infra-nimbus/ansible/terraform.py

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#!/usr/bin/env python
# source: https://github.com/nbering/terraform-inventory
'''
Terraform Inventory Script
==========================
This inventory script generates dynamic inventory by reading Terraform state
contents. Servers and groups a defined inside the Terraform state using special
resources defined by the Terraform Provider for Ansible.
Configuration
=============
State is fetched using the "terraform state pull" subcommand. The behaviour of
this action can be configured using some environment variables.
Environment Variables:
......................
ANSIBLE_TF_BIN
Override the path to the Terraform command executable. This is useful if
you have multiple copies or versions installed and need to specify a
specific binary. The inventory script runs the `terraform state pull`
command to fetch the Terraform state, so that remote state will be
fetched seemlessly regardless of the backend configuration.
ANSIBLE_TF_DIR
Set the working directory for the `terraform` command when the scripts
shells out to it. This is useful if you keep your terraform and ansible
configuration in separate directories. Defaults to using the current
working directory.
ANSIBLE_TF_WS_NAME
Sets the workspace for the `terraform` command when the scripts shells
out to it, defaults to `default` workspace - if you don't use workspaces
this is the one you'll be using.
'''
import sys
import json
import os
import re
import traceback
from subprocess import Popen, PIPE
TERRAFORM_DIR = os.environ.get('ANSIBLE_TF_DIR', os.getcwd())
TERRAFORM_ENV = os.path.join(TERRAFORM_DIR, '.terraform/environment')
TERRAFORM_PATH = os.environ.get('ANSIBLE_TF_BIN', 'terraform')
TERRAFORM_BPK = os.path.join(TERRAFORM_DIR, '.terraform/terraform.tfstate.backup')
def _tf_env():
# way to figure out currenly used TF workspace
try:
with open(TERRAFORM_ENV) as f:
return f.read()
except:
return 'default'
TERRAFORM_WS_NAME = os.environ.get('ANSIBLE_TF_WS_NAME', _tf_env())
ANSIBLE_BKP = os.path.join(TERRAFORM_DIR, 'ansible/inventory', _tf_env())
class TerraformState(object):
'''
TerraformState wraps the state content to provide some helpers for iterating
over resources.
'''
def __init__(self, state_json):
self.state_json = state_json
if "modules" in state_json:
# uses pre-0.12
self.flat_attrs = True
else:
# state format for 0.12+
self.flat_attrs = False
def resources(self):
'''Generator method to iterate over resources in the state file.'''
if self.flat_attrs:
modules = self.state_json["modules"]
for module in modules:
for resource in module["resources"].values():
yield TerraformResource(resource, flat_attrs=True)
else:
resources = self.state_json["resources"]
for resource in resources:
for instance in resource["instances"]:
yield TerraformResource(instance, resource_type=resource["type"])
class TerraformResource(object):
'''
TerraformResource wraps individual resource content and provide some helper
methods for reading older-style dictionary and list values from attributes
defined as a single-level map.
'''
DEFAULT_PRIORITIES = {
'ansible_host': 50,
'ansible_group': 50,
'ansible_host_var': 60,
'ansible_group_var': 60
}
def __init__(self, source_json, flat_attrs=False, resource_type=None):
self.flat_attrs = flat_attrs
self._type = resource_type
self._priority = None
self.source_json = source_json
def is_ansible(self):
'''Check if the resource is provided by the ansible provider.'''
return self.type().startswith("ansible_")
def priority(self):
'''Get the merge priority of the resource.'''
if self._priority is not None:
return self._priority
priority = 0
if self.read_int_attr("variable_priority") is not None:
priority = self.read_int_attr("variable_priority")
elif self.type() in TerraformResource.DEFAULT_PRIORITIES:
priority = TerraformResource.DEFAULT_PRIORITIES[self.type()]
self._priority = priority
return self._priority
def type(self):
'''Returns the Terraform resource type identifier.'''
if self._type:
return self._type
return self.source_json["type"]
def read_dict_attr(self, key):
'''
Read a dictionary attribute from the resource, handling old-style
Terraform state where maps are stored as multiple keys in the resource's
attributes.
'''
attrs = self._raw_attributes()
if self.flat_attrs:
out = {}
for k in attrs.keys():
match = re.match(r"^" + key + r"\.(.*)", k)
if not match or match.group(1) == "%":
continue
out[match.group(1)] = attrs[k]
return out
return attrs.get(key, {})
def read_list_attr(self, key):
'''
Read a list attribute from the resource, handling old-style Terraform
state where lists are stored as multiple keys in the resource's
attributes.
'''
attrs = self._raw_attributes()
if self.flat_attrs:
out = []
length_key = key + ".#"
if length_key not in attrs.keys():
return []
length = int(attrs[length_key])
if length < 1:
return []
for i in range(0, length):
out.append(attrs["{}.{}".format(key, i)])
return out
return attrs.get(key, None)
def read_int_attr(self, key):
'''
Read an attribute from state an convert it to type Int.
'''
val = self.read_attr(key)
if val is not None:
val = int(val)
return val
def read_attr(self, key):
'''
Read an attribute from the underlaying state content.
'''
return self._raw_attributes().get(key, None)
def _raw_attributes(self):
if self.flat_attrs:
return self.source_json["primary"]["attributes"]
return self.source_json["attributes"]
class AnsibleInventory(object):
'''
AnsibleInventory handles conversion from Terraform resource content to
Ansible inventory entities, and building of the final inventory json.
'''
def __init__(self):
self.groups = {}
self.hosts = {}
self.inner_json = {}
def add_host_resource(self, resource):
'''Upsert type action for host resources.'''
hostname = resource.read_attr("inventory_hostname")
if hostname in self.hosts:
host = self.hosts[hostname]
host.add_source(resource)
else:
host = AnsibleHost(hostname, source=resource)
self.hosts[hostname] = host
def add_group_resource(self, resource):
'''Upsert type action for group resources.'''
groupname = resource.read_attr("inventory_group_name")
if groupname in self.groups:
group = self.groups[groupname]
group.add_source(resource)
else:
group = AnsibleGroup(groupname, source=resource)
self.groups[groupname] = group
def update_groups(self, groupname, children=None, hosts=None, group_vars=None):
'''Upsert type action for group resources'''
if groupname in self.groups:
group = self.groups[groupname]
group.update(children=children, hosts=hosts, group_vars=group_vars)
else:
group = AnsibleGroup(groupname)
group.update(children, hosts, group_vars)
self.groups[groupname] = group
def add_resource(self, resource):
'''
Process a Terraform resource, passing to the correct handler function
by type.
'''
if resource.type().startswith("ansible_host"):
self.add_host_resource(resource)
elif resource.type().startswith("ansible_group"):
self.add_group_resource(resource)
def to_dict(self):
'''
Generate the file Ansible inventory structure to be serialized into JSON
for consumption by Ansible proper.
'''
out = {
"_meta": {
"hostvars": {}
}
}
for hostname, host in self.hosts.items():
host.build()
for group in host.groups:
self.update_groups(group, hosts=[host.hostname])
out["_meta"]["hostvars"][hostname] = host.get_vars()
for groupname, group in self.groups.items():
group.build()
out[groupname] = group.to_dict()
return out
class AnsibleHost(object):
'''
AnsibleHost represents a host for the Ansible inventory.
'''
def __init__(self, hostname, source=None):
self.sources = []
self.hostname = hostname
self.groups = set(["all"])
self.host_vars = {}
if source:
self.add_source(source)
def update(self, groups=None, host_vars=None):
'''Update host resource with additional groups and vars.'''
if host_vars:
self.host_vars.update(host_vars)
if groups:
self.groups.update(groups)
def add_source(self, source):
'''Add a Terraform resource to the sources list.'''
self.sources.append(source)
def build(self):
'''Assemble host details from registered sources.'''
self.sources.sort(key=lambda source: source.priority())
for source in self.sources:
if source.type() == "ansible_host":
groups = source.read_list_attr("groups")
host_vars = source.read_dict_attr("vars")
self.update(groups=groups, host_vars=host_vars)
elif source.type() == "ansible_host_var":
host_vars = {source.read_attr(
"key"): source.read_attr("value")}
self.update(host_vars=host_vars)
self.groups = sorted(self.groups)
def get_vars(self):
'''Get the host's variable dictionary.'''
return dict(self.host_vars)
class AnsibleGroup(object):
'''
AnsibleGroup represents a group for the Ansible inventory.
'''
def __init__(self, groupname, source=None):
self.groupname = groupname
self.sources = []
self.hosts = set()
self.children = set()
self.group_vars = {}
if source:
self.add_source(source)
def update(self, children=None, hosts=None, group_vars=None):
'''
Update host resource with additional children, hosts, or group variables.
'''
if hosts:
self.hosts.update(hosts)
if children:
self.children.update(children)
if group_vars:
self.group_vars.update(group_vars)
def add_source(self, source):
'''Add a Terraform resource to the sources list.'''
self.sources.append(source)
def build(self):
'''Assemble group details from registered sources.'''
self.sources.sort(key=lambda source: source.priority())
for source in self.sources:
if source.type() == "ansible_group":
children = source.read_list_attr("children")
group_vars = source.read_dict_attr("vars")
self.update(children=children, group_vars=group_vars)
elif source.type() == "ansible_group_var":
group_vars = {source.read_attr(
"key"): source.read_attr("value")}
self.update(group_vars=group_vars)
self.hosts = sorted(self.hosts)
self.children = sorted(self.children)
def to_dict(self):
'''Prepare structure for final Ansible inventory JSON.'''
return {
"children": list(self.children),
"hosts": list(self.hosts),
"vars": dict(self.group_vars)
}
def _execute_shell():
encoding = 'utf-8'
tf_workspace = [TERRAFORM_PATH, 'workspace', 'select', TERRAFORM_WS_NAME]
proc_ws = Popen(tf_workspace, cwd=TERRAFORM_DIR, stdout=PIPE,
stderr=PIPE, universal_newlines=True)
_, err_ws = proc_ws.communicate()
if err_ws != '':
sys.stderr.write(str(err_ws)+'\n')
sys.exit(1)
else:
tf_command = [TERRAFORM_PATH, 'state', 'pull']
proc_tf_cmd = Popen(tf_command, cwd=TERRAFORM_DIR,
stdout=PIPE, stderr=PIPE, universal_newlines=True)
out_cmd, err_cmd = proc_tf_cmd.communicate()
if err_cmd != '':
sys.stderr.write(str(err_cmd)+'\n')
sys.exit(1)
else:
return json.loads(out_cmd, encoding=encoding)
def _backup_tf(tfstate):
# Crates a state backup in case we lose Consul
with open(TERRAFORM_BPK, 'w') as f:
f.write(json.dumps(tfstate.state_json))
def _backup_ansible(inventory):
# Crates a state backup in Ansible inventory format
text = '# NOTE: This file is generated by terraform.py\n'
text += '# For emergency use when Consul fails\n'
text += '[all]\n'
for hostname, host in sorted(inventory.hosts.items()):
text += (
'{0} hostname={0} ansible_host={1} '
).format(hostname, host.host_vars['ansible_host']) + (
'env={env} stage={stage} data_center={data_center} '+
'region={region} dns_entry={dns_entry}\n'
).format(**host.host_vars)
text += '\n'
for name, hosts in sorted(inventory.groups.items()):
if name in ['_meta', 'all']:
continue
text += '[{}]\n'.format(name)
for hostname in sorted(hosts.hosts):
text += '{}\n'.format(hostname)
text += '\n'
with open(ANSIBLE_BKP, 'w') as f:
f.write(text)
def _main():
try:
tfstate = TerraformState(_execute_shell())
inventory = AnsibleInventory()
for resource in tfstate.resources():
if resource.is_ansible():
inventory.add_resource(resource)
sys.stdout.write(json.dumps(inventory.to_dict(), indent=2))
# backup raw TF state
_backup_tf(tfstate)
# backup ansible inventory
_backup_ansible(inventory)
except Exception:
traceback.print_exc(file=sys.stderr)
sys.exit(1)
if __name__ == '__main__':
_main()