Drop linux capabilities and rework users/groups

* Drop linux capabilities for unprivileged containerized
  worlkoads Kargo configures for deployments.
* Configure required securityContext/user/group/groups for kube
  components' static manifests, etcd, calico-rr and k8s apps,
  like dnsmasq daemonset.
* Rework cloud-init (etcd) users creation for CoreOS.
* Fix nologin paths, adjust defaults for addusers role and ensure
  supplementary groups membership added for users.
* Add netplug user for network plugins (yet unused by privileged
  networking containers though).
* Grant the kube and netplug users read access for etcd certs via
  the etcd certs group.
* Grant group read access to kube certs via the kube cert group.
* Remove priveleged mode for calico-rr and run it under its uid/gid
  and supplementary etcd_cert group.
* Adjust docs.
* Align cpu/memory limits and dropped caps with added rkt support
  for control plane.

Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>

roles/adduser/defaults/main.yml

@@ -1,24 +1,40 @@
 ---
 addusers:
   etcd:
-    name: etcd
+    name: "{{ etcd_user }}"
     comment: "Etcd user"
-    createhome: yes
+    createhome: >-
+      {% if ansible_os_family in ["CoreOS", "Container Linux by CoreOS"] %}no{% else %}yes{% endif %}
     home: "/var/lib/etcd"
     system: yes
-    shell: /bin/nologin
+    shell: /usr/sbin/nologin
+    group: "{{ etcd_group }}"
+    groups: "{{ etcd_cert_group }}"
+    type: >-
+      {% if ansible_os_family in ["CoreOS", "Container Linux by CoreOS"] %}cloud-init{% endif %}
   kube:
-    name: kube
+    name: "{{ kubelet_user }}"
     comment: "Kubernetes user"
-    shell: /sbin/nologin
+    shell: /usr/sbin/nologin
     system: yes
-    group: "{{ kube_cert_group }}"
+    group: "{{ kubelet_group }}"
+    groups: "{{ etcd_cert_group }},{{ kube_cert_group }}"
     createhome: no
+  netplug:
+    name: "{{ netplug_user }}"
+    comment: "Network plugin user"
+    createhome: no
+    system: yes
+    shell: /usr/sbin/nologin
+    group: "{{ netplug_group }}"
+    groups: "{{ etcd_cert_group }}"
 
 adduser:
   name: "{{ user.name }}"
   group: "{{ user.name|default(None) }}"
+  groups: "{{ user.groups|default(None) }}"
   comment: "{{ user.comment|default(None) }}"
   shell: "{{ user.shell|default(None) }}"
   system: "{{ user.system|default(None) }}"
   createhome: "{{ user.createhome|default(None) }}"
+  type: "{{ user.type|default(None) }}"

roles/adduser/handlers/main.yml

@@ -0,0 +1,4 @@
+---
+- name:  User | update users for cloud-init
+  command: /usr/bin/coreos-cloudinit --from-file /etc/{{ user.name }}_user_cloud_init_conf
+  when: ansible_os_family in ["CoreOS", "Container Linux by CoreOS"]

roles/adduser/tasks/main.yml

@@ -1,13 +1,35 @@
 ---
+- name: User | Create Certificate Access Groups
+  group: name={{ item }} system=yes
+  with_items: "{{ user.groups.split(',') }}"
+
 - name: User | Create User Group
   group: name={{user.group|default(user.name)}} system={{user.system|default(omit)}}
 
+- name: User | Create cloud-init user
+  template:
+    dest: /etc/{{ user.name }}_user_cloud_init_conf
+    src: users.j2
+    owner: root
+    mode: 0640
+  notify: User | update users for cloud-init
+  when: "{{ user.type|default('standard') == 'cloud-init' }}"
+
+- meta: flush_handlers
+
+- name: User | Hack groups for existing cloud-init users CoreOS
+  command: /usr/sbin/usermod -aG {{ item }} {{ user.name }}
+  with_items: "{{ user.groups.split(',') }}"
+  when: "{{ ansible_os_family in ['CoreOS', 'Container Linux by CoreOS'] and user.type|default('standard') == 'cloud-init' }}"
+
 - name: User | Create User
   user:
     comment: "{{user.comment|default(omit)}}"
-    createhome: "{{user.create_home|default(omit)}}"
+    createhome: "{{user.createhome|default(omit)}}"
     group: "{{user.group|default(user.name)}}"
+    groups: "{{user.groups|default(omit)}}"
     home: "{{user.home|default(omit)}}"
     shell: "{{user.shell|default(omit)}}"
     name: "{{user.name}}"
     system: "{{user.system|default(omit)}}"
+  when: "{{ user.type|default('standard') != 'cloud-init' }}"

roles/adduser/templates/users.j2

@@ -0,0 +1,15 @@
+#cloud-config
+users:
+- name: {{ user.name  }}
+  gecos: {{ user.comment }}
+  system: {{ user.system|bool }}
+  no-log-init: {{ user.system|bool }}
+  primary-group: {{ user.group }}
+  no-create-home: {{ not user.createhome|bool }}
+  homedir: {{ user.home }}
+  shell: {{ user.shell }}
+  groups: |
+    {% for g in user.groups.split(',') %}
+    - {{ g }}
+    {% endfor %}
+    #

roles/adduser/vars/coreos.yml

@@ -1,8 +0,0 @@
----
-addusers:
-  - name: kube
-    comment: "Kubernetes user"
-    shell: /sbin/nologin
-    system: yes
-    group: "{{ kube_cert_group }}"
-    createhome: no

roles/adduser/vars/debian.yml

@@ -1,15 +0,0 @@
----
-addusers:
-  - name: etcd
-    comment: "Etcd user"
-    createhome: yes
-    home: "/var/lib/etcd"
-    system: yes
-    shell: /bin/nologin
-
-  - name: kube
-    comment: "Kubernetes user"
-    shell: /sbin/nologin
-    system: yes
-    group: "{{ kube_cert_group }}"
-    createhome: no

roles/adduser/vars/redhat.yml

@@ -1,15 +0,0 @@
----
-addusers:
-  - name: etcd
-    comment: "Etcd user"
-    createhome: yes
-    home: "/var/lib/etcd"
-    system: yes
-    shell: /bin/nologin
-
-  - name: kube
-    comment: "Kubernetes user"
-    shell: /sbin/nologin
-    system: yes
-    group: "{{ kube_cert_group }}"
-    createhome: no