Cryostat

A container-native JVM application which acts as a bridge to other containerized JVMs and exposes a secure API for producing, analyzing, and retrieving JDK Flight Recorder data from your cloud workloads.

SEE ALSO

• cryostat-core : the core library providing a convenience wrapper and headless stubs for use of JFR using JDK Mission Control internals.

• cryostat-operator : an OpenShift Operator deploying Cryostat in your OpenShift cluster as well as exposing the Cryostat API as Kubernetes Custom Resources.

• cryostat-web : the React frontend included as a submodule in Cryostat and built into Cryostat's (non-headless mode) OCI images.

• JDK Mission Control for the original JDK Mission Control, which is the desktop application complement to JFR. Some parts of JMC are borrowed and re-used to form the basis of Cryostat. JMC is still a recommended tool for more full-featured analysis of JFR files beyond what Cryostat currently implements.

REQUIREMENTS

Build Requirements:

• Git
• JDK17+
• Maven 3+
• Podman 2.0+

Run Requirements:

• Kubernetes/OpenShift/Minishift, Podman/Docker, or other container platform

BUILD

Setup Dependencies

• Clone and install cryostat-core via it's instructions
• Initialize submodules via: git submodule init && git submodule update

Build project locally

• mvn compile

Build and run project locally in development hot-reload mode

• sh devserver.sh - this will start the Vert.x backend in hot-reload mode, so any modifications to files in src/ will cause a re-compilation and re-deploy. This is only intended for use during development. The web-client assets will not be built and will not be included in the application classpath. To set up the web-client frontend for hot-reload development, see cryostat-web Development Server.

Build and push to local podman image registry

• mvn package
• Run mvn -Dheadless=true clean package to exclude web-client assets. The clean phase should always be specified here, or else previously-generated client assets will still be included into the built image.
• For other OCI builders, use the imageBuilder Maven property. For example, to use docker, run: mvn -DimageBuilder=$(which docker) clean verify

TEST

Unit tests

• mvn test

Integration tests and analysis tools

• mvn verify

Skipping tests

• -DskipUTs=true to skip unit tests
• -DskipITs=true to skip integration tests
• -DskipTests=true to skip all tests

Running integration tests without rebuild

• mvn exec:exec@create-pod exec:exec@start-jfr-datasource exec:exec@start-grafana-dashboard exec:exec@start-container exec:exec@wait-for-container failsafe:integration-test exec:exec@stop-jfr-datasource exec:exec@stop-grafana exec:exec@stop-container exec:exec@destroy-pod
• or bash repeated-integration-tests.sh 1.

RUN

Run on Kubernetes/Openshift

• See the cryostat-operator

Run on local podman*

• run.sh

Run on local podman with Grafana, jfr-datasource and demo application*

• smoketest.sh

*To run on local podman, cgroups v2 should be enabled. This allows resource configuration for any rootless containers running on podman. To ensure podman works with cgroups v2, follow these instructions.

*Requires xpath to be available on your $PATH - ex. dnf install perl-XML-XPath.

Note: If your podman runtime is set to runc v1.0.0-rc91 or later it is not necessary to change it to crun as recommended in the instructions, since this version of runc supports cgroups v2. The article refers to an older version of runc.

CONFIGURATION

Cryostat can be configured via the following environment variables:

Configuration for cryostat

• CRYOSTAT_WEB_HOST: the hostname used by the cryostat web server. Defaults to reverse-DNS resolving the host machine's hostname.
• CRYOSTAT_WEB_PORT: the internal port used by the cryostat web server. Defaults to 8181.
• CRYOSTAT_EXT_WEB_PORT: the external port used by the cryostat web server. Defaults to be equal to CRYOSTAT_WEB_PORT.
• CRYOSTAT_CORS_ORIGIN: the origin for CORS to load a different cryostat-web instance. Defaults to the empty string, which disables CORS.
• CRYOSTAT_MAX_WS_CONNECTIONS: the maximum number of websocket client connections allowed (minimum 1, maximum Integer.MAX_VALUE, default Integer.MAX_VALUE)
• CRYOSTAT_AUTH_MANAGER: the authentication/authorization manager used for validating user accesses. See the USER AUTHENTICATION / AUTHORIZATION section for more details. Set to the fully-qualified class name of the auth manager implementation to use, ex. io.cryostat.net.BasicAuthManager. Defaults to an AuthManager corresponding to the selected deployment platform, whether explicit or automatic (see below).
• CRYOSTAT_PLATFORM: the platform client used for performing platform-specific actions, such as listing available target JVMs. If CRYOSTAT_AUTH_MANAGER is not specified then a default auth manager will also be selected corresponding to the platform, whether that platform is specified by the user or automatically detected. Set to the fully-qualified name of the platform detection strategy implementation to use, ex. io.cryostat.platform.internal.KubeEnvPlatformStrategy.
• CRYOSTAT_ENABLE_JDP_BROADCAST: enable the Cryostat JVM to broadcast itself via JDP (Java Discovery Protocol). Defaults to true.
• CRYOSTAT_JDP_ADDRESS: the JDP multicast address to send discovery packets. Defaults to 224.0.23.178.
• CRYOSTAT_JDP_PORT: the JDP multicast port to send discovery packets. Defaults to 7095.
• CRYOSTAT_CONFIG_PATH: the filesystem path for the configuration directory. Defaults to /opt/cryostat.d/conf.d.

Configuration for Automated Analysis Reports

• CRYOSTAT_REPORT_GENERATION_MAX_HEAP: the maximum heap size used by the container subprocess which forks to perform automated rules analysis report generation. The default is 200, representing a 200MiB maximum heap size. Too small of a heap size will lead to report generation failing due to Out-Of-Memory errors. Too large of a heap size may lead to the subprocess being forcibly killed and the parent process failing to detect the reason for the failure, leading to inaccurate failure error messages and API responses.

Configuration for JMX Cache

• CRYOSTAT_TARGET_CACHE_SIZE: the maximum number of JMX connections to cache. Use -1 for an unlimited cache size (TTL expiration only). Defaults to -1.
• CRYOSTAT_TARGET_CACHE_TTL: the time to live (in seconds) for cached JMX connections. Defaults to 10.

Configuration for Logging

• CRYOSTAT_JUL_CONFIG : the java.util.logging.config.file configuration file for logging via SLF4J Some of Cryostat's dependencies also use java.util.logging for their logging. Cryostat disables some of these by default, because they generate unnecessary logs. However, they can be reenabled by overriding the default configuration file and setting the disabled loggers to the desired level.

Configuration for Event Templates

• CRYOSTAT_TEMPLATE_PATH: the storage path for Cryostat event templates

Configuration for Archiving

• CRYOSTAT_ARCHIVE_PATH: the storage path for archived recordings

MONITORING APPLICATIONS

In order for cryostat to be able to monitor JVM application targets the targets must have RJMX enabled. cryostat has several strategies for automatic discovery of potential targets. Each strategy will be tested in order until a working strategy is found.

The primary target discovery mechanism uses the OpenShift/Kubernetes API to list service endpoints and expose all discovered services as potential targets. This is runtime dynamic, allowing cryostat to discover new services which come online after cryostat, or to detect when known services disappear later. This requires the cryostat pod to have authorization to list services within its own namespace.

The secondary target discovery mechanism is based on Kubernetes environment variable service discovery. In this mode, environment variables available to cryostat (note: environment variables are set once at process creation - this implies that this method of service discovery is static after startup) are examined for the form FOO_PORT_1234_TCP_ADDR=127.0.0.1. Such an environment variable will cause the discovery of a target at address 127.0.0.1, aliased as foo, listening on port 1234.

Finally, if no supported platform is detected, then cryostat will fall back to the JDP (Java Discovery Protocol) mechanism. This relies on target JVMs being configured with the JVM flags to enable JDP and requires the targets to be reachable and in the same subnet as cryostat. JDP can be enabled by passing the flag "-Dcom.sun.management.jmxremote.autodiscovery=true" when starting target JVMs; for more configuration options, see this document . Once the targets are properly configured, cryostat will automatically discover their JMX Service URLs, which includes the RJMX port number for that specific target.

To enable RJMX on port 9091, the following JVM flag should be passed at target startup:

    '-Dcom.sun.management.jmxremote.port=9091'

The port number 9091 is arbitrary and may be configured to suit individual deployments, so long as the port property above matches the desired port number and the deployment network configuration allows connections on the configured port.

Additionally, the following flags are recommended to enable JMX authentication and connection encryption:

-Dcom.sun.management.jmxremote.authenticate=true # enable JMX authentication
-Dcom.sun.management.jmxremote.password.file=/app/resources/jmxremote.password # define users for JMX auth
-Dcom.sun.management.jmxremote.access.file=/app/resources/jmxremote.access # set permissions for JMX users
-Dcom.sun.management.jmxremote.ssl=true # enable JMX SSL
-Dcom.sun.management.jmxremote.registry.ssl=true # enable JMX registry SSL
-Djavax.net.ssl.keyStore=/app/resources/keystore # set your SSL keystore
-Djavax.net.ssl.keyStorePassword=somePassword # set your SSL keystore password

JMX Connectors

Cryostat supports end-user target applications using other JMX connectors than RMI (for example, WildFly remote+http) using "client library" configuration. The path pointed to by the environment variable CRYOSTAT_CLIENTLIB_PATH is appended to Cryostat's classpath. This path should be a directory within a volume mounted to the Cryostat container and containing library JARs (ex. jboss-client.jar) in a flat structure.

EVENT TEMPLATES

JDK Flight Recorder has event templates, which are preset definition of a set of events, and for each a set of options and option values. A given JVM is likely to have some built-in templates ready for use out-of-the-box, but Cryostat also hosts its own small catalog of templates within its own storage. This catalog is stored at the path specified by the environment variable CRYOSTAT_TEMPLATE_PATH. Templates can be uploaded to Cryostat and then used to create recordings.

ARCHIVING RECORDINGS

cryostat supports a concept of "archiving" recordings. This simply means taking the contents of a recording at a point in time and saving these contents to a file to the cryostat process (as opposed to "active" recordings, which exist within the memory of the JVM target and continue to grow over time). The default directory used is /flightrecordings, but the environment variable CRYOSTAT_ARCHIVE_PATH can be used to specify a different path. To enable cryostat archive support ensure that the directory specified by CRYOSTAT_ARCHIVE_PATH (or /flightrecordings if not set) exists and has appropriate permissions. cryostat will detect the path and enable related functionality. run.sh has an example of a tmpfs volume being mounted with the default path and enabling the archive functionality.

SECURING COMMUNICATION CHANNELS

To specify the SSL certificate for HTTPS/WSS and JMX, one can set KEYSTORE_PATH to point to a .jks, .pfx or .p12 certificate file and KEYSTORE_PASS to the plaintext password to such a keystore. Alternatively, one can set KEY_PATH to a PEM encoded key file and CERT_PATH to a PEM encoded certificate file.

In the absence of these environment variables, cryostat will look for a certificate at the following locations, in an orderly fashion:

• $HOME/cryostat-keystore.jks (used together with KEYSTORE_PASS)
• $HOME/cryostat-keystore.pfx (used together with KEYSTORE_PASS)
• $HOME/cryostat-keystore.p12 (used together with KEYSTORE_PASS)
• $HOME/cryostat-key.pem and $HOME/cryostat-cert.pem

If no certificate can be found, cryostat will autogenerate a self-signed certificate and use it to secure HTTPS/WSS and JMX connections.

If HTTPS/WSS (SSL) and JMX auth credentials must be disabled then the environment variables CRYOSTAT_DISABLE_SSL=true and/or CRYOSTAT_DISABLE_JMX_AUTH=true can be set.

In case cryostat is deployed behind an SSL proxy, set the environment variable CRYOSTAT_SSL_PROXIED to a non-empty value. This informs cryostat that the URLs it reports pointing back to itself should use the secure variants of protocols, even though it itself does not encrypt the traffic. This is only required if Cryostat's own SSL is disabled as above.

If the certificate used for SSL-enabled Grafana/jfr-datasource connections is self-signed or otherwise untrusted, set the environment variable CRYOSTAT_ALLOW_UNTRUSTED_SSL to permit uploads of recordings.

Target JVMs with SSL enabled on JMX connections are also supported. In order to allow Cryostat to establish a connection, the target's certificate must be copied into Cryostat's /truststore directory before Cryostat's startup. If Cryostat attempts to connect to an SSL-enabled target and no matching trusted certificate is found then the connection attempt will fail.

USER AUTHENTICATION / AUTHORIZATION

Cryostat has multiple authz manager implementations for handling user authentication and authorization against various platforms and mechanisms. This can be controlled using an environment variable (see the RUN section above), or automatically using platform detection.

In all scenarios, the presence of an auth manager (other than NoopAuthManager) causes Cryostat to expect a token or credentials via an Authorization header on all potentially sensitive requests, ex. recording creations and downloads, report generations.

The OpenShiftPlatformClient.OpenShiftAuthManager uses token authentication. These tokens are passed through to the OpenShift API for authz and this result determines whether Cryostat accepts the request.

The BasicAuthManager uses basic credential authentication configured with a standard Java properties file at $CRYOSTAT_CONFIG_PATH/cryostat-users.properties. The credentials stored in the Java properties file are the user name and a SHA-256 sum hex of the user's password. The property file contents should look like:

user1=abc123
user2=def987

Where abc123 and def987 are substituted for the SHA-256 sum hexes of the desired user passwords. These can be obtained by ex. echo -n PASS | sha256sum | cut -d' ' -f1'.

Token-based auth managers expect an HTTP Authorization: Bearer TOKEN header and a Sec-WebSocket-Protocol: base64url.bearer.authorization.cryostat.${base64(TOKEN)} WebSocket SubProtocol header. The token is never stored in any form, only kept in-memory long enough to process the external token validation.

Basic credentials-based auth managers expect an HTTP Authorization: Basic ${base64(user:pass)} header and a Sec-WebSocket-Protocol: basic.authorization.cryostat.${base64(user:pass)} WebSocket SubProtocol header.

If no appropriate auth manager is configured or can be automatically determined then the fallback is the NoopAuthManager, which does no external validation calls and simply accepts any provided token or credentials.

INCOMING JMX CONNECTION AUTHENTICATION

JMX connections into cryostat are secured using the default username "cryostat" and a randomly generated password. The environment variables CRYOSTAT_RJMX_USER and CRYOSTAT_RJMX_PASS can be used to override the default username and specify a password.