cockroach start-single-node

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This page explains the cockroach start-single-node command, which you use to start a single-node cluster with replication disabled. A single-node cluster is all you need for quick SQL testing or app development.

Tip:

To run a multi-node cluster with replicated data for availability and consistency, use cockroach start and cockroach init.

Synopsis

Start a single-node cluster:

$ cockroach start-single-node <flags>

View help:

$ cockroach start-single-node --help

Flags

The cockroach start-single-node command supports the following general-use, networking, security, and logging flags.

Many flags have useful defaults that can be overridden by specifying the flags explicitly. If you specify flags explicitly, however, be sure to do so each time the node is restarted, as they will not be remembered.

Note:

The cockroach start-single-node flags are identical to cockroach start flags. However, many of them are not relevant for single-node clusters but are provided for users who want to test concepts that appear in multi-node clusters. These flags are called out as such. In most cases, accepting most defaults is sufficient (see the examples below).

General

Flag Description
--attrs Not relevant for single-node clusters. Arbitrary strings, separated by colons, specifying node capability, which might include specialized hardware or number of cores, for example:

--attrs=ram:64gb

These can be used to influence the location of data replicas. See Configure Replication Zones for full details.
--background Set this to start the node in the background. This is better than appending & to the command because control is returned to the shell only once the node is ready to accept requests.

Note: --background is suitable for writing automated test suites or maintenance procedures that need a temporary server process running in the background. It is not intended to be used to start a long-running server, because it does not fully detach from the controlling terminal. Consider using a service manager or a tool like daemon(8) instead.
--cache The total size for caches, shared evenly if there are multiple storage devices. This can be a percentage (notated as a decimal or with %) or any bytes-based unit, for example:

--cache=.25
--cache=25%
--cache=1000000000 ----> 1000000000 bytes
--cache=1GB ----> 1000000000 bytes
--cache=1GiB ----> 1073741824 bytes

Note: If you use the % notation, you might need to escape the % sign, for instance, while configuring CockroachDB through systemd service files. For this reason, it's recommended to use the decimal notation instead.

Default: 128MiB

The default cache size is reasonable for local development clusters. For production deployments, this should be increased to 25% or higher. Increasing the cache size will generally improve the node's read performance. See Recommended Production Settings for more details.
--external-io-dir The path of the external IO directory with which the local file access paths are prefixed while performing backup and restore operations using local node directories or NFS drives. If set to disabled, backups and restores using local node directories and NFS drives are disabled.

Default: extern subdirectory of the first configured store.

To set the --external-io-dir flag to the locations you want to use without needing to restart nodes, create symlinks to the desired locations from within the extern directory.
--listening-url-file The file to which the node's SQL connection URL will be written on successful startup, in addition to being printed to the standard output.

This is particularly helpful in identifying the node's port when an unused port is assigned automatically (--port=0).
--locality Not relevant for single-node clusters. Arbitrary key-value pairs that describe the location of the node. Locality might include country, region, datacenter, rack, etc. For more details, see Locality below.
--max-disk-temp-storage The maximum on-disk storage capacity available to store temporary data for SQL queries that exceed the memory budget (see --max-sql-memory). This ensures that JOINs, sorts, and other memory-intensive SQL operations are able to spill intermediate results to disk. This can be a percentage (notated as a decimal or with %) or any bytes-based unit (e.g., .25, 25%, 500GB, 1TB, 1TiB).

Note: If you use the % notation, you might need to escape the % sign, for instance, while configuring CockroachDB through systemd service files. For this reason, it's recommended to use the decimal notation instead. Also, if expressed as a percentage, this value is interpreted relative to the size of the first store. However, the temporary space usage is never counted towards any store usage; therefore, when setting this value, it's important to ensure that the size of this temporary storage plus the size of the first store doesn't exceed the capacity of the storage device.

The temporary files are located in the path specified by the --temp-dir flag, or in the subdirectory of the first store (see --store) by default.

Default: 32GiB
--max-sql-memory The maximum in-memory storage capacity available to store temporary data for SQL queries, including prepared queries and intermediate data rows during query execution. This can be a percentage (notated as a decimal or with %) or any bytes-based unit, for example:

--max-sql-memory=.25
--max-sql-memory=25%
--max-sql-memory=10000000000 ----> 1000000000 bytes
--max-sql-memory=1GB ----> 1000000000 bytes
--max-sql-memory=1GiB ----> 1073741824 bytes

The temporary files are located in the path specified by the --temp-dir flag, or in the subdirectory of the first store (see --store) by default.

Note: If you use the % notation, you might need to escape the % sign, for instance, while configuring CockroachDB through systemd service files. For this reason, it's recommended to use the decimal notation instead.

Default: 25% Changed in v20.1

The default SQL memory size is suitable for production deployments but can be raised to increase the number of simultaneous client connections the node allows as well as the node's capacity for in-memory processing of rows when using ORDER BY, GROUP BY, DISTINCT, joins, and window functions. For local development clusters with memory-intensive workloads, reduce this value to, for example, 128MiB to prevent out of memory errors.
--pid-file The file to which the node's process ID will be written on successful startup. When this flag is not set, the process ID is not written to file.
--store
-s		 The file path to a storage device and, optionally, store attributes and maximum size. When using multiple storage devices for a node, this flag must be specified separately for each device, for example:

--store=/mnt/ssd01 --store=/mnt/ssd02

For more details, see Store below.
--temp-dir The path of the node's temporary store directory. On node start up, the location for the temporary files is printed to the standard output.

Default: Subdirectory of the first store

Networking

Flag Description
--listen-addr The IP address/hostname and port to listen on for connections from clients. For IPv6, use the notation [...], e.g., [::1] or [fe80::f6f2:::].

Default: Listen on all IP addresses on port 26257
--http-addr The IP address/hostname and port to listen on for Admin UI HTTP requests. For IPv6, use the notation [...], e.g., [::1]:8080 or [fe80::f6f2:::]:8080.

Default: Listen on the address part of --listen-addr on port 8080
--socket-dir New in v20.1: The directory path on which to listen for Unix domain socket connections from clients installed on the same Unix-based machine. For an example, see Connect to a cluster listening for Unix domain socket connections.

Security

Flag Description
--certs-dir The path to the certificate directory. The directory must contain valid certificates if running in secure mode.

Default: ${HOME}/.cockroach-certs/
--insecure Run in insecure mode. If this flag is not set, the --certs-dir flag must point to valid certificates.

Note the following risks: An insecure cluster is open to any client that can access any node's IP addresses; any user, even root, can log in without providing a password; any user, connecting as root, can read or write any data in your cluster; and there is no network encryption or authentication, and thus no confidentiality.

Default: false
--cert-principal-map New in v20.1: A comma-separated list of cert-principal:db-principal mappings used to map the certificate principals to IP addresses, DNS names, and SQL users. This allows the use of certificates generated by Certificate Authorities that place restrictions on the contents of the commonName field. For usage information, see Create Security Certificates using Openssl.
--enterprise-encryption This optional flag specifies the encryption options for one of the stores on the node. If multiple stores exist, the flag must be specified for each store.

This flag takes a number of options. For a complete list of options, and usage instructions, see Encryption at Rest.

Note that this is an enterprise feature.

Store

The --store flag supports the following fields. Note that commas are used to separate fields, and so are forbidden in all field values.

Note:

In-memory storage is not suitable for production deployments at this time.

Field Description
type For in-memory storage, set this field to mem; otherwise, leave this field out. The path field must not be set when type=mem.
path The file path to the storage device. When not setting attr or size, the path field label can be left out:

--store=/mnt/ssd01

When either of those fields are set, however, the path field label must be used:

--store=path=/mnt/ssd01,size=20GB

Default: cockroach-data
attrs Arbitrary strings, separated by colons, specifying disk type or capability. These can be used to influence the location of data replicas. See Configure Replication Zones for full details.

In most cases, node-level --locality or --attrs are preferable to store-level attributes, but this field can be used to match capabilities for storage of individual databases or tables. For example, an OLTP database would probably want to allocate space for its tables only on solid state devices, whereas append-only time series might prefer cheaper spinning drives. Typical attributes include whether the store is flash (ssd) or spinny disk (hdd), as well as speeds and other specs, for example:

--store=path=/mnt/hda1,attrs=hdd:7200rpm
size The maximum size allocated to the node. When this size is reached, CockroachDB attempts to rebalance data to other nodes with available capacity. When there's no capacity elsewhere, this limit will be exceeded. Also, data may be written to the node faster than the cluster can rebalance it away; in this case, as long as capacity is available elsewhere, CockroachDB will gradually rebalance data down to the store limit.

The size can be specified either in a bytes-based unit or as a percentage of hard drive space (notated as a decimal or with %), for example:

--store=path=/mnt/ssd01,size=10000000000 ----> 10000000000 bytes
--store=path=/mnt/ssd01,size=20GB ----> 20000000000 bytes
--store=path=/mnt/ssd01,size=20GiB ----> 21474836480 bytes
--store=path=/mnt/ssd01,size=0.02TiB ----> 21474836480 bytes
--store=path=/mnt/ssd01,size=20% ----> 20% of available space
--store=path=/mnt/ssd01,size=0.2 ----> 20% of available space
--store=path=/mnt/ssd01,size=.2 ----> 20% of available space

Default: 100%

For an in-memory store, the size field is required and must be set to the true maximum bytes or percentage of available memory, for example:

--store=type=mem,size=20GB
--store=type=mem,size=90%

Note: If you use the % notation, you might need to escape the % sign, for instance, while configuring CockroachDB through systemd service files. For this reason, it's recommended to use the decimal notation instead.

Logging

By default, cockroach start-single-node writes all messages to log files, and prints nothing to stderr. However, you can control the process's logging behavior with the following flags:

Flag Description
--log-dir Enable logging to files and write logs to the specified directory.

Setting --log-dir to a blank directory (--log-dir=) disables logging to files. Do not use --log-dir=""; this creates a new directory named "" and stores log files in that directory.
--log-dir-max-size After the log directory reaches the specified size, delete the oldest log file. The flag's argument takes standard file sizes, such as --log-dir-max-size=1GiB.

Default: 100MiB
--log-file-max-size After logs reach the specified size, begin writing logs to a new file. The flag's argument takes standard file sizes, such as --log-file-max-size=2MiB.

Default: 10MiB
--log-file-verbosity Only writes messages to log files if they are at or above the specified severity level, such as --log-file-verbosity=WARNING. Requires logging to files.

Default: INFO
--logtostderr Enable logging to stderr for messages at or above the specified severity level, such as --logtostderr=ERROR

If you use this flag without specifying the severity level (e.g., cockroach start --logtostderr), it prints messages of all severities to stderr.

Setting --logtostderr=NONE disables logging to stderr.
--no-color Do not colorize stderr. Possible values: true or false.

When set to false, messages logged to stderr are colorized based on severity level.

Default: false
--sql-audit-dir If non-empty, create a SQL audit log in this directory. By default, SQL audit logs are written in the same directory as the other logs generated by CockroachDB.

Note that enabling SQL audit logs can negatively impact performance. As a result, we recommend using SQL audit logs for security purposes only. For more information, see the EXPERIMENTAL_AUDIT reference page.

Defaults

cockroach start-single-node uses the equivalent values for these logging flags by default:

  • --log-dir=<first store dir>/logs
  • --logtostderr=NONE

This means, by default, CockroachDB writes all messages to log files, and never prints to stderr.

Standard output

When you run cockroach start-single-node, some helpful details are printed to the standard output:

CockroachDB node starting at 
build:               CCL v20.1.17 @ 2021-05-17 00:00:00 (go1.12.6)
webui:               http://localhost:8080
sql:                 postgresql://root@localhost:26257?sslmode=disable
RPC client flags:    cockroach <client cmd> --host=localhost:26257 --insecure
logs:                /Users/<username>/node1/logs
temp dir:            /Users/<username>/node1/cockroach-temp242232154
external I/O path:   /Users/<username>/node1/extern
store[0]:            path=/Users/<username>/node1
status:              initialized new cluster
clusterID:           8a681a16-9623-4fc1-a537-77e9255daafd
nodeID:              1
Tip:

These details are also written to the INFO log in the /logs directory. You can retrieve them with a command like grep 'node starting' node1/logs/cockroach.log -A 11.

Field Description
build The version of CockroachDB you are running.
webui The URL for accessing the Admin UI.
sql The connection URL for your client.
RPC client flags The flags to use when connecting to the node via cockroach client commands.
logs The directory containing debug log data.
temp dir The temporary store directory of the node.
external I/O path The external IO directory with which the local file access paths are prefixed while performing backup and restore operations using local node directories or NFS drives.
attrs If node-level attributes were specified in the --attrs flag, they are listed in this field. These details are potentially useful for configuring replication zones.
locality If values describing the locality of the node were specified in the --locality field, they are listed in this field. These details are potentially useful for configuring replication zones.
store[n] The directory containing store data, where [n] is the index of the store, e.g., store[0] for the first store, store[1] for the second store.

If store-level attributes were specified in the attrs field of the --store flag, they are listed in this field as well. These details are potentially useful for configuring replication zones.
status Whether the node is the first in the cluster (initialized new cluster), joined an existing cluster for the first time (initialized new node, joined pre-existing cluster), or rejoined an existing cluster (restarted pre-existing node).
clusterID The ID of the cluster.

When trying to join a node to an existing cluster, if this ID is different than the ID of the existing cluster, the node has started a new cluster. This may be due to conflicting information in the node's data directory. For additional guidance, see the troubleshooting docs.
nodeID The ID of the node.
socket New in v20.1: If the --socket-dir flag specifies a directory on which to listen for Unix domain socket connections, this field lists the name of the socket file.

Examples

Start a single-node cluster

  1. Create two directories for certificates:

    icon/buttons/copy 
    $ mkdir certs my-safe-directory
    Directory Description
    certs You'll generate your CA certificate and all node and client certificates and keys in this directory.
    my-safe-directory You'll generate your CA key in this directory and then reference the key when generating node and client certificates.

  2. Create the CA (Certificate Authority) certificate and key pair:

    icon/buttons/copy 
    $ cockroach cert create-ca \
--certs-dir=certs \
--ca-key=my-safe-directory/ca.key

  3. Create the certificate and key pair for the node:

    icon/buttons/copy 
    $ cockroach cert create-node \
localhost \
$(hostname) \
--certs-dir=certs \
--ca-key=my-safe-directory/ca.key

  4. Create a client certificate and key pair for the root user:

    icon/buttons/copy 
    $ cockroach cert create-client \
root \
--certs-dir=certs \
--ca-key=my-safe-directory/ca.key

  5. Start the single-node cluster:

    icon/buttons/copy 
    $ cockroach start-single-node \
--certs-dir=certs \
--listen-addr=localhost:26257 \
--http-addr=localhost:8080 \
--background

icon/buttons/copy 
$ cockroach start-single-node \
--insecure \
--listen-addr=localhost:26257 \
--http-addr=localhost:8080 \
--background

Scale to multiple nodes

Scaling a cluster started with cockroach start-single-node involves restarting the first node with the cockroach start command instead, and then adding new nodes with that command as well, all using a --join flag that forms them into a single multi-node cluster. Since replication is disabled in clusters started with start-single-node, you also need to enable replication to get CockroachDB's availability and consistency guarantees.

  1. Stop the single-node cluster:

    icon/buttons/copy 
    $ cockroach quit \
--certs-dir=certs \
--host=localhost:26257

  2. Restart the node with the cockroach start command:

    icon/buttons/copy 
    $ cockroach start \
--certs-dir=certs \
--listen-addr=localhost:26257 \
--http-addr=localhost:8080 \
--join=localhost:26257,localhost:26258,localhost:26259 \
--background

    The new flag to note is --join, which specifies the addresses and ports of the nodes that will comprise your cluster. You'll use this exact --join flag when starting other nodes as well.

    For a cluster in a single region, set 3-5 --join addresses. Each starting node will attempt to contact one of the join hosts. In case a join host cannot be reached, the node will try another address on the list until it can join the gossip network.

  3. Add two more nodes:

    icon/buttons/copy 
    $ cockroach start \
--certs-dir=certs \
--store=node2 \
--listen-addr=localhost:26258 \
--http-addr=localhost:8081 \
--join=localhost:26257,localhost:26258,localhost:26259 \
--background
    icon/buttons/copy 
    $ cockroach start \
--certs-dir=certs \
--store=node3 \
--listen-addr=localhost:26259 \
--http-addr=localhost:8082 \
--join=localhost:26257,localhost:26258,localhost:26259 \
--background

    These commands are the same as before but with unique --store, --listen-addr, and --http-addr flags, since this all nodes are running on the same machine. Also, since all nodes use the same hostname (localhost), you can use the first node's certificate. Note that this is different than running a production cluster, where you would need to generate a certificate and key for each node, issued to all common names and IP addresses you might use to refer to the node as well as to any load balancer instances.

  4. Open the built-in SQL shell:

    icon/buttons/copy 
    $ cockroach sql --certs-dir=certs --host=localhost:26257

  5. Update preconfigured replication zones to replicate user data 3 times and import internal data 5 times:

    icon/buttons/copy 
    > ALTER RANGE default CONFIGURE ZONE USING num_replicas = 3;
    icon/buttons/copy 
    > ALTER RANGE system CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER database system CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER RANGE liveness CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER RANGE meta CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER TABLE system.public.jobs CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER TABLE system.public.replication_constraint_stats CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER TABLE system.public.replication_stats CONFIGURE ZONE USING num_replicas = 5;

  1. Stop the single-node cluster:

    icon/buttons/copy 
    $ cockroach quit \
--insecure \
--host=localhost:26257

  2. Restart the node with the cockroach start command:

    icon/buttons/copy 
    $ cockroach start \
--insecure \
--listen-addr=localhost:26257 \
--http-addr=localhost:8080 \
--join=localhost:26257,localhost:26258,localhost:26259 \
--background

    The new flag to note is --join, which specifies the addresses and ports of the nodes that will comprise your cluster. You'll use this exact --join flag when starting other nodes as well.

  3. Add two more nodes:

    icon/buttons/copy 
    $ cockroach start \
--insecure \
--store=node2 \
--listen-addr=localhost:26258 \
--http-addr=localhost:8081 \
--join=localhost:26257,localhost:26258,localhost:26259 \
--background
    icon/buttons/copy 
    $ cockroach start \
--insecure \
--store=node3 \
--listen-addr=localhost:26259 \
--http-addr=localhost:8082 \
--join=localhost:26257,localhost:26258,localhost:26259 \
--background

    These commands are the same as before but with unique --store, --listen-addr, and --http-addr flags, since this all nodes are running on the same machine.

  4. Open the built-in SQL shell:

    icon/buttons/copy 
    $ cockroach sql --insecure --host=localhost:26257

  5. Update preconfigured replication zones to replicate user data 3 times and import internal data 5 times:

    icon/buttons/copy 
    > ALTER RANGE default CONFIGURE ZONE USING num_replicas = 3;
    icon/buttons/copy 
    > ALTER RANGE system CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER database system CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER RANGE liveness CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER RANGE meta CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER TABLE system.public.jobs CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER TABLE system.public.replication_constraint_stats CONFIGURE ZONE USING num_replicas = 5;
    icon/buttons/copy 
    > ALTER TABLE system.public.replication_stats CONFIGURE ZONE USING num_replicas = 5;

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