Add Alpine Linux support. (#535)

Add new module cc_apk_configure for creating Alpine /etc/apk/repositories file.
Modify cc_ca_certs, cc_ntp, cc_power_state_change, and cc_resolv_conf for Alpine.
Add Alpine template files for Chrony and Busybox NTP support.
Add Alpine template file for /etc/hosts.

3 files changed, 76 insertions, 0 deletions

diff --git a/templates/chrony.conf.alpine.tmpl b/templates/chrony.conf.alpine.tmpl
new file mode 100644
index 00000000..45efc18c
--- /dev/null
+++ b/templates/chrony.conf.alpine.tmpl
@@ -0,0 +1,38 @@
+## template:jinja
+# Welcome to the chrony configuration file. See chrony.conf(5) for more
+# information about usable directives.
+{% if pools %}# pools
+{% endif %}
+{% for pool in pools -%}
+pool {{pool}} iburst
+{% endfor %}
+{%- if servers %}# servers
+{% endif %}
+{% for server in servers -%}
+server {{server}} iburst
+{% endfor %}
+
+# This directive specifies the location of the file containing ID/key pairs for
+# NTP authentication.
+keyfile /etc/chrony/chrony.keys
+
+# This directive specifies the file into which chronyd will store the rate
+# information.
+driftfile /var/lib/chrony/chrony.drift
+
+# Uncomment the following line to turn logging on.
+#log tracking measurements statistics
+
+# Log files location.
+logdir /var/log/chrony
+
+# Stop bad estimates upsetting machine clock.
+maxupdateskew 100.0
+
+# This directive enables kernel synchronisation (every 11 minutes) of the
+# real-time clock. Note that it can’t be used along with the 'rtcfile' directive.
+rtcsync
+
+# Step the system clock instead of slewing it if the adjustment is larger than
+# one second, but only in the first three clock updates.
+makestep 1 3
diff --git a/templates/hosts.alpine.tmpl b/templates/hosts.alpine.tmpl
new file mode 100644
index 00000000..33c1a941
--- /dev/null
+++ b/templates/hosts.alpine.tmpl
@@ -0,0 +1,28 @@
+## template:jinja
+{#
+This file /etc/cloud/templates/hosts.alpine.tmpl is only utilized
+if enabled in cloud-config.  Specifically, in order to enable it
+you need to add the following to config:
+  manage_etc_hosts: True
+-#}
+# Your system has configured 'manage_etc_hosts' as True.
+# As a result, if you wish for changes to this file to persist
+# then you will need to either
+# a.) make changes to the master file in /etc/cloud/templates/hosts.alpine.tmpl
+# b.) change or remove the value of 'manage_etc_hosts' in
+#     /etc/cloud/cloud.cfg or cloud-config from user-data
+#
+# The following lines are desirable for IPv4 capable hosts
+127.0.1.1 {{fqdn}} {{hostname}}
+127.0.0.1 localhost.localdomain localhost
+127.0.0.1 localhost4.localdomain4 localhost4
+
+# The following lines are desirable for IPv6 capable hosts
+::1 {{fqdn}} {{hostname}}
+::1 localhost6.localdomain6 localhost6
+
+fe00::0 ip6-localnet
+ff00::0 ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+ff02::3 ip6-allhosts
diff --git a/templates/ntp.conf.alpine.tmpl b/templates/ntp.conf.alpine.tmpl
new file mode 100644
index 00000000..59ca8fc1
--- /dev/null
+++ b/templates/ntp.conf.alpine.tmpl
@@ -0,0 +1,10 @@
+## template:jinja
+# /etc/ntp.conf
+#
+# Configuration for Busybox ntpd - it only supports "server" lines.
+
+{% if servers %}# Servers
+{% endif %}
+{% for server in servers -%}
+server {{server}}
+{% endfor %}