Swift has quite verbose logging, and the generated logs can be used for cluster monitoring, utilization calculations, audit records, and more. As an overview, Swift’s logs are sent to syslog and organized by log level and syslog facility. All log lines related to the same request have the same transaction id. This page documents the log formats used in the system.
Note
By default, Swift will log full log lines. However, with the log_max_line_length setting and depending on your logging server software, lines may be truncated or shortened. With log_max_line_length < 7, the log line will be truncated. With log_max_line_length >= 7, the log line will be “shortened”: about half the max length followed by ” ... ” followed by the other half the max length. Unless you use exceptionally short values, you are unlikely to run across this with the following documented log lines, but you may see it with debugging and error log lines.
The proxy logs contain the record of all external API requests made to the proxy server. Swift’s proxy servers log requests using a custom format designed to provide robust information and simple processing. The log format is:
client_ip remote_addr datetime request_method request_path protocol
status_int referer user_agent auth_token bytes_recvd bytes_sent
client_etag transaction_id headers request_time source log_info
request_start_time request_end_time policy_index
| Log Field | Value |
| client_ip | Swift’s guess at the end-client IP, taken from various headers in the request. |
| remote_addr | The IP address of the other end of the TCP connection. |
| datetime | Timestamp of the request, in day/month/year/hour/minute/second format. |
| request_method | The HTTP verb in the request. |
| request_path | The path portion of the request. |
| protocol | The transport protocol used (currently one of http or https). |
| status_int | The response code for the request. |
| referer | The value of the HTTP Referer header. |
| user_agent | The value of the HTTP User-Agent header. |
| auth_token | The value of the auth token. This may be truncated or otherwise obscured. |
| bytes_recvd | The number of bytes read from the client for this request. |
| bytes_sent | The number of bytes sent to the client in the body of the response. This is how many bytes were yielded to the WSGI server. |
| client_etag | The etag header value given by the client. |
| transaction_id | The transaction id of the request. |
| headers | The headers given in the request. |
| request_time | The duration of the request. |
| source | The “source” of the request. This may be set for requests that are generated in order to fulfill client requests, e.g. bulk uploads. |
| log_info | Various info that may be useful for diagnostics, e.g. the value of any x-delete-at header. |
| request_start_time | High-resolution timestamp from the start of the request. |
| request_end_time | High-resolution timestamp from the end of the request. |
| policy_index | The value of the storage policy index. |
In one log line, all of the above fields are space-separated and url-encoded. If any value is empty, it will be logged as a “-”. This allows for simple parsing by splitting each line on whitespace. New values may be placed at the end of the log line from time to time, but the order of the existing values will not change. Swift log processing utilities should look for the first N fields they require (e.g. in Python using something like log_line.split()[:14] to get up through the transaction id).
The source value in the proxy logs is used to identify the originator of a request in the system. For example, if the client initiates a bulk upload, the proxy server may end up doing many requests. The initial bulk upload request will be logged as normal, but all of the internal “child requests” will have a source value indicating they came from the bulk functionality.
| Logged Source Value | Originator of the Request |
| FP | FormPost |
| SLO | Static Large Objects |
| SW | StaticWeb |
| TU | TempURL |
| BD | Bulk Operations (Delete and Archive Auto Extraction) (delete) |
| EA | Bulk Operations (Delete and Archive Auto Extraction) (extract) |
| CQ | Container Quotas |
| CS | Container Sync Middleware |
| TA | TempAuth |
| DLO | Dynamic Large Objects |
| LE | List Endpoints |
| KS | KeystoneAuth |
| RL | Rate Limiting |
| VW | Object Versioning |
| SSC | Server Side Copy |
Swift’s account, container, and object server processes each log requests that they receive, if they have been configured to do so with the log_requests config parameter (which defaults to true). The format for these log lines is:
remote_addr - - [datetime] "request_method request_path" status_int
content_length "referer" "transaction_id" "user_agent" request_time
additional_info server_pid policy_index
| Log Field | Value |
| remote_addr | The IP address of the other end of the TCP connection. |
| datetime | Timestamp of the request, in “day/month/year:hour:minute:second +0000” format. |
| request_method | The HTTP verb in the request. |
| request_path | The path portion of the request. |
| status_int | The response code for the request. |
| content_length | The value of the Content-Length header in the response. |
| referer | The value of the HTTP Referer header. |
| transaction_id | The transaction id of the request. |
| user_agent | The value of the HTTP User-Agent header. Swift services report a user-agent string of the service name followed by the process ID, such as "proxy-server <pid of the proxy>" or "object-updater <pid of the object updater>". |
| request_time | The duration of the request. |
| additional_info | Additional useful information. |
| server_pid | The process id of the server |
| policy_index | The value of the storage policy index. |