Syslog BOSH Release

This is a BOSH release to forward local syslog events in RFC5424 format to a remote syslog endpoint. It currently uses RSYSLOG, which is pre-installed by the stemcell, and blackbox.

There is a separate release to accomplish this on Windows stemcells, which uses blackbox, but not RSYSLOG.

If you have any questions, or want to get attention for a PR or issue please reach out on the #logging-and-metrics channel in the cloudfoundry slack

Usage
Format
Tech Notes
Development

Usage

Download the latest release from bosh.io and include it in your manifest:

releases:
- name: syslog
  version: latest

If you are deploying Cloud Foundry using cf-deployment, there is an ops-file available that will add the syslog release and syslog_forwarder job, and expose configuration variables.

Otherwise, you can co-locate and configure the syslog_forwarder job yourself.

Configure Forwarding

Add the syslog_forwarder job to an instance group to forward all local syslog messages to a syslog endpoint. Configure address and, optionally, port and transport:

instance_groups:
- name: some-instance-group
  jobs:
  - name: syslog_forwarder
    release: syslog
    properties:
    syslog:
      address: <IP or hostname>

By default, if the syslog endpoint is unavailable, messages will be queued. Alternatively, configure fallback_servers for higher availability. Only TCP or RELP are supported for fallback functionality:

properties:
  syslog:
    address: 10.10.10.100
    fallback_servers:
    - address: 10.10.10.101
    - address: 10.10.10.102

TLS is supported with additional properties. The following example forwards syslog messages to papertrail:

properties:
  syslog:
    address: logs4.papertrailapp.com
    port: 12345
    transport: tcp
    tls_enabled: true
    permitted_peer: "*.papertrailapp.com"
    ca_cert: |
      -----BEGIN CERTIFICATE-----
      MIIFdDCCBFygAwIBAgIQJ2buVutJ846r13Ci/ITeIjANBgkqhkiG9w0BAQwFADBv
      ...
      pu/xO28QOG8=
      -----END CERTIFICATE-----
      -----BEGIN CERTIFICATE-----
      MIIENjCCAx6gAwIBAgIBATANBgkqhkiG9w0BAQUFADBvMQswCQYDVQQGEwJTRTEU
      ...
      mnkPIAou1Z5jJh5VkpTYghdae9C8x49OhgQ=
      -----END CERTIFICATE-----

Alternatively, if the intended syslog recipient’s certificate is signed by any Certificate Authority in the BOSH instances’ cert store (most common CAs are included on the stemcell), you can omit the ca_cert field entirely.

If you do include ca_cert, please note that the standard cert store will no longer be referenced. This necessitates including the entire certificate chain.

Message Size Limits

By default, the maximum size of the message is 8kB, but it can be configured up to 99,990B (which is a limitation of the blackbox). If you are using UDP as your communication protocol, you will be limited by that protocol (1kB).

properties:
  syslog:
    max_message_size: 4k

Custom Rule

This release allows a custom rule to be inserted before the rule that accomplishes log forwarding. This can be useful if you only wish to forward certain logs, or if there is a certain type of log you wish to exclude from forwarding.

We have some simple documentation with a few example rules in example-custom-rules.md.

Please note: if your custom rule is invalid, the pre-start script will fail.

Test Store

The syslog_storer is meant for testing. Deploy it and configure your instances to forward logs to it. It provides a BOSH link that the forwarder consumes, so if they are deployed together and the forwarder is otherwise unconfigured, logs should be sent to the storer. It should not be co-located with other jobs which also try to configure syslog. Received logs are stored in /var/vcap/store/syslog_storer/syslog.log.

You can add it to a deployment manifest very simply:

instance_groups:
- name: syslog_storer
  jobs:
  - name: syslog_storer
    release: syslog

Remember to allow inbound traffic on TCP port 514 in your IaaS security groups.

The storer can also be used to test TLS connections. If you provide a Certificate to the syslog.tls properties, you can receive tls messages. You will need to explicitly configure this cert as trusted on the forwarder.

You can also configure the maximum message size of the test store, which is defaulted to 8k using syslog.max_message_size.

Format

This release forwards messages using the RFC5424 standard, which is natively supported by most log platforms.

Forwarded messages are annotated with structured data. The Structured Data ID is instance@47450, which is intended to allow parsing rules specific to the structured data emitted by BOSH instances using this release. (The 47450 is our private enterprise number.) The structured data contains the following fields:

director
deployment
availability zone
instance group
instance ID

The structured data may also contain an optional environment field if provided by the operator.

The whole thing looks something like this:

<$PRI>$VERSION $TIMESTAMP $HOST $APP_NAME $PROC_ID $MSG_ID [instance@47450 director="$DIRECTOR" deployment="$DEPLOYMENT" group="$INSTANCE_GROUP" az="$AVAILABILITY_ZONE" id="$ID"] $MESSAGE

Here are a couple of example messages from diego:

<14>1 2017-01-25T13:25:03.18377Z 192.0.2.10 etcd cloudfoundry-blackbox - [instance@47450 director="test-env" deployment="cf" group="diego_database" az="us-west1-a" id="83bd66e5-3fdf-44b7-bdd6-508deae7c786"] [INFO] the leader is [https://diego-database-0.etcd.service.cf.internal:4001]
<14>1 2017-01-25T13:25:03.184491Z 192.0.2.10 bbs cloudfoundry-blackbox - [instance@47450 director="test-env" deployment="cf" group="diego_database" az="us-west1-a" id="83bd66e5-3fdf-44b7-bdd6-508deae7c786"] {"timestamp":"1485350702.539694548","source":"bbs","message":"bbs.request.start-actual-lrp.starting","log_level":1,"data":{"actual_lrp_instance_key":{"instance_guid":"271f71c7-4119-4490-619f-4f44694717c0","cell_id":"diego_cell-2-41f21178-d619-4976-901c-325bc2d0d11d"},"actual_lrp_key":{"process_guid":"1545ce89-01e6-4b8f-9cb1-5654a3ecae10-137e7eb4-12de-457d-8e3e-1258e5a74687","index":5,"domain":"cf-apps"},"method":"POST","net_info":{"address":"192.0.2.12","ports":[{"container_port":8080,"host_port":61532},{"container_port":2222,"host_port":61533}]},"request":"/v1/actual_lrps/start","session":"418.1"}}

Note: the cloudfoundry-blackbox PROC_ID in the above indicates that the logs have been forwarded from a file by blackbox.

A sample logstash config with filters to extract instance metadata is in examples/logstash-filters.conf.

Tech Notes

RSYSLOG is a system for log processing; it is a drop-in replacement for the UNIX’s venerable syslog. RSYSLOG can be configured as a storer (i.e. it receives log messages from other hosts) or a forwarder (i.e. it forwards system log messages to RSYSLOG storers, syslog servers, or log aggregation services).

The default RSYSLOG configuration file is /etc/rsyslog.conf. On the stemcell, this specifies that configuration in/etc/rsyslog.d/* will also be respected. The RSYSLOG forwarder’s customizations are rendered into several files following the format /etc/rsyslog.d/[0-9][0-9]-syslog-release-*.conf.

Note: syslog-release deletes files in its pattern, and /etc/rsyslog.d/rsyslog.conf, a legacy config location, during prestart.

Blackbox is used for forwarding from files. It was historically an experiment by the Concourse team, but now it’s just used to forward logs from files.

RSYSLOG itself might be able to do this at some point in the future. The current version of rsyslog does not sufficiently support wildcards for our use-case, but it may be worth further exploring in the future.

Development

In order to build releases or run tests, you will need to initialize and update the blackbox submodule:

git submodule update --init --recursive

There’s a suite of acceptance tests in the tests/ directory. To use them, you will need to install Go.

Note that the go.mod and go.sum files in this repo are only for the test code.

The tests expect that your local environment has the BOSH CLI installed and configured correctly to point to a BOSH Director.

The tests can then be run from the top of the repo with ./scripts/test.

For more details, see tests/README.md.

We are unlikely to merge PRs that add features without tests.