Ansible：实现生产者到消费者的映射算法

Question

所以，场景是我有生产者和消费者7:1，我想有一个一致且确定的多重映射b/w 生产者和消费者 在我的服务中。消费者列表在配置中提供给每个生产者，这是通过 ansible 完成的。因此，我尝试 在 ansible 本身中实现映射逻辑，而不是传递整个消费者列表，并在生产者服务中进行。所以，我想到了使用自定义过滤器从消费者列表中过滤出来，并将其分配给生产者。下面是我写的自定义过滤器：

#!/usr/bin/python

class FilterModule(object):

    def filters(self):
        return { 'map_producer_to_consumer': self.map_producer_to_consumer }

    # consumer_servers: complete list of consumers servers
    # producer_id: provided to each producer for mapping purpose
    # producer_count: total no. of producers
    # map_consumer_count: no. of consumers need to be mapped to each producer
    # consumer_count: total no. of consumers

    def map_producer_to_consumer(self, consumer_servers, producer_id, producer_count, map_consumer_count):
        consumer_count = len(consumer_servers)
        index_offset = 0 if  producer_count%consumer_count else 1
        rotation_count = (producer_id/consumer_count) % (map_consumer_count-1) # used for left rotation of mapped servers
        map_consumer_indexes = [ (producer_count*i  + producer_id + index_offset*i) % consumer_count for i in xrange(map_consumer_count)]
        mapped_consumer_servers = [consumer_servers[map_consumer_indexes[0]]]
        for i in xrange(1, map_consumer_count):
            index = (i + rotation_count) % map_consumer_count
            if i + rotation_count >= map_consumer_count:
                mapped_consumer_servers.append( consumer_servers[map_consumer_indexes[index] + 1] )
            else:
                mapped_consumer_servers.append( consumer_servers[map_consumer_indexes[index]] )
        return (',').join(mapped_consumer_servers)

当与这样的静态参数一起使用时，此过滤器按预期工作：

"{{ tsdb_boxes | map_producer_to_consumer(2,3,3) }}"

但我想让它通过 jinja2 模板使用动态参数，例如：

"{{ groups['producers'] | map_producer_to_consumer ({{ consumer_servers }}, {{ producer_id }}, {{ producer_count }}, {{ map_consumer_count }}) }}"

但是由于变量嵌套导致错误，这在Jinja2中是不允许的。如果我尝试这样的事情：

"{{ groups['producers'] }} | map_producer_to_consumer ({{ consumer_servers }}, {{ producer_id }}, {{ producer_count }}, {{ map_consumer_count }})"

它会打印出这样的字符串：

['ip-1', 'ip-2'...] | map_producer_to_consumer (1000, 10, 150, 3)

有人可以建议实现此目标的最佳方法。我应该使用脚本模块并转换 bash 中的逻辑，还是只将其保留在服务中会更好。

Answer 1

来自评论的回答：

Why not try {{ groups['producers'] | map_producer_to_consumer(consumer_servers, producer_id, producer_count, map_consumer_count) }}

还有来自@techraf 的关于嵌套的link。

Ansible：实现生产者到消费者的映射算法

Ansible: Implementing mapping algorithm for producers to consumers

ansible

jinja2

ansible-2.x

ansible-template