rpk topic consume
Consume records from topics.
Consuming records reads from any amount of input topics, formats each record
according to --format, and prints them to STDOUT. The output formatter
understands a wide variety of formats.
The default output format --format json is a special format that outputs each
record as JSON. There may be more single-word-no-escapes formats added later.
Outside of these special formats, formatting follows the rules described below.
Format output
Formatting output is based on percent escapes and modifiers. Slashes can be
used for common escapes:
\t \n \r \\ \xNN
prints tabs, newlines, carriage returns, slashes, or hex encoded characters.p
Percent encoding prints record fields, fetch partition fields, or extra values:
%t topic
%T topic length
%k key
%K key length
%v value
%V value length
%h begin the header specification
%H number of headers
%p partition
%o offset
%e leader epoch
%d timestamp (formatting described below)
%a record attributes (formatting described below)
%x producer id
%y producer epoch
%[ partition log start offset
%| partition last stable offset
%] partition high watermark
%% percent sign
%{ left brace
%} right brace
%i the number of records formatted
MODIFIERS
Text and numbers can be formatted in many different ways, and the default
format can be changed within brace modifiers. %v prints a value, while %v{hex}
prints the value hex encoded. %T prints the length of a topic in ascii, while
%T{big8} prints the length of the topic as an eight byte big endian.
All modifiers go within braces following a percent-escape.
NUMBERS
Formatting number values can have the following modifiers:
ascii print the number as ascii (default)
hex64 sixteen hex characters
hex32 eight hex characters
hex16 four hex characters
hex8 two hex characters
hex4 one hex character
big64 eight byte big endian number
big32 four byte big endian number
big16 two byte big endian number
big8 alias for byte
little64 eight byte little endian number
little32 four byte little endian number
little16 two byte little endian number
little8 alias for byte
byte one byte number
bool "true" if the number is non-zero, "false" if the number is zero
All numbers are truncated as necessary per the modifier. Printing %V{byte} for
a length 256 value will print a single null, whereas printing %V{big8} would
print the bytes 1 and 0.
When writing number sizes, the size corresponds to the size of the raw values,
not the size of encoded values. "%T% t{hex}" for the topic "foo" will print
"3 666f6f", not "6 666f6f".
TIMESTAMPS
By default, the timestamp field is printed as a millisecond number value. In
addition to the number modifiers above, timestamps can be printed with either
Go formatting or strftime formatting:
%d{go[2006-01-02T15:04:05Z07:00]}
%d{strftime[%F]}
An arbitrary amount of brackets (or braces, or # symbols) can wrap your date
formatting:
%d{strftime### [%F] ###}
The above will print " [YYYY-MM-DD] ", while the surrounding three # on each
side are used to wrap the formatting. Further details on Go time formatting can
be found at https://pkg.go.dev/time, while further details on strftime
formatting can be read by checking "man strftime".
ATTRIBUTES
Each record (or batch of records) has a set of possible attributes. Internally,
these are packed into bit flags. Printing an attribute requires first selecting
which attribute you want to print, and then optionally specifying how you want
it to be printed:
%a{compression}
%a{compression;number}
%a{compression;big64}
%a{compression;hex8}
Compression is by default printed as text ("none", "gzip", ...). Compression
can be printed as a number with ";number", where number is any number
formatting option described above. No compression is 0, gzip is 1, etc.
%a{timestamp-type}
%a{timestamp-type;big64}
The record's timestamp type is printed as -1 for very old records (before
timestamps existed), 0 for client generated timestamps, and 1 for broker
generated timestamps. Number formatting can be controlled with ";number".
%a{transactional-bit}
%a{transactional-bit;bool}
Prints 1 if the record a part of a transaction or 0 if it is not.
Number formatting can be controlled with ";number".
%a{control-bit}
%a{control-bit;bool}
Prints 1 if the record is a commit marker or 0 if it is not.
Number formatting can be controlled with ";number".
TEXT
Text fields without modifiers default to writing the raw bytes. Alternatively,
there are the following modifiers:
%t{hex}
%k{base64}
%v{base64raw}
%v{unpack[<bBhH>iIqQc.$]}
The hex modifier hex encodes the text, the base64 modifier base64 encodes the
text with standard encoding, and the base64raw modifier encodes the text with
raw standard encoding. The unpack modifier has a further internal
specification, similar to timestamps above:
x pad character (does not parse input)
< switch what follows to little endian
> switch what follows to big endian
b signed byte
B unsigned byte
h int16 ("half word")
H uint16 ("half word")
i int32
I uint32
q int64 ("quad word")
Q uint64 ("quad word")
c any character
. alias for c
s consume the rest of the input as a string
$ match the end of the line (append error string if anything remains)
Unpacking text can allow translating binary input into readable output. If a
value is a big-endian uint32, %v will print the raw four bytes, while
%v{unpack[>I]} will print the number in as ascii. If unpacking exhausts the
input before something is unpacked fully, an error message is appended to the
output.
HEADERS
Headers are formatted with percent encoding inside of the modifier:
%h{ %k=%v{hex} }
will print all headers with a space before the key and after the value, an
equals sign between the key and value, and with the value hex encoded. Header
formatting actually just parses the internal format as a record format, so all
of the above rules about %K, %V, text, and numbers apply.
EXAMPLES
A key and value, separated by a space and ending in newline:
-f '%k %v\n'
A key length as four big endian bytes, and the key as hex:
-f '%K{big32}%k{hex}'
A little endian uint32 and a string unpacked from a value:
-f '%v{unpack[is$]}'
OFFSETS
The --offset flag allows for specifying where to begin consuming, and
optionally, where to stop consuming. The literal words "start" and "end"
specify consuming from the start and the end.
start consume from the beginning
end consume from the end
:end consume until the current end
+oo consume oo after the current start offset
-oo consume oo before the current end offset
oo consume after an exact offset
oo: alias for oo
:oo consume until an exact offset
o1:o2 consume from exact offset o1 until exact offset o2
@t consume starting from a given timestamp
@t: alias for @t
@:t consume until a given timestamp
@t1:t2 consume from timestamp t1 until timestamp t2
There are a few options for timestamps, with each option being evaluated
until one succeeds:
13 digits parsed as a unix millisecond
9 digits parsed as a unix second
YYYY-MM-DD parsed as a day, UTC
YYYY-MM-DDTHH:MM:SSZ parsed as RFC3339, UTC; fractional seconds optional (.MMM)
-dur duration ago; from now (as t1) or from t1 (as t2)
dur for t2 in @t1:t2, relative duration from t1
end for t2 in @t1:t2, the current end of the partition
Durations are parsed simply:
3ms three milliseconds
10s ten seconds
9m nine minutes
1h one hour
1m3ms one minute and three milliseconds
For example,
-o @2022-02-14:1h consume 1h of time on Valentine's Day 2022
-o @-48h:-24h consume from 2 days ago to 1 day ago
-o @-1m:end consume from 1m ago until now
-o @:-1hr consume from the start until an hour ago
Usage
rpk topic consume TOPICS... [flags]
Flags
| Value | Type | Description |
| -b, --balancer | string | Group balancer to use if group consuming (range, roundrobin, sticky, cooperative-sticky) (default "cooperative-sticky"). |
| --fetch-max-bytes | int32 | Maximum amount of bytes per fetch request per broker (default 1048576). |
| --fetch-max-wait | duration | Maximum amount of time to wait when fetching from a broker before the broker replies (default 5s). |
| -f, --format | string | Output format (see --help for details) (default "json"). |
| -g, --group | string | Group to use for consuming (incompatible with -p). |
| -h, --help | - | Help for consume. |
| --meta-only | - | Print all record info except the record value (for -f json). |
| -n, --num | int | Quit after consuming this number of records (0 is unbounded). |
| -o, --offset | string | Offset to consume from / to (start, end, 47, +2, -3) (default "start"). |
| -p, --partitions | int32 | int32Slice Comma delimited list of specific partitions to consume (default []). |
| --pretty-print | - | Pretty print each record over multiple lines (for -f json) (defaulttrue) |
| --print-control-records | - | Opt in to printing control records. |
| --read-committed | - | Opt in to reading only committed offsets. |
| -r, --regex | - | Parse topics as regex; consume any topic that matches any expression. |
| --brokers | strings | Comma-separated list of broker <ip>:<port> pairs (for example,--brokers '192.168.78.34:9092,192.168.78.35:9092,192.179.23.54:9092'). Alternatively, you may set the REDPANDA_BROKERSenvironment variable with the comma-separated list of broker addresses. |
| --config | string | Redpanda config file, if not set the file will be searched for in the default locations. |
| --password | string | SASL password to be used for authentication. |
| --sasl-mechanism | string | The authentication mechanism to use. Supported values:SCRAM-SHA-256, SCRAM-SHA-512. |
| --tls-cert | string | The certificate to be used for TLS authentication with the broker. |
| --tls-enabled | - | Enable TLS for the Kafka API (not necessary if specifying custom certs). |
| --tls-key | string | The certificate key to be used for TLS authentication with the broker. |
| --tls-truststore | string | The truststore to be used for TLS communication with the broker. |
| --user | string | SASL user to be used for authentication. |
| -v, --verbose | - | Enable verbose logging (default false). |