# mongoc_uri_t

## Synopsis

    typedef struct _mongoc_uri_t mongoc_uri_t;

## Description

`mongoc_uri_t` provides an abstraction on top of the MongoDB connection URI format. It provides standardized parsing as well as convenience methods for extracting useful information such as replica hosts or authorization information.

See Connection String URI Reference on the MongoDB website for more information.

## Format

    mongodb[+srv]://                             <1>
       [username:password@]                      <2>
       host1                                     <3>
       [:port1]                                  <4>
       [,host2[:port2],...[,hostN[:portN]]]      <5>
       [/[database]                              <6>
       [?options]]                               <7>

1. “mongodb” is the specifier of the MongoDB protocol. Use “mongodb+srv” with a single service name in place of “host1” to specify the initial list of servers with an SRV record.

2. An optional username and password.

3. The only required part of the uri. This specifies either a hostname, IPv4 address, IPv6 address enclosed in “[” and “]”, or UNIX domain socket.

4. An optional port number. Defaults to :27017.

5. Extra optional hosts and ports. You would specify multiple hosts, for example, for connections to replica sets.

6. The name of the database to authenticate if the connection string includes authentication credentials. If /database is not specified and the connection string includes credentials, defaults to the ‘admin’ database.

7. Connection specific options.

Note

Option names are case-insensitive. Do not repeat the same option (e.g. “mongodb://localhost/db?opt=value1&OPT=value2”) since this may have unexpected results.

The MongoDB C Driver exposes constants for each supported connection option. These constants make it easier to discover connection options, but their string values can be used as well.

For example, the following calls are equal.

    uri = mongoc_uri_new ("mongodb://localhost/?" MONGOC_URI_APPNAME "=applicationName");
    uri = mongoc_uri_new ("mongodb://localhost/?appname=applicationName");
    uri = mongoc_uri_new ("mongodb://localhost/?appName=applicationName");

## Replica Set Example

To describe a connection to a replica set named ‘test’ with the following mongod hosts:

- `db1.example.com` on port `27017`

- `db2.example.com` on port `2500`

You would use a connection string that resembles the following.

    mongodb://db1.example.com,db2.example.com:2500/?replicaSet=test

## SRV Example

If you have configured an SRV record with a name like “_mongodb._tcp.server.example.com” whose records are a list of one or more MongoDB server hostnames, use a connection string like this:

    uri = mongoc_uri_new ("mongodb+srv://server.example.com/?replicaSet=rs&appName=applicationName");

The driver prefixes the service name with “_mongodb._tcp.”, then performs a DNS SRV query to resolve the service name to one or more hostnames. If this query succeeds, the driver performs a DNS TXT query on the service name (without the “_mongodb._tcp” prefix) for additional URI options configured as TXT records.

On Unix, the MongoDB C Driver relies on libresolv to look up SRV and TXT records. If libresolv is unavailable, then using a “mongodb+srv” URI will cause an error. If your libresolv lacks `res_nsearch` then the driver will fall back to `res_search`, which is not thread-safe.

## IPv4 and IPv6

If connecting to a hostname that has both IPv4 and IPv6 DNS records, the behavior follows RFC-6555. A connection to the IPv6 address is attempted first. If IPv6 fails, then a connection is attempted to the IPv4 address. If the connection attempt to IPv6 does not complete within 250ms, then IPv4 is tried in parallel. Whichever succeeds connection first cancels the other. The successful DNS result is cached for 10 minutes.

As a consequence, attempts to connect to a mongod only listening on IPv4 may be delayed if there are both A (IPv4) and AAAA (IPv6) DNS records associated with the host.

To avoid a delay, configure hostnames to match the MongoDB configuration. That is, only create an A record if the mongod is only listening on IPv4.

## Connection Options

Constant | Key | Default | Description
--- | --- | --- | ---
MONGOC_URI_RETRYREADS | retryreads | true | If “true” and the server is a MongoDB 3.6+ standalone, replica set, or sharded cluster, the driver safely retries a read that failed due to a network error or replica set failover.
MONGOC_URI_RETRYWRITES | retrywrites | true if driver built w/ TLS | If “true” and the server is a MongoDB 3.6+ replica set or sharded cluster, the driver safely retries a write that failed due to a network error or replica set failover. Only inserts, updates of single documents, or deletes of single documents are retried.
MONGOC_URI_APPNAME | appname | Empty (no appname) | The client application name. This value is used by MongoDB when it logs connection information and profile information, such as slow queries.
MONGOC_URI_TLS | tls | Empty (not set, same as false) | {true|false}, indicating if TLS must be used. (See also mongoc_client_set_ssl_opts() and mongoc_client_pool_set_ssl_opts().)
MONGOC_URI_COMPRESSORS | compressors | Empty (no compressors) | Comma separated list of compressors, if any, to use to compress the wire protocol messages. Snappy, zlib, and zstd are optional build time dependencies, and enable the “snappy”, “zlib”, and “zstd” values respectively.
MONGOC_URI_CONNECTTIMEOUTMS | connecttimeoutms | 10,000 ms (10 seconds) | This setting applies to new server connections. It is also used as the socket timeout for server discovery and monitoring operations.
MONGOC_URI_SOCKETTIMEOUTMS | sockettimeoutms | 300,000 ms (5 minutes) | The time in milliseconds to attempt to send or receive on a socket before the attempt times out.
MONGOC_URI_REPLICASET | replicaset | Empty (no replicaset) | The name of the Replica Set that the driver should connect to.
MONGOC_URI_ZLIBCOMPRESSIONLEVEL | zlibcompressionlevel | -1 | When the MONGOC_URI_COMPRESSORS includes “zlib” this options configures the zlib compression level, when the zlib compressor is used to compress client data.
MONGOC_URI_LOADBALANCED | loadbalanced | false | If true, this indicates the driver is connecting to a MongoDB cluster behind a load balancer.
MONGOC_URI_SRVMAXHOSTS | srvmaxhosts | 0 | If zero, the number of hosts in DNS results is unlimited. If greater than zero, the number of hosts in DNS results is limited to being less than or equal to the given value.

Setting any of the *timeoutMS options above to `0` will be interpreted as “use the default value”.

## Authentication Options

Constant | Key | Description
--- | --- | ---
MONGOC_URI_AUTHMECHANISM | authmechanism | Specifies the mechanism to use when authenticating as the provided user. See Authentication for supported values.
MONGOC_URI_AUTHMECHANISMPROPERTIES | authmechanismproperties | Certain authentication mechanisms have additional options that can be configured. These options should be provided as comma separated option_key:option_value pair and provided as authMechanismProperties. Specifying the same option_key multiple times has undefined behavior.
MONGOC_URI_AUTHSOURCE | authsource | The authSource defines the database that should be used to authenticate to. It is unnecessary to provide this option the database name is the same as the database used in the URI.

### Mechanism Properties

Constant | Key | Description
--- | --- | ---
MONGOC_URI_CANONICALIZEHOSTNAME | canonicalizehostname | Use the canonical hostname of the service, rather than its configured alias, when authenticating with Cyrus-SASL Kerberos.
MONGOC_URI_GSSAPISERVICENAME | gssapiservicename | Use alternative service name. The default is `mongodb`.

## TLS Options

Constant | Key | Description
--- | --- | ---
MONGOC_URI_TLS | tls | {true|false}, indicating if TLS must be used.
MONGOC_URI_TLSCERTIFICATEKEYFILE | tlscertificatekeyfile | Path to PEM formatted Private Key, with its Public Certificate concatenated at the end.
MONGOC_URI_TLSCERTIFICATEKEYFILEPASSWORD | tlscertificatekeypassword | The password, if any, to use to unlock encrypted Private Key.
MONGOC_URI_TLSCAFILE | tlscafile | One, or a bundle of, Certificate Authorities whom should be considered to be trusted.
MONGOC_URI_TLSALLOWINVALIDCERTIFICATES | tlsallowinvalidcertificates | Accept and ignore certificate verification errors (e.g. untrusted issuer, expired, etc.)
MONGOC_URI_TLSALLOWINVALIDHOSTNAMES | tlsallowinvalidhostnames | Ignore hostname verification of the certificate (e.g. Man In The Middle, using valid certificate, but issued for another hostname)
MONGOC_URI_TLSINSECURE | tlsinsecure | {true|false}, indicating if insecure TLS options should be used. Currently this implies MONGOC_URI_TLSALLOWINVALIDCERTIFICATES and MONGOC_URI_TLSALLOWINVALIDHOSTNAMES.
MONGOC_URI_TLSDISABLECERTIFICATEREVOCATIONCHECK | tlsdisablecertificaterevocationcheck | {true|false}, indicates if revocation checking (CRL / OCSP) should be disabled.
MONGOC_URI_TLSDISABLEOCSPENDPOINTCHECK | tlsdisableocspendpointcheck | {true|false}, indicates if OCSP responder endpoints should not be requested when an OCSP response is not stapled.

See Configuring TLS for details about these options and about building libmongoc with TLS support.

## Deprecated SSL Options

The following options have been deprecated and may be removed from future releases of libmongoc.

Constant | Key | Deprecated For | Key
--- | --- | --- | ---
MONGOC_URI_SSL | ssl | MONGOC_URI_TLS | tls
MONGOC_URI_SSLCLIENTCERTIFICATEKEYFILE | sslclientcertificatekeyfile | MONGOC_URI_TLSCERTIFICATEKEYFILE | tlscertificatekeyfile
MONGOC_URI_SSLCLIENTCERTIFICATEKEYPASSWORD | sslclientcertificatekeypassword | MONGOC_URI_TLSCERTIFICATEKEYFILEPASSWORD | tlscertificatekeypassword
MONGOC_URI_SSLCERTIFICATEAUTHORITYFILE | sslcertificateauthorityfile | MONGOC_URI_TLSCAFILE | tlscafile
MONGOC_URI_SSLALLOWINVALIDCERTIFICATES | sslallowinvalidcertificates | MONGOC_URI_TLSALLOWINVALIDCERTIFICATES | tlsallowinvalidcertificates
MONGOC_URI_SSLALLOWINVALIDHOSTNAMES | sslallowinvalidhostnames | MONGOC_URI_TLSALLOWINVALIDHOSTNAMES | tlsallowinvalidhostnames

## Server Discovery, Monitoring, and Selection Options

Clients in a mongoc_client_pool_t share a topology scanner that runs on a background thread. The thread wakes every `heartbeatFrequencyMS` (default 10 seconds) to scan all MongoDB servers in parallel. Whenever an application operation requires a server that is not known–for example, if there is no known primary and your application attempts an insert–the thread rescans all servers every half-second. In this situation the pooled client waits up to `serverSelectionTimeoutMS` (default 30 seconds) for the thread to find a server suitable for the operation, then returns an error with domain `MONGOC_ERROR_SERVER_SELECTION`.

Technically, the total time an operation may wait while a pooled client scans the topology is controlled both by `serverSelectionTimeoutMS` and `connectTimeoutMS`. The longest wait occurs if the last scan begins just at the end of the selection timeout, and a slow or down server requires the full connection timeout before the client gives up.

A non-pooled client is single-threaded. Every `heartbeatFrequencyMS`, it blocks the next application operation while it does a parallel scan. This scan takes as long as needed to check the slowest server: roughly `connectTimeoutMS`. Therefore the default `heartbeatFrequencyMS` for single-threaded clients is greater than for pooled clients: 60 seconds.

By default, single-threaded (non-pooled) clients scan only once when an operation requires a server that is not known. If you attempt an insert and there is no known primary, the client checks all servers once trying to find it, then succeeds or returns an error with domain `MONGOC_ERROR_SERVER_SELECTION`. But if you set `serverSelectionTryOnce` to “false”, the single-threaded client loops, checking all servers every half-second, until `serverSelectionTimeoutMS`.

The total time an operation may wait for a single-threaded client to scan the topology is determined by `connectTimeoutMS` in the try-once case, or `serverSelectionTimeoutMS` and `connectTimeoutMS` if `serverSelectionTryOnce` is set “false”.

Constant | Key | Description
--- | --- | ---
MONGOC_URI_HEARTBEATFREQUENCYMS | heartbeatfrequencyms | The interval between server monitoring checks. Defaults to 10,000ms (10 seconds) in pooled (multi-threaded) mode, 60,000ms (60 seconds) in non-pooled mode (single-threaded).
MONGOC_URI_SERVERSELECTIONTIMEOUTMS | serverselectiontimeoutms | A timeout in milliseconds to block for server selection before throwing an exception. The default is 30,0000ms (30 seconds).

MONGOC_URI_SERVERSELECTIONTRYONCE

serverselectiontryonce

If “true”, the driver scans the topology exactly once after server selection fails, then either selects a server or returns an error. If it is false, then the driver repeatedly searches for a suitable server for up to `serverSelectionTimeoutMS` milliseconds (pausing a half second between attempts). The default for `serverSelectionTryOnce` is “false” for pooled clients, otherwise “true”. Pooled clients ignore serverSelectionTryOnce; they signal the thread to rescan the topology every half-second until serverSelectionTimeoutMS expires.

MONGOC_URI_SOCKETCHECKINTERVALMS | socketcheckintervalms | Only applies to single threaded clients. If a socket has not been used within this time, its connection is checked with a quick “hello” call before it is used again. Defaults to 5,000ms (5 seconds).
MONGOC_URI_DIRECTCONNECTION | directconnection | If “true”, the driver connects to a single server directly and will not monitor additional servers. If “false”, the driver connects based on the presence and value of the `replicaSet` option.

Setting any of the *TimeoutMS options above to `0` will be interpreted as “use the default value”.

## Connection Pool Options

These options govern the behavior of a mongoc_client_pool_t. They are ignored by a non-pooled mongoc_client_t.

Constant | Key | Description
--- | --- | ---
MONGOC_URI_MAXPOOLSIZE | maxpoolsize | The maximum number of clients created by a mongoc_client_pool_t total (both in the pool and checked out). The default value is 100. Once it is reached, mongoc_client_pool_pop() blocks until another thread pushes a client.
MONGOC_URI_MINPOOLSIZE | minpoolsize | Deprecated. This option’s behavior does not match its name, and its actual behavior will likely hurt performance.
MONGOC_URI_MAXIDLETIMEMS | maxidletimems | Not implemented.
MONGOC_URI_WAITQUEUEMULTIPLE | waitqueuemultiple | Not implemented.
MONGOC_URI_WAITQUEUETIMEOUTMS | waitqueuetimeoutms | The maximum time to wait for a client to become available from the pool.

## Write Concern Options

Constant | Key | Description
--- | --- | ---

MONGOC_URI_W

w

Determines the write concern (guarantee). Valid values:

- 0 = The driver will not acknowledge write operations but will pass or handle any network and socket errors that it receives to the client. If you disable write concern but enable the getLastError command’s w option, w overrides the w option.

- 1 = Provides basic acknowledgement of write operations. By specifying 1, you require that a standalone mongod instance, or the primary for replica sets, acknowledge all write operations. For drivers released after the default write concern change, this is the default write concern setting.

- majority = For replica sets, if you specify the special majority value to w option, write operations will only return successfully after a majority of the configured replica set members have acknowledged the write operation.

- n = For replica sets, if you specify a number n greater than 1, operations with this write concern return only after n members of the set have acknowledged the write. If you set n to a number that is greater than the number of available set members or members that hold data, MongoDB will wait, potentially indefinitely, for these members to become available.

- tags = For replica sets, you can specify a tag set to require that all members of the set that have these tags configured return confirmation of the write operation.

MONGOC_URI_WTIMEOUTMS | wtimeoutms | The time in milliseconds to wait for replication to succeed, as specified in the w option, before timing out. When wtimeoutMS is 0, write operations will never time out.

MONGOC_URI_JOURNAL

journal

Controls whether write operations will wait until the mongod acknowledges the write operations and commits the data to the on disk journal.

- true = Enables journal commit acknowledgement write concern. Equivalent to specifying the getLastError command with the j option enabled.

- false = Does not require that mongod commit write operations to the journal before acknowledging the write operation. This is the default option for the journal parameter.

## Read Concern Options

Constant | Key | Description
--- | --- | ---
MONGOC_URI_READCONCERNLEVEL | readconcernlevel | The level of isolation for read operations. If the level is left unspecified, the server default will be used. See readConcern in the MongoDB Manual for details.

## Read Preference Options

When connected to a replica set, the driver chooses which member to query using the read preference:

1. Choose members whose type matches “readPreference”.

2. From these, if there are any tags sets configured, choose members matching the first tag set. If there are none, fall back to the next tag set and so on, until some members are chosen or the tag sets are exhausted.

3. From the chosen servers, distribute queries randomly among the server with the fastest round-trip times. These include the server with the fastest time and any whose round-trip time is no more than “localThresholdMS” slower.

Constant | Key | Description
--- | --- | ---

MONGOC_URI_READPREFERENCE

readpreference

Specifies the replica set read preference for this connection. This setting overrides any secondaryOk value. The read preference values are the following:

- primary (default)

- primaryPreferred

- secondary

- secondaryPreferred

- nearest

MONGOC_URI_READPREFERENCETAGS | readpreferencetags | A representation of a tag set. See also Tag Sets.
MONGOC_URI_LOCALTHRESHOLDMS | localthresholdms | How far to distribute queries, beyond the server with the fastest round-trip time. By default, only servers within 15ms of the fastest round-trip time receive queries.
MONGOC_URI_MAXSTALENESSSECONDS | maxstalenessseconds | The maximum replication lag, in wall clock time, that a secondary can suffer and still be eligible. The smallest allowed value for maxStalenessSeconds is 90 seconds.

Note

When connecting to more than one mongos, libmongoc’s localThresholdMS applies only to the selection of mongos servers. The threshold for selecting among replica set members in shards is controlled by the mongos’s localThreshold command line option.

## Legacy Options

For historical reasons, the following options are available. They should however not be used.

Constant | Key | Description
--- | --- | ---
MONGOC_URI_SAFE | safe | {true|false} Same as w={1|0}

## Functions

- mongoc_uri_copy()
- mongoc_uri_destroy()
- mongoc_uri_get_auth_mechanism()
- mongoc_uri_get_auth_source()
- mongoc_uri_get_compressors()
- mongoc_uri_get_database()
- mongoc_uri_get_hosts()
- mongoc_uri_get_mechanism_properties()
- mongoc_uri_get_option_as_bool()
- mongoc_uri_get_option_as_int32()
- mongoc_uri_get_option_as_int64()
- mongoc_uri_get_option_as_utf8()
- mongoc_uri_get_options()
- mongoc_uri_get_password()
- mongoc_uri_get_read_concern()
- mongoc_uri_get_read_prefs()
- mongoc_uri_get_read_prefs_t()
- mongoc_uri_get_replica_set()
- mongoc_uri_get_service()
- mongoc_uri_get_ssl()
- mongoc_uri_get_string()
- mongoc_uri_get_srv_hostname()
- mongoc_uri_get_srv_service_name()
- mongoc_uri_get_tls()
- mongoc_uri_get_username()
- mongoc_uri_get_write_concern()
- mongoc_uri_has_option()
- mongoc_uri_new()
- mongoc_uri_new_for_host_port()
- mongoc_uri_new_with_error()
- mongoc_uri_option_is_bool()
- mongoc_uri_option_is_int32()
- mongoc_uri_option_is_int64()
- mongoc_uri_option_is_utf8()
- mongoc_uri_set_auth_mechanism()
- mongoc_uri_set_auth_source()
- mongoc_uri_set_compressors()
- mongoc_uri_set_database()
- mongoc_uri_set_mechanism_properties()
- mongoc_uri_set_option_as_bool()
- mongoc_uri_set_option_as_int32()
- mongoc_uri_set_option_as_int64()
- mongoc_uri_set_option_as_utf8()
- mongoc_uri_set_password()
- mongoc_uri_set_read_concern()
- mongoc_uri_set_read_prefs_t()
- mongoc_uri_set_username()
- mongoc_uri_set_write_concern()
- mongoc_uri_unescape()