux VM environment (not containers) for namespace syscalls
- Network forwarding and netfilter configuration
- Development tools and debugging utilities
- Comprehensive documentation and validation script

Co-authored-by: bcpeinhardt <[email protected]>

Author: blink-so[bot]

template/.gitignore

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+# Terraform files
+*.tfstate
+*.tfstate.*
+*.tfvars
+*.tfvars.json
+.terraform/
+.terraform.lock.hcl
+terraform.log
+
+# OS generated files
+.DS_Store
+.DS_Store?
+._*
+.Spotlight-V100
+.Trashes
+ehthumbs.db
+Thumbs.db
+
+# IDE files
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+
+# Temporary files
+*.tmp
+*.temp

template/README.md

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+---
+display_name: Jail Development Environment (AWS EC2)
+description: AWS EC2 Linux VM optimized for developing the coder/jail network isolation tool
+icon: ../docs/images/logo.png
+verified: false
+tags: [vm, linux, aws, jail, go, networking, namespaces]
+---
+
+# Jail Development Environment on AWS EC2
+
+This Coder template provisions AWS EC2 VMs specifically configured for developing the [coder/jail](https://github.com/coder/jail) network isolation tool. The template sets up a complete development environment with all necessary dependencies, tools, and configurations.
+
+## What is Jail?
+
+Jail is a network isolation tool for monitoring and restricting HTTP/HTTPS requests from processes. It creates isolated network environments for target processes using Linux namespaces and intercepts traffic through a transparent proxy.
+
+## Features
+
+- **Linux VM Environment**: Full Linux VM (not containers) required for namespace syscalls
+- **Go 1.24+ Development**: Latest Go toolchain automatically installed
+- **Network Tools**: iptables, netfilter, and networking utilities pre-configured 
+- **Development Tools**: Build essentials, debugging tools, and utilities
+- **Jail Pre-installed**: Repository cloned, built, and ready to use
+- **Code Server & JetBrains**: Web-based development environments
+- **Network Configuration**: Proper kernel settings for namespace operations
+
+## Prerequisites
+
+### Authentication
+
+By default, this template authenticates to AWS using the provider's default [authentication methods](https://registry.terraform.io/providers/hashicorp/aws/latest/docs#authentication-and-configuration).
+
+The simplest way is via environment variables (e.g. `AWS_ACCESS_KEY_ID`) or a [credentials file](https://docs.aws.amazon.com/cli/latest/userguide/cli-configure-files.html#cli-configure-files-format). If you are running Coder on a VM, this file must be in `/home/coder/aws/credentials`.
+
+### Required AWS Permissions
+
+The following sample policy allows Coder to create EC2 instances and modify instances provisioned by Coder:
+
+```json
+{
+  "Version": "2012-10-17",
+  "Statement": [
+    {
+      "Sid": "VisualEditor0",
+      "Effect": "Allow",
+      "Action": [
+        "ec2:GetDefaultCreditSpecification",
+        "ec2:DescribeIamInstanceProfileAssociations",
+        "ec2:DescribeTags",
+        "ec2:DescribeInstances",
+        "ec2:DescribeInstanceTypes",
+        "ec2:DescribeInstanceStatus",
+        "ec2:CreateTags",
+        "ec2:RunInstances",
+        "ec2:DescribeInstanceCreditSpecifications",
+        "ec2:DescribeImages",
+        "ec2:ModifyDefaultCreditSpecification",
+        "ec2:DescribeVolumes"
+      ],
+      "Resource": "*"
+    },
+    {
+      "Sid": "CoderResources",
+      "Effect": "Allow",
+      "Action": [
+        "ec2:DescribeInstanceAttribute",
+        "ec2:UnmonitorInstances",
+        "ec2:TerminateInstances",
+        "ec2:StartInstances",
+        "ec2:StopInstances",
+        "ec2:DeleteTags",
+        "ec2:MonitorInstances",
+        "ec2:CreateTags",
+        "ec2:RunInstances",
+        "ec2:ModifyInstanceAttribute",
+        "ec2:ModifyInstanceCreditSpecification"
+      ],
+      "Resource": "arn:aws:ec2:*:*:instance/*",
+      "Condition": {
+        "StringEquals": {
+          "aws:ResourceTag/Coder_Provisioned": "true"
+        }
+      }
+    }
+  ]
+}
+```
+
+## Architecture
+
+This template provisions the following resources:
+
+- **AWS EC2 Instance**: Ubuntu 22.04 LTS with 20GB storage
+- **Network Configuration**: Properly configured for namespace operations
+- **Development Environment**: Complete Go development setup
+- **Jail Installation**: Pre-built and system-wide accessible
+
+## Software Installed
+
+### Core Development
+- **Go 1.24+**: Latest Go compiler and tools
+- **Build Tools**: gcc, make, git, and build-essential
+- **Jail**: Pre-compiled and installed system-wide
+
+### Network Tools
+- **iptables**: Netfilter administration tool
+- **iproute2**: Advanced IP routing utilities  
+- **tcpdump/wireshark**: Network packet analysis
+- **net-tools**: Basic network utilities
+
+### Development Tools
+- **Code Server**: Web-based VS Code editor
+- **JetBrains**: IDE support for Go development
+- **Debug Tools**: gdb, strace, ltrace for troubleshooting
+- **System Tools**: htop, tree, jq for system management
+
+## Getting Started
+
+After your workspace is created:
+
+1. **Access your workspace** via Code Server or JetBrains
+2. **Navigate to jail directory**: `cd ~/jail`
+3. **Build jail**: `make build`
+4. **Run tests**: `make test` (requires sudo for E2E tests)
+5. **Try jail**: `jail --help`
+
+### Example Usage
+
+```bash
+# Test jail with a simple HTTP request
+jail --allow "github.com" -- curl https://github.com
+
+# Monitor all network requests
+jail --log-level info --allow "*" -- your-application
+
+# Block all requests (default deny-all)
+jail -- curl https://example.com  # This will be blocked
+```
+
+### Development Workflow
+
+```bash
+# Make changes to jail source code
+vim ~/jail/jail.go
+
+# Rebuild
+make build
+
+# Test your changes
+./jail --allow "example.com" -- curl https://example.com
+
+# Run full test suite
+sudo make test
+```
+
+## Network Namespace Requirements
+
+This template configures the system for network namespace operations:
+
+- **IP Forwarding**: Enabled for network isolation
+- **Netfilter**: Configured for traffic interception
+- **User Permissions**: Coder user has sudo access for namespace operations
+- **Kernel Features**: Modern Ubuntu 22.04 kernel with namespace support
+
+## Instance Sizing
+
+Default instance size is `t3.medium` (2 vCPU, 4GB RAM) which provides adequate resources for jail development. For intensive development or testing, consider `t3.large` or larger.
+
+## Persistent Storage
+
+This template uses persistent EBS storage. Your development work, built binaries, and git history will persist across workspace restarts.
+
+## Security Considerations
+
+- **Sudo Access**: The coder user has passwordless sudo access required for namespace operations
+- **Network Tools**: Various network administration tools are installed
+- **Kernel Features**: Network forwarding and netfilter capabilities are enabled
+
+This configuration is necessary for jail development but should only be used in trusted environments.
+
+## Troubleshooting
+
+### Jail Binary Not Found
+If jail isn't in PATH, it should be at `/usr/local/bin/jail` or you can rebuild:
+```bash
+cd ~/jail && make build && sudo cp jail /usr/local/bin/
+```
+
+### Network Namespace Issues
+Ensure you're using sudo for operations that require network namespaces:
+```bash
+sudo jail --allow "example.com" -- curl https://example.com
+```
+
+### Go Module Issues
+If Go modules aren't working, ensure GOPATH is set:
+```bash
+export GOPATH=$HOME/go
+export PATH=$PATH:/usr/local/go/bin:$GOPATH/bin
+```
+
+## Contributing to Jail
+
+This environment is set up for contributing to the jail project:
+
+1. Make your changes in `~/jail/`
+2. Test thoroughly with the test suite
+3. Ensure all tests pass: `sudo make test`
+4. Submit pull requests to the main jail repository
+
+## Template Customization
+
+This template can be modified to:
+- Change instance sizes or storage
+- Add additional development tools
+- Modify network configurations
+- Install different Go versions
+- Add custom startup scripts
+
+Edit `main.tf` and the cloud-init templates to customize the environment.

template/cloud-init/cloud-config.yaml.tftpl

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+#cloud-config
+cloud_final_modules:
+  - [scripts-user, always]
+hostname: ${hostname}
+users:
+  - name: ${linux_user}
+    sudo: ALL=(ALL) NOPASSWD:ALL
+    shell: /bin/bash
+    groups: sudo,netdev
+# Enable IP forwarding and other network features needed for jail
+write_files:
+  - path: /etc/sysctl.d/99-jail.conf
+    content: |
+      # Network settings for jail development
+      net.ipv4.ip_forward = 1
+      net.ipv4.conf.all.route_localnet = 1
+      net.netfilter.nf_conntrack_helper = 0
+    permissions: '0644'
+runcmd:
+  - sysctl --system

template/cloud-init/userdata.sh.tftpl

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+#!/bin/bash
+sudo -u '${linux_user}' sh -c '${init_script}'