linuxexpert-practice-labs/labs/ex294/6-2-development-containers/README.md

EX294 6.2: Development containers

Give a project a podman development container, run playbooks against the managed nodes from inside it, and bring it up without VS Code.

Before you start

This VM is the control node. The lab creates the user greg (password Lab-Pass-1) with an SSH key, installs ansible-core and npm, and pulls the image ghcr.io/ansible/community-ansible-dev-tools:latest (public, no login) into greg's podman. Work as greg, in /home/greg/ansible: its ansible.cfg reads the inventory inventory, logs in as devops and becomes root. site.yml checks every node and adds a line to the node's /var/log/lab-runs.log with the playbook's directory, the ansible-core version, and whether it ran in VS Code's terminal.

For tasks 1 and 2 you need VS Code on your own computer with the Remote - SSH and Dev Containers extensions: connect to this VM as greg (with his password, or add your key to his ~/.ssh/authorized_keys), open /home/greg/ansible, and set Dev > Containers: Docker Path to podman.

The managed nodes node1 (10.99.1.11) and node2 (10.99.1.12) are AlmaLinux 10 containers reached over SSH by name; on both, devops accepts greg's key and may use sudo without a password. For a root shell on a node, sudo podman exec -it node1 bash.

Tasks

1. Add a podman .devcontainer/devcontainer.json to /home/greg/ansible that uses the image above, open the project in VS Code with Reopen in Container, and run ansible --version in its terminal: the config file is under /workspaces/, and the version is the image's, not this VM's.
2. Run site.yml against the managed nodes from inside the container. It fails with "Permission denied (publickey...)" until you forward your agent or mount greg's ~/.ssh into the container; then it succeeds.
3. Without VS Code, install the devcontainer CLI (npm install -g @devcontainers/cli, as root), bring the same container up with devcontainer up, and run site.yml with devcontainer exec. The recap matches the run from VS Code.

Hints

• Ansible: Create a Devcontainer in the Command Palette writes the podman file; its runArgs let tools start containers inside it.
• "mounts": ["source=${localEnv:HOME}/.ssh,target=/root/.ssh,type=bind,readonly"], then Dev Containers: Rebuild Container (or devcontainer up --remove-existing-container), since mounts apply only to a new container.
• devcontainer up --workspace-folder . --docker-path podman, and the same options for devcontainer exec.