memcached.json.4.txt

= memcached.json(4)
:doctype: manpage
Trond Norbye <trond.norbye@couchbase.com>

== NAME

memcached.json - memcached configuration file

== DESCRIPTION

*memcached.json* is a JSON encoded file specifying the properties
used to configure the memcached server. Some of the parameters
may be changed at runtime by instructing memcached to reread the
configuration file. These properties is explicitly marked as
such.

The following sections describes the various attributes that may
be specified.

=== root

This is the root directory of the Couchbase server installation.

=== breakpad

The *breakpad* attribute is used to configure the Breakpad crash
catcher. When enabled (and on a supported platform), if memcached
crashes a minidump containing information on the state of memcached
will be written to disk.
It is an object with the following attributes:

    enabled       A boolean value specifying if Breakpad is enabled.
                  If true (and *minidump_dir* is set) minidumps will
                  be output to directory specified by *minidump_dir*.
                  If not specified then defaults to false.

    minidump_dir  A string value specifying the directory to write any
                  outputted minidumps to.  If not specified then
                  Breakpad is not enabled.

    content       A string value specifying what data will be included
                  in generated minidumps. Currently the only permitted
                  value is "default".

*enabled*, *minidump_dir* and *content* may be modified at runtime by
instructing memcached to reread the configuration file.

=== audit_file

Specify the filename containing all of the Audit configurations

=== rbac_file

Specify the filename containing the RBAC database.

=== privilege_debug

The *privilege_debug* attribute is a boolean value that may be set
(in development) to make all missing privilege calls return success
(and the missing privilege is logged). See docs/rbac.md for more
information.

=== ssl_cipher_list

Specify the list of ciphers to use. The format of the string is
described in ciphers ( https://www.openssl.org/docs/apps/ciphers.html
). By default no value is specified causing whatever openssl defaults
to to be enabled. Some values may be:

    HIGH          Only enable "high" encrypthion ciphers (keys > 128
                  bits)

    MEDIUM        In addition to the high encryption ciphers, also
                  allow 128 bit encryption

=== ssl_minimum_protocol

Specify the minimum protocol allowed for ssl. The default disables
SSLv2 and SSLv3 and allows for TLSv1, TLSv1.1 and TLSv1.2. The
string is case insensitive, and the following values may be used:

    TLSv1              Allow TLSv1, TLSv1.1 and TLSv1.2
    TLSv1.1/TLSv1_1    Allow TLSv1.1 and TLSv1.2
    TLSv1.2/TLSv1_2    Allow TLSv1.2

=== threads

The *threads* attribute specify the number of threads used to serve
clients. By default this number is set to 75% of the number of cores
available on the system (but no less than 4). The value for threads
should be specified as an integral number.

=== interfaces

The *interfaces* attribute is used to specify an array of interfaces
memcached should listen at. Each entry in the interfaces array is an
object describing a single interface with the following properties:

    host          A string value specifying the hostname to bind to.
                  If the attribute is missing (or set to "*")
                  IN_ADDR_ANY is used.

    port          An integral number specifying the port number

    IPv4          A boolean value specifying if IPv4 should be enabled
                  or not. By default IPv4 is enabled.

    IPv6          A boolean value specifying if IPv6 should be enabled
                  or not. By default IPv6 is enabled.

    maxconn       An integral number specifying the maximum number of
                  concurrent clients that may be connected.

    backlog       An integral number specifying the backlog size
                  set to listen.

    tcp_nodelay   A boolean value if TCP_NODELAY should be set or not.
                  By default tcp_nodelay is enabled.

    ssl           An object specifying SSL related properties.
                  See below.

    management    A boolean value if this interface is used by the
                  management system.

    protocol      A string value specifying the protocol enabled
                  for this port. If not present the memcached binary
                  protocol is used. Legal values: "memcached"

The *ssl* object contains the two *mandatory* attributes:

    key           A string value with the absolute path to the
	          file containing the private key to use.

    cert          A string value with the absolute path to the
                  file containing the X.509 certificate to use.

*maxconn*, *backlog*, *tcp_nodelay*, *ssl.key* and *ssl.cert* may
be modified by instructing memcached to reread the configuration
file.

=== extensions

The *extensions* attribute is deprecated and no longer in use

=== stdin_listener

The *stdin_listener* attribute is a boolean attribute set to true
if the standard input listener should be used or not.

=== engine

The *engine* parameter is no longer used and ignored.

=== default_reqs_per_event

The *default_reqs_per_event* attribute is an integral value specifying
the number of request that may be served per client before serving
the next client (to avoid starvation). The default value is 20.

*default_reqs_per_event* may be updated by instructing memcached to
reread the configuration file.

=== reqs_per_event_high_priority

The *reqs_per_event_high_priority* attribute is an integral value
specifying the number of request that may be served per high priority
client before serving the next client (to avoid starvation). The
default value is 20.

*reqs_per_event_high_priority* may be updated by instructing memcached
to reread the configuration file.

=== reqs_per_event_med_priority

The *reqs_per_event_med_priority* attribute is an integral value
specifying the number of request that may be served per medium priority
client before serving the next client (to avoid starvation). The
default value is 20.

*reqs_per_event_med_priority* may be updated by instructing memcached
to reread the configuration file.

=== reqs_per_event_low_priority

The *reqs_per_event_low_priority* attribute is an integral value
specifying the number of request that may be served per low priority
client before serving the next client (to avoid starvation). The
default value is 20.

*reqs_per_event_low_priority* may be updated by instructing memcached
to reread the configuration file.

=== bio_drain_buffer_sz

The *bio_drain_buffer_sz* attribute is an integral value specifying
the number of bytes in the BIO drain buffer. This is an interal
setting just used by the engineers for testing.

=== verbosity

The *verbosity* attribute is an integral value specifying the amount
of output produced by the memcached server. By default this value is
set to 0 resulting in only warnings to be emitted. Setting this
value too high will produce a lot of output which is most likely
meaningless for most people.

*verbosity* may be updated by instructing memcached to reread
the configuration file.

=== connection_idle_time

The *connection_idle_time* attribute is an integral value specifying the
number of seconds a connection may be idle until the server will disconnect.

By default the connection idle time is set to 5 minutes.

*connection_idle_time* may be updated by instructing memcached to reread the
configuration file.

=== datatype_json

The *datatype_json* attribute is a boolean value to enable the support
for using the datatype JSON extension. By default this support is *enabled*.

=== datatype_snappy

The *datatype_snappy* attribute is a boolean value to enable the support
for using the datatype snappy extension. By default this support is
*enabled*.

=== max_packet_size

The *max_packet_size* attribute is an integer value that specify the
maximum packet size (in MB) allowed to be received from clients without
disconnecting them. This is a safetynet for avoiding the server to
try to spool up a 4GB packet. When a packet is received on the
network with a body bigger than this threshold EINVAL is returned
to the client and the client is disconnected.

=== saslauthd_socketpath

The *saslauthd_socketpath* attribute is a string value containing
the path to the socket file used by saslauthd. If not specified
the value */var/run/saslauthd/mux* is used.

=== sasl_mechanisms

the *sasl_mechanisms* attribute is a string value containing the SASL
mechanisms that should be available for clients. It is not a dynamic
value and require restart in order to change.

=== ssl_sasl_mechanisms

the *ssl_sasl_mechanisms* attribute is a string value containing the SASL
mechanisms that should be available for clients connecting over SSL.
It is not a dynamic value and require restart in order to change.
By default this value is set to PLAIN (the default value may be cleared
by setting the environment variable `COUCHBASE_I_DONT_TRUST_SSL` to a
non-null value.

=== client_cert_auth

The client_cert_auth object is used to enable client certificate
authentication and control how the username is extracted from the client
certificate. It contains the following attributes.

*state*. Possible values for this paramters can be disabled,
enabled or mandatory. When enabled, if the server will request a
certificate from the client but if the certificate cannot be verified
it will stil allow the connection. In mandatory mode, the client connection
is dropped if the client certificate cannot be verified.

The path attribute specifies the field which will be used to extract the
username from the certificate and map that to user defined in Couchbase.
Currently only subject.cn, san.uri, san.email and san.dnsname are allowed.
This attribute is optional, however if defined, then the provided client
certificates must contain the fields which is used for the mapping,
*and the user must* be defined in Couchbase for the connection to be
established.

The prefix attribute specifices the prefix value to be ignored while
extracting the username from the certificate.

The delimiter attribute can be a string of characters and the parsing
of the username ends when one of the characters in the string is found.

=== dedupe_nmvb_maps

The *dedupe_nmvb_maps* attribute is a boolean value to enable deduplication
of the cluster maps in the "Not My VBucket" response messages sent to
the clients. By default this value is set to false.

=== error_maps_dir

A directory containing one or more JSON-formatted error maps. The error maps
are returned to the client using the GET_ERROR_MAP protocol command.
Multiple error maps correspond to multiple versions.

The format of the error map itself is described in `docs/ErrorMap.md`

=== xattr_enabled

The *xattrs_enabled* attribute is a boolean value to enable or disable
the use of extended attributes on documents. It may be overridden by
privileged connections to allow them to set up replication streams
before users create them.

=== tracing_enabled

The *tracing_enabled* attribute is a boolean value to enable or disable
retrieving tracedata from the server. If enabled, the time the request
took on the server will be sent back as a part of the response.

=== opcode-attributes-override

The *opcode-attributes-override* attribute is an object which follows
the syntax outlined in etc/couchbase/kv/opcode-attributes.d/README.md

=== topkeys_enabled

The *topkeys_enabled* attribute is a boolean value to enable or disable
collection of information about the most frequently used keys. If not
specified its value is set to true.

=== logger

The *logger* attribute is used to specify properties for the logger
used by memcached. It is an object with the following properties:

    filename    The prefix of the files to use for logging. The
                logger appends: nnnnnn.txt to the prefix specified
                where nnnnnn is replaced with a sequence number.
                If no filename is specified, no files will be written.

    buffersize  The buffers used by the logger to buffer data before
                dumping to disk. This property is only used when
                filename is present.

    cyclesize   The number of bytes to write to a file before starting
                a new one.

    sleeptime   The number of seconds to allow buffering before flushing
                to disk.

    unit_test   Boolean variable set to true when used for unit tests

    console     Boolean variable (defaults to true) if log messages
                should be sent to standard error as well.

== EXAMPLES

A Sample memcached.json:

    {
        "root" : "/opt/couchbase",
        "breakpad" :
            {
                "enabled" : true,
                "minidump_dir" : "/opt/couchbase/var/crash",
                "content" : "default"
            },
        "audit_file" : "/opt/couchbase/etc/security/audit.json",
        "rbac_file" : "/opt/couchbase/etc/security/rbac.json",
        "privilege_debug" : false,
        "error_maps_dir": "/opt/couchbase/etc/error_maps",
        "ssl_cipher_list" : "HIGH",
        "threads" : 4,
        "interfaces" :
        [
            {
                "host" : "*",
                "port" : 11209,
                "IPv4" : true,
                "IPv6" : true,
                "maxconn" : 10000,
                "backlog" : 1024,
                "tcp_nodelay" : true,
                "ssl" :
                {
                    "key" : "/etc/memcached/pkey",
                    "cert" : "/etc/memcached/cert"
                },
                "protocol" : "memcached"
            }
        ],
        "stdin_listener" : false,
        "engine" : {
            "module" : "bucket_engine.so",
            "config" : "admin=_admin;default_bucket_name=default;auto_create=false"
        },
        "default_reqs_per_event" : 20,
        "reqs_per_event_high_priority" : 40,
        "reqs_per_event_med_priority" : 20,
        "reqs_per_event_low_priority" : 10,
        "verbosity" : 2,
        "datatype_json" : true,
        "datatype_snappy" : true,
        "max_packet_size" : 25,
        "bio_drain_buffer_sz" : 8192,
        "sasl_mechanisms" : "SCRAM-SHA512 SCRAM-SHA256 SCRAM-SHA1",
        "saslauthd_socketpath" : "/var/run/saslauthd/mux",
        "dedupe_nmvb_maps" : true,
        "xattr_enabled" : true,
        "tracing_enabled" : true,
        "opcode-attributes-override": {
           "version": 1,
           "get": {
              "slow": 200
           }
        }
    }

== COPYRIGHT

Copyright 2016 Couchbase, Inc.