Preserve inode when updating /etc/hosts

Containers configured by tripleo bind-mount /etc/hosts directly,
which means any change to that file has to preserve the original
inode, otherwise the containers will get out of sync with the
host and will not see updates.

Change tripleo_host_entries to not depend on atomic semantics of
ansible, which changes inodes on update. Instead, perform a
non-atomic update to preserve inodes, and rely on the retry
logics of openstack containers to recover from unexpected
behaviour in case /etc/hosts is consumed while it is being updated.

Closes-Bug: #1882290
Change-Id: I34dd9121bbd650b79cb523e4dbed5949a0e7d52d
changes/21/733921/3
Damien Ciabrini 3 years ago
parent f54ec76a4f
commit 7761249774
  1. 44
      tripleo_ansible/roles/tripleo_hosts_entries/tasks/main.yml

@ -15,15 +15,36 @@
# under the License.
- name: Create temporary file for hosts
become: true
tempfile:
state: file
suffix: tmphosts
register: tripleo_hosts_entries_tmp_hosts
check_mode: false
tags:
- tripleo_hosts_entries
- name: Prepare temporary /etc/hosts
become: true
copy:
remote_src: true
src: "{{ tripleo_hosts_entries_hosts_path }}"
dest: "{{ tripleo_hosts_entries_tmp_hosts.path }}"
mode: preserve
tags:
- tripleo_hosts_entries
- name: Remove old Heat hosts configuration (if present)
become: true
blockinfile:
state: absent
path: "{{ tripleo_hosts_entries_hosts_path }}"
path: "{{ tripleo_hosts_entries_tmp_hosts.path }}"
block: ""
marker: "# {mark}"
marker_begin: "HEAT_HOSTS_START - Do not edit manually within this section!"
marker_end: "HEAT_HOSTS_END"
register: tripleo_hosts_entries_heat_marker
tags:
- tripleo_hosts_entries
@ -50,11 +71,11 @@
tags:
- tripleo_hosts_entries
- name: Update /etc/hosts
- name: Prepare new /etc/hosts
become: true
blockinfile:
create: true
path: "{{ tripleo_hosts_entries_hosts_path }}"
path: "{{ tripleo_hosts_entries_tmp_hosts.path }}"
# BOF denotes the beginning of the file.
insertbefore: BOF
block: |
@ -64,5 +85,22 @@
tripleo_hosts_entries_extra_hosts_entries | default([]) %}
{{ host }}
{% endfor %}
register: tripleo_hosts_entries_new_entries
tags:
- tripleo_hosts_entries
- name: Update /etc/hosts contents (if changed)
become: true
# cp preserves the inode of the existing file tripleo_hosts_entries_hosts_path
command: cp "{{ tripleo_hosts_entries_tmp_hosts.path }}" "{{ tripleo_hosts_entries_hosts_path }}"
when: tripleo_hosts_entries_heat_marker.changed or tripleo_hosts_entries_new_entries.changed
tags:
- tripleo_hosts_entries
- name: Clean up temporary hosts file
file:
path: "{{ tripleo_hosts_entries_tmp_hosts.path }}"
state: absent
when: tripleo_hosts_entries_tmp_hosts.path is defined
tags:
- tripleo_hosts_entries

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