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Logtrain

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Overview

Logtrain is a system for dynamically forwarding and transforming logs, similar to fluentd but a bit more specialized to solve two issues...

  1. Have very low overhead (e.g., less than 64Mi)
  2. Dynamically route logs based on various data sources.

Drain Types

Elastic Search

  • es+https://user:password@host?[auth=apikey|bearer|basic]&[index=...]&[insecure=true]
  • es+http://user:password@host?[auth=apikey|bearer|basic]&[index=...]&[insecure=true]

The bearer token is taken from the password portion of the url. Api keys the API id should be used as the username and the API key should be the password. Setting insecure=true ignores certificate failures

Http

  • http://host/path
  • https://host/path?[insecure=true]

Setting insecure=true ignores certificate failures

Syslog

  • syslog+tls://host:port?[ca=]
  • syslog+http://host:port
  • syslog+https://host:port
  • syslog+tcp://host:port
  • syslog+udp:// (aliases, syslog://)

Persistent

  • persistent://key

Persistent storage will fail if persistent storage is not configured (see below). The key may be any value up to 128 characters. The persistent key may only be used on finite resources such as Pods, and cannot be set on deployments, statefulsets, etc.

Using Logtrain API

TODO

Using Logtrain with Kubernetes

Running in Kubernetes

Below is the recommended way of deploying Log Train. Note that this must run as a privileged container, so that it can read files from /var/log/containers. The daemonset also contains an initContainer that will change the sysctl fs.inotify.max_user_instances to 2048 on your nodes (usually from 128).

kubectl apply -f ./deployments/kubernetes/logtrain-serviceaccount.yaml
kubectl apply -f ./deployments/kubernetes/logtrain-service.yaml
kubectl apply -f ./deployments/kubernetes/logtrain-daemonset.yaml

Adding drains in Kubernetes

Once deployed you can use the following annotations on deployments, daemonsets or statefulsets to forward logs.

logtrain.akkeris.io/drains

This annoation is a comma delimited list of drains (See Drain Types above).

logtrain.akkeris.io/hostname

Explicitly set the hostname used when reading in logs from kubernetes, if not set this will default to the name.namespace.

logtrain.akkeris.io/tag

Explicitly set the tag when reading in logs from kuberntes, if not set this will default to the pod name.

Using Logtrain with Servers

TODO

Advanced Configuration

General

  • HTTP_PORT - The port to use for the http server, shared by any http (payload) and http (syslog) inputs.

Postgres (datasource)

Whether to watch a postgres database for information on where to foward logs to.

  • POSTGRES - set to true
  • DATABASE_URL - The database url to use to listen for drain changes.

Kubernetes (datasource)

Whether to watch kubernetes deployments, statefulsets and daemonsets for annotations indicating where logs should be forwarded to.

  • KUBERNETES_DATASOURCE - set to true

Persistent Log Storage

Persistent log storage can be done via a postgres database. Set PERSISTENT_DATABASE_URL to specify the database to store logs in. Logs stored can be retrieved directly through the database in the table logs.data with the key being logs.id column. In addition, logs persisted can be retrieved via the /logs/:key.

  • PERSISTENT - set to true
  • PERSISTENT_DATABASE_URL - A postgres database to store logs in the format of postgres://user:pass@host:5432/dbname.
  • PERSISTENT_PATH - The path on the http end point to respond to log requests, defaults to /logs/

Kubernetes

Whether to watch the KUBERNETES_LOG_PATH directory for pod logs and forward them.

  • KUBERNETES - set to true
  • KUBERNETES_LOG_PATH - optional, the path on each node to look for logs. Defaults to /var/log/containers
  • EXCLUDE_NAMESPACES - optional, a comma separated list of namespaces to ignore

Envoy/Istio

Whether to open a gRPC access log stream end point for istio/envoy to stream http log traffic to.

  • ENVOY - set to true
  • ENVOY_PORT - The port number to listen for gRPC access log streams (default is 9001)

Http (events)

  • HTTP_EVENTS - set to true
  • HTTP_EVENTS_PATH - optional, The path on the http server to receive http event payloads, defaults to /events

Note, the port is inherited from HTTP_PORT. The endpoint only allows one per event over the body and must be the format defined by pkg/output/packet/packet.go.

Syslog (HTTP)

  • HTTP_SYSLOG - set to true
  • HTTP_SYSLOG_PATH - optional, The path on the http server to receive syslog streams as http, defaults to /syslog

Note, the port is inherited from HTTP_PORT.

Syslog (TCP)

  • SYSLOG_TCP - set to true
  • SYSLOG_TCP_PORT - optional, defaults tcp 9002

Syslog (UDP)

  • SYSLOG_UDP - set to true
  • SYSLOG_UDP_PORT - optional, defaults to 9003

Syslog (TLS)

  • SYSLOG_TLS - set to true
  • SYSLOG_TLS_CERT_PEM - The PEM encoded certificate
  • SYSLOG_TLS_CA_PEM - The PEM encoded certificate authority (optional)
  • SYSLOG_TLS_KEY_PEM - The PEM encoded certificate key
  • SYSLOG_TLS_SERVER_NAME - The servername the TLS server should use for SNI
  • SYSLOG_TLS_PORT - optional, defaults to 9004

Akkeris Formatting (optional)

  • AKKERIS=true - for Akkeris formatting of output
  • ONLY_AKKERIS=true - Optional, ignore any other Kubernetes pods

Performance

The logtrain has been tested to be below 64MB (avg 59MB) and < 100m (5%) CPU for 52 pods on a node with 1500+ deployments being watched. For more pods per node or more deployments than the benchmark expect (and reset any limits/requests) for memory.

While targeting a 64MB top limit, logtrain should have a limit of 128MB.

Troubleshooting

Too many open files error

If you receive an error on startup with too many files open error message you'll need to increase the fs.inotify.max_user_instances and user.max_inotify_instances. These are generally set to 128 by default, depending how many pods are running this may be insufficient.

sysctl -w fs.inotify.max_user_instances=2048
sysctl -w user.max_inotify_instances=2048

Developing

Building Logtrain

go build -o logtrain github.com/akkeris/logtrain/cmd/logtrain

go build -o logtail github.com/akkeris/logtrain/cmd/logtail

Testing

go test -v .../.

(Note if you're using GoConvey its best to set the parallel packges to 1 via -packages 1)

Code Coverage

go test -coverprofile cover.out -v ./... && go tool cover -html=cover.out && rm cover.out