The syslog-ng PE application sends the log messages to the official Elasticsearch client library, which forwards the data to the Elasticsearch nodes. The way how syslog-ng PE interacts with Elasticsearch is described in the following steps.
After syslog-ng PE is started and the first message arrives to the elasticsearch2 destination, the elasticsearch2 destination tries to connect to the Elasticsearch server or cluster. If the connection fails, syslog-ng PE will repeatedly attempt to connect again after the period set in time-reopen() expires.
If the connection is established, syslog-ng PE sends JSON-formatted messages to Elasticsearch.
If flush-limit is set to 1: syslog-ng PE sends the message reliably: it sends a message to Elasticsearch, then waits for a reply from Elasticsearch. In case of failure, syslog-ng PE repeats sending the message, as set in the retries() parameter. If sending the message fails for retries() times, syslog-ng PE drops the message.
This method ensures reliable message transfer, but is slow (about 1000 messages/second).
If flush-limit is higher than 1: syslog-ng PE sends messages in a batch, and receives the response asynchronously. In case of a problem, syslog-ng PE cannot resend the messages.
This method is relatively fast (depending on the size of flush-limit, about 8000 messages/second), but the transfer is not reliable. In transport mode, over 5000-30000 messages can be lost before syslog-ng PE recognizes the error. In node mode, about 1000 messages can be lost.
If concurrent-requests is higher than 1, syslog-ng PE can send multiple batches simultaneously, increasing performance (and also the number of messages that can be lost in case of an error). For details, see concurrent-requests().
Version
The syslog-ng PE application can interact with Elasticsearch in the following modes of operation: node, and transport.
The syslog-ng PE application uses the transport client API of Elasticsearch, and uses the server(), port(), and cluster() options from the syslog-ng PE configuration file.
The syslog-ng PE application acts as an Elasticsearch node (client no-data), using the node client API of Elasticsearch. Further options for the node can be describe in an Elasticsearch configuration file specified in the resource() option.
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NOTE:
In Node mode, it is required to define the home of the elasticsearch installation with the path.home parameter in the .yml file. For example: path.home: /usr/share/elasticsearch. |
The elasticsearch2 destination can directly send log messages to Elasticsearch, allowing you to search and analyze your data in real time, and visualize it with Kibana. The elasticsearch2 destination has the following options.
The following options are required: index(), type(). In node mode, either the cluster() or the resource() option is required as well. Note that to use elasticsearch2, you must add the following lines to the beginning of your syslog-ng PE configuration:
@module mod-java @include "scl.conf"
Type: | string |
Default: | The syslog-ng PE module directory: /opt/syslog-ng/lib/syslog-ng/java-modules/ |
Description: The list of the paths where the required Java classes are located. For example, class-path("/opt/syslog-ng/lib/syslog-ng/java-modules/:/opt/my-java-libraries/libs/"). If you set this option multiple times in your syslog-ng PE configuration (for example, because you have multiple Java-based destinations), syslog-ng PE will merge every available paths to a single list.
Description: Include the path to the directory where you copied the required libraries (see Prerequisites), for example, client_lib_dir(/user/share/elasticsearch-2.2.0/lib).
Type: | transport | node |
Default: | node |
Description: Specifies the client mode used to connect to the Elasticsearch server, for example, client-mode("node").
The syslog-ng PE application uses the transport client API of Elasticsearch, and uses the server(), port(), and cluster() options from the syslog-ng PE configuration file.
The syslog-ng PE application acts as an Elasticsearch node (client no-data), using the node client API of Elasticsearch. Further options for the node can be describe in an Elasticsearch configuration file specified in the resource() option.
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NOTE:
In Node mode, it is required to define the home of the elasticsearch installation with the path.home parameter in the .yml file. For example: path.home: /usr/share/elasticsearch. |
Type: | string |
Default: | N/A |
Description: Specifies the name or the Elasticsearch cluster, for example, cluster("my-elasticsearch-cluster"). Optionally, you can specify the name of the cluster in the Elasticsearch resource file. For details, see resource().
Type: | string |
Default: | N/A |
Description: Specifies the URL or the Elasticsearch cluster, for example, cluster-url("http://192.168.10.10:9200")"). Note that this option works only in HTTP mode: client_mode(http)
Type: | number |
Default: | 0 |
Description: The number of concurrent (simultaneous) requests that syslog-ng PE sends to the Elasticsearch server. Set this option to 1 or higher to increase performance. When using the concurrent-requests() option, make sure that the flush-limit() option is higher than one, otherwise it will not have any noticeable effect. For details, see flush-limit().
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Caution:
Hazard of data loss! Using the concurrent-requests() option increases the number of messages lost in case the Elasticsearch server becomes inaccessible. |
Type: | template or template function |
Default: | N/A |
Description: Use this option to specify a custom ID for the records inserted into Elasticsearch. If this option is not set, the Elasticsearch server automatically generates and ID for the message. For example: custom_id(${UNIQID}) (Note that to use the ${UNIQID} macro, the use-uniqid() global option must be enabled. For details, see use-uniqid().)
Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:
reliable() | |||
Type: | yes|no | ||
Default: | no | ||
Description: If set to yes, syslog-ng PE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng PE crash. This solution provides a slower, but reliable disk-buffer option. It is created and initialized at startup and gradually grows as new messages arrive. If set to no, the normal disk-buffer will be used. This provides a faster, but less reliable disk-buffer option.
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disk-buf-size() | |
Type: | number (bytes) |
Default: | |
Description: This is a required option. The maximum size of the disk-buffer in bytes. The minimum value is 1048576 bytes. If you set a smaller value, the minimum value will be used automatically. It replaces the old log-disk-fifo-size() option. |
mem-buf-length() | |
Type: | number (messages) |
Default: | 10000 |
Description: Use this option if the option reliable() is set to no. This option contains the number of messages stored in overflow queue. It replaces the old log-fifo-size() option. It inherits the value of the global log-fifo-size() option if provided. If it is not provided, the default value is 10000 messages. Note that this option will be ignored if the option reliable() is set to yes. |
mem-buf-size() | |
Type: | number (bytes) |
Default: | 163840000 |
Description: Use this option if the option reliable() is set to yes. This option contains the size of the messages in bytes that is used in the memory part of the disk buffer. It replaces the old log-fifo-size() option. It does not inherit the value of the global log-fifo-size() option, even if it is provided. Note that this option will be ignored if the option reliable() is set to no. |
qout-size() | |
Type: | number (messages) |
Default: | 64 |
Description: The number of messages stored in the output buffer of the destination. Note that if you change the value of this option and the disk-buffer already exists, the change will take effect when the disk-buffer becomes empty. |
Options reliable() and disk-buf-size() are required options.
In the following case reliable disk-buffer() is used.
destination d_demo { network("127.0.0.1" port(3333) disk-buffer( mem-buf-size(10000) disk-buf-size(2000000) reliable(yes) dir("/tmp/disk-buffer") ) ); };
In the following case normal disk-buffer() is used.
destination d_demo { network("127.0.0.1" port(3333) disk-buffer( mem-buf-length(10000) disk-buf-size(2000000) reliable(no) dir("/tmp/disk-buffer") ) ); };
Type: | number |
Default: | 5000 |
Description: The number of messages that syslog-ng PE sends to the Elasticsearch server in a single batch.
If flush-limit is set to 1: syslog-ng PE sends the message reliably: it sends a message to Elasticsearch, then waits for a reply from Elasticsearch. In case of failure, syslog-ng PE repeats sending the message, as set in the retries() parameter. If sending the message fails for retries() times, syslog-ng PE drops the message.
This method ensures reliable message transfer, but is slow (about 1000 messages/second).
If flush-limit is higher than 1: syslog-ng PE sends messages in a batch, and receives the response asynchronously. In case of a problem, syslog-ng PE cannot resend the messages.
This method is relatively fast (depending on the size of flush-limit, about 8000 messages/second), but the transfer is not reliable. In transport mode, over 5000-30000 messages can be lost before syslog-ng PE recognizes the error. In node mode, about 1000 messages can be lost.
If concurrent-requests is higher than 1, syslog-ng PE can send multiple batches simultaneously, increasing performance (and also the number of messages that can be lost in case of an error). For details, see concurrent-requests().
Type: | number |
Default: | 0 |
Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received. Note that syslog-ng can add the fractions to non-ISO8601 timestamps as well.
Type: | none | basic | clientcert |
Default: | none |
Description: Determines how syslog-ng PE authenticates to the Elasticsearch server. Depending on the value of this option, you might have to set other options as well. Possible values:
none: Connect to the Elasticsearch server without authentication.
basic: Use password authentication. Also set the http-auth-type-basic-username and http-auth-type-basic-password options.
clientcert: Use a certificate to authenticate. The certificate must be available in a Java keystore. Also set the java-keystore-filepath and java-keystore-password options.
This option is used only in HTTPS mode: client_mode("https"), and is available in syslog-ng PE version
The following simple examples show the different authentication modes.
Simple password authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("basic") http-auth-type-basic-username("example-username") http-auth-type-basic-password("example-password") ); };
Certificate authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("clientcert") java-keystore-filepath("<path-to-your-java-keystore>.jks") java-keystore-password("password-to-your-keystore") ); };
Verify the certificate of the Elasticsearch server without authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("none") java-truststore-filepath("<path-to-your-java-keystore>.jks") java-truststore-password("password-to-your-keystore") ); };
Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng PE client and the Elasticsearch server):
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("clientcert") java-keystore-filepath("<path-to-your-java-keystore>.jks") java-keystore-password("password-to-your-keystore") java-truststore-filepath("<path-to-your-java-keystore>.jks") java-truststore-password("password-to-your-keystore") ); };
Type: | string |
Default: | N/A |
Description: The password to use for password-authentication on the Elasticsearch server. You must also set the http-auth-type-basic-username option.
This option is used only in HTTPS mode with basic authentication: client_mode("https") and http-auth-type("basic"), and is available in syslog-ng PE version
Simple password authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("basic") http-auth-type-basic-username("example-username") http-auth-type-basic-password("example-password") ); };
Type: | string |
Default: | N/A |
Description: The username to use for password-authentication on the Elasticsearch server. You must also set the http-auth-type-basic-password option.
This option is used only in HTTPS mode with basic authentication: client_mode("https") and http-auth-type("basic"), and is available in syslog-ng PE version
Simple password authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("basic") http-auth-type-basic-username("example-username") http-auth-type-basic-password("example-password") ); };
Type: | string |
Default: | N/A |
Description: Name of the Elasticsearch index to store the log messages. You can use macros and templates as well. For example, index("syslog-ng_${YEAR}.${MONTH}.${DAY}").
Type: | string |
Default: | N/A |
Description: Path to the Java keystore file that stores the certificate that syslog-ng PE uses to authenticate on the Elasticsearch server. You must also set the java-keystore-password option.
To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:
keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>
This option is used only in HTTPS mode with basic authentication: client_mode("https") and http-auth-type("clientcert"), and is available in syslog-ng PE version
Certificate authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("clientcert") java-keystore-filepath("<path-to-your-java-keystore>.jks") java-keystore-password("password-to-your-keystore") ); };
Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng PE client and the Elasticsearch server):
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("clientcert") java-keystore-filepath("<path-to-your-java-keystore>.jks") java-keystore-password("password-to-your-keystore") java-truststore-filepath("<path-to-your-java-keystore>.jks") java-truststore-password("password-to-your-keystore") ); };
Type: | string |
Default: | N/A |
Description: The password of the Java keystore file set in the java-keystore-filepath option.
To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:
keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>
This option is used only in HTTPS mode with basic authentication: client_mode("https") and http-auth-type("clientcert"), and is available in syslog-ng PE version
Certificate authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("clientcert") java-keystore-filepath("<path-to-your-java-keystore>.jks") java-keystore-password("password-to-your-keystore") ); };
Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng PE client and the Elasticsearch server):
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("clientcert") java-keystore-filepath("<path-to-your-java-keystore>.jks") java-keystore-password("password-to-your-keystore") java-truststore-filepath("<path-to-your-java-keystore>.jks") java-truststore-password("password-to-your-keystore") ); };
Type: | string |
Default: | N/A |
Description: Path to the Java keystore file that stores the CA certificate that syslog-ng PE uses to verify the certificate of the Elasticsearch server. You must also set the java-truststore-password option.
If you do not set the java-truststore-filepath option, syslog-ng PE does accepts any certificate that the Elasticsearch server shows. In this case, the identity of the server is not verified, only the connection is encrypted.
To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:
keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>
This option is used only in HTTPS mode: client_mode("https"), and is available in syslog-ng PE version
Verify the certificate of the Elasticsearch server without authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("none") java-truststore-filepath("<path-to-your-java-keystore>.jks") java-truststore-password("password-to-your-keystore") ); };
Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng PE client and the Elasticsearch server):
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("clientcert") java-keystore-filepath("<path-to-your-java-keystore>.jks") java-keystore-password("password-to-your-keystore") java-truststore-filepath("<path-to-your-java-keystore>.jks") java-truststore-password("password-to-your-keystore") ); };
Type: | string |
Default: | N/A |
Description: The password of the Java truststore file set in the java-truststore-filepath option.
To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:
keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>
This option is used only in HTTPS mode: client_mode("https"), and is available in syslog-ng PE version
Verify the certificate of the Elasticsearch server without authentication:
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("none") java-truststore-filepath("<path-to-your-java-keystore>.jks") java-truststore-password("password-to-your-keystore") ); };
Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng PE client and the Elasticsearch server):
destination d_elastic { elasticsearch2( client-mode("https") cluster("es-syslog-ng") index("x201") cluster-url("http://192.168.33.10:9200") type("slng_test_type") flush-limit("0") http-auth-type("clientcert") java-keystore-filepath("<path-to-your-java-keystore>.jks") java-keystore-password("password-to-your-keystore") java-truststore-filepath("<path-to-your-java-keystore>.jks") java-truststore-password("password-to-your-keystore") ); };
Type: | list |
Default: | N/A |
Description: Specify the Java Virtual Machine (JVM) settings of your Java destination from the syslog-ng PE configuration file.
For example:
jvm-options("-Xss1M -XX:+TraceClassLoading")
You can set this option only as a global option, by adding it to the options statement of the syslog-ng configuration file.
Type: | number |
Default: | Use global setting. |
Description: The number of messages that the output queue can store.
Accepted values: |
drop-message|drop-property|fallback-to-string| silently-drop-message|silently-drop-property|silently-fallback-to-string |
Default: | Use the global setting (which defaults to drop-message) |
Description: Controls what happens when type-casting fails and syslog-ng PE cannot convert some data to the specified type. By default, syslog-ng PE drops the entire message and logs the error. Currently the value-pairs() option uses the settings of on-error().
drop-message: Drop the entire message and log an error message to the internal() source. This is the default behavior of syslog-ng PE.
drop-property: Omit the affected property (macro, template, or message-field) from the log message and log an error message to the internal() source.
fallback-to-string: Convert the property to string and log an error message to the internal() source.
silently-drop-message: Drop the entire message silently, without logging the error.
silently-drop-property: Omit the affected property (macro, template, or message-field) silently, without logging the error.
silently-fallback-to-string: Convert the property to string silently, without logging the error.
Type: | number |
Default: | 9300 |
Description: The port number of the Elasticsearch server. This option is used only in transport mode: client-mode("transport")
Type: | number (of attempts) |
Default: | 3 |
Description: The number of times syslog-ng PE attempts to send a message to this destination. If syslog-ng PE could not send a message, it will try again until the number of attempts reaches retries, then drops the message.
Type: | string |
Default: | N/A |
Description: The list of Elasticsearch resources to load, separated by semicolons. For example, resource("/home/user/elasticsearch/elasticsearch.yml;/home/user/elasticsearch/elasticsearch2.yml").
Type: | list of hostnames |
Default: | 127.0.0.1 |
Description: Specifies the hostname or IP address of the Elasticsearch server. When specifying an IP address, IPv4 (for example, 192.168.0.1) or IPv6 (for example, [::1]) can be used as well. When specifying multiple addresses, use space to separate the addresses, for example, server("127.0.0.1 remote-server-hostname1 remote-server-hostname2")
This option is used only in transport mode: client_mode("transport")
In version
For example:
destination d_elasticsearch { elasticsearch2( client-lib-dir("/usr/share/elasticsearch/lib/") index("syslog-${YEAR}.${MONTH}.${DAY}") type("syslog") time-zone("UTC") client_mode("http") server("node01 node02") port(9200) ); };
Type: | yes|no |
Default: | no |
Description: By default, when connecting to an Elasticsearch cluster, syslog-ng PE checks the state of the cluster. If the primary shards of the cluster are not active, syslog-ng PE will not send messages, but wait for them to become active. To disable this health check and send the messages to Elasticsearch anyway, use the skip-cluster-health-check(yes) option in your configuration.
Type: | template or template function |
Default: | $(format-json --scope rfc5424 --exclude DATE --key ISODATE @timestamp=${ISODATE}) |
Description: The message as sent to the Elasticsearch server. Typically, you will want to use the command-line notation of the format-json template function.
To add a @timestamp field to the message, for example, to use with Kibana, include the @timestamp=${ISODATE} expression in the template. For example: template($(format-json --scope rfc5424 --exclude DATE --key ISODATE @timestamp=${ISODATE}))
For details on formatting messages in JSON format, see format-json.
Type: | number |
Default: | 0 |
Description: Sets the maximum number of messages sent to the destination per second. Use this output-rate-limiting functionality only when using disk-buffer as well to avoid the risk of losing messages. Specifying 0 or a lower value sets the output limit to unlimited.
Type: | name of the timezone, or the timezone offset |
Default: | unspecified |
Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see Date-related macros.
The timezone can be specified as using the name of the (for example time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format (for example +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.
Version
Type: | rfc3164, bsd, rfc3339, iso |
Default: | rfc3164 |
Description: Override the global timestamp format (set in the global ts-format() parameter) for the specific destination. For details, see ts-format().
The file driver is one of the most important destination drivers in syslog-ng. It allows to output messages to the specified text file, or to a set of files.
The destination filename may include macros which get expanded when the message is written, thus a simple file() driver may create several files: for example, syslog-ng PE can store the messages of client hosts in a separate file for each host. For more information on available macros see Macros of syslog-ng PE.
If the expanded filename refers to a directory which does not exist, it will be created depending on the create-dirs() setting (both global and a per destination option).
The file() has a single required parameter that specifies the filename that stores the log messages. For the list of available optional parameters, see file() destination options.
file(filename options());
destination d_file { file("/var/log/${YEAR}.${MONTH}.${DAY}/messages" template("${HOUR}:${MIN}:${SEC} ${TZ} ${HOST} [${LEVEL}] ${MESSAGE}\n") template-escape(no) ); };
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NOTE:
When using this destination, update the configuration of your log rotation program to rotate these files. Otherwise, the log files can become very large. Also, after rotating the log files, reload syslog-ng PE using the syslog-ng-ctl reload command, or use another method to send a SIGHUP to syslog-ng PE. |
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Caution:
Since the state of each created file must be tracked by syslog-ng, it consumes some memory for each file. If no new messages are written to a file within 60 seconds (controlled by the time-reap() global option), it is closed, and its state is freed. Exploiting this, a DoS attack can be mounted against the system. If the number of possible destination files and its needed memory is more than the amount available on the syslog-ng server. The most suspicious macro is ${PROGRAM}, where the number of possible variations is rather high. Do not use the ${PROGRAM} macro in insecure environments. |
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