From 3dface826f27f16ef74a2bc7a46eca5b83307bda Mon Sep 17 00:00:00 2001
From: Malin Freeborn <malinfreeborn@posteo.net>
Date: Sat, 16 Aug 2025 02:54:41 +0200
Subject: [PATCH] playing with ansible

---
 system/ansible/ansible_with_docker.md | 114 ++++++++++++++++++++++++++
 virtualization/docker.md              |   1 +
 2 files changed, 115 insertions(+)
 create mode 100644 system/ansible/ansible_with_docker.md

diff --git a/system/ansible/ansible_with_docker.md b/system/ansible/ansible_with_docker.md
new file mode 100644
index 0000000..3b765fa
--- /dev/null
+++ b/system/ansible/ansible_with_docker.md
@@ -0,0 +1,114 @@
+---
+title: "Ansible with Docker"
+tags: [ "system", "ansible", "docker" ]
+requires: [ "Docker" ]
+---
+
+Set up two containers: `deb` and `arch`, add them to an `ansible` hosts file, then do a 'ping' to see if they respond.
+
+## Required Packages
+
+- `ansible`
+- `jq`
+- `docker`
+
+## Debian Container
+
+```sh
+docker run -di --rm --name deb --hostname deb debian
+docker exec -it deb sh -c 'apt update && apt -y install openssh-server python3 sudo'
+```
+
+Generate the host's ssh keys, then start the ssh daemon:
+
+```sh
+docker exec -it deb sh -c 'ssh-keygen -A'
+docker exec -d deb /usr/sbin/sshd -D
+```
+
+## Arch Linux Container
+
+```sh
+docker run -di --rm --name arch --hostname arch archlinux
+docker exec -it arch sh -c 'pacman -Syu --noconfirm python sudo openssh'
+docker exec -it arch sh -c 'ssh-keygen -A'
+docker exec -d arch /usr/sbin/sshd -D
+```
+
+## `ssh` Keys
+
+Copy across your public ssh key to the container's `authorized_keys` file:
+
+```sh
+pubkey=~/.ssh/id_rsa.pub
+for hostname in arch deb; do
+    docker cp $pubkey $hostname:/root/.ssh/authorized_keys
+    docker exec -it $hostname sh -c "chown -R root:root /root/.ssh/"
+    docker exec -it $hostname sh -c "chmod -R 700 /root/.ssh/"
+done
+```
+
+## Hosts File
+
+Find name of containers' IPv4 addresses.
+
+```sh
+docker network inspect bridge
+```
+
+The output is awful.
+Use `jq` to parse the `json`:
+
+```sh
+docker network inspect bridge  | jq -r '.[].Containers | .[].IPv4Address'
+```
+
+Now put those into a host file:
+
+```sh
+docker_hosts=hosts.txt
+echo '[containers]' > $docker_hosts
+
+docker network inspect bridge  | \
+    jq -r '.[].Containers | .[] | "root@" + .IPv4Address' | \
+    cut -d/ -f1 >> $docker_hosts
+```
+
+You may need to add those host keys to your known hosts file.
+Either connect interactively, or (for scripts):
+
+```sh
+hosts="$(docker network inspect bridge  | jq -r '.[].Containers | .[] | .Name + " " + .IPv4Address' | \
+    cut -d/ -f1)"
+
+echo "$hosts"
+
+echo "$hosts" | while read hostname ip; do
+    printf "%s" "$ip"
+    key="$(docker exec $hostname cat /etc/ssh/ssh_host_ed25519_key.pub)"
+    echo "$ip $key" >> ~/.ssh/known_hosts
+done
+```
+
+Check if they ping:
+
+```sh
+ansible -i $docker_hosts all -m ping
+```
+
+This command produces an irritating warning about the python interpreter (i.e., `python3`).
+
+Make the warning shut-up:
+
+```sh
+echo '
+[containers:vars]
+ansible_python_interpreter=/usr/bin/python3.13' >> $docker_hosts
+```
+
+Now the ping is cleaner:
+
+```sh
+ansible -i $docker_hosts all -m ping
+```
+
diff --git a/virtualization/docker.md b/virtualization/docker.md
index 5997c69..9c5aeb0 100644
--- a/virtualization/docker.md
+++ b/virtualization/docker.md
@@ -1,6 +1,7 @@
 ---
 title: "Docker"
 tags: [ "documentation", "virtualization" ]
+requires: [ "Managing Groups" ]
 ---
 ```sh
 sudo pacman -S docker