docker-logstash-kubernetes

Logstash container for pulling docker logs with kubernetes metadata support. Additionally logs are pulled from systemd journal too.

Logstash tails docker logs and extracts pod, container_name, namespace, etc. The way this works is very simple. Logstash looks at an event field which contains full path to kubelet created symlinks to docker container logs, and extracts useful information from a symlink name. No access to Kubernetes API is required.

Other outputs can be added in the future.

Requirements

You need to have kubelet process running on the host. Normally kubelet creates symlinks to container logs from /var/log/containers/ to /var/lib/docker/containers/. So for that you need to make sure that logstash has access to both directories.

For logstash to be able to pull logs from journal, you need to make sure that logstash can read /var/log/journal.

Also, logstash writes sincedb file to its home directory, which by default is /var/lib/logstash. If you don't want logstash to start reading docker or journal logs from the beginning after a restart, make sure you mount /var/lib/logstash somewhere on the host.

Configuration

As usual, configuration is passed through environment variables.

• LS_HEAP_SIZE - logstash JVM heap size. Defaults to 500m.
• LS_LOG_LEVEL - Logstash log level. Default: error.
• LS_PIPELINE_BATCH_SIZE - Size of batches the pipeline is to work in. Default: 125
• INPUT_JOURNALD - Enable logs ingestion from journald. Default: true.
• INPUT_KUBERNETES_AUDIT - Enable kubernetes audit logs ingestion. Default: true.
• OUTPUT_ELASTICSEARCH - Enable logs output to ElasticSearch. Default true.
• ELASTICSEARCH_FLUSH_SIZE - Bulk index flush size. Default: 500
• ELASTICSEARCH_IDLE_FLUSH_TIME - Bulk index idle flush time in seconds. Default: 1
• ELASTICSEARCH_HOST - ElasticSearch host, can be comma separated. Default: 127.0.0.1:9200.
• ELASTICSEARCH_SSL_ENABLED - Elasticsearch SSL flag. Default: false.
• ELASTICSEARCH_CA_CERTIFICATE_PATH - The path to the .pem file that contains the Certificate Authority’s certificate.
• ELASTICSEARCH_CERTIFICATE_VERIFICATION - Elasticsearch SSL cerificate verification. Default: true.
• ELASTICSEARCH_USER - Elasticseach basic auth username. Default: "".
• ELASTICSEARCH_PASSWORD - Elasticsarch basic auth password. Default: "".
• ELASTICSEARCH_INDEX_SUFFIX - ElasticSearch index suffix. Default: "".
• LOGSTASH_ARGS - Sets additional logstash command line arguments.

Running

$ docker run -ti --rm \
    -v /var/lib/logstash-kubernetes:/var/lib/logstash:z \
    -v /var/log/journal:/var/log/journal:ro \
    -v /var/lib/docker/containers:/var/lib/docker/containers:ro \
    -v /var/log/containers:/var/log/containers:ro \
    -e ELASTICSEARCH_HOST=my-est-host.local:9200 \
    quay.io/ukhomeofficedigital/logstash-kubernetes:v0.4.0