Mongo proxy

Fault injection

The Mongo proxy filter supports fault injection. See the v2 API reference for how to configure.

Statistics

Every configured MongoDB proxy filter has statistics rooted at mongo.<stat_prefix>. with the following statistics:

Name Type Description
decoding_error Counter Number of MongoDB protocol decoding errors
delay_injected Counter Number of times the delay is injected
op_get_more Counter Number of OP_GET_MORE messages
op_insert Counter Number of OP_INSERT messages
op_kill_cursors Counter Number of OP_KILL_CURSORS messages
op_query Counter Number of OP_QUERY messages
op_query_tailable_cursor Counter Number of OP_QUERY with tailable cursor flag set
op_query_no_cursor_timeout Counter Number of OP_QUERY with no cursor timeout flag set
op_query_await_data Counter Number of OP_QUERY with await data flag set
op_query_exhaust Counter Number of OP_QUERY with exhaust flag set
op_query_no_max_time Counter Number of queries without maxTimeMS set
op_query_scatter_get Counter Number of scatter get queries
op_query_multi_get Counter Number of multi get queries
op_query_active Gauge Number of active queries
op_reply Counter Number of OP_REPLY messages
op_reply_cursor_not_found Counter Number of OP_REPLY with cursor not found flag set
op_reply_query_failure Counter Number of OP_REPLY with query failure flag set
op_reply_valid_cursor Counter Number of OP_REPLY with a valid cursor
cx_destroy_local_with_active_rq Counter Connections destroyed locally with an active query
cx_destroy_remote_with_active_rq Counter Connections destroyed remotely with an active query
cx_drain_close Counter Connections gracefully closed on reply boundaries during server drain

Scatter gets

Envoy defines a scatter get as any query that does not use an _id field as a query parameter. Envoy looks in both the top level document as well as within a $query field for _id.

Multi gets

Envoy defines a multi get as any query that does use an _id field as a query parameter, but where _id is not a scalar value (i.e., a document or an array). Envoy looks in both the top level document as well as within a $query field for _id.

$comment parsing

If a query has a top level $comment field (typically in addition to a $query field), Envoy will parse it as JSON and look for the following structure:

{
  "callingFunction": "..."
}
callingFunction
(required, string) the function that made the query. If available, the function will be used in callsite query statistics.

Per command statistics

The MongoDB filter will gather statistics for commands in the mongo.<stat_prefix>.cmd.<cmd>. namespace.

Name Type Description
total Counter Number of commands
reply_num_docs Histogram Number of documents in reply
reply_size Histogram Size of the reply in bytes
reply_time_ms Histogram Command time in milliseconds

Per collection query statistics

The MongoDB filter will gather statistics for queries in the mongo.<stat_prefix>.collection.<collection>.query. namespace.

Name Type Description
total Counter Number of queries
scatter_get Counter Number of scatter gets
multi_get Counter Number of multi gets
reply_num_docs Histogram Number of documents in reply
reply_size Histogram Size of the reply in bytes
reply_time_ms Histogram Query time in milliseconds

Per collection and callsite query statistics

If the application provides the calling function in the $comment field, Envoy will generate per callsite statistics. These statistics match the per collection statistics but are found in the mongo.<stat_prefix>.collection.<collection>.callsite.<callsite>.query. namespace.

Runtime

The Mongo proxy filter supports the following runtime settings:

mongo.connection_logging_enabled
% of connections that will have logging enabled. Defaults to 100. This allows only a % of connections to have logging, but for all messages on those connections to be logged.
mongo.proxy_enabled
% of connections that will have the proxy enabled at all. Defaults to 100.
mongo.logging_enabled
% of messages that will be logged. Defaults to 100. If less than 100, queries may be logged without replies, etc.
mongo.mongo.drain_close_enabled
% of connections that will be drain closed if the server is draining and would otherwise attempt a drain close. Defaults to 100.
mongo.fault.fixed_delay.percent
Probability of an eligible MongoDB operation to be affected by the injected fault when there is no active fault. Defaults to the percentage specified in the config.
mongo.fault.fixed_delay.duration_ms
The delay duration in milliseconds. Defaults to the duration_ms specified in the config.

Access log format

The access log format is not customizable and has the following layout:

{"time": "...", "message": "...", "upstream_host": "..."}
time
System time that complete message was parsed, including milliseconds.
message
Textual expansion of the message. Whether the message is fully expanded depends on the context. Sometimes summary data is presented to avoid extremely large log sizes.
upstream_host
The upstream host that the connection is proxying to, if available. This is populated if the filter is used along with the TCP proxy filter.