This will allow json logging in nginx ingress controllers which greatly
improves ease of log indexing and searching via elasticsearch.
After this change is made, users could set the following property in the
ingress configmap to enable json logging:
log-format-upstream: '{"proxy_protocol_addr": "$proxy_protocol_addr", "proxy_add_x_forwarded_for": "$proxy_add_x_forwarded_for", "remote_user": "$remote_user", "time_iso8601": "$time_iso8601", "request": "$request", "status": "$status", "body_bytes_sent": "$body_bytes_sent", "http_referer": "$http_referer", "http_user_agent": "$http_user_agent", "request_length": "$request_length", "request_time": "$request_time", "proxy_upstream_name": "$proxy_upstream_name", "upstream_addr": "$upstream_addr", "upstream_response_length": "$upstream_response_length", "upstream_response_time": "$upstream_response_time", "upstream_status": "$upstream_status"}'
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