14.64. taler.conf(5)¶

14.64.1. Name¶

taler.conf - Taler configuration file

14.64.2. Description¶

The configuration file is line-oriented. Blank lines and whitespace at the beginning and end of a line are ignored. Comments start with # or % in the first column (after any beginning-of-line whitespace) and go to the end of the line.

The file is split into sections. Every section begins with [SECTIONNAME] and contains a number of options of the form OPTION=VALUE. There may be whitespace around the = (equal sign). Section names and options are case-insensitive.

The values, however, are case-sensitive. In particular, boolean values are one of YES or NO. Values can include whitespace by surrounding the entire value with " (double quote). Note, however, that there are no escape characters in such strings; all characters between the double quotes (including other double quotes) are taken verbatim.

Values that represent a time duration are represented as a series of one or more NUMBER UNIT pairs, e.g. 60 s, 4 weeks 1 day, 5 years 2 minutes.

Values that represent an amount are in the usual amount syntax: CURRENCY:VALUE.FRACTION, e.g. EUR:1.50. The FRACTION portion may extend up to 8 places.

Values that represent filenames can begin with a /bin/sh-like variable reference. This can be simple, such as $TMPDIR/foo, or complex, such as ${TMPDIR:-${TMP:-/tmp}}/foo. The variables are expanded either using key-values from the [PATHS] section (see below) or from the environment (getenv()). The values from [PATHS] take precedence over those from the environment. If the variable name is found in neither [PATHS] nor the environment, a warning is printed and the value is left unchanged. Variables (including those from the environment) are expanded recursively, so if FOO=$BAR and BAR=buzz then the result is FOO=buzz. Recursion is bounded to at most 128 levels to avoid undefined behavior for mutually recursive expansions like if BAR=$FOO in the example above.

The [PATHS] section is special in that it contains paths that can be referenced using $ in other configuration values that specify filenames. Note that configuration options that are not specifically retrieved by the application as filenames will not see “$”-expressions expanded. To expand $-expressions when using taler-config, you must pass the -f command-line option.

The system automatically pre-populates the [PATHS] section with a few values at run-time (in addition to the values that are in the actual configuration file and automatically overwriting those values if they are present). These automatically generated values refer to installation properties from GNU autoconf. The values are usually dependent on an INSTALL_PREFIX which is determined by the --prefix option given to configure. The canonical values are:

LIBEXECDIR = $INSTALL_PREFIX/taler/libexec/
DOCDIR = $INSTALL_PREFIX/share/doc/taler/
ICONDIR = $INSTALL_PREFIX/share/icons/
LOCALEDIR = $INSTALL_PREFIX/share/locale/
PREFIX = $INSTALL_PREFIX/
BINDIR = $INSTALL_PREFIX/bin/
LIBDIR = $INSTALL_PREFIX/lib/taler/
DATADIR = $INSTALL_PREFIX/share/taler/

Note that on some platforms, the given paths may differ depending on how the system was compiled or installed, the above are just the canonical locations of the various resources. These automatically generated values are never written to disk.

Files containing default values for many of the options described below are installed under $TALER_PREFIX/share/taler/config.d/. The configuration file given with -c to Taler binaries overrides these defaults.

A configuration file may include another, by using the @INLINE@ directive, for example, in main.conf, you could write @INLINE@ sub.conf to include the entirety of sub.conf at that point in main.conf.

Be extra careful when using taler-config -V VALUE to change configuration values: it will destroy all uses of @INLINE@ and furthermore remove all comments from the configuration file!

14.64.2.1. GLOBAL OPTIONS¶

The following options are from the “[taler]” section and used by virtually all Taler components. Note: work is ongoing to obsolete these options, but for now they are in use.

CURRENCY: Name of the currency, e.g. “EUR” for Euro.
CURRENCY_ROUND_UNIT: Smallest amount in this currency that can be transferred using the underlying RTGS. For example: “EUR:0.01” or “JPY:1”.

The “[PATHS]” section is special in that it contains paths that can be referenced using “$” in other configuration values that specify filenames. For Taler, it commonly contains the following paths:

TALER_HOME: Home directory of the user, usually “${HOME}”. Can be overwritten by testcases by setting ${TALER_TEST_HOME}.
TALER_DATA_HOME: Where should Taler store its long-term data. Usually “${TALER_HOME}/.local/share/taler/”.
TALER_CONFIG_HOME: Where is the Taler configuration kept. Usually “${TALER_HOME}/.config/taler/”.
TALER_CACHE_HOME: Where should Taler store cached data. Usually “${TALER_HOME}/.cache/taler/”.
TALER_RUNTIME_DIR: Where should Taler store system runtime data (like UNIX domain sockets). Usually “${TMP}/taler-system-runtime”.

14.64.2.2. CURRENCY SPECIFICATIONS¶

Sections with a name of the form “[currency-$NAME]” (where “$NAME” could be any unique string) are used to specify details about how currencies should be handled (and in particularly rendered) by the user interface. A detailed motivation for this section can be found in DD51. Different components can have different rules for the same currency. For example, a bank or merchant may decide to render Euros or Dollars with always exactly two fractional decimals, while an Exchange for the same currency may support additional decimals. The required options in each currency specification section are:

ENABLED: Set to YES or NO. If set to NO, the currency specification section is ignored. Can be used to disable currencies or select alternative sections for the same CODE with different choices.
CODE: Code name for the currency. Can be at most 11 characters, only the letters A-Z are allowed. Primary way to identify the currency in the protocol.
NAME: Long human-readable name for the currency. No restrictions, but should match the official name in English.
FRACTIONAL_INPUT_DIGITS: Number of fractional digits that users are allowed to enter manually in the user interface.
FRACTIONAL_NORMAL_DIGITS: Number of fractional digits that will be rendered normally (in terms of size and placement). Digits shown beyond this number will typically be rendered smaller and raised (if possible).
FRACTIONAL_TRAILING_ZERO_DIGITS: Number of fractional digits to pad rendered amounts with even if these digits are all zero. For example, use 2 to render 1 USD as $1.00.
ALT_UNIT_NAMES: JSON map determining how to encode very large or very tiny amounts in this currency. Maps a base10 logarithm to the respective currency symbol. Must include at least an entry for 0 (currency unit). For example, use {“0”:”€”} for Euros or “{“0”:”$”} for Dollars. You could additionally use {“0”:”€”,”3”:”k€”} to render 3000 EUR as 3k€. For BTC a typical map would be {“0”:”BTC”,”-3”:”mBTC”}, informing the UI to render small amounts in milli-Bitcoin (mBTC).

14.64.2.3. EXCHANGE OPTIONS¶

The following options are from the “[exchange]” section and used by most exchange tools.

DB

Plugin to use for the database, e.g. “postgres”.

SERVE

Should the HTTP server listen on a UNIX domain socket (set option to “unix”) or on a TCP socket (set option to “tcp”)?

UNIXPATH

Path to listen on if we “SERVE” is set to “unix”.

UNIXPATH_MODE

Access permission mask to use for the “UNIXPATH”.

PORT

Port on which the HTTP server listens, e.g. 8080.

BIND_TO

Hostname to which the exchange HTTP server should be bound to, e.g. “localhost”.

MASTER_PUBLIC_KEY

Crockford Base32-encoded master public key, public version of the exchange’s long-time offline signing key. This configuration option is also used by the auditor to determine the public key of the exchange which it is auditing.

AML_THRESHOLD

Largest amount in this currency that can be transferred per month without an AML staff member doing a (manual) AML check. For example: “USD:1000000”.

KYC_AML_TRIGGER

Program to run on KYC attribute data to decide whether we should immediately flag an account for AML review. Program must return 0 if a manual AML review is not needed, and non-zero to trigger an AML review. The KYC attribute data of the new user will be passed on standard-input.

STEFAN_ABS

Absolute amount to add as an offset in the STEFAN fee approximation curve (see DD47). Defaults to CURRENCY:0 if not specified.

STEFAN_LOG

Amount to multiply by the base-2 logarithm of the total amount divided by the amount of the smallest denomination in the STEFAN fee approximation curve (see DD47). Defaults to CURRENCY:0 if not specified.

STEFAN_LIN

Linear floating point factor to be multiplied by the total amount to use in the STEFAN fee approximation curve (see DD47). Defaults to 0.0 if not specified.

BASE_URL

The base URL under which the exchange can be reached. Added to wire transfers to enable tracking by merchants. Used by the KYC logic when interacting with OAuth 2.0.

TOPLEVEL_REDIRECT_URL

Where to redirect visitors that access the top-level “/” endpoint of the exchange. Should point users to information about the exchange operator. Optional setting, defaults to “/terms”.

AGGREGATOR_IDLE_SLEEP_INTERVAL

For how long should the taler-exchange-aggregator sleep when it is idle before trying to look for more work? Default is 60 seconds.

CLOSER_IDLE_SLEEP_INTERVAL

For how long should the taler-exchange-closer sleep when it is idle before trying to look for more work? Default is 60 seconds.

TRANSFER_IDLE_SLEEP_INTERVAL

For how long should the taler-exchange-transfer sleep when it is idle before trying to look for more work? Default is 60 seconds.

WIREWATCH_IDLE_SLEEP_INTERVAL

For how long should the taler-exchange-wirewatch sleep when it is idle before trying to look for more work? Default is 60 seconds.

AGGREGATOR_SHARD_SIZE

Which share of the range from [0,..2147483648] should be processed by one of the shards of the aggregator. Useful only for Taler exchanges with ultra high-performance needs. When changing this value, you must stop all aggregators and run “taler-exchange-dbinit -s” before resuming. Default is 2147483648 (no sharding).

SIGNKEY_LEGAL_DURATION

For how long are signatures with signing keys legally valid?

MAX_KEYS_CACHING

For how long should clients cache /keys responses at most?

MAX_REQUESTS

How many requests should the HTTP server process at most before committing suicide?

TERMS_DIR

Directory where the terms of service of the exchange operator can be fund. The directory must contain sub-directories for every supported language, using the two-character language code in lower case, e.g. “en/” or “fr/”. Each subdirectory must then contain files with the terms of service in various formats. The basename of the file of the current policy must be specified under TERMS_ETAG. The extension defines the mime type. Supported extensions include “html”, “htm”, “txt”, “pdf”, “jpg”, “jpeg”, “png” and “gif”. For example, using a TERMS_ETAG of “0”, the structure could be the following:

$TERMS_DIR/en/0.pdf
$TERMS_DIR/en/0.html
$TERMS_DIR/en/0.txt
$TERMS_DIR/fr/0.pdf
$TERMS_DIR/fr/0.html
$TERMS_DIR/de/0.txt

TERMS_ETAG

Basename of the file(s) in the TERMS_DIR with the current terms of service. The value is also used for the “Etag” in the HTTP request to control caching. Whenever the terms of service change, the TERMS_ETAG MUST also change, and old values MUST NOT be repeated. For example, the date or version number of the terms of service SHOULD be used for the Etag. If there are minor (e.g. spelling) fixes to the terms of service, the TERMS_ETAG probably SHOULD NOT be changed. However, whenever users must approve the new terms, the TERMS_ETAG MUST change.

PRIVACY_DIR

Works the same as TERMS_DIR, just for the privacy policy.

PRIVACY_ETAG

Works the same as TERMS_ETAG, just for the privacy policy.

14.64.2.4. EXCHANGE KYC PROVIDER OPTIONS¶

The following options must be in the section “[kyc-provider-XXX]” sections.

COST: Relative cost of the KYC provider, non-negative number.
LOGIC: API type of the KYC provider.
USER_TYPE: Type of user this provider is for, either INDIVIDUAL or BUSINESS.
PROVIDED_CHECKS: List of checks performed by this provider. Space-separated names of checks, must match check names in legitimization rules.

14.64.2.4.1. EXCHANGE KYC OAUTH2 OPTIONS¶

The following options must be in the section “[kyc-provider-XXX]” sections with “LOGIC = oauth2”.

KYC_OAUTH2_VALIDITY: Duration (e.g. “12 months”) of the validity of the performed KYC check. Can be “forever”.
KYC_OAUTH2_AUTHORIZE_URL: URL of the OAuth2 endpoint to be used for KYC checks. The authorize URL is where the exchange will redirect the client to begin the authorization process. Example: “http://localhost:8888/oauth/v2/authorize”. To use the plugin in combination with the Challenger service’s /setup step, append “#setup”, thus “https://challenger.example.com/authorize#setup”. Here, “#setup” is not a fragment but merely a hint to the logic to determine the full authorization URL via the /setup/$CLIENT_ID handler.
KYC_OAUTH2_TOKEN_URL: URL of the OAuth2 endpoint to be used for KYC checks. This is where the server will ultimately send the authorization token from the client and obtain its access token (which currently must be a “bearer” token). Example: “http://localhost:8888/oauth/v2/token” (or just “/token”)
KYC_OAUTH2_INFO_URL: URL of the OAuth2-protected resource endpoint, where the OAuth 2.0 token can be used to download information about the user that has undergone the KYC process. The exchange will use the access token obtained from the KYC_AUTH2_AUTH_URL to show that it is authorized to obtain the details. Example: “http://localhost:8888/api/user/me” or “http://localhost:8888/oauth/v2/info”
KYC_OAUTH2_CLIENT_ID: Client ID of the exchange when it talks to the KYC OAuth2 endpoint.
KYC_OAUTH2_CLIENT_SECRET: Client secret of the exchange to use when talking to the KYC Oauth2 endpoint.
KYC_OAUTH2_POST_URL: URL to which the exchange will redirect the client’s browser after successful authorization/login for the KYC process. Example: “http://example.com/thank-you”
KYC_OAUTH2_CONVERTER_HELPER: Helper to convert JSON with KYC data returned by the OAuth2.0 info endpoint into GNU Taler internal format. Specific to the OAuth 2.0 provider.
KYC_OAUTH2_DEBUG_MODE: Set to YES to allow error responses to include potentially sensitive private information (such as full responses from the OAuth 2.0 server) that might aid in debugging problems. Should be set to “NO” in production.

14.64.2.4.2. EXCHANGE KYC KYCAID OPTIONS¶

The following options must be in the section “[kyc-provider-XXX]” sections with “LOGIC = kycaid”.

KYC_KYCAID_VALIDITY: Duration (e.g. “12 months”) of the validity of the performed KYC check. Can be “forever”.
KYC_KYCAID_AUTH_TOKEN: Authentication token to access the KYC service.
KYC_KYCAID_FORM_ID: ID that specifies the form to use for the KYC process.
KYC_KYCAID_POST_URL: URL to which the exchange will redirect the client’s browser after successful authorization/login for the KYC process.

14.64.2.4.3. EXCHANGE KYC PERSONA OPTIONS¶

The following options must be in the section “[kyc-provider-XXX]” sections with “LOGIC = persona”.

KYC_PERSONA_VALIDITY: Duration (e.g. “12 months”) of the validity of the performed KYC check. Can be “forever”.
KYC_PERSONA_AUTH_TOKEN: Authentication token to access the KYC service.
KYC_PERSONA_SALT: Salt value to use for request idempotency. Optional, generated at random per process if not given.
KYC_PERSONA_SUBDOMAIN: Subdomain to use under Persona.
KYC_PERSONA_CONVERTER_HELPER: Helper to convert JSON with KYC data returned by Persona into GNU Taler internal format. Should probably always be set to “taler-exchange-kyc-persona-converter.sh”.
KYC_PERSONA_POST_URL: URL to which the exchange will redirect the client’s browser after successful authorization/login for the KYC process.
KYC_PERSONA_TEMPLATE_ID: ID of the Persona template to use.

14.64.2.4.4. EXCHANGE KYC PERSONA GLOBAL OPTIONS¶

The following option must be in the section “[kyclogic-persona]”.

WEBHOOK_AUTH_TOKEN: Authentication token Persona must supply to our webhook. This is an optional setting.

14.64.2.5. EXCHANGE EXTENSIONS OPTIONS¶

The functionality of the exchange can be extended by extensions. Those are shared libraries which implement the extension-API of the exchange and are located under $LIBDIR, starting with prefix libtaler_extension_. Each extension can be enabled by adding a dedicated section “[exchange-extension-<extensionname>]” and the following option:

ENABLED: If set to YES the extension <extensionsname> is enabled. Extension-specific options might be set in the same section.

14.64.2.5.1. EXCHANGE EXTENSION FOR AGE RESTRICTION¶

The extension for age restriction support can be enabled by adding a section “[exchange-extension-age_restriction]” with the following options:

ENABLE

Must be set to YES in order to activate the extension.

AGE_GROUPS

A colon-seperated string of increasing non-negative integers, defining the buckets of age groups supported by the exchange. Each integer marks the beginning of the next age group. The zero’th age group implicitly starts with 0. For example, the string “10:18” would define three age groups:

Group 0: ages 0 through 9 (including)

Group 1: ages 10 through 17 (including)

Group 2: ages 18 and above

If not provided, the default value is “8:10:12:14:16:18:21”.

Note: Age restriction is bound to specific denominations and must be enabled for each selected denomination in the corresponding section by adding the option AGE_RESTRICTED = YES, see EXCHANGE COIN OPTIONS. However, the age groups are defined globally for all denominations.

14.64.2.6. EXCHANGE OFFLINE SIGNING OPTIONS¶

The following options must be in the section “[exchange-offline]”.

MASTER_PRIV_FILE: Location of the master private key on disk. Only used by tools that can be run offline (as the master key is for offline signing). Mandatory.
SECM_TOFU_FILE: Where to store the public keys of both crypto helper modules. Used to persist the keys after the first invocation of the tool, so that if they ever change in the future, this is detected and the tool can abort. Mandatory.
SECM_DENOM_PUBKEY: Public key of the (RSA) crypto helper module. Optional. If not given, we will rely on TOFU. Note that once TOFU has been established, this option will also be ignored.
SECM_ESIGN_PUBKEY: Public key of the (EdDSA) crypto helper module. Optional. If not given, we will rely on TOFU. Note that once TOFU has been established, this option will also be ignored.

14.64.2.7. EXCHANGE RSA CRYPTO HELPER OPTIONS¶

The following options must be in the section “[taler-exchange-secmod-rsa]”.

LOOKAHEAD_SIGN: How long do we generate denomination and signing keys ahead of time?
OVERLAP_DURATION: How much should validity periods for coins overlap? Should be long enough to avoid problems with wallets picking one key and then due to network latency another key being valid. The DURATION_WITHDRAW period must be longer than this value.
SM_PRIV_KEY: Where should the security module store its long-term private key?
KEY_DIR: Where should the security module store the private keys it manages?
UNIXPATH: On which path should the security module listen for signing requests?

Note that the taler-exchange-secmod-rsa also evaluates the [coin_*] configuration sections described below.

14.64.2.8. EXCHANGE CS CRYPTO HELPER OPTIONS¶

The following options must be in the section “[taler-exchange-secmod-cs]”.

LOOKAHEAD_SIGN: How long do we generate denomination and signing keys ahead of time?
OVERLAP_DURATION: How much should validity periods for coins overlap? Should be long enough to avoid problems with wallets picking one key and then due to network latency another key being valid. The DURATION_WITHDRAW period must be longer than this value.
SM_PRIV_KEY: Where should the security module store its long-term private key?
KEY_DIR: Where should the security module store the private keys it manages?
UNIXPATH: On which path should the security module listen for signing requests?

Note that the taler-exchange-secmod-cs also evaluates the [coin_*] configuration sections described below.

14.64.2.9. EXCHANGE EDDSA CRYPTO HELPER OPTIONS¶

The following options must be in the section “[taler-exchange-secmod-eddsa]”.

LOOKAHEAD_SIGN: How long do we generate denomination and signing keys ahead of time?
OVERLAP_DURATION: How much should validity periods for coins overlap? Should be long enough to avoid problems with wallets picking one key and then due to network latency another key being valid. The DURATION_WITHDRAW period must be longer than this value.
DURATION: For how long should EdDSA keys be valid for signing?
SM_PRIV_KEY: Where should the security module store its long-term private key?
KEY_DIR: Where should the security module store the private keys it manages?
UNIXPATH: On which path should the security module listen for signing requests?

14.64.2.10. EXCHANGE DATABASE OPTIONS¶

The following options must be in the section “[exchangedb]”.

IDLE_RESERVE_EXPIRATION_TIME: After which time period should reserves be closed if they are idle?
LEGAL_RESERVE_EXPIRATION_TIME: After what time do we forget about (drained) reserves during garbage collection?
AGGREGATOR_SHIFT: Delay between a deposit being eligible for aggregation and the aggregator actually triggering.
DEFAULT_PURSE_LIMIT: Number of concurrent purses that a reserve may have active if it is paid to be opened for a year.

14.64.2.11. EXCHANGE POSTGRES BACKEND DATABASE OPTIONS¶

The following options must be in section “[exchangedb-postgres]” if the “postgres” plugin was selected for the database.

CONFIG: How to access the database, e.g. “postgres:///taler” to use the “taler” database. Testcases use “talercheck”.

14.64.2.12. EXCHANGE ACCOUNT OPTIONS¶

An exchange (or merchant) can have multiple bank accounts. The following options are for sections named “[exchange-account-SOMETHING]”. The SOMETHING is arbitrary and should be chosen to uniquely identify the bank account for the operator. These options are used by the taler-exchange-aggregator, taler-exchange-closer, taler-exchange-transfer and taler-exchange-wirewatch tools.

PAYTO_URI: Specifies the payto://-URL of the account. The general format is payto://$METHOD/$DETAILS. Examples: payto://x-taler-bank/localhost:8899/Exchange or payto://iban/GENODEF1SLR/DE67830654080004822650/ or payto://iban/DE67830654080004822650/ (providing the BIC is optional). Note: only the wire-method is actually used from the URI.
ENABLE_DEBIT: Must be set to YES for the accounts that the taler-exchange-aggregator and taler-exchange-closer should debit.
ENABLE_CREDIT: Must be set to YES for the accounts that the taler-exchange-wirewatch should check for credits. It is yet uncertain if the merchant implementation may check this flag as well.

Additionally, for each enabled account there MUST be another matching section named “[exchange-accountcredentials-SOMETHING]”. This section SHOULD be in a secret/ configuration file that is only readable for the taler-exchange-wirewatch and taler-exchange-transfer processes. It contains the credentials to access the bank account:

WIRE_GATEWAY_URL: URL of the wire gateway. Typically of the form https://$HOSTNAME[:$PORT]/taler-wire-gateway/$USERNAME/ where $HOSTNAME is the hostname of the system running the bank (such as the Taler Python bank or the Nexus) and $USERNAME is the username of the exchange’s bank account (usually matching the USERNAME option used for authentication). Example: https://bank.demo.taler.net/taler-wire-gateway/Exchange/.
WIRE_GATEWAY_AUTH_METHOD: This option determines how the exchange (auditor/wirewatch/aggregator) authenticates with the wire gateway. Choices are basic and none.
USERNAME: User name for basic authentication with the wire gateway.
PASSWORD: Password for basic authentication with the wire gateway.

14.64.2.13. EXCHANGE COIN OPTIONS¶

The following options must be in sections starting with "[coin_]" and are largely used by taler-exchange-httpd to determine the meta data for the denomination keys. Some of the options are used by the taler-exchange-secmod-rsa to determine which RSA keys to create (and of what key length). Note that the section names must match, so this part of the configuration MUST be shared between the RSA helper and the exchange. Configuration values MUST NOT be changed in a running setup. Instead, if parameters for a denomination type are to change, a fresh section name should be introduced (and the existing section should be deleted).

VALUE: Value of the coin, e.g. “EUR:1.50” for 1 Euro and 50 Cents (per coin).
DURATION_WITHDRAW: How long should the same key be used for clients to withdraw coins of this value?
DURATION_SPEND: How long do clients have to spend these coins?
DURATION_LEGAL: How long does the exchange have to keep records for this denomination?
FEE_WITHDRAW: What fee is charged for withdrawal?
FEE_DEPOSIT: What fee is charged for depositing?
FEE_REFRESH: What fee is charged for refreshing?
FEE_REFUND: What fee is charged for refunds? When a coin is refunded, the deposit fee is returned. Instead, the refund fee is charged to the customer.
CIPHER: What cryptosystem should be used? Must be set to either “CS” or “RSA”. The respective crypto-helper will then generate the keys for this denomination.
RSA_KEYSIZE: What is the RSA keysize modulos (in bits)? Only used if “CIPHER=RSA”.
AGE_RESTRICTED: Setting this option to YES marks the denomination as age restricted (default is NO). For this option to be accepted the extension for age restriction MUST be enabled (see EXCHANGE EXTENSION FOR AGE RESTRICTION).

14.64.2.14. MERCHANT OPTIONS¶

The following options are from the “[merchant]” section and used by the merchant backend.

DB: Plugin to use for the database, e.g._“postgres”.
SERVE: Should the HTTP server listen on a UNIX domain socket (set option to “unix”) or on a TCP socket (set option to “tcp”)?
BASE_URL: Which base URL should the merchant backend assume for itself in the protocol. Optional. If not given, the base URL will be constructed from X-Forwarded-Host, X-Forwarded-Port and X-Forwarded-Prefix headers that a reverse-proxy should be setting.
UNIXPATH: Path to listen on if we “SERVE” is set to “unix”.
UNIXPATH_MODE: Access permission mask to use for the “UNIXPATH”.
PORT: Port on which the HTTP server listens, e.g. 8080.
BIND_TO: Hostname to which the merchant HTTP server should be bound to, e.g. “localhost”.
LEGAL_PRESERVATION: How long do we keep data in the database for tax audits after the transaction has completed? Default is 10 years.
FORCE_AUDIT: Force the merchant to report every transaction to the auditor (if the exchange has an auditor)? Default is NO. Do not change except for testing.

14.64.2.15. MERCHANT POSTGRES BACKEND DATABASE OPTIONS¶

The following options must be in section “[merchantdb-postgres]” if the “postgres” plugin was selected for the database.

CONFIG: How to access the database, e.g. “postgres:///taler” to use the “taler” database. Testcases use “talercheck”.

14.64.2.16. KNOWN EXCHANGES (for merchants)¶

The merchant configuration can include a list of known exchanges if the merchant wants to specify that certain exchanges are explicitly trusted. For each trusted exchange, a section [merchant-exchange-$NAME] must exist, where $NAME is a merchant-given name for the exchange. The following options must be given in each “[exchange-$NAME]” section.

EXCHANGE_BASE_URL: Base URL of the exchange, e.g. “https://exchange.demo.taler.net/”
MASTER_KEY: Crockford Base32 encoded master public key, public version of the exchange’s long-time offline signing key. Can be omitted, in that case the exchange will NOT be trusted unless it is audited by a known auditor. Omitting MASTER_KEY can be useful if we do not trust the exchange without an auditor, but should pre-load the keys of this particular exchange on startup instead of waiting for it to be required by a client.
CURRENCY: Name of the currency for which this exchange is used, e.g. “KUDOS”. The entire section is ignored if the currency does not match the currency we use, which must be given in the [taler] section.
DISABLED: Set to YES to disable this exchange. Optional option, defaults to NO.

14.64.2.17. AUDITOR OPTIONS¶

The following options must be in section “[auditor]” for the Taler auditor.

DB: Plugin to use for the database, e.g. “postgres”
AUDITOR_PRIV_FILE: Name of the file containing the auditor’s private key.
PUBLIC_KEY: Crockford Base32 encoded auditor public key. Used by (online) auditor processes that do not have access to the (offline) auditor private key file.
BASE_URL: Base URL of the auditor, e.g. “https://auditor.demo.taler.net/”
SERVE: Should the HTTP server listen on a UNIX domain socket (set option to “unix”) or on a TCP socket (set option to “tcp”)?
UNIXPATH: Path to listen on if we “SERVE” is set to “unix”.
UNIXPATH_MODE: Access permission mask to use for the “UNIXPATH”.
PORT: Port on which the HTTP server listens, e.g. 8080.
BIND_TO: Hostname to which the merchant HTTP server should be bound to, e.g. “localhost”.

14.64.2.18. AUDITOR POSTGRES BACKEND DATABASE OPTIONS¶

The following options must be in section “[auditordb-postgres]” if the “postgres” plugin was selected for the database.

CONFIG: How to access the database, e.g. “postgres:///taler” to use the “taler” database. Testcases use “talercheck”.

14.64.2.19. Bank Options¶

The following options must be in section “[bank]” for the taler-fakebank-run(1) command. They are not used by the exchange or LibEuFin!

HTTP_PORT: On which TCP port should the (fake)bank offer its REST API.
RAM_LIMIT: This gives the number of transactions to keep in memory. Older transactions will be overwritten and history requests for overwritten transactions will fail.

14.64.2.20. Taler-mdb Options¶

Taler-mdb is a component to run GNU Taler as a payment system on vending machines using the multi-drop bus protocol. These options are thus not useful for most users. Note that right now, the cancel button is hard-coded to be using GPIO pin 23.

ADVERTISEMENT_COMMAND: Program to run while not vending, possibly useful to show advertisements on the screen (optional).
ESSID: ESSID to advertise to wallets for use as an open WiFi to make payments (optional).
FULFILLMENT_MSG: Message shown to users by their wallets upon successful payment. If “${PRODUCT_DESCRIPTION}” appears in the message, it will be replaced with the description of the product that was sold.
BACKEND_BASE_URL: Base URL (possibly including instance) for the Taler merchant backend used to process payments.
BACKEND_AUTHORIZATION: Full HTTP “Authorization” header (usually with a Bearer token) to be send to the merchant backend for authorization of requests. Mandatory.
FRAMEBUFFER_BACKLIGHT: Name of the file used to control brightness of the display. Optional. Defaults to “/sys/class/backlight/soc:backlight/brightness” if not given.
FRAMEBUFFER_DEVICE: Name of the framebuffer device to use. Defaults to “/dev/fb1” if not given.
UART_DEVICE: Name of the UART device to use. Defaults to “/dev/ttyAMA0” if not given.
FAIL_COMMAND: Command to run to display a failure to the user. If not given, errors will not be properly shown.

Each products being sold must be configured in a section where the name starts with “product-“. In these sections, the options that must be provided are:

NUMBER: Number identifying the slot in the vending machine that corresponds to this product.
INSTANCE: Instance to use for the payment. Optional. If not given, the BACKEND_BASE_URL from “[taler-mdb]” will be used.
BACKEND_AUTHORIZATION: Full HTTP “Authorization” header (usually with a Bearer token) to be send to the merchant backend for authorization of requests. Optional, will use global BACKEND_AUTHORIZATION setting from “[taler-mdb]” if missing.
DESCRIPTION: Human-readable description of the product. Use “empty” if the product is known to be sold out (only effective if selling out is enabled via command-line).
PRICE: Actual price of the product, as a Taler amount (“$CURRENCY:$VALUE.$FRACTION”).
KEY: Key used to select the product from the console during testing. Optional.
THUMBNAIL: Name of a filename with a preview image of the product to be given to the wallet. Optional. Only “.png”, “.jpg”, “.jpeg” and “.svg” are supported at this time.

14.64.3. SEE ALSO¶

taler-exchange-dbinit(1), taler-exchange-httpd(1), taler-exchange-offline(1), taler-auditor-offline(1).

14.64.4. BUGS¶

Report bugs by using https://bugs.taler.net/ or by sending electronic mail to <taler@gnu.org>.

14.63. taler-wallet-cli(1)

15. Complete Index