# Logs

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.

## Proxy Logs

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. It is possible to change this format with the `log_msg_template` config parameter. The default log format is:

    {client_ip} {remote_addr} {end_time.datetime} {method} {path} {protocol}
        {status_int} {referer} {user_agent} {auth_token} {bytes_recvd}
        {bytes_sent} {client_etag} {transaction_id} {headers} {request_time}
        {source} {log_info} {start_time} {end_time} {policy_index}
        {access_user_id}

Some keywords, signaled by the (anonymizable) flag, can be anonymized by using the transformer ‘anonymized’. The data are applied the hashing method of `log_anonymization_method` and an optional salt `log_anonymization_salt`.

Some keywords, signaled by the (timestamp) flag, can be converted to standard dates formats using the matching transformers: ‘datetime’, ‘asctime’ or ‘iso8601’. Other transformers for timestamps are ‘s’, ‘ms’, ‘us’ and ‘ns’ for seconds, milliseconds, microseconds and nanoseconds. Python’s strftime directives can also be used as tranformers (a, A, b, B, c, d, H, I, j, m, M, p, S, U, w, W, x, X, y, Y, Z).

Example:

    {client_ip.anonymized} {remote_addr.anonymized} {start_time.iso8601}
        {end_time.H}:{end_time.M} {method} acc:{account} cnt:{container}
        obj:{object.anonymized}

Log Field | Value
client_ip | Swift’s guess at the end-client IP, taken from various headers in the request. (anonymizable)
remote_addr | The IP address of the other end of the TCP connection. (anonymizable)
end_time | Timestamp of the request. (timestamp)
method | The HTTP verb in the request.
domain | The domain in the request. (anonymizable)
path | The path portion of the request. (anonymizable)
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. (anonymizable)
user_agent | The value of the HTTP User-Agent header. (anonymizable)
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. (anonymizable)
transaction_id | The transaction id of the request.
headers | The headers given in the request. (anonymizable)
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.
start_time | High-resolution timestamp from the start of the request. (timestamp)
end_time | High-resolution timestamp from the end of the request. (timestamp)
ttfb | Duration between the request and the first bytes is sent.
policy_index | The value of the storage policy index.
account | The account part extracted from the path of the request. (anonymizable)
container | The container part extracted from the path of the request. (anonymizable)
object | The object part extracted from the path of the request. (anonymizable)
pid | PID of the process emitting the log line.
wire_status_int | The status sent to the client, which may be different than the logged response code if there was an error during the body of the request or a disconnect.
access_user_id | The user ID for logging. Middlewares should set environ[‘swift.access_logging’][‘user_id’] to identify the user for logging purposes. For S3 API requests, this contains the S3 access key ID. Other auth middlewares should set user-specific identifiers. For requests without auth middleware support, this field will be “-“.

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).

Note

Some log fields (like the request path) are already url quoted, so the logged value will be double-quoted. For example, if a client uploads an object name with a `:` in it, it will be url-quoted as `%3A`. The log module will then quote this value as `%253A`.

### Swift Source

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)
AQ | Account Quotas
CQ | Container Quotas
CS | Container Sync Middleware
TA | TempAuth
DLO | Dynamic Large Objects
LE | List Endpoints
KS | KeystoneAuth
RL | Rate Limiting
RO | Read Only
VW | Versioned Writes
SSC | Server Side Copy
SYM | Symlink
SH | Container Sharding
S3 | AWS S3 Api
OV | Object Versioning
EQ | Etag Quoter

## Storage Node Logs

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 time between request received and response started. Note: This includes transfer time on PUT, but not GET.
additional_info | Additional useful information.
server_pid | The process id of the server
policy_index | The value of the storage policy index.

this page last updated: 2026-08-18 20:34:00

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