Algorand Indexer

The Indexer is a standalone service that reads committed blocks from the Algorand blockchain and maintains a database of transactions and accounts that are searchable and indexed.

Building from source

Development is done using the Go Programming Language, the version is specified in the project's go.mod file.

Run make to build Indexer, the binary is located at cmd/algorand-indexer/algorand-indexer.

Requirements

All recommendations here should be be used as a starting point. Further benchmarking should be done to verify performance is acceptible for any application using Indexer.

Versions

• Database: Postgres 13

System

For a simple deployment the following configuration works well:

• Network: Indexer, Algod and PostgreSQL should all be on the same network.
• Indexer: 2 CPU and 8 GB of ram.
• Database: When hosted on AWS a db.r5.xlarge instance works well.
• Storage: 20 GiB

A database with replication can be used to scale read volume. Configure multiple Indexer daemons with a single writer and multiple readers.

Quickstart

Indexer is part of the sandbox private network configurations, which you can use to get started.

Features

• Search and filter accounts, transactions, assets, and asset balances with many different parameters.
• Pagination of results.
• Enriched transaction and account data:
  • Confirmation round (block containing the transaction)
  • Confirmation time
  • Signature type
  • Close amounts
  • Create/delete rounds.
• Human readable field names instead of the space optimized protocol level names.

Contributing

Contributions welcome! Please refer to our CONTRIBUTING document.

Usage

The most common usage of the Indexer is expecting to be getting validated blocks from a local algod Algorand node, adding them to a PostgreSQL database, and serving an API to make available a variety of prepared queries. Some users may wish to directly write SQL queries of the database.

Indexer works by fetching blocks one at a time, processing the block data, and loading it into a traditional database. There is a database abstraction layer to support different database implementations. In normal operation, the service will run as a daemon and always requires access to a database.

Modes

There are two primary modes of operation:

• Database updater
• Read only

In both configurations, a postgres connection string is required. Both DSN and URL formats are supported, details are available here.

In addition, the indexer uses a data directory that stores data needed for runtime operation and configuration. See the Data Directory documentation for how to (re-)initialize this directory in case it is lost or needs to be re-created.

Database updater

In this mode, the database will be populated with data fetched from an Algorand archival node. Because every block must be fetched to bootstrap the database, the initial import for a ledger with a long history will take a while. If the daemon is terminated, it will resume processing wherever it left off.

Keeping the indexer daemon as close as possible to the database helps minimize latency. For example, if using AWS EC2 and RDS, we suggest putting EC2 in the same VPC, Region, and even Availability Zone.

You should use a process manager, like systemd, to ensure the daemon is always running. Indexer will continue to update the database as new blocks are created.

To start indexer as a daemon in update mode, provide the required fields:

~$ algorand-indexer daemon --data-dir /tmp --algod-net yournode.com:1234 --algod-token token --genesis ~/path/to/genesis.json  --postgres "user=readonly password=YourPasswordHere {other connection string options for your database}"

Alternatively if indexer is running on the same host as the archival node, a simplified command may be used:

~$ algorand-indexer daemon --data-dir /tmp --algod-net yournode.com:1234 -d /path/to/algod/data/dir --postgres "user=readonly password=YourPasswordHere {other connection string options for your database}"

Read only

It is possible to set up one daemon as a writer and one or more readers. The Indexer pulling new data from algod can be started as above. Starting the indexer daemon without $ALGORAND_DATA or -d/--algod/--algod-net/--algod-token will start it without writing new data to the database. For further isolation, a readonly user can be created for the database.

~$ algorand-indexer daemon --data-dir /tmp --no-algod --postgres "user=readonly password=YourPasswordHere {other connection string options for your database}"

The Postgres backend does specifically note the username "readonly" and changes behavior to avoid writing to the database. But the primary benefit is that Postgres can enforce restricted access to this user. This can be configured with:

CREATE USER readonly LOGIN PASSWORD 'YourPasswordHere';
REVOKE ALL ON ALL TABLES IN SCHEMA public FROM readonly;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO readonly;

Authorization

When --token your-token is provided, an authentication header is required. For example:

~$ curl localhost:8980/transactions -H "X-Indexer-API-Token: your-token"

Disabling Parameters

The Indexer has the ability to selectively enable or disable parameters for endpoints. Disabling a "required" parameter will result in the entire endpoint being disabled while disabling an "optional" parameter will cause an error to be returned only if the parameter is provided.

Viewing the Current Configuration

The Indexer has a default set of disabled parameters. To view the disabled parameters issue:

~$ algorand-indexer api-config

This will output ONLY the disabled parameters in a YAML configuration. To view all parameters (both enabled and disabled) issue:

~$ algorand-indexer api-config --all

Interpreting The Configuration

Below is a snippet of the output from algorand-indexer api-config:

/v2/accounts:
    optional:
        - currency-greater-than: disabled
        - currency-less-than: disabled
/v2/assets/{asset-id}/transactions:
    optional:
        - note-prefix: disabled
        - tx-type: disabled
        - sig-type: disabled
        - before-time: disabled
        - after-time: disabled
        - currency-greater-than: disabled
        - currency-less-than: disabled
        - address-role: disabled
        - exclude-close-to: disabled
        - rekey-to: disabled
    required:
        - asset-id: disabled

Seeing this we know that the /v2/accounts endpoint will return an error if either currency-greater-than or currency-less-than is provided. Additionally, because a "required" parameter is provided for /v2/assets/{asset-id}/transactions then we know this entire endpoint is disabled. The optional parameters are provided so that you can understand what else is disabled if you enable all "required" parameters.

NOTE: An empty parameter configuration file results in all parameters being ENABLED.

For more information on disabling parameters see the Disabling Parameters Guide.

Metrics

The /metrics endpoint is configured with the --metrics-mode option and configures if and how Prometheus formatted metrics are generated.

There are different settings:

Setting	Description
ON	Metrics for each REST endpoint in addition to application metrics.
OFF	No metrics endpoint.
VERBOSE	Separate metrics for each combination of query parameters. This option should be used with caution, there are many combinations of query parameters which could cause extra memory load depending on usage patterns.

Connection Pool Settings

One can set the maximum number of connections allowed in the local connection pool by using the --max-conn setting. It is recommended to set this number to be below the database server connection pool limit.

If the maximum number of connections/active queries is reached, subsequent connections will wait until a connection becomes available, or timeout according to the read-timeout setting.

Settings

Settings can be provided from the command line, a configuration file, or an environment variable

Command Line Flag (long)	(short)	Config File	Environment Variable
postgres	P	postgres-connection-string	INDEXER_POSTGRES_CONNECTION_STRING
data-dir	i	data	INDEXER_DATA
pidfile		pidfile	INDEXER_PIDFILE
algod	d	algod-data-dir	INDEXER_ALGOD_DATA_DIR / ALGORAND_DATA
algod-net		algod-address	INDEXER_ALGOD_ADDRESS
algod-token		algod-token	INDEXER_ALGOD_TOKEN
server	S	server-address	INDEXER_SERVER_ADDRESS
no-algod		no-algod	INDEXER_NO_ALGOD
token	t	api-token	INDEXER_API_TOKEN
metrics-mode		metrics-mode	INDEXER_METRICS_MODE
logfile	f	logfile	INDEXER_LOGFILE
loglevel	l	loglevel	INDEXER_LOGLEVEL
max-conn		max-conn	INDEXER_MAX_CONN
write-timeout		write-timeout	INDEXER_WRITE_TIMEOUT
read-timeout		read-timeout	INDEXER_READ_TIMEOUT
max-api-resources-per-account		max-api-resources-per-account	INDEXER_MAX_API_RESOURCES_PER_ACCOUNT
max-transactions-limit		max-transactions-limit	INDEXER_MAX_TRANSACTIONS_LIMIT
default-transactions-limit		default-transactions-limit	INDEXER_DEFAULT_TRANSACTIONS_LIMIT
max-accounts-limit		max-accounts-limit	INDEXER_MAX_ACCOUNTS_LIMIT
default-accounts-limit		default-accounts-limit	INDEXER_DEFAULT_ACCOUNTS_LIMIT
max-assets-limit		max-assets-limit	INDEXER_MAX_ASSETS_LIMIT
default-assets-limit		default-assets-limit	INDEXER_DEFAULT_ASSETS_LIMIT
max-balances-limit		max-balances-limit	INDEXER_MAX_BALANCES_LIMIT
default-balances-limit		default-balances-limit	INDEXER_DEFAULT_BALANCES_LIMIT
max-applications-limit		max-applications-limit	INDEXER_MAX_APPLICATIONS_LIMIT
default-applications-limit		default-applications-limit	INDEXER_DEFAULT_APPLICATIONS_LIMIT
enable-all-parameters		enable-all-parameters	INDEXER_ENABLE_ALL_PARAMETERS
catchpoint		catchpoint	INDEXER_CATCHPOINT

Command line

The command line arguments always take priority over the config file and environment variables.

~$ ./algorand-indexer daemon --data-dir /tmp --pidfile /var/lib/algorand/algorand-indexer.pid --algod /var/lib/algorand --postgres "host=mydb.mycloud.com user=postgres password=password dbname=mainnet"`

Data Directory

The Indexer data directory is the location where the Indexer can store and/or load data needed for runtime operation and configuration.

It is a required argument for Indexer daemon operation. Supply it to the Indexer via the --data-dir/-i flag.

It is HIGHLY recommended placing the data directory in a separate, stateful directory for production usage of the Indexer.

For more information on the data directory see Indexer Data Directory.

Auto-Loading Configuration

The Indexer will scan the data directory at startup and load certain configuration files if they are present. The files are as follows:

• indexer.yml - Indexer Configuration File
• api_config.yml - API Parameter Enable/Disable Configuration File

NOTE: It is not allowed to supply both the command line flag AND have an auto-loading configuration file in the data directory. Doing so will result in an error.

To see an example of how to use the data directory to load a configuration file check out the Disabling Parameters Guide.

Example environment variable

Environment variables are also available to configure indexer. Environment variables override settings in the config file and are overridden by command line arguments.

The same indexer configuration from earlier can be made in bash with the following:

~$ export INDEXER_POSTGRES_CONNECTION_STRING="host=mydb.mycloud.com user=postgres password=password dbname=mainnet"
~$ export INDEXER_PIDFILE="/var/lib/algorand/algorand-indexer.pid"
~$ export INDEXER_ALGOD_DATA_DIR="/var/lib/algorand"
~$ export INDEXER_DATA="/tmp"
~$ ./algorand-indexer daemon

Configuration file

Default values are placed in the configuration file. They can be overridden with environment variables and command line arguments.

The configuration file must named indexer.yml and placed in the data directory (see above). The filepath may be set on the CLI using --configfile or -c but this functionality is deprecated.

Here is an example indexer.yml file:

postgres-connection-string: "host=mydb.mycloud.com user=postgres password=password dbname=mainnet"
pidfile: "/var/lib/algorand/algorand-indexer.pid"
algod-data-dir: "/var/lib/algorand"

Place this file in the data directory (/tmp/data-dir in this example) and supply it to the Indexer daemon:

~$ ./algorand-indexer daemon --data-dir /tmp/data-dir

Systemd

/lib/systemd/system/algorand-indexer.service can be partially overridden by creating /etc/systemd/system/algorand-indexer.service.d/local.conf. The most common things to override will be the command line and pidfile. The overriding local.conf file might be this:

[Service]
ExecStart=
ExecStart=/usr/bin/algorand-indexer daemon --data-dir /tmp --pidfile /var/lib/algorand/algorand-indexer.pid --algod /var/lib/algorand --postgres "host=mydb.mycloud.com user=postgres password=password dbname=mainnet"
PIDFile=/var/lib/algorand/algorand-indexer.pid

The systemd unit file can be found in source at misc/systemd/algorand-indexer.service

Note that the service assumes an algorand group and user. If the Algorand package has already been installed on the same machine, this group and user has already been created. However, if the Indexer is running stand-alone, the group and user will need to be created before starting the daemon:

adduser --system --group --home /var/lib/algorand --no-create-home algorand

Once configured, turn on your daemon with:

sudo systemctl enable algorand-indexer
sudo systemctl start algorand-indexer

If you wish to run multiple indexers on one server under systemd, see the comments in /lib/systemd/system/algorand-indexer@.service or misc/systemd/algorand-indexer@.service

Unique Database Configurations

Load balancing

If indexer is deployed with a clustered database using multiple readers behind a load balancer, query discrepancies are possible due to database replication lag. Users should check the current-round response field and be prepared to retry queries when stale data is detected.

Custom indices

Different application workloads will require different custom indices in order to make queries perform well. More information is available in PostgresqlIndexes.md.

Transaction results order

The order transactions are returned in depends on whether or not an account address filter is used.

When searching by an account, results are returned most recent first. The intent being that a wallet application would want to display the most recent transactions. A special index is used to make this case performant.

For all other transaction queries, results are returned oldest first. This is because it is the physical order they would normally be written in, so it is going to be faster.

Migrating from Indexer v1

Indexer v1 was built into the algod v1 REST API. It has been removed with the algod v2 REST API, all of the old functionality is now part of this project. The API endpoints, parameters, and response objects have all been modified and extended. Any projects depending on the old endpoints will need to be updated accordingly.

Building

Indexer is built using an in-house task framework called mule (it has since been open-sourced).

Please refer to the build docs in the mule/ directory.